Boston Spa Parish Council Boston Spa Hydro Power Project Boston Spa Hydro Feasibility Study Report Issue | 10 November 2014 This report takes into account the particular instructions and requirements of our client. It is not intended for and should not be relied upon by any third party and no responsibility is undertaken to any third party. Job number 234641-00 Ove Arup & Partners Ltd Admiral House Rose Wharf 78 East Street Leeds LS9 8EE United Kingdom www.arup.com
Transcript
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
Issue | 10 November 2014
This report takes into account the particular instructions and requirements of our client.
It is not intended for and should not be relied upon by any third party and no responsibility is undertaken to any third party. Job number 234641-00
Ove Arup & Partners Ltd Admiral House Rose Wharf 78 East Street Leeds LS9 8EE United Kingdom www.arup.com
2 Local Community Support and Stakeholder Engagement 6
3 Local Community Benefits 10
3.1 Sustainability 11 3.2 Income 12 3.3 Investment 12 3.4 Personal Involvement and Income 12 3.5 Local Power Use 13 3.6 Education 13 3.7 Neighbouring Parishes 13
4 Site, Operation and Technology 14
4.1 Data resources 14 4.2 Site Evaluation 19 4.3 Turbine Options 25 4.4 Proposed Solution 27
Executive Summary Boston Spa Parish Council commissioned Arup to complete a feasibility study into the possibility of installing hydro generation equipment on the weir at Boston Spa. The study includes assessment of technological, environmental, social and financial considerations for this site.
The stated intention is to provide a stream of income for use on projects that benefit the local community by the generation of renewable energy. This sits within the local Neighbourhood Plan and would contribute to the objectives laid out in that plan for the local area.
The Parish Council do not anticipate owning and operating the turbine directly and seek to establish a separate legal entity for the purpose of managing the design, construction and operation of the hydro power facility. The most common form of structure employed by small community hydro schemes is the Industrial Providential Society for the Benefit of the Community (now known as a Registered Society). Further investigation is required to confirm the suitability of this entity for the requirements of a Parish Council.
The fundraising require for this scheme is likely to compose of a mixture of borrowing and community shares. The Parish Council have already identified potential lenders.
The key stakeholders are: the landowner and scheme proposers Boston Spa Parish Council; the residents of Boston Spa Parish; local Angling Clubs; the local historical society; residents of Thorp Arch Parish on the opposite bank with visibility of the site; other amenity users.
The support of the community has been gauged by surveys and drop in sessions with plans and visualisations on display. The majority of respondents were positive about the scheme and keen to see it developed provided that it was done with sensitivity for the location. There are concerns from the local Angling Club about the impact on their use of the river and from residents of properties on the opposite bank about the potential noise and visual intrusion. All of these can be managed by careful selection of equipment and design of the scheme to minimise the impact on others.
The net head over the weir is 1.8-1.9m which means that it is right at the bottom end of the range for Kaplan or axial flow devices. Many suppliers were unable to offer a turbine for this installation although a couple of options were found. The most common turbine type available for this head is an Archimedes screw. The screw turbine has lower screening requirements and is mechanically simpler than the other options. It is likely that this would be the best option for this site.
Feedback has been sought from the local planning authority Leeds City Council who have indicated a number of issues that would need to be resolved for the scheme to progress. It is expected that all these can be achieved and the planning application would be acceptable.
The Environment Agency pre-application was reviewed and comments received. A number of requests have been made by the fisheries team which appear to be beyond the normal requirements for hydro power, these require further review to resolve. It is believed that a compromise could be reached which would allow this scheme to meet with the approval of the Environment Agency.
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There is the potential for a net income to Boston Spa Parish Council which would be committed to use on projects which benefit the local community. There remain some issues and risks which require resolving but the scheme appears to offer a viable investment that could be pursued.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
1 Introduction This report describes the feasibility study for a hydro power scheme at Boston Spa weir on the River Wharfe. The proposed scheme involves capturing flows on the right (South) bank of the river.
The report was commissioned by Boston Spa Parish Council as part of the development of a Neighbourhood Plan seeking to identify and work towards goals important to the local community.
The funding for this study was obtained through a Stage 1 grant from the Government funded Waste and Resources Action Programme (WRAP) as part of the Rural Community Energy Fund (RCEF). This scheme provides assistance to community groups for investment in the feasibility and pre-planning stages of a renewable energy project. Additional guidance and assistance was provided in the arrangement of this study.
The idea behind the scheme came from Boston Spa Parish Council and was tested locally in a Parish Survey. The majority of respondents were in favour of considering hydro power and the report commissioned to consider the options.
The key requirements at this early feasibility stage are as follows:
x Consultation with stakeholders
x Technical feasibility and design options
x Energy and revenue estimates
x Construction and maintenance cost estimation
x Environmental and ecological impact
x Flood impact and hydrology
x Social and amenity impact
x Funding sources
x Recommendations and next steps
As a community scheme engagement with the local residents and users of the riverside amenity was a critical component of the feasibility study. In fact the communication with residents began months before the feasibility study was undertaken.
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2 Local Community Support and Stakeholder Engagement
The following local stakeholders have been identified. Various contacts have been made and described below. Further engagement will be required as the scheme progresses.
2.1.1 Boston Spa Parishioners The following meetings, consultations and events have taken place so far:
2.1.1.1 Parish Council Meetings Updates on progress of the study are given at monthly meetings. Minutes of these meetings are publicly available on the Council’s website.
2.1.1.2 Annual Parish Meeting In May 2014 a member of the Parish Council gave a report on progress to date at the Annual Parish Meeting. It was stated that a survey of river flow showed that there is sufficient flow for a 100kW scheme and that such a scheme could yield £100,000/year. However the total scheme would cost in the order of £1,000,000 so loan repayments and maintenance cost would have a significant impact on income. For these reasons it was stated that the final report would include a robust financial model.
Following the meeting, a local journalist with the Ripon Gazette provided an article summarising the plan for a potential hydro turbine published online on 25th May 2014 (online Ripon Gazette).
2.1.1.3 Neighbourhood Plan Initial consultation on the inclusion of a hydro turbine in the Neighbourhood Plan, was provided in a questionnaire sent to all parishioners. In July 2013 results of the Neighbourhood Plan survey showed that 67% of those responding to the survey would support a mini hydro scheme on the weir.
The main public consultation so far for the turbine was carried out in conjunction with the Boston Spa Neighbourhood Plan.
This meeting was publicised by the following methods:
x Letters issued to all parishioners, Thorp Arch Parish Council, residents of Thorp Arch Mill
x Posters and fliers on noticeboards in the village
x An article in the Ripon Gazette, published online on 3rd July 2014 (online Ripon Gazette) following on from the piece on 25th May.
Fifty one comment sheets were completed by visitors to the consultation sessions, some left comments, others simply stated their support or objection to the scheme.The following feedback was received:
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
x 32 people were in favour, 14 not sure, 2 not in favour and 3 abstained.
x 24 people indicated they would be interested in investing the scheme.
A full list of all comments can be found in Appendix CC7, with a set of responses drafted for issue on the Neighbourhood Plan website.
Some of the boards on display and the feedback from attendees at this event are included in Appendix C7. The list below highlights the key themes raised:
x Noise impact
x Visual impact
x Disruption of flows
x Who benefits?
x Impact on anglers and other stakeholders
x Financial returns
x Impact on the heritage of the site
2.1.2 Residents of Thorp Arch Mill The properties that form Thorp Arch Mill are the main group of properties (along with a small number on Mill Lane) for whom a hydro turbine on the weir would be visible.
The Neighbourhood Plan community event includes a visualisation of the turbine from the area of these properties to help them to understand the impact it might have. Invitation letters were sent out to all residents and several attended over the two days. Feedback indicated most were not opposed to the scheme in principle but expressed understandable concern about potential noise and visual impact. Overall most residents from the Mill and from Mill Lane preferred Location 4 where the turbine was mostly concealed behind the fish pass.
2.1.3 Thorp Arch Parish Council The Parish boundary runs along the mid-point of the River Wharfe and the North bank of the River is within the Thorp Arch Parish Council (TAPC) area.
In December 2013 BSPC wrote to TAPC informing them that they had received funding to undertake a feasibility study to assess the suitability of the weir in Boston Spa for a mini hydro scheme. TAPC have continued to ask for more information, the response from BSPC is that we are awaiting the results of the feasibility study.
Thorp Arch parish Council and residents were invited to the drop in sessions and several residents both attended and provided feedback as recorded in Appendix C7.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
2.1.4 Angling Club There are two angling clubs with an interest in the local area: the Boston Spa Angling Club, and Bradford Number One Angling Association. A contact from the Boston Spa Angling Club met with the Ecologist at the weir site and provided initial thoughts on the following areas relevant to the turbine development:
x Fish species
x Fish behaviour and locations
x Habitats and river features relevant to fish
x Fish pass operation
x Impacts of hydro turbines on fish and angling
x Access to the river
The Angling Club is not in favour of the installation of a hydro turbine on the weir at Boston Spa. The reasoning given is that fish can be damaged by turbines and that changing flow patterns can affect weir pools and spawning grounds, thus impacting on fish populations and angling amenity.
This is a common issue with hydro power schemes and needs to be addressed during detailed design so that the angling amenity is preserved.
The consultations with Boston Spa Angling Club are expected to continue as the scheme develops. Attempts have also been made to contact Bradford Number One Angling Association. To date no responses have been received to emails issued requesting feedback.
2.1.5 Canoe Club The configuration of the inlet and outlet channels of any turbine will have bar screens which prevent any persons in the river entering the turbine. Canoeists interests are not primarily around safety but relating to the impediment to recreation that weirs and the flow changes hydro turbines create can bring.
The weir itself includes a vertical drop and is not suitable for canoes to cross, there is no alternative canoe passage.
At Boston Spa a fish pass is already in place and the limited space available for the turbine is unlikely to make inclusion of a canoe pass practical. In addition there is very rarely any additional funding source available to support the desires of improved watersports facilities.
Email correspondence with local representatives of Canoe England who know the location provided the following feedback:
x Canoeists paddle the Wharfe regularly but the weir is vertical and un-shootable, as is the fish pass.
x They portage, [land and carry their boats] in the public park around the right hand side of the fish pass.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
x They land as close to the weir as possible and launch below as close as possible.
x Their request would be that there is provision to get out of the water and back into it with craft with the minimum of fuss
Further consultation would be recommended to determine how frequently this stretch of river is paddled and any impact the turbine would have on the amenity of the area.
2.1.6 Heritage Groups Representatives of the Boston Spa Archaeology and Heritage Group (BSAHG) have been involved in the initial discussions regarding options for the turbine locations. Two significant concerns were raised:
x Preservation of Dam House
x Preservation of Holgate Lane
The Boston Spa Heritage List is included in Appendix CC5 which contains details of these and other local heritage interest points. Discussion of the consideration required for the two heritage assets is considered below.
2.1.6.1 Dam House The Dam House is not a Listed Structure, however it does have local heritage importance and interest. The description of Dam House from the report “Deep Dale to Holgate. A Heritage Survey”, 2009, and the Information Board at bottom of Holgate Lane provides the following information:
“Remains of Dam House water basement. Rare example of industrial archaeology and a valuable part of early Boston Spa history. Uncertain date of origin. Has part filled-in ‘leat’ now visible as shallow depression, arched culvert into building and remains of two stone tanks, possibly used for flax-retting in the C18-19. High quality magnesian limestone ashlar masonry and hand carved water management features. Upper storey (perhaps storeroom or dwelling and later reputedly the ferryman’s or river keeper’s house) was demolished mid C20th. Water basement suffered river damage since.”
The impact on Dam House has been the source of some debate during the feasibility study. While on the one hand all involved would like to preserve and celebrate the industrial heritage of the village, the position of the structure significantly compromises hydro turbine options. Two of the proposed options could avoid impact on Dam House (Locations 1& 3), the other two options would require at least partial removal or modification of the structure (locations 2&4).
As outlined in Section 4, Location 1 has been excluded on the basis of visual impact and construction risk. Location 3 was rejected in favour of Location 2 or 4 by most respondents at the public consultation; mostly due to a greater visual impact from the opposite bank, using a larger area of the BSPC riverside clearing, and additional construction costs.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
If the turbine scheme is to proceed, agreement must be reached on what is done with Dam House. Discussion between BSPC, BSAHG, the EA and the LCC Planning department will be require to determine the solution.
2.1.6.2 Holgate Lane The access route to the site is via Holgate Lane. This old lane is full of character and any changes to the route for permanent vehicle access would affect the appeal of the historic lane. The report “Deep Dale to Holgate. A Heritage Survey”, 2009, commissioned by BSPC describes the lane as follows:
Holgate Lane, like Deep Dale valley, would have been created by an ice-age melt-water channel through the magnesian limestone. Prehistoric flint found. Ancient ‘hollow-way’ and part of a medieval route from Clifford to Thorp Arch, which continued via a ford before the bridge to Thorp Arch existed. It is now a bridle way. Remains of old edging wall near lower end (as seen on old photographs). Interesting part-eroded Cadeby limestone algal reef dome with glacial till above it three quarters down lane on left.
The intention of the scheme is to have little or no longer term impact on the appearance and use of Holgate Lane. In the short term the track will require modification to allow large heavy vehicles to access the riverbank. This can be temporary changes which are removed following completion of the work.
The proposed grid connection, as outlined in a Budget Quotation by Northern Power Grid, includes a high voltage (11kV) cable buried beneath the bridleway as the connection to the turbine site.
3 Local Community Benefits The main public consultation to date was organised to coincide with the presentation of the Boston Spa Neighbourhood Plan to local residents.
Neighbourhood Plans have stemmed from changes in Government Policy which devolve some decisions from Local Authorities and Councils to smaller groups and local stakeholders. This empowers local communities to influence policy that affects their homes and livelihoods.
Residents, business interests, landowners, support services and voluntary organisations of Boston Spa have the opportunity to significantly influence the Leeds Plan via the formulation of a Neighbourhood Plan covering the civil parish of Boston Spa.
Boston Spa Vision:
To be an identifiable village community which has a proud sense of history and purpose; which is largely self-sufficient and which is an attractive place to live, work in and to visit.
The Neighbourhood Plan Steering Group have set out this vision for Boston Spa and consulted with the residents in a variety of ways to develop that vision into a
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
comprehensive set of goals for the Neighbourhood Plan. At the time of writing the full Plan has not yet been published but the initial list of criteria is shown below:
1. Seek to retain the character, scale and quality of the built environment
2. Limit the scale of housing development whilst addressing a shortage of affordable homes both to buy and rent. It will seek to prevent building beyond the existing built up areas
3. Encourage a vibrant retail and service sector
4. Increase green spaces and make them more accessible for the benefit of all age groups
5. Promote healthy and active lifestyles by encouraging sporting and other physical activities such as walking and cycling whilst supporting wide ranging social activities
6. Assess safety for pedestrians and cyclists and evaluate cycle route/ lanes
7. Ensure suitable provision is made for high quality education and healthcare allowing for predicted population growth
8. Ensure traffic speed is controlled and car parking in the village is adequate for its needs
9. Promote Boston Spa as a place to visit and to enjoy its amenities with the riverside given greater prominence
10. The Plan will be designed to benefit all the village residents from the young to the elderly
11. It will respect the need for sustainability, the protection of the countryside and wildlife habitat and take positive actions to reduce our reliance on fossil fuels
As the turbine forms a component of this plan, benefiting the community is an integral part of the idea behind the scheme. A number of different avenues are available and consider a little further below.
3.1 Sustainability Item 11 states the aim to contribute to the sustainability of local activities. Renewable energy, if developed in appropriate locations, is an important part of the package of options that contribute to sustainability within society. Local communities contributing towards the energy they use by generation of their own renewable energy is a small scale but nonetheless essential component of the drive to a lower carbon economy.
The wider definitions of sustainability include economic and social concerns which the turbine may also contribute to by provision of resources to use for other schemes. If the scheme also contributes to the local economy by enhancing amenity and awareness of the attractive riverside location then there are further contributions to the overall sustainability of the investment which may result.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
3.2 Income In addition to being considered as a direct result of Item 11, the intention of BSPC is that any income generated by a turbine installation would be used to fund schemes which directly contribute to achievement of some of the other goals. The potential for establishing a suitable legal entity to manage the turbine with the sole purpose of providing income for investments driven by the Neighbourhood Plan is being considered to facilitate this direction of resources.
In this way, the revenue could be used to fund local projects and initiatives that are in line with the goals agreed during consultation for this plan.
