Clean Renewable Energy
Solar Thermal

Solar energy is the harnessing of the sun's energy in order to produce electricity. In solar thermal power plants various techniques are used in order to concentrate the sun's energy and to thereafter use it as a heat source. This heat is then use to heat water and turn it into stem which will then turn a turbine and generate electricity in the same way as coal fired power stations and nuclear power stations.

How it works

There are many different ways to concentrate the sun's energy and use it to produce electricity:

• Long troughs of U-shaped mirrors focus sunlight on a pipe of oil that runs through the middle. The hot oil is then used to boil the water for electricity generation.
• Moveable mirrors focus the sun's rays on a collector tower, where a receiver is situated. Molten salt flowing throughout the receiver is heated to run a generator.

Other solar technologies are passive e.g. windows placed on the sunny side of the house allow the sunlight to heat heat-absorbent materials on the walls and floor. These surfaces then release the heat at night to warm the building. Absorbent plates can be placed on a roof and can heat liquids in tubes that supply the house with hot water.

Advantages

Solar thermal energy is considered to be inexhaustible as well as pollution and often noise free. The technology is very versatile i.e. it can be used in many places around the world. It can even be used in outer space to power the satellites in Earth's orbit. It can even power cabins located deep in the Rocky Mountains as easily as it can power urban buildings.

Disadvantages

Unfortunately, there are also many problems that arise when using this technology e.g. solar energy doesn't work at night without the use of a storage device like a battery, also cloudy, rainy weather greatly affects this technology making it unreliable even during the day. The technology is also very expensive and vast tracts of land are required to collect the sun's energy fast enough to satisfy the needs of the people.

Despite all the drawbacks, in the last 15 years solar energy usage has surged at about 20 percent, due to falling prices and its gains in efficiency.   

References

1. National Geographic Society (2008) Solar Power Energy Information ,Solar Power Energy Facts [Online] (Updated 2008)
Available at: http://environment.nationalgeographic.com/environment/global-warming/solar-power-profile.html

Background Image:
James Balog, 2007, Mer De Glace Glacier[electronic image]
Available at: http://www.environment.nationalgeographic.com
Accessed 27 February 2009

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