Renewable Firewood Stoves; a community approach to
widespread installation and fuelling suitable for future
inclusion in the RHIJeremy Thorp
Cwm Harry28th March 2012
Project Funding and timescales
• This project has been funded through the LEAF project (Local Energy Assessment Fund) set up by DECC and administered through the Energy Saving Trust.
• Funding was confirmed on 7th February, and the project had to be complete by the end of the Financial year (31st March)
Project team
Cwm Harry Project management and direction
Chris Laughton, Rob Gwillim,
Jacinta Macdermot
Stove monitoring techniques
Shareenergy (Jon Halle) & ROCBF
(Mick Brown)
Business and financial modelling
HES (Alison Davies, Dave Luckhurst) User focus groups
Establishing potential demand
Coed Cymru (David Jenkins) Supply options and constraints
Derwas Ltd Stove supply and installations
Why?
• Non-domestic Renewable Heating Incentive (RHI) offers 7.6p/kWh to users of log batch boilers, wood pellet boilers and wood chip boilers but not log stoves.
• Domestic RHI (phase 2) due to be introduced Summer 2013
• Phase 2 expected to exclude wood stoves same as phase 1
Why are log stoves excluded?
1. Difficult to measure heat output2. Difficult to establish sustainability of fuel
supply
1. Difficult to measure heat output• RHI is based on total heat delivered. For pellet
stoves, chip stoves etc, delivered heat would be measured using heat meter in hot water pipes
• Log stoves deliver most heat as radiant – more difficult to measure
• Deemed heat – difficult as log stoves often used as supplementary heating
2. Difficult to establish sustainability of fuel supply
• DECC argue that you cannot ensure that users are not burning coal (or other non-sustainable fuel) on a log stove
Solutions:1. Measurement of heat output
• Is direct measurement possible?• Can we produce a look-up
table to convert between something measurable (e.g. Flue surface temperature) and heat output?
• Experiments have been carried out to investigate this possibility (see separate presentation)
Solutions:1. Measurement of heat output
• Are there alternative ways of measuring heat output?
• Can we deduce from fuel input an assumption on efficiency of burn?
• How could this be set up in an auditable way?
Measuring fuel use
• Set up company (ESCo) which can take out a long term contract with the client
• Volume of wood delivered would be auditable• Demonstrates proof also of the sustainability
of supply (as long as the ESCo can demonstrate it purchases from sustainable sources)
Measuring fuel use• Could either measure at household level or at
ESCo level• At household level – need accurate data on
weight, species, water content, of each batch delivered
• At ESCo level, only need to prove gross weight, species, etc for supplies coming into the ESCo
• ESCo could receive the RHI on behalf of households, and distribute to them
Measuring fuel input
• The household would have to have a new efficient stove installed by the ESCo to qualify
• The ESCo would install the stove, provide training on use, maintain (sweep chimney) once a year and contract to provide wood for 10 year period
What is the price of log fuel?
• What is the price of heat from logs (compared to oil and gas)
• Does it need a subsidy from RHI, and if so, how much?
• What is the price elasticity?• What is the aesthetic value of a log fire? • What is the “nuisance” cost of lighting it?
What price are logs?
• “Farm gate” price of 5p – 8p/kWh (based on 1m3 bag of hardwood at £37.50 and 1m3 softwood at £27.50)• (Assumes overall efficiency of stove of 50%)
• Need approx 7.6p/kWh (to achieve same income per acre as rent from grass keep)
Public acceptance
• Set up user focus groups• Address questions such as:
• Convenience compared to oil/gas• Reliability of fuel supplies (wood and oil/gas)• Storage of wood fuel
• Question? How do we attribute a price to side issues such as the aesthetic attraction, the inconvenience factor, the carbon reduction effect?
Evidence from focus groups• The majority want to use wood for the following reasons:
• cost, personal satisfaction, environmental benefits
• Of particular interest is the agreement that they all felt a sense of satisfaction / a relationship with their stove and wood fuel and enjoyed the process
• Questions to address in the second group: • Options for “firewood club”, (ESCO / Co-op...)• Discuss options for storage at scale• Cost of keeping warm• Barriers to change
• Skills e.g. lighting fires• Rented accommodation• Alternative uses of the heat • Expert advice on installation, fuel and maintenance
Focus group feedback• People want to be actively engaged, not at a distance
as they are with oil and gas where delivery is in someone else's hands leaving the home owner out of control
• Importance of price for wood fuel, • Awareness of how to use wood heating most
effectively, etc
Supply versus demand
• What is the potential volume of wood fuel available for household use in the UK?