3.3 Investment During development of a hydro turbine scheme it would be possible to make small changes to the area around the turbine to improve access to the river for walkers, anglers and canoeists. Feedback from local angling and canoeing groups identified access to the river via the steep banks as a limitation to their ability to enjoy the river amenity.
Promoting these activities and designing a turbine scheme to enhance, not detract from, the enjoyment of these two groups as well as walkers and cyclists could be integral to the turbine project and widen the benefit beyond the contribution to finances and sustainability. Items 4, 5, 9 and 10 are all related to how people enjoy and use the space around them and developing the turbine provides an opportunity for change that could help achieve those goals too.
3.4 Personal Involvement and Income One member of the community already identified himself as having experience in renewable energy schemes and has offered assistance. There may be the opportunity for others to use their skills in finance, coordination, design, fundraising or management to get involved and develop the project. There may also be the potential for an operational role once the turbine is installed. BSPC aim to pursue all relevant opportunities for local involvement.
The inclusion of community shares in any funding options would allow others to invest in renewable technology on their doorstep and receive a share in the revenue received.
3.4.1 Management Whatever form of entity is used for the delivery and on-going operation of the hydro turbine there will be a requirement for administrative, financial and governance roles. These are likely to be part time and may be paid or voluntary depending on the structure selected. The Parish Council are committed to using the skills of local individuals and companies to assist where possible.
3.4.2 Maintenance Some on-going maintenance tasks required for the turbine can only be carried out by specialist suppliers. There are other tasks such as screen cleaning, lubrication
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
and day to day management which could be contracted to a local company. Options for this will be explored further as the project progresses.
3.5 Local Power Use The revenue estimates assume that all power is sold to the grid. It may be possible to consider local energy sales by a process called Sleeving or Third Party Netting.
This involves a tripartite arrangements including electricity supplier, generator and large end user. The user buys output direct from generator under a Power Purchase Agreement which is then “sleeved” / on-sold via an electricity supplier under electricity supply agreement(s). Some energy suppliers offer a service to assist with arranging sleeving agreements including introductions to potential energy users.1 BSPC are investigating local opportunities to offer renewable energy to large energy users.
These are legal agreements and not always cheap and simple to arrange but may allow BSPC to sell the energy produced for a slightly higher rate than the guaranteed export tariff. It would also allow the energy user to buy renewable energy at a rate potentially lower than their standard energy purchase price so the benefits are shared.
3.6 Education As with most renewable schemes there is an opportunity to engage with local schools and community groups to provide an educational resource. Displays, visits and presentations are all possible avenues for using a local project to make contact with different people and promote sustainability and responsible use of resources.
3.7 Neighbouring Parishes Up to this point the project has been driven and coordinated by BSPC as the landowner of the potential hydro turbine site. The Thorp Arch Mill properties and other residences on Mill Lane from where the turbine would be visible are situated within TAPC boundary.
As stakeholders both TAPC and the residents of that parish have been consulted. General feeling is that a turbine is welcome, however those closest to the weir have concerns regarding visual appearance and noise.
4 Site, Operation and Technology To determine the right solution for Boston Spa Weir the information available bout the river, the site and the technology available must be reviewed.
4.1 Data resources Data obtained and utilised in assessment:
x Flow data
x Head data
x Turbine Types
x Turbine efficiency
x Electrical Connections
x Fish Pass design documentation
x Land Registry
4.1.1 Flow Data The flow in the River Wharfe is recorded at a number of EA gauging stations. The closest stations to Boston Spa are:
x Flint Mill Weir (Gauge 27002) approximately 2.2km upstream
x Tadcaster (Gauge 27089) approximately 8.2km downstream
Average daily flow rate data from 1966 to 2011 is available for Flint Mill Weir. The data for Tadcaster is likely to be less representative of this site due to the increased distance and the potential for further inflows between the two points. For this reason only the Flint Mill data has been used in the assessment of flows.
The estimated energy generation is based on data from over 50 years of measured flow data from Flint Mill Weir which should provide a reasonable estimate.
The Environmental Agency guidance for the development of hydropower schemes advocates an operating envelope within the following parameters:
x Maximum design flow equal to the mean flow, Qmean
x Hands-Off Flow (HOF), a condition which restricts abstraction, equal to the flow exceeded for 95% of the year Q95. The turbine(s) would have to stop operating at flows below Q95 plus the turbine start up flow.
Table 1 below summarises the flow characteristics of the River Wharf during the measured period.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
This data indicates the likelihood of flow volumes received based purely on historical data, made up from 56 years of measurements.
One of the key concerns with hydro power is annual variation, and the associated increases or decreases associated with the flow regime. Using the long term average can lead people to expect consistent returns each year when in fact there is a normal variation in annual flows and yearly power output will not be a consistent value.
To try to give some clarity on the sort of variation experienced at this site we have considered the range of annual flows seen as well as the overall long term pattern.
Within the period measured the annual flow varied quite significantly, with some very wet years and a wide range of lower flows. Figure 1 shows the annual average flows throughout the measured period. These are taken from the mean flow each year, then arranged from highest (wettest) to lowest (driest). When plotted in this form the data it is possible to see that even accounting for seasonal highs and lows, some years a much wetter or dryer than the long term average.
The long term average flow is Qmean = 17.52m3/s. The two red lines show that the top 10% of the data has an average flow over 22m3/s and the bottom 10% of the data has an average flow below 13m3/s.
Figure 1: Flint Mill Average Annual Flow
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
To give an idea of the impact of the variability of flows on a hydro turbine output a consistently wet year with approximately the 10th percentile average flow (1986) and a consistently dry year with approximately the 90th percentile flow (1989) were selected for comparison.
The curves in Figure 2 indicate the flow duration curves within those years and show the effect on operation of an example turbine due to changes in the flow regime.
Again, the data is organised not in time order, but from the highest flows to the lowest flows recorded during the year. This allows the reader to see what proportion of the year the flow is greater than a certain value e.g. Q10 is the flow that the river exceeds on average for 10% of the year. This is shown on the blue line at 10% exceedance and has the value 41.50m3/s (See Table 1 for further points on the average flow duration curve)
The years shown were fairly consistently wetter or dryer than average. There are other years which show periods of very high flows, and periods of very low flows. There is an element of risk in all estimates of energy production based on historical data, it is impossible to predict what the river flows will be during the life of a turbine.
To assist with understanding of that risk, financial return estimates will be made using the average flows, and annual income data also estimated on the representative wet and dry years to allow comparison. This provides a sensitivity analysis to indicate what effect the variation in flows have on the generation, revenue and therefore financial viability of the scheme.
Figure 2: Flow Duration Curve using average and consistently dry and wet years
In the dry year, the example turbine operates at full capacity less than 50% of the time, whereas in the consistently wet year it could operate at full capacity for over 70% of the time.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
Energy calculations for payback will be based on long term trends as over time the wet and dry years would average out. There will however always be short term variation which can affect revenues in a positive or negative fashion.
No allowance has been made for increasing flows or changes in river characteristics due to climate change.
4.1.2 Head Data The difference in water level between the upstream and downstream channels is the net head and determines the energy available for recovery. The net head estimates have been made by hydraulic calculation of discharges over the weir under the range of flow conditions. This was done and approved under the fish pass contract for the Environment Agency and has therefore not been repeated.
No additional surveys or measurements have been taken as spot samples will provide limited information. The dry head of the weir varies along its length, depending on the profile of the downstream river channel at its foot and is not used in calculating the energy available. The levels used for calculation of the energy available are the differences in water level upstream and downstream at varying flows as it is the movement of water that drives the turbine.
A net head of 1.89-1.97m is available between the Q95 hands off flow and the Q10 flow at which the fish pass is no longer useable for migration. At this stage no assessment has been made of the changes in level at flows higher than Q10. The calculation on which the fish pass design is based indicate that at Q95 the net head is 1.97m and at Q10 it is 1.89m. Allowing for the additional friction losses of a turbine inlet and outlet channel the net head has been assumed as 1.8m across the whole range of flows.
Although on some weirs the net head varies significantly even between Q95 and Q10, at this location the variation is quite small and therefore it is assumed for calculation that the net head remains consistent across the full operating range of the turbine.
4.1.3 Turbine Types Turbine quotations have been sought from a variety of supplier. Each was provided with the head and flow data summary and a description of the location. Due to the low head available a number of suppliers have had to decline to offer a turbine.
Two Archimedes screw suppliers and two Kaplan type turbine suppliers have offered options for this location.
4.1.4 Turbine Efficiency The data used to calculate energy production for each type of turbine relies on supplier efficiency data for the particular turbine type. Data is available for the Archimedes screw turbines and one of the Kaplan options but the third supplier
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4.1.5 Fish Pass Design The fish pass on the weir was installed by the Environment Agency in 2010. The Parish Council were granted permission by the EA to use design information from the fish pass scheme in the hydro turbine feasibility and design process. The terms and conditions of use and the correspondence on this issue are included in Appendix EC3. The following documents were included in that permission:
Table 2: Environment Agency Documents
Drawings
211614 Topo Survey
211614_001_AB_Boston Spa Fish Pass General Arrangement
211614_002_AB_Boston Spa Fish Pass General Concrete Detail
211614_004_AB_Boston Spa Fish Pass Hardware Details
211614_005_AB_Boston Spa Fish Pass Upstream Security Screen Details
211614_006_AB_Boston Spa Fish Pass Debris Boom Details
211614_007_AB_Boston Spa Fish Pass Cover Detail
211614_008_AB_Boston Spa Fish Pass Cross Sections
Documents
0011Assessment of design water levels Final version
Boston Spa Calcs 1A (2)
Spreadsheets
Water levels spreadsheet
Weir calculator spreadsheet (unverified)
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
4.1.6 Land Registry Land Registry enquiries have been made for both banks of the river to clarify ownership and identify stakeholders. Details are included in Section 5.3.
4.2 Site Evaluation The following table outlines the comparison between the different options for locating the turbine(s). These are qualitative considerations which affect the turbine position, selection and overall design.
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Sum
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Ass
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Loc
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Loc
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Loc
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Loc
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Arc
him
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Scr
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A –
30k
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Arc
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Scr
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B –
100
kW
Arc
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100
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B –
100
kW K
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A
– 1
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B
– 1
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urbi
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100k
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1 En
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t A
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viro
nmen
t A
genc
y.
Add
ition
al
cond
ition
s may
be
appl
ied
to th
e de
sign
.
The
Envi
ronm
ent
Age
ncy
wou
ld n
ot
supp
ort a
turb
ine
in
this
pos
ition
as i
t is
not o
ptim
al fo
r fis
h pa
ss o
pera
tion.
Th
e En
viro
nmen
t A
genc
y w
ould
not
su
ppor
t a tu
rbin
e in
th
is p
ositi
on a
s it i
s no
t opt
imal
for f
ish
pass
ope
ratio
n.
1A
Pre-
plan
ning
co
nsul
tatio
n co
mm
ents
This
was
the
pref
erre
d op
tion
for
the
plan
ners
.
Publ
ic c
onsu
ltatio
n in
dica
ted
this
was
no
t a p
refe
rred
op
tion.
The
or
ient
atio
n of
the
turb
ine
faci
ng
dire
ctly
tow
ards
Th
orp
Arc
h M
ill
was
dee
med
less
ac
cept
able
than
op
tions
whe
re th
e tu
rbin
e is
ang
le
away
from
the
Mill
.
Th
is w
as n
ot a
pr
efer
red
optio
n fo
r th
e pl
anne
rs.
Pref
erre
d by
mos
t re
spon
dent
s at
publ
ic c
onsu
ltatio
n (w
hen
com
pare
d to
O
ptio
n 3)
due
to
smal
ler f
ootp
rint a
nd
orie
ntat
ion
of th
e tu
rbin
e.
1B
Am
enity
&
Aes
thet
ics
Maj
or v
isua
l in
trusi
on fr
om b
oth
bank
s. C
lose
st
optio
n to
resi
dent
ial
prop
ertie
s.
Fenc
ing
to p
reve
nt
acce
ss m
ay a
dd to
vi
sual
intru
sion
.
Min
imal
impa
ct o
n cu
rren
t foo
tpat
h.
Smal
ler t
urbi
ne a
nd
build
ing.
Mor
e ac
cess
ible
for v
isito
r vi
ewin
g.
Bui
ldin
g an
d tu
rbin
e in
terf
eres
with
vie
ws
from
sout
h ba
nk
look
ing
acro
ss fi
sh
pass
and
wei
r.
Still
vis
ually
in
trusi
ve fr
om
oppo
site
ban
k bu
t im
pact
redu
ced.
Mor
e ac
cess
ible
for
visi
tor v
iew
ing.
Bui
ldin
g an
d tu
rbin
e in
terf
eres
with
vie
ws
from
sout
h ba
nk
look
ing
acro
ss fi
sh
pass
and
wei
r.
Still
vis
ually
in
trusi
ve fr
om
oppo
site
ban
k bu
t im
pact
redu
ced
(v
Loca
tion
1).
Bui
ldin
g tu
cked
ba
ck in
to b
ank
redu
ces v
isua
l in
trusi
on.
Mor
e ac
cess
ible
for
visi
tor v
iew
ing.
Bui
ldin
g an
d tu
rbin
e im
pact
on
curr
ent
foot
path
. Div
ersi
on
requ
ired.
Bui
ldin
g tu
cked
ba
ck in
to b
ank
redu
ces v
isua
l in
trusi
on.
Mor
e ac
cess
ible
for
visi
tor v
iew
ing.
Bui
ldin
g an
d tu
rbin
e im
pact
on
curr
ent
foot
path
. Div
ersi
on
requ
ired.
Bui
ldin
g tu
cked
ba
ck in
to b
ank
redu
ces v
isua
l in
trusi
on.
Shor
test
cha
nnel
s (of
ba
nk o
ptio
ns).
Min
imal
impa
ct o
n cu
rren
t foo
tpat
h.
Can
inte
grat
e w
ith
Dam
Hou
se a
nd a
dd
to a
esth
etic
s. Sy
nerg
ies w
ith
prev
ious
use
of
wat
er p
ower
at t
his
site
.
Bui
ldin
g tu
cked
ba
ck in
to b
ank
redu
ces v
isua
l in
trusi
on.
Shor
test
cha
nnel
s (of
ba
nk o
ptio
ns).
Min
imal
impa
ct o
n cu
rren
t foo
tpat
h.
Can
inte
grat
e w
ith
Dam
Hou
se a
nd a
dd
to a
esth
etic
s. Sy
nerg
ies w
ith
prev
ious
use
of
wat
er p
ower
at t
his
site
.
Will
not
off
er si
ngle
tu
rbin
e so
twin
tu
rbin
e m
ay b
e la
rges
t bui
ldin
g of
al
l opt
ions
.
Dra
win
gs in
dica
te a
ve
ry d
eep
exca
vatio
n re
quire
d fo
r dra
ft tu
be.
Bos
ton
Spa
Par
ish
Cou
ncil
Bos
ton
Spa
Hyd
ro P
ower
Pro
ject
Bos
ton
Spa
Hyd
ro F
easi
bilit
y S
tudy
Rep
ort
| Is
sue
| 10
Nov
embe
r 201
4
J:\2
3000
0\23
4641
-00\
0 A
RU
P\0
-04
ME
ICA\
0-04
-08
RE
POR
TS\IS
SUE
\201
4-11
-10
FEA
SIBI
LITY
RE
POR
T - I
SSU
E.D
OC
X
Page
21
L
ocat
ion
Ass
essm
ent
Cri
teri
a
Loc
atio
n 1
Loc
atio
n 2
Loc
atio
n 3
Loc
atio
n 4
Arc
him
edes
Scr
ew
A –
30k
W
Arc
him
edes
Scr
ew
B –
100
kW
Arc
him
edes
Scr
ew
A –
100
kW
Arc
him
edes
Scr
ew
B –
100
kW K
apla
n Pi
t Tur
bine
A
– 1
00kW
A
rchi
med
es S
crew
B
– 1
00kW
Kap
lan
Pit T
urbi
ne
C -
100k
W A
xial
Fl
ow T
urbi
ne
1C
Impa
ct o
n he
ritag
e si
te
No
impa
ct o
n D
am
Hou
se.
Loss
of p
art o
f the
w
eir s
truct
ure.
Perm
anen
t dam
age
to th
e D
am H
ouse
si
te c
an b
e m
itiga
ted.
Ris
k of
dam
age
durin
g co
nstru
ctio
n.
Vie
ws o
f the
Dam
H
ouse
par
tially
ob
scur
ed b
y th
e ne
w
stru
ctur
e.
