Though most renewable energy projects are large scale, they can be made smaller. These are residential and rural off-grid applications where renewable energy is crucial. Some of these technologies, including wind power devices such as turbines, are often considered to be quite beautiful and are a subject of many pieces of art.
The three main energy sources are the sun, wind, and water.
Most renewable energy sources are powered by the sun. The amount of heat radiation into space is equal to incoming solar radiation, which results in the level of energy that is the Earth's climate. The hydrosphere of water absorbs a large percentage of the incoming radiation, and wave motions then play a role in the process of transferring mechanical energy between the atmosphere and the ocean. These things all contribute to renewable energy. This energy is instantly replenished as it is used.
Wind generators range from around 600 kW to 5MW of rated power. Wind turbines are most common for commercial use. Areas where winds are strong and constant are preferred sites. These include high altitude sites and offshore sites. Because wind speed is not constant, the annual energy production is not as large as other generators. Globally, long-technical potential of wind energy is believed to be five times the total of current globe-wide wind production. This would be 40 times the current electricity demand.
Water power, also known as hydropower, is energy in the form of water. This can be found in things as minor as a slow flowing stream of water. Hydroelectricity is a term used for large-scale hydropower generators. Micro-hydro systems can produce up to 100 kW of power. These are used in water-rich areas. Damless hydro systems are able to derive kinetic energy from rivers and oceans without using a dam.
Ocean energy is another popular renewable energy source which harnesses the power of the sea. With the use of current power and ocean thermal energy conversion, an immense amount of energy is collected. Tidal and wave power are also an energy system used within ocean energy harnessing.
Solar energy is the most commonly known renewable form of energy. It can be used in both residential and commercial situations. With the use of photovoltaic solar cells, it is possible to collect enough energy for 75%-100% of residential needs. It is possible to collect electrical energy as well as radiant energy which allows for heating of water, for the generation of cool air, and more. Solar energy can also be used for floor-coil heating or to heat swimming pools.
Conventional fossil fuels are, by their nature, finite and will ultimately be depleted. Integrating renewable energy sources into our power supply reduces greenhouse emissions today and provides a path for the transition to a world without fossil fuels tomorrow.