• How many households would a log stove be appropriate for?
What is the potential volume of wood fuel available for household use in the UK?
• How much fuel wood could be obtained from existing sustainable sources?
• Address issues of:• Alternative uses of timber (saw-wood, mdf production)• Need to maximise value obtained from woodland• Use of the waste stream (equal in size to home grown
timber)• Large quantities currently used for dual-firing of coal
fired power station
What is the potential volume of wood fuel available for household use in the UK?
• UK total woodland area 3,078,000 hectares• (870,000 managed by Forestry Commission)• Total harvest 9.5 million green tonnes coniferous, 0.5
million tonnes broadleaf timber• = 3.25 green tonnes /ha/yr• State forest in Wales 7.5 green tonnes /ha/yr• Hence theoretical additional 4.25 green tonnes/ha/yr
from 3,002,000 hectares = 12 million green tonnes per year = 19 million Mwh = 0.6 million homes
Supply• For Powys 75,083 hectares of woodland• Survey indicates woodlands are adequately
but not heavily stocked• Suggest 4.2 m3/yr could be harvested, of
which, 40% is firewood.• Suggest county yield of 80,000 m3 hardwood
and 400,000 m3 softwood suitable for firewood
• Off the mains gas grid• Demographics – (<70 yrs, disabilities etc)• Logistics (can a flue be installed, is there room
for a stove, storage space for fuel, not high-rise flats etc)
• What is the typical carbon saving per household?
How many households would a log stove be appropriate for?
Carbon saving from households
• Estimate of 21% of households not on mains gas grid could benefit from installation of a log stove
• Estimate 5m3 of dry logs used in average dwelling
• Estimate 2.5 tonnes CO2 saving per household
• National potential – 2 million tonnes carbon saving per annum
6 models
1a No RHI, Green Deal funding for stove installation
1b No RHI, private loan fund for stove installation
1c No RHI, log fuel supply only
2a RHI certification obtained on stoves
2b RHI certified log fuel
2c RHI certified co-operative ESCo model
No RHI
With RHI
Model maps
Fuel supplier
Social Enterprise
Heat user
Government
ContractsGoods
Money
1a: No RHI, Green Deal funding for stove installation
Fuel supplier
Social Enterprise
Heat user
Government
Sup
ply
of
sto
ve
Fuel supply
Payments for fuel + Green Deal chargeP
aym
ents
ba
sed
On
fuel
usa
ge
Payments based on fuel usage, passed on
Green deal agreement
ContractsGoods
Money
Gre
en d
eal
agre
eme
nt
Green deal agreement
1b: no RHI, private loan fund for stove installation
Fuel supplier
Social Enterprise
Heat user
Initi
al
loan
Fuel supply
Payments for fuel
Reg
ular
loa
n re
paym
ent
s
Loa
n ag
reem
ent
ContractsGoods
Money
Sup
ply
of
sto
ve
1c: no RHI, fuel supply only
Fuel supplier
Social Enterprise
Heat userFuel supply
Payments for fuel
ContractsGoods
Money
Fuel supply contract
Payments for fuel
2a : RHI certification obtained on stoves
Fuel supplier
Social Enterprise
Heat user
Government
Purchase of stove
Fuel supply
RHI Payments basedon heat usage
Lea
se
ContractsGoods
Money
Stove supplier
Installation of stoveRHI accreditation
Purchase of fuel
RHI registration
2b : RHI certified log fuel
Fuel supplier
Social Enterprise
Heat user
Government
Purchase of stove
Fuel supply
Pur
cha
se o
f fu
el
RHI Payments basedon fuel usage
ContractsGoods
Money
Stove supplier
Installation of stove
RHI registration
Fuel supply contract
RH
I ac
cre
dita
tion
Pos
sibl
e R
HI
accr
edita
tion
2c : RHI certified log fuel ESCo model
Fuel supplier
Social Enterprise
Heat user
Government
Purchase of stove
Fuel supply
Pay
men
ts b
ase
d O
n he
at
usag
e
RHI Payments basedon heat usage
ES
Co
cont
ract
ContractsGoods
Money
Stove supplier
Installation of stove
RHI registration
Purchase of fuel
For each model:
Is it viable - worth pursuing?
What are the barriers/hurdles to pursuing this?
1a No RHI, Green Deal funding for stove installation
1b No RHI, private loan fund for stove installation
1c No RHI, log fuel supply only
2a RHI certification obtained on stoves
2b RHI certified log fuel
2c RHI certified co-operative ESCo model
No RHI
With RHI