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Energy Sources Used to Generate Electricity

Electricity may be generated by any source that can provide sufficient energy to strip electrons from their atomic orbitals. Large-scale electricity generation follows from a short list of energetic sources that are preferred for their energy containment, availability and efficiency of use. Although the U.S. Department of Energy investigates a diverse array of energy sources that includes those that are environmentally conscious (such as solar, wind, renewables and bioenergy), those preferred by U.S. power plants as of 2010 were still fossil fuels.

Coal
- Coal-fired power plants supply more than half of the electricity consumed in the United States. This makes coal the most used energy source for the purpose of electricity generation. This fossilized plant matter is known as "captured sunlight," releasing large amounts of energy and greenhouse gases upon combustion.
  
  Coal burning is not environmentally friendly. However, the United States owns one quarter of the planet's coal supply, making the resource an abundant source of energy for the country. The Department of Energy contracts with the private sector in coal-free emissions research and development to mediate the environmental concerns of burning coal uncleanly. The objective in this research is to ultimately design an emission-free coal burning plant so that the entirety of the nation's coal reserves can be tapped. Despite environmental concerns, the power plants in the U.S. generated 1,764,486 thousand Megawatt-hours (MWh) of electricity from coal in 2009.
Natural Gas
- Natural gas is a clean-burning alternative to coal and tends to be used as such. In 2009, U.S. power plants produced 920,378 thousand MWh of electricity with natural gas, up from 882,981 in 2008. The amount of electricity produced by coal declined from the year before in 2009. According to the Department of Energy, 900 of the next 1,000 power plants to be built (as of 2010) will use natural gas a primary energy source.
Petroleum
- Although petroleum is the main energy source for transportation systems, it is also used by some U.S. power plants. Its main usage is seen in the Northeastern United States, where consumers depend on this resource for heating needs. In 2009, U.S. power plants generated 25,792 thousand MWh of electricity from liquid petroleum.
Other Sources
- Other energy sources used for electricity generation include nuclear and hydropower. Nuclear energy is fast approaching the level of use of natural gas as an energy resource. In 2009, U.S. power plants produced 798,745 thousand MWh of electricity from nuclear energy. Hydropower is currently rated at a 28 million household capacity in the United States.

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