Perm
anen
t los
s of a
t le
ast p
art o
f the
Dam
H
ouse
(1 A
rch)
.
Ris
k of
furth
er
dam
age
durin
g co
nstru
ctio
n.
Rem
aini
ng p
arts
of
the
Dam
Hou
se n
ot
likel
y to
be
visi
ble.
Smal
l gap
may
ac
cum
ulat
e de
bris
/litte
r.
Perm
anen
t im
pact
on
her
itage
site
. D
epth
of c
hann
el
may
aff
ect s
tabi
lity
of st
ruct
ure.
Ris
k of
dam
age
durin
g co
nstru
ctio
n.
Vis
ibili
ty re
duce
d du
e to
turb
ine
&
cont
rol b
uild
ing.
A
cces
s to
Dam
H
ouse
redu
ced.
Will
cro
ss th
e bu
ried
culv
erts
and
mos
t lik
ely
dest
roy
or
dam
age
any
hist
oric
st
ruct
ures
.
Perm
anen
t im
pact
on
her
itage
site
. D
epth
of c
hann
el
may
aff
ect s
tabi
lity
of st
ruct
ure.
Ris
k of
dam
age
durin
g co
nstru
ctio
n.
Vis
ibili
ty re
duce
d du
e to
turb
ine
&
cont
rol b
uild
ing.
A
cces
s to
Dam
H
ouse
redu
ced.
Will
cro
ss th
e bu
ried
culv
erts
and
mos
t lik
ely
dest
roy
or
dam
age
any
hist
oric
st
ruct
ures
.
Arc
hes i
ncor
pora
ted
into
out
let s
truct
ure
with
re-b
uild
and
st
reng
then
ing.
Pr
eser
ved
and
used
.
Will
requ
ire re
mov
al
of b
urie
d cu
lver
ts
and
loss
of s
ome
feat
ures
such
as
floor
s.
Arc
hes i
ncor
pora
ted
into
out
let s
truct
ure
with
re-b
uild
and
st
reng
then
ing.
Pr
eser
ved
and
used
.
Will
requ
ire re
mov
al
of b
urie
d cu
lver
ts
and
loss
of s
ome
feat
ures
such
as
floor
s.
Prob
able
loss
of
who
le D
am H
ouse
st
ruct
ure.
1D
Floo
d R
isk
Obs
truct
ion
with
in
mai
n ch
anne
l of
river
. Hig
hest
floo
d ris
k op
tion.
Bui
ldin
g w
ithin
flo
od z
one
but l
ower
im
pact
than
stru
ctur
e on
the
wei
r.
Bui
ldin
g w
ithin
flo
od z
one
but l
ower
im
pact
than
stru
ctur
e on
the
wei
r. La
rger
bu
ildin
g th
an 2
A
Bui
ldin
g w
ithin
flo
od z
one
but l
ower
im
pact
than
stru
ctur
e on
the
wei
r.
Bui
ldin
g w
ithin
flo
od z
one
but l
ower
im
pact
than
stru
ctur
e on
the
wei
r.
Bui
ldin
g w
ithin
flo
od z
one
but l
ower
im
pact
than
stru
ctur
e on
the
wei
r.
Red
uced
impa
ct o
n dr
y ar
eas o
f cha
nnel
(b
etw
een
fish
pas &
ba
nk).
Bui
ldin
g w
ithin
flo
od z
one
but l
ower
im
pact
than
stru
ctur
e on
the
wei
r.
Red
uced
impa
ct o
n dr
y ar
eas o
f cha
nnel
(b
etw
een
fish
pas &
ba
nk).
Bui
ldin
g w
ithin
flo
od z
one
but l
ower
im
pact
than
stru
ctur
e on
the
wei
r.
Red
uced
impa
ct o
n dr
y ar
eas o
f cha
nnel
(b
etw
een
fish
pas &
ba
nk).
Bos
ton
Spa
Par
ish
Cou
ncil
Bos
ton
Spa
Hyd
ro P
ower
Pro
ject
Bos
ton
Spa
Hyd
ro F
easi
bilit
y S
tudy
Rep
ort
| Is
sue
| 10
Nov
embe
r 201
4
J:\2
3000
0\23
4641
-00\
0 A
RU
P\0
-04
ME
ICA\
0-04
-08
RE
POR
TS\IS
SUE
\201
4-11
-10
FEA
SIBI
LITY
RE
POR
T - I
SSU
E.D
OC
X
Page
22
L
ocat
ion
Ass
essm
ent
Cri
teri
a
Loc
atio
n 1
Loc
atio
n 2
Loc
atio
n 3
Loc
atio
n 4
Arc
him
edes
Scr
ew
A –
30k
W
Arc
him
edes
Scr
ew
B –
100
kW
Arc
him
edes
Scr
ew
A –
100
kW
Arc
him
edes
Scr
ew
B –
100
kW K
apla
n Pi
t Tur
bine
A
– 1
00kW
A
rchi
med
es S
crew
B
– 1
00kW
Kap
lan
Pit T
urbi
ne
C -
100k
W A
xial
Fl
ow T
urbi
ne
2 En
viro
nmen
t O
nly
affe
ctin
g bu
ilt
stru
ctur
es n
o lo
ng
term
hab
itat
dist
urba
nce
on o
r by
the
bank
.
Pote
ntia
l dam
age
to
trees
on
acce
ss
rout
e.
Hyd
rom
orph
olog
y of
the
river
mod
ified
by
cha
nges
to fl
ow
regi
me.
Slig
htly
le
sser
impa
ct th
an
loca
tions
on
the
bank
.
Perm
anen
t los
s of
trees
for i
nlet
ch
anne
l and
co
nstru
ctio
n - c
rane
ac
cess
to in
stal
l tu
rbin
e.
Low
er ri
sk o
f da
mag
e to
tree
s on
acce
ss ro
ute
due
to
smal
ler t
urbi
ne.
Hyd
rom
orph
olog
y of
the
river
mod
ified
by
cha
nges
to fl
ow
regi
me.
Gre
ater
per
man
ent
loss
of t
rees
for i
nlet
ch
anne
l and
co
nstru
ctio
n - c
rane
ac
cess
to in
stal
l tu
rbin
e.
Pote
ntia
l dam
age
to
trees
on
acce
ss
rout
e.
Hyd
rom
orph
olog
y of
the
river
mod
ified
by
cha
nges
to fl
ow
regi
me.
Tree
loss
sim
ilar t
o 2B
.
Gre
ater
vol
ume
of
exca
vatio
n &
co
nstru
ctio
n.
Pote
ntia
l dam
age
to
trees
on
the
acce
ss
rout
e.
Hyd
rom
orph
olog
y of
the
river
mod
ified
by
cha
nges
to fl
ow
regi
me.
Tree
loss
sim
ilar t
o 2B
.
Gre
ater
vol
ume
of
exca
vatio
n &
co
nstru
ctio
n.
Pote
ntia
l dam
age
to
trees
on
the
acce
ss
rout
e.
Hyd
rom
orph
olog
y of
the
river
mod
ified
by
cha
nges
to fl
ow
regi
me.
Perm
anen
t los
s of
trees
nea
r fis
hpas
s in
let.
Pote
ntia
l dam
age
to
trees
on
the
acce
ss
rout
e.
Hyd
rom
orph
olog
y of
the
river
mod
ified
by
cha
nges
to fl
ow
regi
me.
Perm
anen
t los
s of
trees
nea
r fis
hpas
s in
let.
Low
er ri
sk o
f da
mag
e to
tree
s on
acce
ss ro
ute
due
to
smal
ler t
urbi
ne.
Hyd
rom
orph
olog
y of
the
river
mod
ified
by
cha
nges
to fl
ow
regi
me.
Perm
anen
t los
s of
trees
nea
r fis
hpas
s in
let.
Low
er ri
sk o
f da
mag
e to
tree
s on
acce
ss ro
ute
due
to
smal
ler t
urbi
ne.
Hyd
rom
orph
olog
y of
the
river
mod
ified
by
cha
nges
to fl
ow
regi
me.
3 Ec
olog
y B
at ro
ost p
oten
tial i
n th
e tre
es o
n ac
cess
ro
ad.
Otte
r act
ivity
not
ed
by th
e w
eir.
Min
k pr
esen
t.
Him
alay
an B
alsa
m
pres
ent o
n th
e ba
nk
and
upst
ream
.
Bat
roos
t pot
entia
l in
Dam
Hou
se a
nd
seve
ral t
rees
nea
r w
eir a
nd o
n ac
cess
ro
ad.
Otte
r & M
ink
pres
ent.
Him
alay
an B
alsa
m
pres
ent.
Tree
s at r
isk
of
rem
oval
mos
tly
syca
mor
e (n
on-
nativ
e)
Bat
roos
t pot
entia
l in
Dam
Hou
se a
nd
seve
ral t
rees
nea
r w
eir a
nd o
n ac
cess
ro
ad.
Otte
r & M
ink
pres
ent.
Him
alay
an B
alsa
m
pres
ent.
Tree
s at r
isk
of
rem
oval
mos
tly
syca
mor
e (n
on-
nativ
e)
Bat
roos
t pot
entia
l in
Dam
Hou
se a
nd
seve
ral t
rees
nea
r w
eir a
nd o
n ac
cess
ro
ad.
Otte
r & M
ink
pres
ent.
Him
alay
an B
alsa
m
pres
ent.
Tree
s at r
isk
of
rem
oval
mos
tly
syca
mor
e (n
on-
nativ
e)
Bat
roos
t pot
entia
l in
Dam
Hou
se a
nd
seve
ral t
rees
nea
r w
eir a
nd o
n ac
cess
ro
ad.
Otte
r & M
ink
pres
ent.
Him
alay
an B
alsa
m
pres
ent.
Tree
s at r
isk
of
rem
oval
mos
tly
syca
mor
e (n
on-
nativ
e)
Bat
roos
t pot
entia
l in
Dam
Hou
se a
nd
seve
ral t
rees
nea
r w
eir a
nd o
n ac
cess
ro
ad.
Otte
r & M
ink
pres
ent.
Him
alay
an B
alsa
m
pres
ent.
Tree
s at r
isk
of
rem
oval
mos
tly
syca
mor
e (n
on-
nativ
e)
Bat
roos
t pot
entia
l in
Dam
Hou
se a
nd
seve
ral t
rees
nea
r w
eir a
nd o
n ac
cess
ro
ad.
Otte
r & M
ink
pres
ent.
Him
alay
an B
alsa
m
pres
ent.
Tree
s at r
isk
of
rem
oval
mos
tly
syca
mor
e (n
on-
nativ
e)
Bat
roos
t pot
entia
l in
Dam
Hou
se a
nd
seve
ral t
rees
nea
r w
eir a
nd o
n ac
cess
ro
ad.
Otte
r & M
ink
pres
ent.
Him
alay
an B
alsa
m
pres
ent.
Tree
s at r
isk
of
rem
oval
mos
tly
syca
mor
e (n
on-
nativ
e)
4 C
ivil
Elem
ents
Sh
ort i
nlet
and
out
let
chan
nels
. Rel
ativ
ely
smal
l foo
tprin
t.
May
be
able
to u
se
parts
of e
xist
ing
stru
ctur
e to
supp
ort
the
turb
ine
civi
l co
nstru
ctio
n
Long
er in
let
chan
nel.
Mod
ifica
tions
to th
e up
stre
am e
nd o
f the
fis
hpas
s and
elv
er
pass
exi
t.
Mak
es g
ood
use
of
the
fish
pass
st
ruct
ure
to su
ppor
t tu
rbin
e.
Long
er in
let
chan
nel.
Mod
ifica
tions
to th
e up
stre
am e
nd o
f the
fis
hpas
s and
elv
er
pass
exi
t.
Mak
es g
ood
use
of
the
fish
pass
st
ruct
ure
to su
ppor
t tu
rbin
e.
Ver
y lo
ng d
eep
inle
t ch
anne
l.
Larg
e fo
otpr
int.
Con
side
r cov
erin
g.
Inde
pend
ent o
f do
wns
tream
sect
ion
of fi
shpa
ss st
ruct
ure.
Ver
y lo
ng d
eep
inle
t ch
anne
l.
Cou
ld c
onsi
der l
arge
di
amet
er b
urie
d pi
pe
inle
t to
redu
ce
visi
ble
foot
prin
t and
po
tent
ially
cos
t.
Inde
pend
ent o
f do
wns
tream
sect
ion
of fi
shpa
ss st
ruct
ure.
Com
pact
, sho
rt ch
anne
ls, b
ut
requ
ires c
aref
ul
wor
k in
and
aro
und
hist
oric
stru
ctur
es.
Dee
p st
ruct
ure
adja
cent
to fi
sh p
ass.
Stab
ilisa
tion
requ
ired.
Turb
ine
inst
alla
tion
belo
w g
roun
d re
quire
s lar
ger
exca
vatio
n.
Dee
p st
ruct
ure
adja
cent
to fi
sh p
ass.
Stab
ilisa
tion
requ
ired.
Bos
ton
Spa
Par
ish
Cou
ncil
Bos
ton
Spa
Hyd
ro P
ower
Pro
ject
Bos
ton
Spa
Hyd
ro F
easi
bilit
y S
tudy
Rep
ort
| Is
sue
| 10
Nov
embe
r 201
4
J:\2
3000
0\23
4641
-00\
0 A
RU
P\0
-04
ME
ICA\
0-04
-08
RE
POR
TS\IS
SUE
\201
4-11
-10
FEA
SIBI
LITY
RE
POR
T - I
SSU
E.D
OC
X
Page
23
L
ocat
ion
Ass
essm
ent
Cri
teri
a
Loc
atio
n 1
Loc
atio
n 2
Loc
atio
n 3
Loc
atio
n 4
Arc
him
edes
Scr
ew
A –
30k
W
Arc
him
edes
Scr
ew
B –
100
kW
Arc
him
edes
Scr
ew
A –
100
kW
Arc
him
edes
Scr
ew
B –
100
kW K
apla
n Pi
t Tur
bine
A
– 1
00kW
A
rchi
med
es S
crew
B
– 1
00kW
Kap
lan
Pit T
urbi
ne
C -
100k
W A
xial
Fl
ow T
urbi
ne
5 B
uild
abili
ty
Wor
king
with
in th
e riv
er c
hann
el.
Hig
hest
risk
co
nstru
ctio
n ac
tiviti
es in
clud
ing
flood
risk
, H&
S,
stab
ility
of e
xist
ing
stru
ctur
es, d
elay
s et
c.
Con
ditio
n of
wei
r no
t kno
wn.
Turb
ine
furth
est
from
ban
k, re
quire
s la
rges
t cra
ne fo
r lif
ting
in (a
nd o
ut
late
r for
re
pair/
repl
acem
ent)
Cab
ling
to a
nd fr
om
turb
ine
diff
icul
t to
conn
ect,
may
requ
ire
over
head
line
to
cros
s fis
h pa
ss.
Red
uced
risk
, la
rgel
y in
the
bank
. R
isk
of d
esta
bilis
ing
exis
ting
herit
age
infr
astru
ctur
e.
Serv
ices
in th
e ba
nk?
Rer
oute
Fis
hpas
s te
lem
etry
duc
ts a
nd
cabl
ing.
Unk
now
n gr
ound
co
nditi
ons.
Lim
ited
coff
er d
ams
upst
ream
and
do
wns
tream
for
cons
truct
ion.
Inle
t cha
nnel
dee
per
than
fish
pas
s co
nstru
ctio
n. M
ay
requ
ire u
nder
pinn
ing
or st
ablis
ing
wor
ks
to fi
sh p
ass.
Red
uced
risk
, la
rgel
y in
the
bank
. R
isk
of d
esta
bilis
ing
exis
ting
herit
age
infr
astru
ctur
e.
Serv
ices
in th
e ba
nk?
Rer
oute
Fis
hpas
s te
lem
etry
duc
ts a
nd
cabl
ing.
Unk
now
n gr
ound
co
nditi
ons.
Lim
ited
coff
er d
ams
upst
ream
and
do
wns
tream
for
cons
truct
ion.
Inle
t cha
nnel
dee
per
than
fish
pas
s co
nstru
ctio
n. M
ay
requ
ire u
nder
pinn
ing
or st
ablis
ing
wor
ks
to fi
sh p
ass.
Gre
ater
vol
ume
of
cons
truct
ion,
sim
ple
but r
isks
are
slig
htly
in
crea
sed.
Serv
ices
in th
e ba
nk?
