Renewable energy sourcesBiomassBiomass is a term given to organic matter of recent origin (and therefore does not include fossil fuels which have evolved over millions of years) and it is also sometimes known as bioenergy or biofuel. Biomass is a renewable source of energy, although care must be taken that the fuel is from sustainable sources in order that resources aren’t depleted.The production and use of biomass is a carbon neutral process as the carbon dioxide released when energy is generated is balanced by that absorbed during the fuel’s production. Biomass is produced from organic materials which come either directly from plants or indirectly from industrial, commercial, domestic or agricultural products, and these are divided into two categories.
The main type of biomass used in a domestic environment is wood in the form of wood pellets, chips or logs. This fuel can be used for a stand-alone wood pellet stove to heat a room (some of which can also be fitted with a back boiler to provide hot water) or for a wood pellet boiler connected to the central heating and the hot water system. A stand-alone heater would cost approximately £3000 installed whilst a typical 15KW boiler would be in from £5000 to £11,000 including the flue. Both systems do, of course, having running costs as the fuel has to be purchased, and they are therefore usually most cost effective in locations without a gas supply. Grants are available from the Low Carbon Buildings Programme, however, towards installation costs – visit www.lowcarbonbuildings.co.uk for more information. GeothermalGeothermal energy is the natural heat of the earth. Thermal energy is continuously generated by the decay of radioactive isotopes of underground rocks and is stored in the earth’s interior. As such geothermal energy is an inexhaustible supply of heat making it one of the forms of renewable energy we have at our disposal.The temperature at the earth’s core is estimated to be about 4000°C. This drops to 1200°C in the lava of active volcanoes and the temperature of thermal springs is approximately 350°C. Geothermal energy has been used for thousands of years particularly in the case of hot springs. These have been used for localised bathing and cooking as well as for creating bathing complexes such as those built by the Romans in Bath.Geothermal energy is currently third amongst renewable energy sources for power production in terms of worldwide usage, but there is still an enormous amount of untapped potential. Geothermal heat is classified as low temperature (less than 90°C), moderate temperature (90-150°C) or high temperature (greater than 150°C). Low temperature sources exist everywhere and it is these that the ground source heat pumps tap into. Water is pumped through warm ground to heat or cool buildings and the geothermal energy can also be used to supply buildings with hot water. For more information on ground source heat pumps, Geothermal Energy Ground Source Heat Pumps - Click HereGeothermal energy can also be used for electricity production whereby a turbine is driven by steam which in turn drives a power generator. More information on geothermal energy can be found at International Geothermal Association Greener EnergyGreen energy is effectively a term which can be interchangeable with Renewable Energy. Today over 2% of electricity in the UK comes from green energy sources and by 2010 the government target is for this to exceed 10%. As supplies of fossil fuels continue to diminish we need to look at alternatives for the future.A perceived problem with green energy is that supplies can be intermittent particularly in the case of energy sources such as solar and wind. This is, however, also the case for fossil fuel and nuclear powered stations which are closed for maintenance or due to technical difficulties. A report has been carried out by the UK Energy Research Centre (UKERC) which concluded that, whilst backup is required to overcome intermittency, this is not a big problem. It is worth noting, for example, that some forms of green energy such as Biomass or Hydro Electric Power can be stored and used when required.The National Energy Foundation runs a number of schemes to promote green energy. For example, the Energy For Good scheme works in partnership with Local Authorities, County Councils and EST Advice Centres to help householders interested in green energy for their homes. This scheme is currently being rolled out so visit the National Energy Foundation website for more information. The Green Energy Machine is a large van made available by the National Energy Foundation for use at public events. It includes demonstrations of Wind Power and Solar Power and is ideal for schools fairs or exhibitions. Visit the Green Energy Machine pages of the NEF website for details. Hydro ElectricHydro electric power produces one fifth of the world’s electricity and this percentage is much higher in many developing countries. Hydro electric power systems work by converting potential energy stored in water held at height into kinetic energy to turn a turbine in order to produce electricity. This is a mature technology with water mills already extensively used by the time of the industrial revolution.There are a number of main components to a modern hydro electric power system. The intake of water is often incorporated into a weir to divert the water flow from its course. A penstock pipe then takes the water from the intake to the turbine. This is in a powerhouse where a turbine and generator convert the power of the water to electricity. An outflow then releases the water back to the watercourse and underground or overhead cables transmit the electricity to the property or national grid.Hydro electric power systems can be built on a large or small scale with useful power available even from small streams. It is important, however, to get good quality advice with a resource assessment best carried out by a micro-hydro consultant if you are interested in looking into a small scale hydro electric power system. For more information on micro hydro power, sometimes known as mini hydro power, visit our micro hydro