Microrenewables

Kevin LindegaardRenewable Energy Development Officer

Dorset County Council24 April 2007

Microrenewables

Heating• Solar water heating• Heat pumps• Pellet and log boilers

Electricity• Photovoltaics (PV)• Small scale wind turbines• Micro hydro

Energy basics

• Unit of power is the Watt (W)

• 1 kW = 1000 W

• To convert power to energy multiply by number of hours

• Using a 100 watt bulb for 10 hours

= 1000 Watt hours = 1kWh

Domestic energy use

• Electricity = 2,500 - 5,000 kWh

• Gas = 8,000-25,000 kWh

• Oil = 4,000 litres

Energy Use in the Home

Hot water24%

Lights and appliances

13%

Cooking 5%

Heating 58%

1 kWh of electricity costs 10p 1 kWh of gas = 2.5p1 kWh of oil = 4p

Solar Water Heating

Flat plate Evacuated tubeUnglazed

Increasing efficiency/cost

Domestic systems

• 50% of hot water needs overall• 80-100% of needs in summer • 3-4m2 array • Roof should face between SE and

SW and avoid shading• 35-45° pitched roof or mounted on A-

frames• Need to have new hot water tank• 1500-2000 kWh/year• 20-30 years useful life

What does it cost?

Technology Installation 2 m2 3 m2 4 m2 6 m2

Flat plate

Closed

Installer / £3,150 £4,200 £5,000

DIY / / £1,500 £2,500

Open(direct)

Installer / £3,400 / /

DIY / £2,500/ /

Evacuated tube

Installer £4,200 £5,500 / /

DIY £2,115 /

DIY = VAT @ 17.5% and no grant Installer = VAT @ 5% and £400 grant

What is the pay back?

• Savings are best in off-gas areas

• Long paybacks but fossil fuel prices increasing

Pay back*

DIY 9 years

Flat plate 17 years

Evacuated tube

31 years

* Based on replacing on peak electricity saving £162 per annum

Opportunities

• Domestic hot water (not heating)

• New build eco homes

• B&B, hotels

• Swimming pools

• Campsites

Heat Pumps

• Ground source

• Air source

• Water source

•Harness solar energy stored •in ground, air or water sources•Uses electricity to drivecompressor to raise heat to useful temperature •1 kWh of electricity in provides •about 3-4kWh of useful heating

Options

• Provides space &/or DHW, (potential also for summer cooling)

• Best niche is new build, because:

- Well insulated

- Combine with other works

- Best with under floor heating• Limited visual impact

What does it cost?

Cost including distribution system

Grant

8 kW Ground source HP

£10,000 -13,000 £1200

7 kW Air source HP

£6,000 £0

8 kW Water Source HP

£6,500 £0

Pay back ~15-20 years

Biomass heating

Rika Thermia

Room heater

Boilers

Stove with back boiler

ExtraflameÖkofen

KWB

Herz

Kalorina

Heating with wood pellets

• Room heaters or back boilers

• 3 times greater density than wood chip

• Flowable

• Cheaper to transport than other biomass

• Compact and clean handling (dust free) for domestic market

• Automatic ignition and feed

• Cope with variable load demands

and can be operated on a timer

• Integral hopper

• Very efficient with low emissions

Showstoppers?

• Need space for fuel storage• Good access for deliveries• Bulk buying is best - bagged pellets are

2x the price ofbulk deliveries

• More hands on• Ash removal

Vigas

Froling

Pyromat

Log boilers

Log boilers

Vigas 25 boiler• Very efficient and as sensitive and

controllable as an oil boiler• 120-litre log magazine - stores enough

logs for about 14 hours burning • 4 kg/hour and will use about 12 tonnes

or 25 m3 of cut logs per year • Hands on – manual filling• £4,500 (£5,300 with 1000 litre

accumulator tank)

25 year fuel costs

Fuel type Unit cost 25 year cost*

Heating oil 40p litre £40,714

Gas 2.5p/kWh £18,750

Wood pellet £160 tonne £24,000

Grain £85 tonne £15,300

Logs £80 tonne £14,100

* Based on annual fuel usage of 30,000 kWh

How much do they cost ?