Rer
oute
Fis
hpas
s te
lem
etry
duc
ts a
nd
cabl
ing.
Unk
now
n gr
ound
co
nditi
ons
Lim
ited
coff
er d
ams
upst
ream
and
do
wns
tream
for
cons
truct
ion.
Ris
k of
dam
age
to
the
Dam
Hou
se
Stru
ctur
e - w
ork
to
mai
ntai
n it
may
be
diff
icul
t.
Gre
ater
bel
ow
grou
nd c
onst
ruct
ion.
Sam
e la
rge
foot
prin
t of
ban
k us
ed fo
r in
let c
hann
el.
Serv
ices
in th
e ba
nk?
Rer
oute
Fis
hpas
s te
lem
etry
duc
ts a
nd
cabl
ing.
Unk
now
n gr
ound
co
nditi
ons
Dee
per e
xcav
atio
ns.
Incr
ease
d ci
vil
wor
ks c
ompl
exity
.
Turb
ine
requ
ires
wat
ertig
ht b
elow
gr
ound
cha
mbe
r.
Ris
k of
dam
age
to
the
Dam
Hou
se
Stru
ctur
e - w
ork
to
mai
ntai
n it
may
be
diff
icul
t
Wor
k in
/clo
ser t
o riv
er b
ank
than
2&
3.
Incr
ease
d co
ffer
dam
re
quire
men
ts
upst
ream
..
Rer
oute
EA
te
lem
etry
.
Unk
now
n gr
ound
co
nditi
ons.
Dam
Hou
se
dism
antli
ng a
nd re
-bu
ildin
g w
ill re
quire
m
ore
spec
ialis
t sk
ills.
Goo
d us
e of
fish
pa
ss st
ruct
ure
but
may
requ
ire
impr
ovem
ent f
or
cont
inuo
us fl
ows
pass
ing.
6 A
cces
s
Turb
ine
diam
eter
3.
9m. A
cces
s ver
y tig
ht m
ay re
quire
so
me
tree
pinn
ing
or
cutti
ng to
inst
all.
Acc
ess a
roun
d tu
rbin
e di
ffic
ult a
s in
the
river
cha
nnel
.
Turb
ine
Dia
met
er
<3m
shou
ld fi
t dow
n th
e ac
cess
trac
k w
ithou
t tre
e da
mag
e.
Acc
ess a
roun
d tu
rbin
e in
clud
es d
ry
river
cha
nnel
and
fis
h pa
ss.
Turb
ine
diam
eter
3.
Acc
ess v
ery
tight
m
ay re
quire
som
e tre
e pi
nnin
g or
cu
tting
to in
stal
l.
Turb
ine
diam
eter
3.
9m A
cces
s ver
y tig
ht m
ay re
quire
so
me
tree
pinn
ing
or
cutti
ng to
inst
all..
Acc
ess a
roun
d th
e tu
rbin
e al
l fro
m th
e ba
nk.
Turb
ine
diam
eter
ap
prox
. 2m
. Sho
uld
fit d
own
the
acce
ss
track
with
out t
ree
dam
age.
Turb
ine
diam
eter
3.
9m A
cces
s ver
y tig
ht m
ay re
quire
so
me
tree
pinn
ing
or
cutti
ng to
inst
all.
Acc
ess a
roun
d th
e tu
rbin
e al
l fro
m th
e ba
nk.
Turb
ine
diam
eter
ap
prox
. 2m
. Sho
uld
fit d
own
the
acce
ss
track
with
out t
ree
dam
age
Turb
ine
diam
eter
ap
prox
. 2m
. Sho
uld
fit d
own
the
acce
ss
track
with
out t
ree
dam
age
Bos
ton
Spa
Par
ish
Cou
ncil
Bos
ton
Spa
Hyd
ro P
ower
Pro
ject
Bos
ton
Spa
Hyd
ro F
easi
bilit
y S
tudy
Rep
ort
| Is
sue
| 10
Nov
embe
r 201
4
J:\2
3000
0\23
4641
-00\
0 A
RU
P\0
-04
ME
ICA\
0-04
-08
RE
POR
TS\IS
SUE
\201
4-11
-10
FEA
SIBI
LITY
RE
POR
T - I
SSU
E.D
OC
X
Page
24
L
ocat
ion
Ass
essm
ent
Cri
teri
a
Loc
atio
n 1
Loc
atio
n 2
Loc
atio
n 3
Loc
atio
n 4
Arc
him
edes
Scr
ew
A –
30k
W
Arc
him
edes
Scr
ew
B –
100
kW
Arc
him
edes
Scr
ew
A –
100
kW
Arc
him
edes
Scr
ew
B –
100
kW K
apla
n Pi
t Tur
bine
A
– 1
00kW
A
rchi
med
es S
crew
B
– 1
00kW
Kap
lan
Pit T
urbi
ne
C -
100k
W A
xial
Fl
ow T
urbi
ne
7 O
pera
tion
&
Scre
enin
g Tr
ash
scre
en o
nly
requ
ired.
Deb
ris
defle
ctor
at i
nlet
es
sent
ial f
or th
is
loca
tion.
Turb
ine
/ tra
sh
scre
en a
t inc
reas
ed
risk
of d
ebris
due
to
posi
tion
furth
er o
ut
into
cha
nnel
.
Tras
h sc
reen
onl
y re
quire
d. D
ebris
de
flect
or a
t inl
et.
Obl
ique
ent
ranc
e m
ay re
duce
deb
ris.
Com
bine
d de
bris
de
flect
or fo
r fis
h pa
ss/tu
rbin
e co
uld
be in
stal
led.
Tras
h Sc
reen
onl
y re
quire
d. D
ebris
de
flect
or a
t inl
et.
Obl
ique
ent
ranc
e m
ay re
duce
deb
ris.
Com
bine
deb
ris
defle
ctor
for f
ish
pass
/turb
ine
coul
d be
inst
alle
d.
Tras
h Sc
reen
onl
y re
quire
d. D
ebris
de
flect
or a
t inl
et.
Obl
ique
ent
ranc
e m
ay re
duce
deb
ris.
Com
bine
deb
ris
defle
ctor
for f
ish
pass
/turb
ine
coul
d be
inst
alle
d.
Req
uire
s fis
h sc
reen
at
inle
t and
out
let.
Spec
ies t
o be
agr
eed
with
EA
.
Obl
ique
ent
ranc
e m
ay re
duce
deb
ris.
Com
bine
deb
ris
defle
ctor
for f
ish
pass
/turb
ine
coul
d be
inst
alle
d.
May
requ
ire fi
sh
scre
en a
t inl
et a
nd
outle
t. D
iscu
ssio
n re
quire
d w
ith E
A to
de
term
ine
appr
oach
.
Obl
ique
ent
ranc
e m
ay re
duce
deb
ris.
Com
bine
d de
bris
de
flect
or fo
r fis
h pa
ss/tu
rbin
e co
uld
be in
stal
led.
Req
uire
s fis
h sc
reen
at
inle
t and
out
let.
Spec
ies t
o be
agr
eed
with
EA
.
Obl
ique
ent
ranc
e m
ay re
duce
deb
ris.
Com
bine
deb
ris
defle
ctor
for f
ish
pass
/turb
ine
coul
d be
inst
alle
d.
Req
uire
s fis
h sc
reen
at
inle
t and
out
let.
Spec
ies t
o be
agr
eed
with
EA
.
Obl
ique
ent
ranc
e m
ay re
duce
deb
ris.
Com
bine
deb
ris
defle
ctor
for f
ish
pass
/turb
ine
coul
d be
inst
alle
d.
8 M
aint
enan
ce
Pede
stria
n ac
cess
to
turb
ine
only
.
Rep
lace
men
t of
parts
(eve
n sm
alle
r co
mpo
nent
s)
prob
ably
requ
iring
cr
ane/
hiab
Clo
ser t
o th
e ba
nk.
Still
requ
ires
brid
ge/w
alkw
ay
from
ban
k to
turb
ine
hous
e.
Pede
stria
n ac
cess
on
ly ri
ght u
p to
bu
ildin
g.
Loca
tion
amon
gst
the
trees
may
in
crea
se sc
reen
cl
eani
ng fr
eque
ncy.
Clo
ser t
o th
e ba
nk.
Still
requ
ires
brid
ge/w
alkw
ay
from
ban
k to
turb
ine
hous
e.
Pede
stria
n ac
cess
on
ly ri
ght u
p to
bu
ildin
g.
Loca
tion
amon
gst
the
trees
may
in
crea
se sc
reen
cl
eani
ng fr
eque
ncy.
Veh
icul
ar a
cces
s to
turb
ine
hous
e po
ssib
le.
Loca
tion
amon
gst
the
trees
may
in
crea
se sc
reen
cl
eani
ng fr
eque
ncy.
Veh
icul
ar a
cces
s to
turb
ine
hous
e po
ssib
le.
Req
uire
men
t for
fish
sc
reen
may
incr
ease
m
aint
enan
ce c
osts
.
Loca
tion
amon
gst
the
trees
may
in
crea
se sc
reen
cl
eani
ng fr
eque
ncy
Veh
icul
ar a
cces
s to
turb
ine
hous
e po
ssib
le.
Poss
ibili
ty o
f re
quiri
ng fi
sh
scre
ens w
ould
in
crea
se
mai
nten
ance
re
quire
men
ts.
Loca
tion
amon
gst
the
trees
may
in
crea
se sc
reen
cl
eani
ng fr
eque
ncy.
Veh
icul
ar a
cces
s to
turb
ine
hous
e po
ssib
le.
Req
uire
men
t for
fish
sc
reen
may
incr
ease
m
aint
enan
ce c
osts
.
Loca
tion
amon
gst
the
trees
may
in
crea
se sc
reen
cl
eani
ng fr
eque
ncy
Veh
icul
ar a
cces
s to
turb
ine
hous
e po
ssib
le.
Req
uire
men
t for
fish
sc
reen
may
incr
ease
m
aint
enan
ce c
osts
.
Loca
tion
amon
gst
the
trees
may
in
crea
se sc
reen
cl
eani
ng fr
eque
ncy
9 Sa
fety
&
Secu
rity
Easi
er to
mak
e se
cure
. Ove
rhea
d ca
ble
vuln
erab
le to
th
eft -
mor
e ob
viou
s.
Ove
rhea
d ca
ble
at
grea
ter r
isk
of
dam
age
by tr
ees a
nd
wea
ther
impa
cts.
Loca
tion
is a
de
terr
ent t
o ca
sual
tre
spas
sing
.
Mor
e ac
cess
ible
. C
ablin
g be
twee
n ba
nk a
nd tu
rbin
e un
certa
in.
Inle
t cha
nnel
re
quire
s cov
erin
g or
fe
ncin
g.
Mor
e ac
cess
ible
. C
ablin
g be
twee
n ba
nk a
nd tu
rbin
e un
certa
in.
Inle
t cha
nnel
nee
ds
cove
ring
or fe
ncin
g.
Cab
ling
all b
urie
d.
Publ
ic a
cces
s can
be
rest
ricte
d or
en
cour
aged
.
Inle
t cha
nnel
sa
fety
/sec
urity
re
quire
s cov
erin
g or
fe
ncin
g. L
onge
r ch
anne
l req
uire
s m
ore
prot
ectio
n.
C
ablin
g al
l bur
ied.
Pu
blic
acc
ess c
an b
e re
stric
ted
or
enco
urag
ed a
s pr
efer
red.
Cab
ling
all b
urie
d.
Publ
ic a
cces
s can
be
rest
ricte
d or
en
cour
aged
as
pref
erre
d.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
4.3 Turbine Options Detailed quotes have been provided by four turbine suppliers. These are included in Appendix B1.
In theory the EA may permit a turbine using up to Qmean river flow. This could enable a turbine of over 200kW to be installed. In practice there is a balance required between generating the maximum energy possible, the impact on the local area and the overall revenue received.
4.3.1 Axial Flow Turbines Discussions were held with all suppliers on the potential options for this site. The axial flow turbine supplier initially offered two turbines at 122kW each. The overall energy produced by this option would have been far in excess of that available from a single Archimedes screw. However the installation (shown on plans in Appendix B1) would have been very large and would not have been suitable for the location. The inlet channels, building and screening required would have dominated the riverbank and been a significant visual intrusion on a local beauty spot.
A single axial turbine option was requested and provided. Although the turbine itself is a smaller diameter than an Archimedes screw the building in which it would be installed requires space on all sides of the turbine for maintenance access and ancillary equipment. It can actually end up being a larger construction than and equivalent power output screw turbine.
This type of equipment always requires screening with openings in the region of 10mm to keep fish out of the turbine. This is not only an additional cost, but also presents an on-going maintenance problem. On a heavily wooded river such as the Wharfe there is extensive natural vegetation debris present which can easily block a screen and limit the volume of water that can pass through. This is in evidence on the fish pas which has a 100mm bar screen and is regularly blocked with twigs and leaves requiring manual removal.
The guidance from BSPC was that this risk of reduced flow (and hence power) and maintenance burden was one that would not be undertaken unless there was a significant financial benefit to doing so.
4.3.2 Kaplan Pit Turbines A single Kaplan Pit turbine could also be provided which could use the maximum flow available, Qmean and generate up to 270kW. They also offered a single 100kW option of the same type of turbine.
The images in Appendix B1 show the scale of the larger turbine installation. This type of turbine is installed below ground and requires significant excavation. Although the overall cost may not be much higher than an Archimedes screw for a small turbine, the risk of unknown ground conditions and delays due to difficulty in excavation are much higher.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
According to their rough estimates the 270kW turbine would generate 50% more energy each year than the smaller version, but due to the FiT arrangement, only receive 28% extra revenue. (This summary is included in Appendix B1)
Turbines rated at 15-100kW receive a higher Feed in Tariff than turbines rated 100-500kW. This is due to the higher cost per kW of installing small turbines which means many opportunities are never developed. The change in FiT at 100kW can have the seemingly perverse result that a 150kW turbine could generate more energy than a 100kW turbine on the same location, but generate a lower overall revenue. When the additional cost of the larger turbine is taken into account it is rarely cost effective to install a turbine between 100-250kW, as a 100kW version at the same location would have a better balance of cost and revenue.
For this reason they offered a quote for a 100kW option which is both smaller, and therefore more in keeping with the surroundings, but also likely to be more cost effective overall.
As with the axial turbine, screening is always required with this type of turbine. It is also a large construction relative to the turbine diameter to allow for the complex civil works and access requirements to the turbine in a below ground chamber.
4.3.3 Archimedes Screw Turbines For the Archimedes screw turbines the largest single turbines offered vary from 4-4.5m from different suppliers. This is largely due to the difficulty in transporting any screws larger than this on public roads and normal haulage equipment. These have maximum flow capacity of 9-11m3/s and corresponding power output of 130-150kW at this site.
To achieve a higher power output a multiple screw option would be required. As with the axial flow turbine, having two turbines would make the installation physically much bigger. It would dominate the riverbank and result in a loss of more of the clearing than a single turbine option.
For this reason a single screw option was preferred. As with the other turbines, the change in FiT at 100kW means that the largest turbines available would probably earn less income than a 100KW version.
For this reason the screw turbine options proposed were both 100kW units from two suppliers.
These do not require fine fish screens and therefore have a lower risk of blinding and lower maintenance liability. They also have the advantage that most of the construction is only as wide as the turbine and therefore although larger than the axial and pit options, the control building and excavations could actually be smaller.
4.3.4 Preferred Option On cost, complexity and size, the Archimedes screw options have been agreed as preferable to the Axial and Pit turbine options at this location.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
Screening was a key criteria in this decision, it would be necessary to install mechanically raked screens to avoid manual maintenance on a regular basis. These are large, usually unattractive and require access for maintenance. On the downstream side, due to the gap between the turbine and the bank, access to a screen would require a bridge or walkway which would further increase the visual impact of the scheme.
It was felt that there was a need to minimise both the aesthetic impact of the scheme and the screening requirements. For this reason an Archimedes screw would be the preferred solution, ideally a single 100kW screw turbine to maximise FiT revenue. Although it is believed that the turbine proposed could be brought to site with some minor modifications to Holgate Lane, there is a possibility that access issues may slightly restrict the diameter of the screw or the type of casing it comes with.
Screws can be supplied pre-installed within a steel trough. Although this reduces the installation time and risk, it also increases the diameter of the delivered components and may therefore be unsuitable for this narrow access route. It is recommended that a transport company nominated by the screw turbine supplier is invited to attend site to provide guidance on the limitations of the access route and any impact that would have on the turbine selected.
