Posted by: dorsetcpre | September 30, 2010

RENEWABLE ENERGY

Dorset County Council are currently refreshing the Bournemouth, Dorset, and Poole renewable energy strategy to bring it up to date. The public consultation period runs from June to September 2011 and the documents can be found on the Dorset County Council’s website http://www.dorsetforyou.com/402620.

A large scale photovoltaic array

A large scale photovoltaic array

What is Renewable Energy?

Renewable energies are those where the fuel is replenished at about the same rate as it is used up. Their use adds little or no carbon dioxide to the atmosphere and they are thus described as being carbon neutral. They include solar, tidal, wave, biomass and wind, all of which are produced directly or indirectly by the sun, together with tidal and geothermal energies.

Natural reserves of oil, gas and coal, now largely imported from abroad, have been rapidly used up over the past two hundred years. These supplies will not last indefinitely and burning all this carbon has added substantially to the amount of carbon dioxide in the earth’s atmosphere.

Saving Energy in the home Most of the energy in the home is used for space heating and hot water. We can all save energy with loft and cavity wall insulation, double glazing, thick carpets and draught proofing. AA-rated white goods and low-energy light bulbs can also help. Each will save money, and generally make the house more comfortable.

Solar energy The passive solar design of a new building to a preferred orientation and with solar glass will reduce energy consumption throughout the life of the building.

Solar thermal systems Flat plate or evacuated tube collectors use the sun to heat domestic water and swimming pools. Dorset has some of the best sunshine in the country and large numbers of these can be seen everywhere.

Solar photovoltaics Several varieties of silicon semi-conducting cells are used to convert light into electricity. There are no moving parts, no noise and the new Feed In Tariff gives a fair return on the, substantial, investment. An inverter is needed to convert DC power into AC.

A biomass burner with a big hopper and a screw-thread fuel feed

A biomass burner with a big hopper and a screw-thread fuel feed

Biomass is an all-embracing term for any sort of organic replenishable material for use in a boiler. Examples include dead trees and fallen timber, wood chips, grain, and willow coppice or miscanthus grown for the purpose. Carbon dioxide is produced during combustion but absorbed by the new trees planted to replace those being burned. Animal waste and domestic waste can also be used as fuel. Domestic wood burners are very popular, and larger plants include the proposed Combined Heat and Power plant at Dorset Green and a variety of incinerators used by local councils for domestic waste.

Anaerobic Digestion Food waste can be digested anaerobically to produce heat for the production of electricity.

Methane can be collected from landfill sites and burned in a heat engine to produce electricity.

Winds are caused by uneven solar heating of the lands and the seas. Wind power can be used to turn a small domestic windmill or a large industrial wind turbine but the power is intermittent and totally unpredictable.

Waves are created by winds, and a plastic pumping engine has been developed which is self lubricating and not corroded by sea water. It will pump water up to a reservoir at about one hundred feet, which can then drive a turbine to produce electricity.       

Hydroelectricity is produced on a relatively large scale with dams and turbines. It can also be produced with modern turbines on our rivers especially at the sites of old water mills where some of the infrastructure is still in place. Some have been built in Somerset and the Stour Vale Hydro Group is now designing several installations.

Heat Pumps rely on the same principle as a refrigerator but work the other way round. They extract solar energy which has been stored in the air, in water, or in the ground and use a compressor to raise it to a useful temperature. These are most suitable for a new build.

Tides are generated by the movement of the moon and also by the sun and the planets and are highly predictable and reliable. Tidal barrages have been used for many years and a Severn Barrage could generate 8% of the Nation’s total electricity but there are serious environmental concerns.        

Marine turbines can be sited in predictable tidal streams away from shipping or fishing interests. They can be made on a large scale but fast-moving and corrosive sea water presents considerable engineering problems.

Geothermal energy originates from the heat in the core of the earth and has been used in district heating schemes in Southampton and elsewhere.

I have a lot more information on Renewable Energy and would be happy to discuss any of these matters at greater length with anyone who is interested. Please contact me, Dr John Larkin, Dorset CPRE, Minerals and Waste Adviser, at info@dorset-cpre.org.uk.

By Dr John Larkin

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