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19 August 2008 @ 12:33 am
Renewable Sources  
Part of the 'We Can Solve It' campaign is to ensure 100% clean energy in the United States within 10 years. To do this, the United States needs to adopt renewable sources of energy that do not emit greenhouse gas emissions. This post is designed to explain the primary sources of energy we can look into using. For the PDF, click here, and for the text version, please click on the cut.

Wind Power: Wind energy is harnessed by building towers with a generator and propellor blades on top. When wind hits the propellor blades, the generator is triggered, which in turn produces electricity. Wind towers that are larger in size and number create more energy. These are best used where wind is commonplace, such as coastal areas and plains areas. These towers are typically built into farms, so a large amount of energy can be harnessed and used effectively. Wind power is beneficial because wind is free, no greenhouse gases are emitted, and energy can be brought to remote areas. The disadvantage is that wind is not readily available in some places, which would make wind towers inefficient in certain areas. If enough wind farms are built (wecansolveit proposes a national grid, of sorts) in the most efficient areas, a fair part of the country can be powered by wind power. For more information, click here.

Geothermal power: Geothermal energy takes advantage of hot, molten rock underneath the Earth. Heat is continually produced beneath the surface, so geothermal power is another good renewable source of energy. To capture it, we use geothermal power plants. We tap into the hot regions and allow cold water to seep down into the Earth. This water is heated by the rocks and rises back up to the surface. Geothermal power plants purify the resulting steam from this heated water and use it to drive turbines, which drive electric generators. There are a few different types of geothermal power plants, but this is the essential process. While, like wind power, this could not be the sole method of powering a nation, it can still do a significant part in reducing greenhouse gas emissions. For more information, click here.

Solar Photovoltaics: These are also known as solar panels. Solar panels contain cells that are specially designed to produce an electric current when exposed to light. There's a lot of science involved in how the electricity if created, which you can read about here if you're interested. Essentially, however, when enough of these cells are layered together, they can produce panels which are capable of providing fair amounts of energy. This method is useful because the sun is available in almost all regions throughout the year - an abundant power source promises more energy than some of the other methods, like wind power. Advances in this technology also allow us to create energy even at low levels of sunshine. Additionally, the source of energy is free. While there is an initial cost for installation of panels, there is no monthly fee for electricity. Like the other methods, it does not emit greenhouse gas emissions. All buildings cannot benefit from solar panels, however. Solar panels must be placed in a precise location which some buildings cannot provide, and some places simply do not get enough sunshine to benefit greatly from this source. It is, however, an excellent option for the places that can take advantage of the large amount of sun.

Solar Thermal Energy: Solar thermal energy is one of the most cost-efficient renewable energy sources. It captures thermal, or heat energy from the sun. The most effective way to utilize solar thermal energy is through a solar thermal power plant. These concentrate the sun's radiation through trough collectors composed of parabolically shaped mirrors. The energy from the sun's rays is focused from these onto receivers. Thermo-oil that flows through the receivers is heated, which allows a heat exchanger to generate steam. The steam is pressurized inside a turbine which drives the generator, which provides energy. The advantage of these systems is that they can still provide energy even when the sun is not shining. This is one of the methods that is being most advocated, because it can impact a much larger population than the other methods. After all, it works just like a steam power plant, but without the waste. For more information on solar thermal power plants, click here (PDF), and for more information on solar thermal energy in general, please click here.

These are the four primary renewable energy sources that would be most efficient in creating a clean energy nation. Which of these methods do you like most? Which do you think will help us most in creating a clean energy nation within 10 years? Are there any other renewable sources of energy that you think would be efficient?