The two turbine suppliers consulted gave different diameters for the 100kW turbine option, if the access restriction is very tight, it may mean the smaller diameter turbine is the better options
4.4 Proposed Solution Initially there were two options that stand out (for Archimedes Screw Turbines):
x Option 2 – Preferred by BSPC
x Option 4 – Preferred by respondents at public consultation
Both of these options are based on fitting the turbine between the fish pass and the bank keeping as close as possible to the line of the fish pass.
Option 4 places the turbine at the head of the fish pass and reduces visibility of the screw itself to residents on the opposite bank. For this reason, when shown both Option 3 and 4 in visualisations at public consultations the public clearly expressed a preference not to be able to see the screw.
Feedback from the Environment Agency was that only Location 2 was acceptable as the other locations could reduce the effectiveness of the fish pass operation. The local planning authority also preferred Location 2.
Although this location was not considered the best by the public, there is potential that the design could be made to create similar features to those preferred about Location 4, the angle of the turbine and the aesthetics of the installation.
4.4.1 Civil Works The civil works required for the turbine installation include the following components:
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
x Excavation and disposal of both natural material and rock
x A reinforced concrete structure forming the base and walls of the inlet, outlet and turbine channels.
x Channel covers including support beams
x Generator building
x Stone facing for exposed channel walls
x Scour protection mattress
x Modifications to fish pass side wall
x Modifications to the Dam House structure
x Tree clearance & replanting
x Access improvements
x Temporary works including cofferdams, pumping and access
Additional considerations include risk allowances for unknown ground conditions and risks of working in the river. The costs of these civil elements and approximate volumes are included in Appendix F1
4.4.2 Turbine Selection and Layout The turbine likely to be used for the Boston Spa site is a 100kW Archimedes screw turbine. Two options have been offered by different suppliers. The dimensions slightly vary but the packages are very similar. Either turbine could be used in any of the four potential locations.
The most cost effective solution is a single turbine which brings the power output just below the 100kW boundary for the FiT subsidy. A detailed survey of the access route into site will confirm any impact that the access layout will have on turbine selection.
The layouts of all four potential locations are indicated in the plan in Appendix A.
4.4.3 Electrical Systems An enquiry was sent to Northern Power Grid (NPG) requesting a budget quotation for the cost of a new connection for the hydro turbine at this location.
The quote (included in Appendix B3) indicates an estimated cost of £70k plus VAT = £84k.
Further clarification was requested from NPG to identify their proposed route and scope. The proposed solution is as follows:
x Connection at 11kV at the substation on Boston Spa High Street.
x Buried 11kV cable under pavements and down Holgate Lane to the site
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
x Pole mounted transformer located in the clearing adjacent to the turbine
The budget quote was not based on a full survey, and the NPG engineer had not visited site. He raised the concern that the position of a pole mounted transformer by the river bank may be difficult due to the tree coverage.
There may be aesthetic implications to the positioning of the transformer and it is likely that this would need to be reviewed in detail with NPG to determine a solution that fits in with the location.
Due to the volume of requests that are received for speculative renewable energy applications, NPG provide a desk study only budget quotation. In order to engage with them and have the opportunity to discuss detailed options for connection it is likely that a request for a firm quotation would be required. This would require further details of the generator and electrical system and has therefore been undertaken at this stage but is recommended as part of the next stage of works.
When further requests have been submitted to NPG it is recommended that the location of a pole mounted transformer be reviewed to determine the correct scope for a firm quotation for the grid connection.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
5.1 Planning Permission Leeds City Council Planning Officer Clive Saul has been nominated to provide a pre-planning opinion on the hydro turbine proposal.
He has been provided with a description of the scheme and a sketch showing the options available. Additional information has been provided regarding the size and visual impact of the turbine and building. Clive also requested further details about any potential restriction placed on the scheme by Holgate Lane.
The Planners consider Location 2 to be the most suitable position. Impacts on bridleways and the access road were the key concerns raised. These will need to be addressed in detail in the full planning submission.
5.2 Environment Agency The Environment Agency is the regulatory body for the watercourse and all hydro turbine schemes require an application for abstraction and in some instances, impoundment licences.
EA pre-application forms WR316 and WR325 have been completed and submitted with accompanying background information. Karen Wooster has been appointed as the Account Manager.
The information provided in included in Appendix C2. The responses from the EA are summarised below and included in full in Appendix C3.
5.2.1 Licences The type of licence required for this scheme is a transfer abstraction licence. An Impoundment Licence is not required. There is cost of £1.5k for the application, with and an additional £1k for advertising the scheme for comment. These have been added to the further works list in Section 7.
The abstraction licence is valid for three years. If the abstraction has not commenced by that time is it no longer valid.
5.2.2 Abstraction Sensitivity Level The Abstraction Sensitivity Band is identified by the EA as ASB 2. The level assumed in the pre-application was Level 3 which is High Sensitivity. ASB2 indicates that the river is designated as Medium Sensitivity.
The designation indicates that with a Q95/Qmean value of < 0.2 (this site is 0.14) the Hands Off Flow of Q95 is appropriate for this river.
Above that flow the operator would be permitted to abstract up to 40% of the total annual volume of water in the river abov Q95. At this site it is estimated that the 100kW turbine option would abstract approximately 32% of the flow above Q95.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
5.2.3 Geomorphology and WFD It is a requirement of the full turbine application that a report is provided on the current status of the waterbody under the Water Framework Directive (WFD) and what potential impact the turbine could have on that status.
It is also a requirement to provide a report on the morphology of the river including the weirpool, depleted reach and any geopmorphological features identified. The impact of the turbine on all these features must be assessed and mitigated where necessary.
The EA have also requested an assessment of the potential for bed and bank scour.
These requests are included in the further works identified in Section 7 and estimated costs provided.
5.2.4 Fisheries Impact The installation of a hydro turbine on any inland water course has the potential to affect local fisheries by changing patterns and access for upstream and downstream migration. Changes in the flow regime can also affect the availability of habitats upstream, downstream and in any depleted reach.
The weir at Boston Spa is impassable to fish due to the vertical face of the structure.
To resolve this barrier a Larinier Fish Pass was constructed in 2010 by the Environment Agency, designed by Arup. As referenced in Section 4, permission was sought and granted by the EA for BSPC to use the design data from the fish pass scheme to inform the hydro turbine design.
The EA guidance states “A new hydropower scheme should not make it more difficult for fish to move up or downstream”2. An initial review of the fishpass design data suggests that it should be possible to design the inlet and outlet from the turbine as well as the level control to ensure that the fish pass received the required flows.
The existing fish pass is a multi-species Larinier pass suitable for coarse and salmonid species with an eel pass within the same envelope.
The turbine selected is in accordance with the EA criteria3 for fish screening listed in the table below:
Table 4: Turbine Screening Criteria
Measure EA Requirement Proposed Design
Diameter (Min to avoid fish screening)
> 2.2m (for 4 bladed screw)
Max 3.9m
2 Guidance for run-of-river hydropower - Fish passage. Environment Agency December 2013 3 Guidance for run-of-river hydropower - Screening. Environment Agency December 2013
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
Maximum speed (rpm) < 30 rpm (for 4 bladed turbine)
19.8 rpm
Tip Speed (to use hard bumpers)
< 3.5m/s 4.04 m/s
Compressible rubber bumpers required
Tip Speed (to avoid fish screening)
< 5.0 m/s 4.04 m/s
By using this guidance, the turbine should be fitted with compressible rubber bumpers due to the tip speed exceeding 3.5m/s. All other criteria laid out are met and therefore the guidance indicates that a trash screen with 100mm apertures is suitable for this installation.
The additional detail of the gap time between blades will be required to confirm if further screening is required.
5.2.4.1 Initial Response The initial response received from the EA Included the following requests:
x The turbine should be co-located with the fish pass.
x Fish pass approval will be required
x A bywash or notch may be required for downstream migration
x An environmental report on the impact on downstream habitats
x Provision of access to the fish pass for on-going maintenance
x Possible provision of Lamprey passage (if confirmed required by Natural England)
x Screening and turbine design in accordance with the guidance documents (as highlighted above). Compressible rubber bumpers will be required.
x Work to be undertaken outside migration periods
Most of these are already incorporated into the scheme however a small number may require further action:
Further clarification was requested on the location of the turbine and the inclusion of a bywash/notch. These are discussed below.
A lamprey pass, (if required) requires the provision of a smooth, probably stainless steel, plate on the side wall of the fish pass for the fish to grip onto as they climb the pass. This could be incorporated if required. Natural England should be consulted to confirm if this is a need for this location.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
It is assumed that the migration periods referred to are for salmonid species.
Atlantic salmon – generally, spawning occurs between November-December but in some cases (particularly in larger rivers) this may extend from October-late February.
Brown trout/Sea trout – Salmo trutta species has two alternative life-cycle patterns - a freshwater resident form referred to as 'brown trout' and an anadromous (sea going) form referred to as 'sea trout' . Despite being freshwater-resident, brown trout can undertake significant migrations within freshwater (including migration of juveniles from nursery areas and between feeding areas, etc). For sea trout, generally, spawning begins in mid-October and continues through to early January.
Based on these species this would imply that construction in the river should take place between February and October to avoid these migration periods. Clarification should be sought from the EA as to whether any other species should be considered.
5.2.4.2 Additional Feedback To clarify the requirements and review alternatives a site meeting was arranged with representatives of the Fisheries team. The full response is included in Appendix C3.
The first issue discussed was the location of the turbine. It was confirmed that the co-located position mentioned correlates to Location 2 and that the alternative options for turbine location would not be acceptable.
A bywash is a significant construction, and would require additional cost and construction. It was discussed and agreed that a notch would be more appropriate if downstream migration provision is to be included.
On the question of whether a notch was necessary there was less clarity. The following responses were received after the meeting:
x “Flows down the fish pass: In the pre-app, the applicant proposes to have only 0.792 m3/s in the pass up to around Q40. Fisheries does not think that this is sufficient. Our suggestion would be (as a minimum) that the turbine could not operate until a flow of 1.272m3/s (about 7% QMean) and ha of 43cms is achieved in the pass. This should then be maintained as minimum flow and level in the fish pass throughout the turbine operation. As an aside, Hydrology figures will need to be checked as I believe that the applicant has based his calculations on estimates.”
x “Downstream Fish Passage: As a very minimum, a good depth of water should be retained in the pass in order to aid downstream migration (h of minimum 30 cms required, ideally 40 cms). The pre-app proposal does not meet this h until Q40. In short, we do not generally promote such passes as good, primary ‘stand-alone’ downstream routes. In order to facilitate effective downstream fish passage, we recommend that a notch is installed in the weir (preferably towards the left bank).”
x A bigger aperture screen than 100 mm MAY be better for fisheries. However to make an informed decision, we still need to know the gap time
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
between blades. If the time gap is insufficient, we may not want to open up the turbine as a route for larger fish such as kelts etc.
The first point is at odds with the guidance which indicates an abstraction Hands Off Flow (HOF) of Q95.The requested flow is not achieved in the fish pass until the river flow reaches approximately Q50. They are effectively asking for a HOF of Q50 which would render any hydro scheme uneconomical and is not in line with the EA guidance on hydro power.
The range of acceptable flows in a fish pass is 5-10% of Qmean, therefore it should be acceptable to operate the fish pass with 5% of the Qmean flow. Requesting a minimum of 7% before the turbine operates would suggest that the EA fish pass design criteria were incorrect. This request is at odds with the published guidance and ruinous to all hydro prospects. The financial assessment has been done on the basis that the guidance document criteria are acceptable and the conditions proposed are not required as they are a long way from the normal conditions. The impact of the requests is considered for information on Location 2B only.
The second point asks for a minimum of 300mm in the fish pass or a notch. This does not occur until the river reaches approximately Q84 and consequently suggests HOF of that value. This would have an impact on turbine operation and energy production and could make the installation uneconomical.
As the fish pass was installed without a bywash or notch it would naturally be assumed that the design of the fish pass is sufficient for the needs of the species present in the river. The request indicates that the EA do not believe the existing pass is suitable and therefore request further work. If this belief is correct and mitigation is required it is recommended that a review is carried out to consider:
x Would a notch located adjacent to the fish pass be a viable option?
x What would the hydraulic impact of a notch on either bank be on the operation of the fish pass or turbine?
x Whether the 300mm requirement is absolute or whether a compromise on could be reached?
As an example a target level of 290mm in the fish pass would change the HOF to approximately Q90 and significantly reduce the impact of the request on the output of the turbine.
A notch, if required, would ideally be situated on the left bank. As this land is not owned by Boston Spa Parish Council, the notch would be within the main river channel unlike the turbine construction, and the location is physically separate from the turbine construction it would add significant cost, complexity and risk to the scheme. It is unlikely that this would be pursued as a viable option.
If a notch adjacent to the fish pass were acceptable, the impact on the hydro turbine and the fish pass would still need to be assessed. Due to the uncertainty around what is required the financial assessment is based on the standard Q95 HOF is used although the potential impact of a Q84 or Q90 HOF is considered for Location 2B.
The guidance on downstream migration provisions is much less clearly defined than for upstream migration and therefore it will be necessary to engage with the EA in further discussion to resolve these issues.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
5.2.4.3 Upstream Fish Passage With careful hydraulic design the fish pass and turbine should be suitable for combined operation. EA guidelines state “Where a fish pass is already present, or where a fish pass is provided by the scheme, the downstream fish pass entrance should be co-located with the discharge from the turbine(s). The turbine flow will help attract more fish to the vicinity of an adjacent fish pass entrance.”4
The turbine discharge from location 2 would be adjacent to the downstream end of the fishpass. The discharge channel should be designed to reduce velocity of the flow from the turbine to less than half the velocity of the fish pass discharge. This should allow fish to correctly identify the route for upstream migration.
The requests made by the EA for changes to the operation of the fish pass will need to be considered in more detail. They are not in line with the standard fish pass guidance and will affect the overall operation and performance of the turbine system.
5.2.4.4 Downstream Migration The request for modifications to the operating regime of the turbine to improve downstream migration need to be considered in more detail. This is an area of uncertainty which needs to be clarified as it could have a significant impact on the scheme.
5.2.4.5 Eel Passage The eel pass location may become unsuitable with a turbine installed as eels are inclined to travel adjacent to the bank. It is likely that the eel pass would need to be relocated to the bank side of the turbine so that it performs correctly.
5.2.5 Other Water Users The EA expect the applicant to consult with other water users. This includes anyone who currently abstracts water from the river whose use of the water might be affected. There are no obvious abstractions in the area however it is recommended that this is investigated in case of unknown users.
It also includes amenity users and specific reference is made to a requirement for consultation with Boston Spa Angling Club. This has already been started but will need to be continued prior to submission of a formal application to the EA.
5.2.5.1 Abstraction Rights During public consultation, we have become aware that there is some confusion over whether TAPC have a right to benefit financially from the turbine scheme due to the position of the parish boundary at the middle of the river channel. To clarify the point:
4 Guidance for run-of-river hydropower - Fish passage. Environment Agency December 2013
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
Neither parish council has any automatic ownership or usage rights over the water within the river for hydropower or any other use. Land ownership of riverbank or bed, or position of parish council boundary does not imply licence to abstract, obstruct or discharge any of the water in the channel.
The right to use and control water in the River Wharfe lies with the Environment Agency. Any party can apply to use the water for a hydro turbine however if the applicant is not the landowner any licence must be considered in conjunction with access agreements and permission to construct on a third party’s land.
5.2.6 Flood Risk There is a requirement to apply for a Flood Defence Consent for the turbine intake and discharge. These are dealt with by the Account Manager.
There is also a requirement for a Flood Risk Assessment (as identified in Section 5.5). A level 1 Assessment has already been completed, which identified further work. The scope of further work should be discussed with the EA prior to starting work to ensure that it is sufficient to satisfy their requirements.
5.2.7 Protected Sites or Species The EA require a full Phase 1 Habitat Survey (as included in Section 6) with breeding birds, bats and otters requiring particular consideration. These surveys have been highlighted as required and are included in the further works listed in Section 7.
5.3 Land Ownership Land Registry searches have been completed for both sides of the river and additional information provided from the Boston Spa Parish Council Records. Details of Land Ownership are included in the summary in Appendix C4.
Boston Spa Parish Council owns the land on which the turbine would be constructed and retains the right of access to this location. BSPC ownership extends to the midpoint of the weir, the remaining half being jointly owned by Thorp Arch Mill Management Company Limited and included in the 150 year lease of the owners of 14 properties on site.
