Environmental Information Exchange

Renewable sources of energy

Source of energy that are naturally replenished are an important factor in reducing carbon emissions in the UK.  In the future energy will be generated by a combination of methods both on a national and local scale.  Organisations, however, might consider what renewable energy options may be suitable for their premises, building, and operations.  As always, renewable solutions are secondary to the reduction of wasted energy through efficiency actions.

Solar Photovoltaic (PV)

Requires daylight (not direct sunlight) to transform solar radiation directly into electricity to run appliances and lighting. PV systems can be used on buildings with roofs or walls facing within 90 degrees of south as long as no other buildings or trees overshadow it, as this would decrease output. The panels are costly, heavy and require a strong roof to take their weight with size of panels needed dictated by the amount of electricity required. Grid connected systems require little maintenance and generally involve only cleaning the panels while stand alone systems require maintenance on other system components such as batteries.

Ground Source Heat Pumps

Uses buried loops to tap into heat stored in the earth from the sun's radiation and transfer it into buildings to provide space heating and in some cases pre-heat domestic hot water. When getting a ground source heat pump, it is important to take into account:
- The amount of space available
- The suitability of the ground for digging trenches or boreholes.
- The fuel type being replaced, the heat distribution system, and insulation measures already in place, in order to maximise savings and increase the system’s efficiency.
Ground source heat pumps have high installation costs but relatively low maintenance costs. As electricity is used to power the pumps, it is advisable to have a back up system in place.

Biomass boilers

Burns straw, logs or wood chips and are especially attractive for businesses generating these as by-products to produce plentiful heat and hot water. Installation costs depend on size of burner, type of fuel used and amount of automation of system.

Solar water heating This technology transfers solar radiation into water to increase its temperature.  There are different technologies and water can be boosted to hotter temperatures using an emersion heater.  As with solar PV panels, orientation of the panels need to be optimised for sun exposure.  Installation is expensive, so the best payback is realised at sites with high daytime demand for hot water.
Air source heat pumps Air source heat pumps extract energy from the air by transferring heat stored in the air and boosting it through compression of a liquid. This is passed on either to a radiating heat system or a warm air system.  Energy in air is constantly replenished and present even at temperatures below freezing.  Air source heat pumps are most efficient in well insulated buildings, particularly when replacing a more costly form of heating such as electricity or solid fuels.

Wind power

Roof mounted turbines can be installed on buildings and vary in size and power output. Electricity generated by wind turbines is highly dependent on the speed and direction of wind - the greater the wind speed, the more electricity will be generated and the faster the investment will be paid off. It is advisable to undertake a professional assessment of local wind speeds for at least one year before putting up a wind turbine which is a difficult, expensive and time consuming venture.