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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