Ownership details for Holgate Lane are not clear from any of the records. Further investigation may be required to confirm the status of this land.
5.4 Access Holgate Lane is the only current viable access route to site for large vehicles. As a historic route it has some local interest and additional care was used during the fish pass scheme to minimise damage and restore to original condition upon completion. The heritage implications are discussed in Section Error! Reference source not found.. The practical implications are described here; both initial disruption for construction, and long term impacts have been considered.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
5.4.1 Construction Access The construction of the turbine will require access to site for heavy plant and machinery, and delivery of the turbine itself which is a wide load.
Construction of the fish pass in 2010 required similar levels of construction traffic, cabins and equipment to be brought to the site location. Temporary road surface was installed and removed at completion. Similar modifications would be required for the construction period for a turbine.
The unique component of this construction would be the delivery of the turbine itself. Transported on a flat-bed vehicle, an Archimedes screw the maximum width, the screw diameter of nearly 4m, would be approximately 3m above ground.
A walkover of the access road has been undertaken to identify any obstacles that may obstruct the delivery of a hydro turbine to the site and the following potential issues have been identified:
x Immediately before the entrance to the un-surfaced lane there is a passage between the church and a stone wall. The width of this passage is thought to be sufficient, however as the vehicle would be required to the turn slightly at this point it is suggested that a transport company be consulted for confirmation.
x The wooden bollards at the top of the lane would require removal and reinstatement.
x There are low stone retaining walls in a couple of places which may restrict vehicle width (although fish pass construction vehicles were able to pass through this restriction).
x There are mature trees along the route. Some of these may require a branch cutting back to make clearance for the widest part of the load
x There is young growth including saplings which may need to be trimmed or tied back to prevent them creating a restriction.
With some short term interventions it is believed that a turbine could be brought down this lane, although the space is very tight and vegetation may require removal or restraining to make it possible.
It is recommended that the turbine supplier’s transport company be requested to visit site and carry out a full survey to identify any restrictions and assess any impact on turbine selection and choice of casing that may result.
5.4.2 Maintenance Access Long term there is a desire to maintain Holgate Lane in its present condition and avoid the need to create a permanent road surface for vehicular access. The maintenance requirements of an Archimedes Screw have been reviewed to assess how often access is required and what type of vehicles may be used. Table 5 and Table 6 show the expected access requirements for the site.
At this stage it does not seem that any of the maintenance frequencies specified would require permanent modification of the access route.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
5.4.3 Alternative Access Routes Alternative routes to site are very limited and if vehicular access could be arranged it would probably require double handling of larger components. If Holgate Lane does prove too narrow for the 100kW turbine it may be necessary to compromise a little on output to facilitate installation.
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Tabl
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Ann
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and
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Tabl
e 6:
Est
imat
ed E
A a
cces
s req
uire
men
ts
Fish
pas
s acc
ess r
equi
rem
ents
Fr
eque
ncy
Acc
ess r
equi
red
Impa
ct o
n H
olga
te la
ne
Scre
en c
lean
ing
Unk
now
n Pe
dest
rian,
van
or 4
x4
Bol
lard
rem
oval
Ass
et in
spec
tion
1-2
year
s V
an o
r 4x5
B
olla
rd re
mov
al
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
5.5 Flood Risk Assessment A Level 1 Flood Risk Screening Study has been carried out in accordance with guidelines provided in the National Planning Policy Framework (NPPF). The purpose of this study is to identify any flooding or surface water management issues relating to the site that may affect its use and warrant further investigation. The findings and conclusions are summarised below and the full report can be found in Appendix D.
5.5.1 Fluvial Flood Risk Flooding from the river is the most obvious flood risk at this location. The Flood Risk Screening Study has found that the Environment Agency Flood Maps indicate that this site lies within the area at >1% risk of flooding annually.
The Leeds City Council Strategic Flood Risk Assessment indicates that the hydro turbine and control building would be installed within what is considered functional floodplain. This suggests the expected annual probability of flooding is 5%.
The water level occurring during these events is not specified and would need to be identified by further modelling.
5.5.2 Other Flood Risk Sources Both surface water and groundwater flood sources have been considered. Both are expected to be a minimal risk for this location but will need to be appropriately considered during the design.
5.5.3 Recommendations In response to current flood risk and future changes due to climate change it is recommended that the turbine, generator and associated control equipment be protected from flooding to the level of the 1 in 200 year event return period.
It will be necessary to determine this level in discussion with the Environment Agency. The EA should already have a numerical flood model of this location and may be willing to make it available for the purposes of making this assessment for a fee.
Further discussion with the Environment Agency will be possible following submission of the hydro-power pre-application forms. This issue will be raised with the Account Manager at that stage.
5.6 Stakeholder Consultation Stakeholder consultation has already been considered in Section 2. It will be a key component of the planning process therefore documentation of what has been done and the feedback from third parties will be included.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
6.1 Phase 1 Habitat Survey In order to assess the potential impact of the scheme on the local environment an ecology walk over and Phase 1 Habitat survey was carried out. The full report is included in Appendix E however the key highlights are identified in this section:
6.1.1 Bats The site includes potential habitats for Bats in both ivy covered trees and the remains of Dam House. Although no evidence of bats been found it is recommended that surveys are completed to identify if there are any bats present.
6.1.2 Otters Otter presence was identified and has been confirmed by local fishermen. It is recommended a riverbank survey is carried out to identify any holts in the vicinity of the construction site.
The Environment Agency should be consulted regarding the potential for White Clawed Crayfish in the river.
6.1.3 Trees There will be some impact on trees, both along the access track Holgate Lane, and on the bank adjacent to the fishpass. On Holgate Lane it is recommended any trees which provide obstruction to vehicle passage are trimmed or pinned back not removed.
Trees on the bank likely to require removal should be replaced on a two to one basis with native species. The trees most likely to be affected are Sycamores.
6.1.4 Invasive Species The invasive species Himalayan Balsam has been identified on the bank and close to the fishpass. It is recommended that either the plant is treated for removal prior to the work being undertaken, or method statements and a protection procedure are put in place to contain any contaminated material and prevent further spread of the plant.
6.2 Fisheries Impact The installation of a hydro turbine on any inland water course has the potential to affect local fisheries by changing patterns and access for upstream and downstream migration. Changes in the flow regime can also affect the availability of habitats upstream, downstream and in any depleted reach.
The turbine itself has been demonstrated to comply with the EA guidelines for screening requirements and 100mm or wider spacing would be suitable. Due to the EA Fisheries team concerns about water levels within the fish pass it may be
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
necessary to modify the operating range of the turbine or provide an additional bywash or notch for downstream migration.
It is recommended that more detailed work is undertaken to determine a suitable arrangement to ensure the fishpass and turbine can operate effectively in parallel.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
7 Financial Assessment To assess the financial viability of this scheme the costs and revenues have been estimated to enable assessment of the viability of the scheme. These are categorised as:
x Capital costs – one off costs to develop the scheme
x Operation & maintenance costs - on-going costs for running the turbine
x Funding costs – repayments, interest and fees for borrowing
x Revenue – income from all sources
Each of these items is explored in more detail I this section.
7.1 Capital Costs A full break down of the costs estimated will be included in Appendix F; the main costs and a description of how each is built up are included below.
7.1.1 Development Costs A number of surveys, studies and assessments are required to clarify the constraints on the turbine installation and the resulting design.
An allowance of £50k has been made, which includes the components in sections 7.1.1.1 to 7.1.1.10 that have been identified throughout the preceding sections of this report.
7.1.1.1 Environment Agency Licences The EA charge a fee of £1.5k for the licence application and may charge an additional £1k for advertising the scheme for comment.
Estimated cost of £2.5k
7.1.1.2 Planning Costs An allowance should be made for preparation and submission of a planning application for this site. It is recommended that the design is developed a little further prior to completion of the planning application, including attention to the presentation of the control building and turbine as part of the riverbank.
Estimated cost of £2-3k
7.1.1.3 Noise Survey / Assessment It is recommended that an assessment of the potential noise impact of the turbine is made. The manufacturer will supply data for their turbine, gearbox and generator, however the design of the building, the layout of the site and the noise generated by the existing flow over the weir all affect whether there is any noise impact created by a turbine. A survey of the background noise due to the weir may also be required to inform the study.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
7.1.1.4 Topographical Survey Planning submissions and the EA permitting process will require the production of drawings of both the immediate area and a wider setting to inform the decisions made by both organisations. An existing topo survey is available for the fish pass and surrounding area which has been made available by the EA for this scheme. In addition Ordnance Survey mapping data has been purchased which provides outlines for other features in the wider area.
Unfortunately the coordinates between the topo survey and the OS map do not match and when overlaid, there is an offset of a few meters between the two drawings.
It is not possible to identify which is incorrect without further investigation. It is suggested a fairly limited survey is undertaken to identify the correct position of the key features so that the two sets of data can be corrected and aligned. This will be important for creating the drawings required by others for approval processes. Expected costs are based on a day on site by a small survey team.
Estimated cost of £2k.
7.1.1.5 Access Survey A detailed survey of Holgate Lane is recommended to confirm the suitability of the route for turbine installation. It is suggested that one of the transport companies used by the turbine suppliers is used to ensure that they are familiar with the load in question.
Estimated Cost of £2-£3k.
7.1.1.6 Ecological Surveys An initial ecology survey indicated the possible presence of a number of protected species that will require further surveys. These are clarified in Section 6.
Estimated cost of £3-4k
7.1.1.7 Flood Risk Modelling The flood risk report identified a potential requirement for additional modelling or use of the EA models if available to identify the flood risk impact of the scheme and identify appropriate design flood levels.
Estimated cost of £2k to determine a level
Additional cost of £3k if the EA require modelling to assess downstream impacts
7.1.1.8 Geomorphology / WFD Assessment In the EA response the need to carry out a WFD assessment was highlighted to provide information regarding the impact of the turbine on the geomorphology
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
and general health of the river system in the vicinity of the weir. An initial assessment would highlight any further study required. Approximate prices for this work are:
High level WFD study – Estimated cost of £1.5k
WFD compliance assessment – Estimated cost of £2.5k
7.1.1.9 Physical Hydraulic Modelling It is recommended that a physical model is constructed and tested to identify current and future flow conditions within the river. Of particular concern are the issues related to erosion changes due to the fish pass, and the potential for the turbine to exacerbate these changes.
Estimated cost of £12-15k
7.1.1.10 Outline Design & Tender Preparation An allowance has been made for the preparation of an outline design and tender documents for a design and build contract.
Estimate cost of £10-15k
An additional allowance is suggested for detailed investigation of the EA requests relating to the fish pass operation, considering the hydraulic impact of the various options and the effect on energy production and financial returns.
Estimated cost of £2-3k
7.1.2 Construction Costs Typically Design & Build (D&B), contracting with a principal contractor.
The capital costs have been estimated based on:
x Turbine cost = Supplier Quotes + allowances for additional elements such as covers
x Civil works = estimate of scope, and cost for each option. Details included in Appendix F
x Electrical connection = Quote from Northern Power Grid £84k for 100kW option
7.1.2.1 Fish Deterrent or Screening For all Kaplan or axial flow turbine options an allowance of £50k has been made for fish screening. This allowance has also been added to the screw turbine option in Location 4 as a precaution as this has the potential to create a dead end and screening may be required to prevent fish becoming disoriented and missing the fish pass. Further discussion with the EA would clarify if this allowance is required.
7.1.3 Design / Administration Costs An allowance of 10% of the total cost has been made for Contractor’s design and project management of the scheme. The value varies with each option as a proportion of the overall development and construction costs.
7.1.4 Risk No quantified risk allowance has been included in the overall cost assessment. Elements within the civil costs include a level of contingency to account for changes as the design develops.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
7.2 Operation & Maintenance Costs Based on an Archimedes screw turbine the following costs should be expected for maintenance and replacement of equipment over time. For Kaplan turbine alternatives a slightly different set of costs would be expected. Further discussion with potential suppliers would provide more information for Kaplan options.
7.2.1 Routine Maintenance System routine maintenance is likely to include the following:
x Daily or weekly site visits may be required to clear screen. Assume 1 hour per week, £20 per hour.
x Lubrication of the upper bearing – this is done using an automatic greasing system that only requires refilling once per year, taking about 1 hour. Assume £100 per visit.
x Lubrication of generator bearings. This is done once every 6 months using a manual grease gun, taking about 10 minutes. Assume £100 per visit.
x Change gearbox oil. This is done every 2 years or longer if an oil test confirms that the life can be extended at this time. Time required approximately 4 hours, with the cost of the oil itself at approximately £1,600.
x Change hydraulic oil used for sluice gates and brake. Once every 2 years. Time required 2 hours with oil costs of approximately £300.
x Change brake pads when worn. This depends on the frequency of emergency stops, but would typically be every 2 years. Cost approximately £500.
x An annual inspection required by a qualified hydro engineer. Assume £200 per visit.
7.2.2 Overhaul A fund/contingency should be considered to support overhaul of major items of machinery over the lifetime of the project. The following allowances are recommended5:
x Fish bumper replacement every 5 years – allow £500
x Control panel fuses / main breaker replacement every 5 years – allow £600
x Silt clearance from inlet channel every 5 years – allow £3,000
x Generator replacement every 10 years – allow £8,000
x Level sensor replacement every 10 years – allow £700
5 Guidance eon maintenance, replacement and repair is provided by Hexham Rover Hydro http://hexhamriverhydro.files.wordpress.com/2013/06/appendix-16-maintenance-replacement-and-repair.pdf
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
x Brake drum replacement every 10 years – allow £1,200
x Flexible coupling rubber replacement every 10 years – allow £3,000
x Gearbox overhaul every 20 years – allow £9,000
x Control panel drives every 20 years – allow £11,000
x Sluice gate refurbishment every 20 years – allow £10,000
x Curved mesh replacement every 20 years – allow £7,500
x Repair handrail and flooring every 20 years – allow £13,000
x Access road repairs after overhaul access every 5 years – allow £500
7.2.3 Other Costs Insurance will be required for the turbine and associated equipment. It is estimated that around £4,000 should be included in the budget.
Depending on the arrangements of the operating entity Small Business Rate may be applicable.
7.2.4 Total Operational Costs Based on the assumptions of costs and frequencies outlined below the following cost estimates have been made for operation, maintenance and insurance in each year of operation for the 100kW Screw options:
Table 7: 100kW Screw Annual Operation and Maintenance Costs
These estimates of costs per year are used in the financial assessment. A full breakdown can be found in Appendix B2 and a description of the activities and costs required in included in the previous sections. The average annual operation and maintenance cost for the 100kW screw comes in at just under £12,000 (including £4,000 per year insurance).
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
Estimates for the smaller screws and Pit and Axial turbine options are included in Appendix B1. Due to a lack of further detail from suppliers these have been based on the 100kW screw turbine and scaled up or down as appropriate. Scaling and the justification applied are included in the table below:
Table 8: O&M Costs for all Options
Type Rating No. Total Installed Capacity
Scaling Factor
Average Annual
Cost
Assumption
kW - kW % p/kWh
Screw 100 1 100 100% £12,000 Based on the costs outline in Table 7 averaged over the 40
year period
Screw 100 1 100 120% £14,400 As above but for Option 4A
only, as include an extra cost for screen maintenance
Screw 30 1 30 50% £6,000 Some costs will reduce for
smaller components but other remain constant.
Pit 100 1 100 140% £16,800 More complex mechanical components.
Axial 100 1 100 140% £16,800 More complex mechanical
components, two units required but some costs only apply once.
Fish Screening n/a n/a n/a 20% £2,400
Additional allowance for maintenance of fish screens
where required
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
7.3.1 Export Tariff A Power Purchase Agreement with a third party can be used for offsetting their electricity use. The most common route is sale of electricity on the open market (export to ‘grid’).
The sale of energy to the grid is at a guaranteed rate through the Export Tariff, current value 4.77 p/kWh. Other hydro power schemes have reported that agreements have been reached for higher export rates which are negotiated with the energy company. This may also be possible for Boston Spa and should be explored when selecting the energy user.
This information is available directly from Ofgem via the website, which also provides updates on any changes.6
7.3.2 Feed in Tariff The UK government’s Feed-in Tariff (FiT) scheme, introduced in 2010, provides an incentive for renewable energy generation. Generators receive a payment for each unit of electricity generate, and a smaller payment for electricity exported to the grid. The scheme is funded through a levy on electricity suppliers.