power page.The cost of a small scale system is difficult to estimate without taking all factors into consideration, but a typical 5KW domestic system may cost in the region of £20,000 to £25,000. The Low Carbon Buildings Programme does, however, offer grants to householders of up to £1000 per KW installed up to a maximum of £2500 or 30% of the total installed cost. For more information on hydro electric power, including information on hydro electric power installations in the UK, visit the British Hydro Power Association Solar PowerThe term solar power is used to describe a number of methods of harnessing energy from the sun. As fossil fuel sources deplete and environmental concerns about greenhouse gases increase, renewable energies such as solar power are increasing in popularity across the world including the UK.There are two types of solar power, solar electric power which use photovoltaic cells to convert solar radiation into electricity, and solar thermal energy where the sun’s energy is used to heat water. Photovoltaic cells consist of one or two layers of a semi conducting material, usually silicon. When light shines on the cell it creates an electric field across the layers, causing electricity to flow. The greater the intensity of the light, the greater the flow of electricity. Solar thermal energy is a relatively simple process where water is pumped into solar panels and, as it passes through them, is heated and then stored in a tank ready for use. The water will stay hot for around 24 hours. In both cases solar panels are usually fitted to the roof and work during daylight hours, however with a new house being built from the ground-up it may be possible to integrate them more seamlessly into the house. It is a misconception that solar panels only work with direct sunlight and solar power collectors can heat water on a very cloudy day (luckily for us in the UK)! While solar power will not usually completely support a central heating system or provide enough electricity for all a home’s requirements, a substantial supply of power or domestic hot water can be provided. Solar powered toys, games and gadgets Wind Power (Wind Power)The use of wind power has been around for thousands of years in different forms and nowadays is mainly used to generate electricity. Take a look at our wind energy facts page for some of the ways wind power was used in days gone by. The proper name of a wind generator is actually “Wind Energy Converter” which is a device that converts the potential energy in the wind to another form of Wind Power energy. This can either be mechanical or electrical. When the wind blows, the rotor blade stops a percentage of the wind. That percentage is converted into energy. According to physics, the maximum amount of wind energy that can be converted is 59.3%. This is known as the Betz Limit. There are a number of types of wind generators and research has been done on virtually every possible concept with the objective of producing the maximum amount of power for the lowest cost at the highest possible reliability. Experiments have found the horizontal axis upwind or down wind design to be the best concept. The most common designs include:
Wind power is proportional to the cube of the wind's speed, so relatively minor increases in speed result in large changes in potential output. Individual turbines vary in size and power output from a few hundred watts to two or three megawatts (as a guide, a typical domestic system would be 2.5 - 6 kilowatts, depending on the location and size of the home). Small domestic systems cost as little as £1500 installed. These costs are inclusive of the turbine, mast, inverters, battery storage (if required) and installation, however it's important to remember that costs always vary depending on location and the size and type of system. British Wind Energy Association has more information on wind power. Renewable energyRenewable energy is a term used to describe a variety of energy sources which do not have a finite supply. In contrast, energy sources such as coal, oil and gas are non-renewable forms of energy and will one day run out. In fact supplies of these fossil fuels are already severely depleted and we need to look carefully at other sources of energy for the future. Renewable energy sources also have a further advantage over traditional fuels as they do not have the same negative environmental impact caused by CO2 emissions. There are five main types of renewable energy, namely solar power, wind power, hydropower, biomass energy and geothermal power. Wood PelletsWood pellets are a type of Biomass and are a carbon neutral fuel. The carbon dioxide released when the wood pellets are burnt is cancelled out due to the fact that trees absorb carbon dioxide as they grow. Even taking into account the fossil fuel emissions from planting, harvesting, processing and transporting the wood, replacing fossil fuels with wood will typically reduce net carbon dioxide emissions by over 90%.Wood pellets are usually made from highly compressed waste such as sawdust, ground woodchips or bark. The material binds together naturally although maize starch is sometimes the only additive included in the manufacturing process. There is a well established market for wood pellets in North America, Sweden, Austria and Denmark and work on the development of the UK market began in 1999, with this country now seeing an emerging industry.Wood pellets have a high energy content similar to high quality coal and can be used in specially designed stoves and boilers. Some existing solid fuel and oil boilers can also be converted for use with wood pellets. For more information on Wood Pellet Fuelled Stoves and Wood Pellet Boilers follow the links to other pages on the UK Energy Saving site. This type of fuel is also relatively inexpensive and is exempt from the Climate Change Levy. Even the ash left over after burning wood pellets is useful. Due to its high mineral content, it can be recycled to fertilise forests, parks or gardens. Eco Dating site for Chiswick and the West London Area Thanx! |
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