Sustainable Energy Management Options for Totara Bank

Project for Master of Technology: MUCER

Mandy Armstrong

Project Intent

• Provide a decision-support framework for investment in sustainable distributed generation energy systems for a multi-lot development

• Establish the significant criteria influencing the economic, environmental & social viability of a net-billed system (look beyond ‘payback’)

• Identify the best mix of energy-use options, including the impact of energy-efficient house design on system performance

2

Totara Bank Energy Concept

• All lots are designed to make maximum use of solar energy• Coppicing firewood is provided for heating energy.• Building Performance Indexes are specified by floor area to

maximise energy efficient design• Each lot is limited to maximum current of 30A & 1

switchboard.• The site is designed with each lot connected to an internal

grid, with 1 ICP connecting Totara Bank to the network.• Reconciliation of energy use will be done through Residents

Association rules.

3

Decision Support Framework - Structure

4

Energy Balance Inputs

• Demand data (10min) supplied from Beacon/BRANZ monitoring of an Auckland house (energy efficient)

• Climate translation analysis using ALF 3.1 to assess likely heating requirements for the Wairarapa– Assumed morning & evening heating, to a minimum of

15oC; with kWh/day based on calculated AHE’s for May-September

• NIWA Cliflo data (hrly) used for radiation & wind supply• Hourly Energy Balances done for February & July only, for one

lot.• More fine tuning needed!

5

Energy Balance - Summer

6

2.5kW Proven turbine

Energy Balance - Winter

7

2.5kW Proven turbine

Peak Demand: 2.8 kW, 9.30 am!

Data Analysis Considerations

• Although a detailed data set has been used, it is only for one house.– Other data sources include HEEP & another Wairarapa house

• Considering electricity-based load only; (direct use of gas can reduce electricity demand yet still contribute to total energy demand)

• Behaviour assumptions have to be made – as important as appliances & heating. – Peak is lower than expected, but daily use is higher. Why?

• Energy Balances then rolled up for 8 lots

8

Connection Scenarios

1.Radial connection/embedded network– Each lot as individual generators with own grid connection

& I-E meters– Baseline scenario (current standard practise)

Individual Network connections at boundary

Flow in both directions

I-E

I-E I-E

I-E

Generation area

9

Network

Connection Scenarios

2.Internal Loop connection – Individual lot generator, single grid connection– Customer network

I-E

I-E

Flow in both directions

Generation area

Lot surplus ‘sold’/distributed to other lots as first priority; then exported to network

I-EI-E

I-E

10

Network connection at boundary

Connection Scenarios

3.Internal Loop connection – Whole site as generator, single grid connection– Customer network

I-E

I-E

Flow in both directions

Generation area - supply connected to each lot

Lot surplus ‘sold’ to other lots as first priority; then exported to network

I-E

I-E

I-El

11

Network connection at boundary

Connection Scenarios

4.Internal Loop connection – Individual lot generator plus whole site generation, single

grid connection– Customer network

I-E

I-E

Flow in both directions

Generation areaSupply connected to each lot

Lot surplus ‘sold’ to other lots as first priority; then exported to network

I-EI-E

I_E

12

Network connection at boundary

Connection Issues

• There won’t be much economic benefit from net-billing in the short term if not enough excess energy (unless can somehow supply back at peak times) ref to Anita’s data!

• Meter technology is changing rapidly, although NZ is still lagging in use of smart meters:– Lease rather than own– TOU is possible, but not common or encouraged– A customer network also requires data logger system– Interface with the retailer an issue for customer to access data– Data access from TOU meters is the best way to manage load, but will be

interesting to achieve...

• Current smart meter initiatives focussed on benefits to the retail supply chain

13

Energy Model Next Steps

• Confirm proportion of load to be met by available resources, as well as considering:– How much to invest in PV &/or future generation options?– Is storage desirable for the long-term?– What about genset? What about charging electric cars?

• Explore further opportunities to manage demand profile & reduce overall demand– Work on an “ideal” demand profile for future dwellings

• Start talking about costs, issues, opportunities etc for the connection scenarios with lines company, meter suppliers, test houses & retailers

14