“Renewable energy is derived from natural processes that are replenished constantly. In its various forms, it derives directly from the sun, or from heat generated deep within the earth. Included in the definition is electricity and heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources, and biofuels and hydrogen derived from renewable resources.” (Source: International Energy Agency – “Renewable Energy….into the Mainstream” 2002)
Renewable energy is a way of shifting our dependence on fossil fuels to sources of energy that will help to reduce greenhouse gases, and also reduce a reliance on imported fuels.
Renewable energy resources are constantly replenished through the cycles of nature – their supply will never be exhausted. The alternative, fossil fuels, on the other hand, are finite resources and will become increasingly scarce and expensive to extract.
Benefits of Renewable Energy:
- reduced CO2 emissions
- secure and stable energy supply for the long term
- reduced reliance on expensive fuel imports
- investment and employment in indigenous renewable energy projects
SOURCES OF RENEWABLE ENERGY
Solar energy derives from the sun, in the form of sun radiation. There are many applications of solar energy, including solar water heating and solar powered electrical generation which relies on photovaltics.
- Passive solar means converting the sun’s energy, without use of any mechanical activities, to generate heat, light or cause air movement. An example would be a solarium. Even something as simple as a green house, uses the sun’s energy to help grow plants.
- Active solar means the same use of the sun’s energy as above, but with the additional use of electrical or mechanical equipment. An example of this would be the solar collectors in a solar water heating system.
- Solar applications are generally classified as either passive or active.
Wind power is the conversion of wind energy into a useful form of energy, such as using wind turbines to make electricity, wind mills for mechanical power, wind pumps for pumping water or drainage, or sails to propel ships. We in Ireland are becoming more aware of the growth of wind-farms both onshore and offshore, some people even have domestic wind turbines.
The energy from water, or hydro-power has huge potential, due to the fact that it is several hundred times denser than it, even a little stream can generate considerable amounts of energy. In Ireland, for example, the ESB has developed a number of hydro-electrical plants throughout the river network to harness this energy. One of the largest of these is located on the river Shannon at Ardnacrusha.
Biomass is biological material. which can be derived from either plant, animal or vegetable. Plant matter is typically used for electricity generation or to produce heat. Some examples include the use of wood pellet, wood chip, waste wood, grain husks, municipal waste or bioethanol derived from corn. There are appliances which can use these materials to generate heat such as a wood pellet stove.
This is energy derived from the earth itself. It is the use of the heat from the earth’s core. Think of the hot springs of Iceland, which people for centuries have used for bathing. More commonly in Ireland we can use geothermal heat-pumps or ground source heat pumps for our central heating systems. Essentially, these heat pumps are used to force the transfer of heat – exchanging heat with the ground.