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Renewable energy

All the energy we use comes from the earth. The electricity we use every day doesn't come directly from the earth, but we make electricity using the earth's resources, like coal or natural gas.

Both coal and natural gas are called "fossil fuels" because they were formed deep under the earth during dinosaur times.

The problem is that fossil fuels can't be replaced - once we use them up, they're gone forever. Another problem is that fossil fuels can cause pollution.

Renewable energy is made from resources that Mother Nature will replace, like wind, water and sunshine.

Renewable energy is also called "clean energy" or "green power" because it doesn't pollute the air or the water.

Sun power (solar power) can make electricity by using things called photovoltaic cells (often just called PV - easier to say) which fit on the roofs or walls of your houses or apartment blocks. Some special cars can run on PV electricity and theres even a race across Australia in which the cars run only on solar power

Sun power can heat water in solar panels (like radiators but instead of giving out heat, they grab it from the Sun). This is then stored in a big tank so you can have hot showers and so on. Solar collectors can pick up the sun's heat even on cloudy days

Hydroelectric power makes electricity by using the energy from falling water. The water comes from big dams across rivers, and flows down great tubes to drive electricity generators. Most of the worlds biggest rivers are already used for this

Wind power can drive a turbine with a propeller (like some airplanes have) and make electricity. Wind power is getting really important in some countries.

Wave power can also drive generators but this is still a very new idea. Just a few experimental machines are in use today.

Tides - you know, when the sea goes up and down twice a day - can drive generators too. There's just one example of this in action at a place called La Rance in France. Other parts of the world with big tides could be useful too, but a big dam has to be built to trap the moving seawater

Biogas (methane) for cooking and heating can be made from human sewage and farm animals' waste. (Phew! Yuk! … but very useful.) It's made in special tanks called biodigesters. Landfills - that's where people's garbage gets dumped - also produce methane gas as the rubbish rots. Usually this is collected and used to make electricity

Biofuels: Because plants and trees soak up CO₂ like sponges, making the carbon into wood and putting back oxygen into the air, people can grow fuel without adding CO₂ pollution to the air. It's called 'carbon neutral'. In Brazil, people pioneered growing sugar cane plants to make alcohol which they use to power almost half the countrys cars. In other countries, people plant special trees (like willow) which grow fast and you can cut them down without killing them - so they keep on re-growing. This is called coppicing. You can use the wood for burning to make heat as well as other things.

Fuel cells make electricity directly from hydrogen, a very light gas. The cells don’t burn the hydrogen. Instead it reacts with oxygen (in the air) to make electricity. The only ‘waste’ is water. Soon cars will run with fuel cells powering electric motors so they are silent and make no pollution. They can also make power for houses so there’d be no need for big polluting power stations. One way people can make hydrogen is by using sunlight to split water into hydrogen and oxygen gases. Scientists are still searching for a good way to do this.

Geothermal energy is energy tapped from inside the Earth. It's the only renewable energy source which has nothing to do with the Sun. Deep down, it's very hot. Sometimes these hot rocks break through the surface to form volcanoes. By drilling holes down into areas where hot rocks are close to the surface, people can generate electricity and heat buildings. One type of geothermal energy uses geothermal heat pumps to make hot water for home heating. A heat pump is a sort of reversed refrigerator.

Source

http://tiki.oneworld.net

http://www.alliantenergykids.com