BACK

WHAT IS RENEWABLE ENERGY?

Renewable energy is a form of energy that is replaced rapidly by natural processes such as power generated from the sun or from the wind . The energy obtained from sources that are continually replaced, unlike fossil fuels of which there is a finite supply. Most renewable sources of energy are non-polluting and come from nature.

Renewable Energy Sources capture their energy from existing flows of energy, such as sunshine, wind, flowing water, biological processes, and geothermal heat flows. Renewable energy resources may be used directly, or used to create other more convenient forms of energy Following are some of the main types of renewable energy and alternative fuels, which together supply about 10 percent of the world's total energy.

Solar :

The earth receives as much energy from sunlight in 20 days as the planet's entire reserves of fossil fuels. The energy transmitted from the sun in the form of electromagnetic radiation. The most successful examples of energy extraction from the sun are so far solar cells used in satellites and solar collectors used to heat water. In homes Solar power is widely used to heat water in swimming pools and for domestic use and even for air conditioning.

Solar power can also be used to:

•  generate electricity using solar cells
•  generate electricity using thermal power plants
•  generate electricity using solar towers
•  heat buildings, through heat pumps
•  heat foodstuffs, through solar ovens

Tests are being carried out on solar towers, in which a large number of mirrors focus the sun's rays on one point on top of the tower, which stores the sun's energy in molten salt, allowing the plant to generate power day and night.

Hydro :

Hydropower is the energy obtained from flowing water. Energy in water can be harnessed and used for this usefulness, in the form of motive energy or temperature differences. The most common application is the dam This source remains the world's top source of renewable energy. Apart from hydroelectric dams, mini-hydro's using the flow of water in rivers as well as ocean waves and tidal power can also be harnessed to drive turbines.

Wind :

Wind power is the extraction of energy by wind turbines . The power in the wind can be extracted by having it act on moving wings that exert torque on the rotor.

The amount of power transferred depends on the wind speed (cubed), the swept area (linearly), and the density of the air (linearly).An estimated 1 to 3 percent of the energy from the Sun that hits the earth is converted into wind energy.

Most of this wind energy can be found at high altitudes where continuous wind speeds of over 160 km/h (100 mph) are common. Eventually, the wind energy is converted through friction into diffuse heat all through the earth's surface and atmosphere. Like solar, wind power is growing rapidly with large installations built in Europe and the United States and many planned or under construction in Asia . Small turbines can be used by homeowners and remote villages not connected to the grid.

Biomass :

Biomass is organic non-fossil material that comprises the mass of all biological organisms, dead or alive, excluding biological mass that has been transformed by geological processes into substances such as coal or petroleum .Burning wood for cooking is the oldest example of using biomass, a term for any sort of vegetation, such as grass, trees, leaves or even municipal waste that can be burned on its own, or co-fired in other power plants, to generate electricity. Biomass can also be used to produce liquid fuels, for example, ethanol from sugar cane, and gaseous fuels, such as methane from rubbish dumps .

Bio-fuels : Bio-diesel is made by transforming animal fat or vegetable oil with alcohol and can be directly substituted for diesel either as neat fuel or as an additive. In Europe , the largest producer and user of bio-diesel, the fuel is usually made from canola oil. In the United States , the second largest producer and user, bio-diesel is usually made from soybean oil or recycled restaurant grease. These fuels produce much less pollution, and engines need no significant modifications. As a result, biofuels are seen by many as a way to reduce the amount of carbon dioxide released into the atmosphere by using them to replace non-renewable sources of energy.

Geothermal :

Geothermal energy ultimately comes from radioactive decay in the core of the Earth, which heats the Earth from the inside out, and from the sun, which heats the surface. Where hot underground steam or water can be tapped and brought to the surface it may be used to generate electricity. This uses the heat generated at the point where tectonic plates collide, and volcanoes, shallow magma and hot springs are present. This heat and steam is used to drive turbines in many countries.

Hydrogen :

Weight for weight, hydrogen has the highest energy of any gaseous fuel and is increasingly seen as a fuel for the future. Hydrogen is the third most abundant element on the earth's surface, where it is found primarily in water (H 2 O) and organic compounds. It is generally produced from hydrocarbons or water; and when burned as a fuel, or converted to electricity, it joins with oxygen to again form water. The challenge for the energy industry is how to source hydrogen in an environmentally sustainable manner as well as improve the efficiency of fuel cells, which use hydrogen to make electricity. Other problems include storage of the highly flammable gas and safety of distribution.

Almost all hydrogen produced today is from splitting natural gas. The thermal energy for the process comes from the combustion of fossil fuels. Splitting the water molecule through electrolysis can also produce hydrogen. This process requires substantial amounts of electricity, and solar energy is being used on a small scale in Europe .