Solar PV cells - detailed briefing available

Photo-voltaic cells are made up of a couple of layers of a semi-conducting material. When solar energy from the sun hits the cells, it creates an electric field across the layers, which causes electricity to flow. In Glasgow, Queen's Cross Housing Association, with solar power company solarcentury, has fitted PV cells in developments in north-west Glasgow, which it estimates will cut resident's electricity bills by around 75%.

Costs and grants:Costs can be around £4,000 - £9,000 per kWp installed, with mostdomestic systems usually between 1.5 and 2 kWp. Funding up to a maximumof £15,000 subject to an overall 50% limit of the installed cost(exclusive of VAT) from the government's Low Carbon Building Programme.

Useful links: Low carbon buildings programme • solarcentury • SCHRI

Solar water heating - detailed briefing available

Solar panels fitted to the roof retain heat and transfer it to a fluid, which then heats water in a hot water tank. You may be surprised to learn that Scotland is one of the best suited places in Europe for this type of technology. The Bridge of Don Academy in Aberdeen has the UK's largest solar energy system heating the school swimming pool.

Costs and grants: Around £2,000 for a flat-plate collector solar water heating which should halve the water heating bills of a typical house. Grants for up to 30% of the cost (up to £4,000) are available from the Scottish Community Renewables Council (SCHRI) for fully-installed systems.

Useful links: Solartwin • Solheat • SCHRI • Soar Trade Assocation

Wind turbines - detailed briefing available

These generate power by converting kinetic energy from the wind into rotating shaft power, which in turn generates electricity. Turbinesvary in size and power and can be mounted on a building orfreestanding. Some models plug directly in to the circuitry of thehouse while others can be linked up to the electricty meter allowingexcess electricity to be returned to the grid.

Costs and grants:From around £1,500 for a small rooftop system (which would power a TV,DVD player, computer, fridge, freezer and several lights) to between£4,000 and £18,000 for fully-installed systems to meet the needs of ahousehold or community building. Grants of one third of the cost (up toa maximum of £4,000) are available to householders from SCHRI.

Useful links: Proven Energy • Windsave • Renewable Devices • SCHRI

Hydropower

Produces power by converting potential energy stored in water held at height to turn a turbine that then produces electricity. As this requires an existing body of water, it is more suited to rural areas.

Costs and grants: Hydro costs are very site-specific but household size systems from an existing water source can cost from £4,000 upwards depending on scale. Hydro schemes are eligible for SCHRI grants.

Useful links: British Hydropower Association • SCHRI

Ground source - detailed briefing available

A ground loop, made of lengths of pipe buried in the ground, is filled with a mixture of water and antifreeze, which is pumped round the pipe absorbing heat from the ground and transferring it to a hot water tank. The tank feeds the distribution system, which can be underfloor heating, radiators or water storage for hot water supply. Orkney Housing Association has installed ICE Energy heat pumps to power underfloor heating and water heating in 19 flats in Kirkwall, reducing CO2 emissions by 75%.

Costs and grants: Costs vary depending on the property, location and type of system. A typical household system could cost between £6,000 - £10,000 plus the cost of connection to the distribution system. Ground source heat pumps are eligible for SCHRI grants.

Useful links: UK Heat Pump Network • Earthwise • Heat Pump Association • SCHRI

Biomass - detailed briefing available

Burning of organic matter, such as wood, animal or food processing waste. For households, wood is usually used. Wood pellets, chips or logs are burned in either a stand-alone stove or boiler connected to central heating and hot water systems.

Costs and grants: Fully installed stand-alone room heaters cost from £1,500-£3,000. A 20kW pellet boiler (the average size needed for a three bed semi-detached house) is around £5,000. Biomass boilers are eligible for SCHRI grants.

Useful links: Use woodfuel • The Log Pile • British Biofuels • SCHRI