Energy is the capacity of a system to do work. In effect, the amount of energy something has refers to its capacity to cause things to happen. That system may be a jet carrying hundreds of passengers across the ocean, a human body growing bone cells, or a kite rising on the wind. In moving or growing, each of these systems is doing work and using energy. It can neither be created nor destroyed but only be changed from one type to another.
Energy that is generated by resources that are naturally replenished on a human timescale, such as sunlight, wind, tides, waves, and geothermal heat is called Renewable Energy. It can be found in various forms and e.g. derive directly from the sun or from heat generated deep within the earth.
Learn more about renewable energies on www.iea.org.
One of the most famous types of renewable energies is Solar Energy – the Latin word for sun. More energy from the sun falls on the earth in one hour than is used by everyone in the world in one year. It is a powerful source of energy that can be used to heat, cool, and light homes and businesses. There is a variety of technologies that convert sunlight into usable energy for buildings. The most commonly used solar technologies are solar water heating and solar photovoltaics for electricity generation.
Hydropower is generated in over 150 countries, developed, emerging and developing. It derives energy from turbines being spun by fresh flowing water in rivers or man-made installations. Since water has an about 800 times higher density than air, even a slow flowing stream of water or moderate sea swell can yield considerable amounts of energy. Therefore 16% of the world’s total electricity demand is currently generated by hydropower.
Geothermal Energy is the thermal energy generated and stored in the earth. Its heat can be drawn from hot water or steam reservoirs deep in the earth and accessed by drilling. It is also a very energy efficient renewable technology for heating and cooling processes inside buildings. With the aid of a Geothermal Heat Pump and Heat Exchanger heat energy is moved into the earth (for cooling) and out of the earth (for heating) on a varying seasonal basis.
Another popular type of renewable energy is Wind Energy. Airflows can be used to run wind turbines and generate energy. Areas where winds are stronger and more constant such as offshore and high altitude sites are preferred locations for wind farms.
Biomass is biological material derived from living, or recently living organisms such as organic kitchen waste, plant or animal matter. As an energy source, biomass can either be used directly via combustion to produce heat, or indirectly after converting it to various forms of biofuel.