Renewable energy comes from sources which cannot be used up, such as wind, sun, water and waves, rather than from fossil fuels such as oil and coal.

Using renewable energy is an integral part of the UK Government's long-term aim of reducing carbon emissions. The current target is a 60 per cent reduction by 2050.

The government wants 10 per cent of electricity to be supplied by renewable sources by 2010. In 2005, 4.2 per cent of the UK's electricity supply came from all sources of renewable energy, so there is still some way to go.

Various renewable energy sources are being developed by the Department for Business, Enterprise and Regulatory Reform (BERR), formerly the Department for Trade and Industry, with the help of the Department for the Environment, Food and Rural Affairs (Defra), including:

• wind
• biomass
• solar
• hydroelectric
• geothermal
• wave and tidal

The National Energy Foundation is a leading charity advising on the sustainable use and production of energy, and is an expert on renewables. Visit the website for more information.

Wind

Wind power is usually generated by wind turbines situated either onshore or offshore. Wind is the third largest contributor of renewable energy in the UK, after biomass and hydroelectric power.

In total, both offshore and onshore turbines currently provide justover 0.3 per cent of the UK’s electricity supply, enough to supply around 400,000 households.

On and offshore wind energy is expected to make up to half of the government's 10 per cent renewable energy target. This figure might change - BERR has recently announced plans for a vast increase in the number and size of offshore turbines.

There are now 6 offshore wind farms in the UK with several more in the pipeline.

More information on all current onshore and offshore wind farms in the UK can be found on the British Wind Energy Association's website. Find out more about wind power on the BERR website.

Biomass

Biomass is organic material made from plants and animals. It is arenewable energy source because we can always grow more trees and crops, and waste will always exist. It doesn't include fossil fuels, which take millions of years to create.

When burned, the chemical energy in biomass is released as heat. Wood waste or garbage can be burned to produce steam for making electricity, or to provide heat to industries and homes.

Burning biomass is not the only way to release its energy. It can be converted to other usable forms like methane gas, or fuels such asethanol and biodiesel.

Find out more about how the UK is currently using biomass on the BERR website. And visit the Biomass Energy Centre for more information about what fuels are being researched and developed.

SolarH

Solar energy involves capturing and harnessing the sun’s energy. There are 3 main ways of doing this:

• passive solar design ensures that a building's form and fabric captures the sun's energy and reduces the need for artificial light and heating.
• active solar water heating converts solar radiation into heat, which can be used directly or stored.
• solar photovoltaic (PV) panels or solar cells convert daylight into electricity.

There is a small market for active solar heating in the UK, withfairly steady sales since the mid-1980s. Around 10,000 solar thermal systems are installed in the UK every year, and there are now over 100,000 in place.

Find out about current UK use of solar energy on the BERR website. And check out the Energy Saving Trust's information about solar energy.

Hydroelectricity

Hydroelectricity is electricity generated by water. In a typical scheme, the water stored in a reservoir - often created by damming a river - is converted into energy as it is piped into water turbines. The turbines are coupled to generators to produce electricity.

Hydroelectric power provides about one-fifth of the world's electricity, supplying more than a billion people.

The UK currently generates about 0.8 per cent of its electricity from hydroelectric schemes - most of which are found in the Scottish Highlands.

Find out more about the current UK use of hydroelectricity on the BERR website.

Geothermal

Geothermal power - heat stored below the earth's surface - can be generated as energy using different types of power plants.

There is currently only one geothermal power plant in use in the UK. It has been estimated however, that there are 1,550 large UK industrial sites where heat-pump systems could be installed.

Find out more about georthermal power in the UK on the BERR website.

Wave and Tidal

Both wave energy and tidal power involve harnessing the movement and energy contained in the ocean and converting it into electrical power.

Wave

Ocean waves can, in theory, provide an unlimited source of renewable energy. There is tremendous energy in the ocean and in many areas of the world the wind blows with enough consistency and force to provide continuous waves. Wave power devices extract energy directly from the surface motion of waves which can be converted into electricity by wave power machines.

These machines can be positioned either on the shoreline or in deeper waters offshore. There are 2 wave power devices in the UK - the LIMPET (Land Installed Marine Powered Energy Transformer) on the Scottish island of Islay and the Pelamis sea snake at the European Marine Energy Centre in Scotland, where it is undergoing testing.

Other plans include devices in the Orkneys, off northern Scotland, and a development off the north coast of Cornwall.

Find out about more current UK use of wave energy on the BERR website.

Tidal

Tidal power exploits the movement of water caused by tidal currentsor the rise and fall in sea levels due to the tides. Although not yetwidely used, it has potential for future electricity generation and ismore predictable than wind energy and solar power.

The technology required to harness tidal energy is well established; however, it remains expensive and there are relatively few applications - around 40 - worldwide.

The UK has built some of the only tidal power sites in the world on its west coast and at least 30 additional places have been identified around the country. One of the most advanced prototypes, currently supported under BERR's Technology Programme, is the Seaflow project, which has been running off the north Devon coast since June 2003.

Find out more about UK use of tidal power on the BERR website.