Utilization of natural resources such as sunlight, wind, water and biomass to fulfill our energy need in such an efficient manner that it dose not damage the delicate environmental balance is called renewable energy.
Simplest possible example can be that of biogas generation, Biogas is considered to be a source of renewable energy. This is because the production of biogas depends on the supply of grass, which usually grows back each year. By comparison, the natural gas used in most of our homes is not considered a form of renewable energy. Natural gas formed from the fossilized remains of plants and animals-a process that took millions of years. These resources do not “grow back” in a time scale that is meaningful for humans.
With our ever increasing human race and its limited resources it is important for us to work in a consistent manner to create a world that fulfills its energy needs through resources that are not destined to drain out like fossil fuel.
Renewable energy technologies are sometimes criticized for being unreliable or unsightly, yet the market is growing for many forms of renewable energy. Wind power has a worldwide installed capacity of 74,223 MW and is widely used in several European countries and the USA.The manufacturing output of the photovoltaic industry reached more than 2,000 MW per year in 2006, and PV power plants are particularly popular in Germany. Solar thermal power stations operate in the USA and Spain, and the largest of these is the 354 MW SEGS power plant in the Mojave Desert. The world's largest geothermal power installation is The Geysers in California, with a rated capacity of 750 MW. Brazil has one of the largest renewable energy programs in the world, involving production of ethanol fuel from sugar cane, and ethanol now provides 18 percent of the country's automotive fuel. Ethanol fuel is also widely available in the USA.
The majority of renewable energy technologies are directly or indirectly powered by the sun. The Earth-Atmosphere system is in equilibrium such that heat radiation into space is equal to incoming solar radiation, the resulting level of energy within the Earth-Atmosphere system can roughly be described as the Earth's "climate." The hydrosphere (water) absorbs a major fraction of the incoming radiation. Most radiation is absorbed at low latitudes around the equator, but this energy is dissipated around the globe in the form of winds and ocean currents. Wave motion may play a role in the process of transferring mechanical energy between the atmosphere and the ocean through wind stress.Solar energy is also responsible for the distribution of precipitation which is tapped by hydroelectric projects, and for the growth of plants used to create biofuels.
Renewable energy flows involve natural phenomena such as sunlight, wind, tides and geothermal heat, as the International Energy Agency explains:
"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, hydro power, biomass, geothermal resources, and biofuels and hydrogen derived from renewable resources.Each of these sources has unique characteristics which influence how and where they are used. All in all it should be our utmost responsibility to work steadily to enhance the chances of producing the world which fulfil its energy needs through environment friendly renewable resources.