Fuel type Boiler make and model

Approx cost inc installation

Wood pellet Okofen 25 kW £15,000

Grain Kalorina 25 kW £7,000

Logs Vigas 25 kW £4,500

£1500 grant availablePay back 5-15 years versus oil

Photovoltaics (PV)

Polycrystalline SiThin Film

Increasing efficiency/cost

Monocrystalline Si

Photovoltaics (PV)• Use semi-conductor cells to convert light

into electricity

• Inverter turns direct current (DC) into alternating current (AC) which can be used or sold to the grid

• Low maintenance, with 25 year lifespan

• Can be roof mounted (bolt-on)

or roof integrated

• Work best in direct sunlight

- need to avoid shading

• Remote applications

PV Domestic system

• 1.5-2kWp

• 12-24 modules area of 12-40m2

• 1500 kWh/year

• £12-14,000

• 30% grant available

• Lifestyle changes

• 800 kWh per annum would save about £96 per annum against buying electricity from the grid – no pay back

Roof mounted wind

• Need to be on high buildings• Designed to work in turbulent

conditions• Limited planning issues in

non listed buildings• Wind speeds avg 3.5 m/s• 1.5 kW – supposedly

produces 1000 kWh p/a Windsave 1 kW

Swift 1.5 kW

What does it cost?

Rotor (M)

Rated power

Power output p.a. at Total cost

inc. installation

LCBP Grant 5.0

m/s5.5 m/s

Windsave 1.75 1000W883 kWh

1,000 kWh

£1,600 £480

Swift 2.1 1500W1,031 kWh

1,307 kWh

£4,500-£6500

£1,350

Pay back ?

Stand alone wind turbines

Iskra 5 kW

Proven 2.5 -15 kW

Costs, outputs and sizes

Proven

2.5 kW

Proven

6 kW

Iskra

5 kW

Price inc installation £14,000 £21,000 £18,000

Grant £2,500 £5,000 £5,000

Tower height (m) 6.5 or 11 9 or 15 12 or 15

Blade diameter (m) 3.5 5.5 5.7

Output (kWh/yr) 3,500 at 5 ms

10,000 at 5 ms

5,000 at 4 ms

Pay back ~11 years

Micro Hydro

• Run of river schemes e.g. historic

water mills or hilly areas with spring

fed streams

• Generally < 100 kW

• Can be used in rivers with as little

as 1m heads

• Most cost effective of all renewable

resources where suitable sites exist

How it works

Micro Hydro – pros & cons

Weirs and leats are in many cases still usable Zero annual fuel costs & low running costs Long lifetime - generator (15 yrs), turbine (25yrs) High reliability and availability High load factor (50-70%) Reasonable pay back period (<10 years) River flow rates vary so low output in summer Grid connections can be expensive Low electricity prices paid to small producers Planning

How much does it cost?

• Installation costs ≈ £2000/kW

• A 10 kW system would cost £20,000

• LCBP grant - max of £5000

• Payback = 9.5 years

More information

• Low Carbon Buildings Programmewww.lowcarbonbuildings.org.uk

• Energy Saving Trust case studieswww.est.org.uk/myhome

• Dorset Energy Groupwww.dorsetforyou.com/climatechange

• Renewable Energy Associationwww.r-e-a.net

More information

• Solar Trade Association www.greenenergy.org.uk/sta • Ground Source Heat Pump Association

www.nef.org.uk/gshp • British Wind Energy Association

www.bwea.com/small • British Hydropower Association

www.british-hydro.org • Biomass Energy Centre

www.biomassenergycentre.org.uk 01420 526197• Woodfuel South West Advice Service

08450 740674• Woodfuel suppliers

www.logpile.co.uk 01908 665555