Sunday, November 23, 2008

The Power of the Sun

Recent advancements may increase solar cell efficiency


The demand for energy in the US is rising much faster than the projected increase in domestic energy production. The Energy Information Administration forecasts that the US energy demand will grow almost 50 percent by 2030. In order to meet these demands, the electric utility industry is expected to invest $750 billion in power plants, environmental technology, and transmission and distribution lines (“Annual Energy Outlook 2008”). Already, according to the EPA, the average American family spends $1900 per year on energy bills (“Fall 2006 Energy Star News”). Clearly, energy is an important part of everyday life. However, energy use is also affecting the environment in which we live and so alternative sources must be found. One potential alternative source is solar energy.




Solar energy is a renewable energy source since it is continuously provided by the sun. It is also beneficial because it produces no emissions, almost no solid waste, and produces no long term damages to the land. The two major categories of solar energy technology are photovoltaic and solar-thermal (“Non-Hydroelectric Renewable Energy”).







Photovoltaic cells are made up of semiconductors, usually silicon. When light hits the cell, a certain portion of its energy is transferred to the semiconductor material, which knocks electrons loose and allows them to flow freely. The PV cell has an electric field that forces all of the electrons to flow in one direction, producing a current that in turn produces power. For example, those solar cells found in calculators are PV cells (Aldous, 2000).














Video: Solar Energy Panels - How They Work










On the other hand, solar-thermal technologies concentrate the sun’s energy using mirrors or other reflective devices to heat a liquid and create steam that is used to turn a generator and create electricity (“Non-Hydroelectric Renewable Energy”). Many solar-thermal devices are used to heat swimming pools.






New technological advances are increasing the efficiency of solar cells and therefore further increasing the potential of solar energy. Researchers have just recently produced an anti-reflective coating that not only improves the efficiency of the cell but also allows sunlight to be absorbed from almost any angle. The coating was created by scientists from the Future Chips Constellation at Rensselaer Polytechnic Institute using nanotechnology. To put things into perspective, a normal silicon solar cell absorbs just over two thirds of sunlight while a solar cell treated with the anti-reflective coating absorbs 96.21 percent. The coating is comprised of seven tiny layers made of silicon dioxide and titanium dioxide. The series of layers helps to “bend” the flow of light, capturing more sunlight than before. The coating can be applied to almost any photovoltaic material. Finally, solar cells are usually placed in locations facing south in order to collect the most sunlight for a longer part of the day. However, with this new technology, solar cells may be placed in varying locations (Knight, 2008).


Nevertheless, there are a few possible caveats of the new coating. The tiny layers can be fragile and more effort needs to be put into making them stronger. Others say that the coating will only produce four or five percent more power than regular solar cells. Finally, the solar cell coating has not been produced in bulk and so it is still unknown how successful it will be (Knight, 2008).


References

Aldous, Scott. "How Solar Cells Work." 01 April 2000. HowStuffWorks.com.

“Annual Energy Outlook 2008”. June 2008. Energy Information Administration.
<
http://www.eia.doe.gov/oiaf/forecasting.html >

“Fall 2006 Energy Star News”. Energy Star.
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Knight, Matthew. “New nano coating boosts solar efficiency”. 12 November 2008. CNN. <
http://www.cnn.com/2008/TECH/science/11/12/solar.coating/index.html?iref=newssearch>

“Non-Hydroelectric Renewable Energy”. 28 December 2007. U.S. Environmental Protection Agency. <
http://www.epa.gov/cleanenergy/energy-and-you/affect/non-hydro.html#solar>
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2 comments:

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Universal Solar said...

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