Details of how to apply for the FiT (through the ROO-FIT route for hydro schemes) are available on the Ofgem website.7 Additional guidance is also available specifically for community groups.8
Two routes are available –
x Full Accreditation which is for schemes which are already installed and due to be commissioned in the next two months.
x Preliminary Accreditation which is for proposed schemes and allows the owner to get a guaranteed FiT rate once the scheme is installed even if the rate has change in the intervening period.
BSPC should consider applying as soon as possible under the preliminary accreditation which would provide greater certainty of future income. Full accreditation is still required however additional tariff protection is provided.
Guidance for preliminary accreditation is available through Ofgem9. For hydro a two year deadline for commissioning is applied after which the guaranteed rate will expire. Applying too early or changing the scheme between application and construction can invalidate the agreed rate.
The FiT rates increase with inflation each year but are also expected to reduce by a variable percentage each year (depending on the number of schemes
registered/installed in the previous year). Ofgem announced a reduction in the FiT of 10% from 1st October 2014.
This reduced rate stands at 17.75 p/kWh, reduced from 19.72 p/kWh prior to the change.
It is assumed that the FiT rate is reduced by a further 5% in April 2015, but is reduced and 5%for 2016/2017; the estimated FiT rates for the next two financial years are shown in Table 9. These are based on the assumptions stated and if Government Policy changes the FiT rate by a greater or lesser degree there will be a resultant impact on the potential revenue. An assumed RPI of 2.5% has been applied to rates for future years although this too is subject to change.
For the purposes of this assessment it is assumed that the turbine is pre-registered in 2015/16 financial year and therefore eligible for the rates assumed.
Table 9: Feed in Tariff rates
Total Installed Capacity
Current FiT 2014/15 10
p/kWh
Estimated FiT 2015/16 p/kWh
Estimated FiT 2016/17 p/kWh
< 15 kW 19.01 18.51 18.03
15 – 100 kW 17.75 17.28 16.83
100 – 500 kW 14.03 13.66 13.30
7.3.3 Other Revenue In addition to the above sources of income below, ‘capital allowances’ tax relief on company profits may be applicable on the hydropower plant. Most businesses can claim Annual investment allowance (AIA) for expenditure on plant and machinery.
Writing-down allowances (WDA) are also likely to be applicable which are annual allowances that you can claim to reduce or 'write down' any remaining balance of capital expenditure on plant and machinery that you have not already claimed a capital allowance for, referred to as a 'pool' of 'unrelieved' expenditure.11
These are not applicable to all sites and have therefore not been included in this assessment.
7.3.4 Total Revenue Total revenue per kWh is therefore:
x 17.28 p/kWh + 4.77 p/kWh = 22.05 p/kWh for turbines <100kW
For all the turbine types and sizes considered in this assessment total annual revenue has been estimated based on Average, Wet and Dry years as described in Section 4.1.1.
Table 10: Total Revenue
Type Rating No. Total Installed Capacity
FiT Rate 2015/16
Export Rate
Average Annual Revenue
Dry Year
Revenue
Wet Year
Revenue
kW - kW p/kWh p/kWh £ £ £
Screw 100 1 100 17.28 4.77 115,000 88,000 141,000
Screw 30 1 30 17.28 4.77 42,000 31,000 46,000
Pit 100 1 100 17.28 4.77 112,000 84,000 139,000
Axial 100 1 100 17.28 4.77 110,000 82,000 137,000
If the turbine is registered later the FiT rate would potentially drop based on the degression rates. Appropriately timed Preliminary Accreditation for the ROO-FIT scheme would potential reduce the risk of changes to the FiT affecting income.
Bos
ton
Spa
Par
ish
Cou
ncil
Bos
ton
Spa
Hyd
ro P
ower
Pro
ject
Bos
ton
Spa
Hyd
ro F
easi
bilit
y S
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Tabl
e 11
: Cos
ts a
nd R
even
ue
L
ocat
ion
Ass
essm
ent
Cri
teri
a
Loc
atio
n 1
Loc
atio
n 2
Loc
atio
n 3
Loc
atio
n 4
Arc
him
edes
Scr
ew
A –
30k
W
Arc
him
edes
Scr
ew
B –
100
kW
Arc
him
edes
Scr
ew
A –
100
kW
Arc
him
edes
Scr
ew
B –
100
kW K
apla
n Pi
t Tur
bine
A
– 1
00kW
A
rchi
med
es S
crew
B
– 1
00kW
Kap
lan
Pit T
urbi
ne
C -1
00kW
Axi
al
Flow
Tur
bine
1 R
ated
Pow
er o
utpu
t 1
x 10
0kW
1
x 30
kW
1 x
100k
W
1 x
100k
W
1 x
100k
W
1 x
100k
W
1 x
100k
W
1 x
100k
W
2 Es
timat
ed A
nnua
l G
ener
atio
n 50
0,00
0 kW
h 20
0,00
0kW
h 50
0,00
0 kW
h 50
0,00
0 kW
h 51
0,00
0 kW
h 50
0,00
0 kW
h 51
0,00
0 kW
h 50
0,00
0 kW
h
3 Es
timat
ed A
nnua
l R
even
ue
£115
,000
£4
2,00
0 £1
15,0
00
£115
,000
£1
12,0
00
£115
,000
£1
12,0
00
£110
,000
4 Es
timat
ed A
nnua
l M
aint
enan
ce C
osts
£1
2,00
0 £6
,000
£1
2,00
0 £1
2,00
0 £1
6,80
0 £1
4,40
0 £1
6,80
0 £1
6,80
0
5 N
et A
nnua
l Rev
enue
(e
xcl f
inan
ce c
osts
) £1
03,0
00
£36,
000
£103
,000
£1
03,0
00
£95,
200
£100
,600
£9
5,20
0 £9
3,20
0
6 C
apita
l Cos
t - T
urbi
ne
£220
,000
£1
00,0
00
£220
,000
£2
20,0
00
£260
,000
£2
20,0
00
£260
,000
£2
00,0
00
7 C
apita
l Cos
t - C
ivil
Wor
ks
£510
,000
£4
70,0
00
£560
,000
£6
40,0
00
£530
,000
£4
70,0
00
£440
,000
£4
40,0
00
8 El
ectri
cal C
onne
ctio
n C
ost
£84,
000
£84,
000
£84,
000
£84,
000
£84,
000
£84,
000
£84,
000
£84,
000
9 D
evel
opm
ent C
osts
£5
0,00
0 £5
0,00
0 £5
0,00
0 £5
0,00
0 £5
0,00
0 £5
0,00
0 £5
0,00
0 £5
0,00
0
10
Sub-
Tot
al
£864
,000
£7
04,0
00
£914
,000
£9
94,0
00
£924
,000
£8
24,0
00
£834
,000
£7
74,0
00
11
Des
ign
/ Adm
in (1
0%)
£86,
400
£70,
400
£91,
400
£99,
400
£92,
400
£82,
400
£83,
400
£77,
400
12
Tot
al C
apita
l Cos
t £9
50,4
00
£774
,400
£1
,005
,400
£1
,093
,400
£1
,016
,400
£9
06,4
00
£917
,400
£8
51,4
00
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
7.4 Funding Costs A variety of options are available for funding a hydro turbine scheme which leaves a level of uncertainty in the cost of finance for assessing overall financial viability of the project. The options are considered in more detail in Section 8 however for the purposes of the financial assessment three funding options have been considered.
7.4.1 Self Funded If a developer is part of a larger organisation or independently wealthy it may be possible to self fund. In this instance the costs of funding are considered to be zero although in reality it will be an opportunity cost assessment of what return alternative uses of the cash funding could have brought in.
Self funding is uncommon and most developers, including Boston Spa Parish Council would require at least some component of debt or equity.
7.4.2 Debt Funding
BSPC have made enquiries regarding funding and have been provisionally offered a loan with the following terms: Table 12: Borrowing Terms Available
Terms Option 1 Option2
Total Loan Value £500,000 £500,000
Repayment Period 20 years 10 years
Interest Rate 5.5% 5%
Annual Repayment £41,840 £64,752
Total Annuity Repaid £836,793 £647,523
The capital costs remaining once the £500k loan is included are shown in Error! Reference source not found. below. The full calculation of the repayment costs is included in Appendix F2.
Table 13: Debt Funding Costs Option Capital Cost Remaining
At the end of the 20 year repayment period, the ownership of that proportion of the turbine system resides entirely with the developer and all remaining revenues are recovered.
7.4.3 Equity Funding / Community Shares There are a variety of community share schemes which have been used and the terms and conditions vary from project to project. Many are based on a percentage return on the initial investment, and some have a short term delay on payments to enable the turbine developers to get up and running. For this assessment a maximum payment of 3% is assumed.
There are many more options available. BSPC are considering the detail of a number of existing funding schemes separately to this assessment so the two options included here are simply examples to allow comparison with debt funding options.
Assuming that the initial £500k loan is made available the remaining balance is assumed to be raised by community share offers.
The terms of these share offers allow interest to be paid only when sufficient funds are available, therefore there may be years where no payment is made.
Table 14: Community Share Payments Option Capital Cost 3% annual
Annual payments may continue in perpetuity or for a fixed period. The developer does not retain full ownership of the turbine system.
Annual payments for the community share options are generally lower than for a debt funded scheme. The ability of the developer to raise the required funds in a timely fashion will be affected by the terms and conditions of payment established for the community funding options. Many community schemes are delayed by the difficulty in raising funds which may have an impact on potential revenue as FiT rates fall and other subsidy rates are adjusted. There will inevitably be a necessity to compromise to balance costs and timescales of funding.
Boston Spa Parish Council Boston Spa Hydro Power ProjectBoston Spa Hydro Feasibility Study Report
There are also usually terms in community share agreement which allow the developer to pay the 3% only when the income and costs allow. In years where flow is significantly below average or major maintenance is required there may be no payment to shareholders.
7.4.4 Payment Profiles The effects of the source of funding on the long term profitability of a scheme are not just tied in with the interest payments on either the debt or equity obtained. The repayment profiles also affect future profitability. This is particularly important where a scheme relies on the Feed in Tariff for income, because this is only guaranteed for 20 years.
In the 21st year income will drop significantly and if on-going operation, maintenance and administration costs are high enough, the addition of any funding costs on top of that may reduce the income to zero or mean the scheme actually costs more than it delivers. Figure 3 shows revenue, loan repayments and equity payments for Option 2B over a 40 year period.
These are based on the £500k loan offered, both 10 and 20 year payback options, and the remaining funding coming from community shares with a maximum return of 3% interest (payments starting after 2 years).
Figure 3: Payment Profiles
Total Revenue is initially high and rising based on a feed in tariff and energy sale income which adjusts with inflation. After 20 years the income drops to energy sales only (still assumed to increase with inflation).
A debt funded scheme with 20 year payback requires maximum funding costs at the time when income is highest. The equity funded scheme has initially lower payments but with no end date it has the potential to significantly reduce net income once FiT subsidies end.
Most community share schemes do include the option to pay less than the 3% target if the revenues are not sufficient to achieve that level of interest. Repeated
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non-payment of interest may lead some shareholders to request to ‘cash in’ their shares which would incur a cost to the scheme. There is risk associated with all funding sources, having a mixture of funding sources helps to balance the impacts of each.
BSPC will need to consider the impacts of securing loans against a 10 or 20 year payback period. The overall cost of the longer repayments is higher but the initial income and therefore expenditure for community schemes would be higher.
7.5 Financial Returns The financial viability of any scheme depends upon its ability to satisfy those funding it with returns that meet their expectations. The returns in this type of scheme are heavily dependent on the source of funding, both in terms of the balance of debt and equity, and the terms and conditions applied to each. For each different option the capital and maintenance costs required and the revenue received will affect the overall value of the scheme. The following calculations are presented:
x Simple payback – the period it would take to recover investment if the project was cash funded and no discount rate is applied to future revenues. This is often used as a method for high level screening of possible sites/solutions as it is very simple to calculate. This is presented for all options.
x Net present value based on £500k debt funding with the remaining funding raised through community shares paid at 3%. Using standard terms and conditions to estimate the cost of borrowing from a bank or other funder, plus an estimated discount rate applied to future costs & revenues. This is presented for all options.
7.5.1 Simple Payback Simple payback is the first calculation for a high level assessment of viability for an investment, calculated using the equation below:
It simply indicates, with no allowance made for the cost of borrowing or for the discount applied to future earnings and costs, the approximate time it takes to pay for the initial expenditure. It is useful for comparison of options and for ruling out further work where proposals clearly demonstrate extended payback periods. Net Annual revenue is calculated as:
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Table 15 shows that due to the limited variation in cost and revenue between the options, most of the 100kW options have a simple payback within the range 8-10 years. The 30kW option for Location 2, smaller to avoid impact on the Dam House structure, has a much longer simple payback at 19 years. It is clear from this that the smaller turbine is not a viable option; further financial analysis in the following sections confirms this. Table 15: Simple Payback Estimates Option Capital Cost Average Net
Annual Revenue
Simple Payback
1 (100kW Screw) £950,000 £108,000 9.2 years 2A (30kW screw) £774,000 £40,000 21.5 years 2B (100kW screw) £1,005,000 £108,000 9.8 years 3A (100kW screw) £1,093,000 £108,000 10.6 years 3B (100kW Kaplan) £1,016,000 £105,200 10.7 years 4A (100kW screw) £906,000 £105,600 9.0 years 4B (100kW Kaplan) £917,000 £105,200 9.6 years 4C (100kW axial) £851,000 £103,200 9.1 years
7.5.2 Debt and 3% Community Share Funded Assuming the 20 year £500k loan outlined in Section 7.4.2 and the remaining funds raised through community shares with a maximum 3% interest payment the following annual net income is estimated for each of the different options:
As with the simple payback, it is clear that the 30kW turbine is not a viable investment. The potential annual income available for use in community projects ranges from £40-50k pre-tax.
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7.5.3 Net Present Value For each of these options the Net Present Value of the investment has been assessed.
Assumptions are as follows:
x FiT rate 2015/16 applied
x Revenue increases in line with inflation of 2.5%
x £500k loan with terms of 5.5% over 20 years
x Operation and maintenance costs are laid out as per the detailed assessment in Section 7.2.4 and not applied as an average
x Operation and maintenance costs increase in line with inflation of 2.5%
x A 6% discount factor is applied to all future costs and revenues
x NPV is rounded to nearest £1k
The initial capital cost is included for all NPV calculations. For debt repayments only the interest component of the loan repayment is included in the NPV calculation to avoid double counting the initial capital cost. For equity funded schemes the full annual payment is included as the ownership of the asset is never returned to BSPC.
The payback period indicated is the year in which the NPV becomes positive.
The summary for each site is included and then more detail provided for Location 2B. Location 2A has been excluded as it is not a viable options.
7.5.3.1 Location 1 Table 17: Location 1 NPV
Funding Source Net Present Value (40 yr)
Payback
Self Funded £591,000 11-12 years
Debt & Community Shares (3% Payments) £194,000 16-17
For full details of the calculations behind the NPV estimate refer to the spreadsheets in Appendix F3.
7.5.3.2 Location 3A Table 18: Location 3A NPV
Funding Source Net Present Value (40 yr)
Payback
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For full details of the calculations behind the NPV estimate refer to the spreadsheets in Appendix F6.
The impact of the additional capital cost of civil works required for Location 3 is clearly indicated in the lower NPV calculations and the longer payback periods.
7.5.3.3 Location 3B Table 19: Location 3B NPV
Funding Source Net Present Value (40 yr)
Payback
Self Funded £395,000 13-14 years
Debt & Community Shares (3% Payments) -£31,000 23-24 years
For full details of the calculations behind the NPV estimate refer to the spreadsheets in Appendix F7.
The impact of the additional capital cost of civil works required for Location 3 is clearly indicated in the lower NPV calculations and the longer payback periods.
7.5.3.4 Location 4A Table 20: Location 4A NPV
Funding Source Net Present Value (40 yr)
Payback
Self Funded £587,000 10-11 years
Debt & Community Shares (3% Payments) £210,000 15-16 years
For full details of the calculations behind the NPV estimate refer to the spreadsheets in Appendix F8.
The lower civil costs for Location 4 bring the payback periods down and increase the overall value of the scheme over a 40 year period.
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Debt & Community Shares (3% Payments) £112,000 16-17 years
For full details of the calculations behind the NPV estimate refer to the spreadsheets in Appendix F9.
7.5.3.6 Location 4C Table 22: Location 4C NPV
Funding Source Net Present Value (40 yr)
Payback
Self Funded
Debt & Community Shares (3% Payments)
For full details of the calculations behind the NPV estimate refer to the spreadsheets in Appendix F10.
Although the Location 4 solutions show the highest NPV values of all the schemes, 4B&C involve the Kaplan and Axial turbines which involve screening and higher maintenance risks, and 4A is not the ideal position for integration with the fishpass.
The objection of the Environment Agency to this location means that the most financially attractive options are not viable. The option that the EA would accept is Location 2, which although not the best option from a financial point of view, is still viable.
7.5.4 Location 2B Location 2 is the selected option for this site due to the preferences expressed by bother the local planning authority and the EA. That is not to say it is without its risks and complications but there is the possibility of reaching a compromise with other interested parties which will to provide a scheme that satisfies the maximum number of stakeholders.
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For this reason Location 2B has been considered in greater detail. Following the discussions with the EA there is a suggestion that they may wish to see operating conditions that are different from those outlined in the hydropower guidance documents. Full details are included in Appendix F5
The changes requested are discussed elsewhere, however the implications for the financial conditions are the changes to Hands Off Flow and the resulting reduction in energy production and revenue.
Condition 1 - maintain a minimum of 1.27m3/s in the fishpass. Effectively this requires the turbine to remain idle until Q50 or higher. This reduces energy output by 42% from the standard Q95 Hands Off Flow and does not pay back. This option could not be pursued.
Condition 2 – maintain a minimum 300mm depth (h) in the fish pass at all times. This equates approximately to a Hands Off Flow of Q84 and a 12% reduction in energy output. This condition has a significant impact on payback and it would not be recommended to pursue this option.
Condition 3 – potential compromise of 290mm in the fish pass. This would improve downstream migration in the fishpass and potentially removed the need for a notch. This options has not been discussed with the EA but is a suggested option for future negotiations.
As can be seen, the impact of the EA additional requests could be very significant for the overall viability of the scheme and therefore the detailed design will need to develop a solution that can be porposed to the EA which provides an acceptable compromise or achieves their requirements without impacting on the viability of the scheme.
Table 23: Location 2A Detailed NPV
Funding Source Net Present Value (40 yr)
Payback
Self Funded Standard Q95 Hands Off Flow £535,000 12-13 years
20 Yr Debt & Community Shares (3% Payments) - Standard Q95 Hands Off Flow
£114,000 17-18 years
10 Yr Debt & Community Shares (3% Payments) - Standard Q95 Hands Off Flow
£138,000 17-18 years
Condition 1 – Q50 Hands Off Flow -£644,000 -
Condition 2 – Q84 Hands Off Flow -£97,000 -
Condition 3 – Q90 Hands Off Flow £40,000 18-19 years
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The stated intention of the BSPC hydro turbine investment is to provide income that is used for the benefit of the community.
To consider what structures and organisations might be the most suitable for this type of investment experience elsewhere in the UK has been considered. There are many potential structures, as outlined in Appendix I, however many of these are not directly applicable to a community hydro power scheme. So a review of the types of structure used by community schemes has been considered to provide more closely relevant information.
At least 5,000 community energy groups are recorded as active in the UK since 2008.12 Groups vary in size, although many have a small core of dedicated volunteers who organise activities.
Community energy in the UK is currently focused largely on renewable electricity generation, with the most prevalent technologies being solar PV and onshore wind.13
Figure 4: Location of community energy groups in the UK14
8.1 Small Community Hydro Schemes Small scale community hydro schemes are less common than wind or PV due to the more limited opportunities, and restrictions to access to those opportunities for community groups. A number of schemes have been identified which are similar in scope to the potential scheme at Boston Spa.
x Stockport Hydro Ltd (an Industrial and Provident Society for the Benefit of the Community) have developed Stockport Otterspool Weir15 – 68kW
12 Community Energy in the UK: Part 2, DECC, 2014 www.gov.uk/government/publications/community-energy-in-the-uk-part-2 13 Responses from the Call for Evidence, Community Energy in the UK: Part 2, DECC, 2014: https://www.gov.uk/government/publications/community-energy-in-the-uk-part-2 and Local Energy Assessment Fund evaluation, DECC 2014. 14 DECC Community Energy Strategy https://www.gov.uk/government/publications/community-energy-strategy 15 www.stockport-hydro.co.uk
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capacity with two Archimedean screws – funding was obtained from the Regional Development Agency North West Development Agency (now abolished), a community share offer (raised more than £250k) and a bank loan. Minimum investment for the share offer was £250 with tax relief through the government’s Enterprise Investment Scheme (EIS)16 of 30% for investments above £500.
x River Bain Hydro Ltd has been established as an Industrial and Provident Society for the Benefit of the Community in development of the Bainbridge hydro scheme17 – a 45kW Archimedes screw scheme funded through a combination of community shares, grant funding, and a loan from a charity bank. The scheme also secured funding from the Regional Development Agency ‘Yorkshire Forward’ (now abolished), and the ‘Yorkshire Dales National Park Authority’s Sustainable Development Fund’.
x Saddleworth Community Hydro, an Industrial and Provident Society for the Benefit of the Community, has established the Saddleworth Hydro project18 – The first community-owned ‘high head’ scheme in England, crossflow turbine with a capacity of 50kW. A share offer was used to generate £120k.
x Settle Hydro, an Industrial and Provident Society for the Benefit of the Community – A single 46kW Archimedes screw turbine installed in 2009. Two community share issues have been completed, one for the initial funding and one more recently for transfer of debt into shares.
x Harlaw Hydro Ltd, an Industrial and Provident Society for the Benefit of the Community installed a 65kW crossflow turbine – raising £303k through community share offer.
x Abingdon hydro an Industrial and Provident Society for the Benefit of the Community – was set up by local residents to generate hydroelectric power from Archimedes screw turbines.
x Halton Lune Hydro Ltd, an Industrial and Provident Society for the Benefit of the Community – delivering a 160kW Kaplan hydro scheme. The company been set up by Halton Community Association, the initial plan was to convert into a Community Interest Company (CIC) however the conditions of the CIC are more restrictive on the payments allowable to shareholder, therefore the Industrial and Provident Society was selected instead. All profits will go to the Halton Lune Trust, a registered charity for the benefit of the community.
x Ham Hydro, another Industrial and Provident Society for the Benefit of the Community – Archimedes screw scheme using ‘pioneer share offer’ to raise £150k, assisted by ‘Leapfrog’.
x Sheffield Renewables – although the scheme was not completed, the share offer was initially presented on the basis of an Industrial and Provident Society.
x Whalley Community Hydro Ltd (An Industrial and Provident Society for the Benefit of the Community) is another example.
16 EIS is designed to help smaller higher-risk trading companies to raise finance by offering a range of tax reliefs to investors who purchase new shares in those companies. www.hmrc.gov.uk/eis 17 http://riverbainhydro.co.uk 18 www.h2ope.co.uk/index.php/Project/show/saddleworth-hydro
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x The Goring and Streatley Hydro Power Project follows the same pattern.
8.2 Selected Structures All of the hydro scheme reviewed above have selected the legal entity of Industrial and Provident Society for Community Benefit (IPS).
An IPS must be run for the benefit of the community and exists to provide services to people other than its own members. Profits must be invested into the community through the organisation, with restrictions on what return can be distributed to members, usually limited to percentage of their investment. The business involved is required to justify why a Society is more appropriate than registering as a company under the Companies Act.
Some of the organisations listed above have also established a charitable trust to which all profits are transferred for investment. This allows for two separate entities, one focussed on the practical and financial aspects of operating a turbine, and a second which exists solely for the investment of the funds for the charitable causes. This may help separate activities that require different skills and allow more people form the community to contribute.
This Society was administered under the Industrial and Provident Societies Act 1965, which has recently been renamed, and then superseded by the Co-operative and Community Benefit Societies Act 2014. The legal entity would now be called a Registered Society.
Although there is a full and detailed summary of all the potential options for hydro turbine schemes in Appendix I, given the predominance of this form of structure within community hydro schemes (and some wind and PV examples as well) it seems highly likely that this would be the most suitable for Boston Spa.
It is recommended that BSPC carry out further investigation into the appropriateness of this business structure for their needs. It does not appear that any of the schemes identified have a direct link to a Parish Council so there may be differences not accounted for in this review.
Standard sets of Rules for these schemes are available which are acceptable to the Financial Conduct Authority (FCA), these also allow the scheme to be eligible for Enterprise Investment Scheme (EIS) Tax Relief which can provide additional benefit to both the Society and those who invest in shares. Further details are available from the FCA website19 and advice may be available through third party advisors, several of which have links to the schemes listed above and have provided advice on formation of the Society vehicles. A number of these third parties are listed in the summary report of funding and structures in Appendix I.
8.3 Funding Most of these schemes have raised the required finance through a combination of loans and community shares. This balance allows a compromise between the smaller payments required for community shares against the need for quick fundraising which a loan can often provide.
The websites of the various schemes provide an excellent insight into the particular complexities of community shares, management of community schemes and fundraising in general.
Some, once the scheme is up and running, have chosen to issue additional sums of community shares in order to pay off the debt funding early and reduce financial risk. When confirming any loan, early repayment conditions should be reviewed to identify if this is a potential option for later in the scheme.
Many of the groups have also used the assistance of renewable energy promotion or supporting companies who offer loans, grants and advice. Partnership organisations can offer valuable support during the complex process of arranging legal bodies and committing to turbine construction. It is recommended that BSPC investigate potential partners who could offer assistance in this manner.
8.3.1 Grants Grants from public funds will in most cases exclude the recipient from obtaining FiT payments. However there are exemptions including ‘Permitted Grants’ which allow the recipient to claim FiTs. These include funds required for reasonable additional costs of an installation to avoid or mitigate environmental harm20. In the case of hydro power, grants specifically used to fund measures to protect fish or other wildlife would fall under this category.
Advice on the use of grants can be obtained from the Ofgem website. The Energy Saving Trust are promoted by Ofgem as a first point of contact for FiT information and may be able to provide more detailed advice on the use of grants.
9 Scheduling There are a number of key stages required in the continued development of a hydropower scheme. For a community group this process can take much longer than for a commercial entity due to the difficulties in obtaining funding and reliance on volunteers and good will for a lot of the organisation and promotional work required. An approximate timeline for activity is suggested below, however every scheme is different and this is only a guideline. It may be possible to run some of these processes in parallel which reduces the overall timescale.
1. Further Investigations – 6 months (up to 12 months for ecological surveys due to timing required for particular species)
2. Planning Application and Environment Agency Permitting – 3 to 6 months (Discharge of Conditions may occur later after Contractor’s detailed design)
3. Establishing a commercial hydro power entity – 3 to 6 months (estimated)
4. Fundraising – 6 months to two years. Information gathered by Sheffield Renewables and Hexham Hydro schemes indicates that this can take even longer in some cases.
5. Tender Preparation for a Design & Build contract – 3 months
6. Contractor detailed design and procurement – 3 to 6 months
7. Construction – 6 months (see the draft sequence in Figure 6)
An indicative example of how the programme might fit together is shown in Figure 5. This is intended to show how the different items of scope may fit together although in reality there is always a lot more crossover between elements than can be shown on a simple plan such as this.
Ecology surveys are sensitive to the time of year they can be undertaken. These will need to be complete prior to the submission of the planning application and the EA Application and may therefore drive the overall timescale of the process.
It is considered likely that the earliest possible delivery of a turbine for a community scheme is probably two years. Programmes of four to five years are not unusual when community groups take on this kind of challenge.
At Boston Spa one of the significant hurdles often encountered – landownership – is not likely to be an issue as the council are already in possession of the land in question. In many schemes before the planning stage, there would be a protracted period of negotiation required to agree land issues which can add months or years to the process. Avoiding this element of the work reduces the risk of delays due to access rights but does not change any of the obligations to consider other stakeholders.
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10 Conclusions & Recommendations There is a feasible opportunity for development of a hydro turbine at Boston Spa. There is sufficient flow and head for a turbine and there are several configurations which appear to deliver a viable economic solution.
There are some issues which require further investigation to develop this feasibility assessment into a final solution.
10.1 Technical A 100kW turbine is recommended as the most suitable technical solution. It has not been possible to carry out a full survey of the access route so although it is believed that the turbine will fit, it is recommended that a survey is completed. This will confirm the size and specification of the turbine and give indication of any special requirements for the delivery process.
The design of the electrical connection to grid is currently only a budget quote and included a pole mounted transformer on the river bank. There may be difficulties with the presence of trees and also the aesthetics of the transformer. It is suggested that during detailed design further discussion is held with NPG to develop the design for the electrical connection.
The turbine building is located in a functioning flood plain. The building should be designed to be protected against a 1 in 200 flood level. Consultation with the EA and potentially modelling to determine the design level will be required.
There have been reports of changes to the flow regime within the river since the installation of the fishpass leading to new erosion hotspots and swirl patterns at high flows. It is recommended that physical modelling is carried out to analyse the impact of the changing flow regime over the weir on erosion and fishpass operation.
10.2 Environmental The impact of the EA requests for fish pass integration are a critical condition for the viability of this scheme. It is recommended that this is reviewed in more detail and the impact of the different options for upstream and downstream migration, turbine operation and if a notch is required, safety, access and maintenance.
A small number of environmental surveys are recommended to determine if protected species are likely to be affected by the works. It is recommended that an ecologist is employed to carry out the surveys at an appropriate time.
Invasive species Himalayan Balsam has been identified in the vicinity of the potential development. It is recommended that this is treated for removal or carefully managed during construction.
A WFD assessment including a geomorphological assessment is required to identify any changes to sediment and habitats which would impact on the ecology of the river. This is required by the EA and also links with a requirement to investigate the potential impact of scour created by the changing flow patterns.
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10.3 Economic The costs, revenues and financial returns presented in this feasibility study are based on an initial design and estimate of the scope and costs. To determine the most viable solution requires further design to clarify scope and make more precise cost estimates. It also requires a more detailed assessment of the options of financial resourcing for the scheme from both debt and equity resources available to BSPC.
Further consideration is required into the different types of organisations and structures which could be used to manage the turbine construction and operation. The Registered Society option seems the most common for this type of scheme but alternatives may also be suitable. The costs and resources required for different types of organisation will vary and some may suit BSPC and the community they are serving better than others. BSPC are not able to take on the responsibility for constructing and operating the turbine directly, and most public feedback indicated a preference that the two functions were kept separate and the turbine was not allowed to distract from the normal work of the parish council.
10.4 Heritage The impact on Holgate Lane and Dam House is of considerable importance to local heritage groups and enthusiasts. The options acceptable to the EA and planning authority do have a significant impact on Dam House which would be permanent. Detailed design should consider in greater depth the potential for minimising the impact on the existing structure, re-using the component parts and incorporating design features which reference the history of the site.
10.5 Social There is significant support for a hydro turbine scheme within the local community. Key concerns are aesthetics, noise and impact on amenities such as angling, walking and canoeing.
There is potential for designing a scheme that benefits the local community and amenity users. It is recommended that BSPC continue to engage directly with amenity groups and provide opportunities for them to contribute to the discussion and design.
The property owners on the opposite bank need to be included in on-going design development and their concerns relating to the turbine addressed directly and carefully.
10.6 Planning & Permitting During the investigation, ownership of the land has been established. It was unclear from both a Land Registry search and from BSPC’s own records what party owns Holgate Lane. It may be worth doing a little further investigation to be sure there are no unexpected issues relating to this access route.
An initial opinion has been sought from the planning department of Leeds City Council. Of the locations considered, option 2 was the council’s preferred
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solution. The full response from the planning department can be found in Appendix C1
Hydropower Pre-Application forms have been submitted to the Environment Agency for review. A full response from the EA is included in Appendix C3. A number of critical operating details will need to be determined before the full application can be submitted particularly in relation to the fish pass operation and the additional requests made by the fisheries team.
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11 Key Actions All the next steps of investigation and design will incur cost. Prior to embarking on any further work BSPC will need to identify and secure funding such as the WRAP stage 2 loan, which could enable the council to take the recommendations forward.
Critical to the financial performance of the scheme will be the EA requirements regarding fish passage implications. A design review of the requests made regarding fish pass flow rates and water depths will be required to present a scheme design that is capable of satisfying the fisheries team and providing a viable return on investment.
The investigations and surveys highlighted in this report require approximately £50k of expenditure for the list of studies included in Section 7.1.1. There may also be a need for additional design work to incorporate the results of those investigations into the current proposals or modify the proposals to suit.
It is recommended that BSPC engage with potential funders to determine their requirements for the second stage of study and tailor the work recommended here to satisfy any criteria that may be associated with the loans offered.
Appendix A
Site Drawing
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