The United States is the largest consumer of electricity in the world, and therefore has to generate a large amount of electricity to meet the demands. Several different power generation methods are used to meet these demands.
The type of power generation used can depend on location, available resources, and necessary scale. Small wind farms generate power for local users, while large coal-fired power plants can generate electricity for an entire region. Each of these power generation methods has its own engineering challenges in terms of plant design and construction, plant operation and maintenance, and dealing with any by-products of the power generation process.
According to the U.S. Energy Information Administration, the United States generated 3,953,111 thousand megawatts of power in 2009. () The three most used energy generation processes were coal, natural gas, and nuclear power. However, other energy generation methods have been growing over the last decade, particularly the renewable energy sector.
Coal Fired Power Plants
Coal-fired power plants generate the largest fraction of power in the United States, some 1,764,486 thousand megawatts of power in 2009, or 45% of all power generated. Coal-fired power plants burn the coal to create heat, which in turn boils a working fluid that is used to drive a turbine and generate electricity. The United States is rich in coal deposits, particularly in the areas of the Appalachian Mountains in the east and the Wyoming area of the Rocky Mountains in the west. Railroads, although no longer dependent on coal for power, are still vital in the delivery of coal from mine to plant.
Natural Gas Power Plants
Natural gas power plants operate on essentially the same premise as a coal-fired power plant: the natural gas is used as a fuel to heat a working fluid that is used in turn to drive a turbine and generate electricity. In 2009, the United States was the world’s largest producer of natural gas, and 23% of all power generated in the United States was from natural gas plants. Natural gas burns cleaner than coal, but still generates carbon dioxide and other emissions when burned.
Nuclear Power
Nuclear power remains the third largest source of electricity production in the United States, with 798,745 thousand megawatts of power generated in 2009, or 20% of total energy production. Nuclear power harnesses the energy of controlled fission reactions to generate heat that boils a working fluid that in turn drives a turbine. Nuclear power is clean and efficient, although the radioactivity of nuclear fuels requires significant safeguards within the plant and methods for disposing or recycling of spent fuel.
Hydropower
Hydropower harnesses the flow of water to drive a turbine that generates electricity. Hydroelectric power generation is the most widely used renewable energy source. In 2009, the United States generated 272,131 thousand megawatts of electricity through hydropower. Hydropower generally involves building a dam within a water way to build up water depth, increasing the potential energy of the stored water. The water enters the turbines at the base of the dam where the pressure is highest. Hydropower itself does not create any by-products, but the construction of dams can drastically impact plant and animal life in the river, as well as affect people who live near the river.
Wind Power
Wind power has been harnessed for thousands of years, and has a very small impact on the environment. Wind power is generated by moving air turning the blades of a wind turbine, which in turn generates electricity. Wind power is most effective in certain geographies where wind is concentrated, and generally have to be placed on high towers to take advantage of the smoother winds located away from the ground. In 2009, 70,761 thousand megawatts of wind power were generated in the United States, or about 1.8% of all power generated that year.
Biomass
One of the more visible energy production methods today is biomass, which is essentially the incineration of plant material or fuel derived from plant material. Biomass can be as simple as logs burned in a wood stove, or as complex as ethanol fuel derived from corn. Other categories that are considered biomass can be municipal waste, landfill gas, and agricultural by-products. Biomass fuel can be generated using waste products from other processes, such as wood pellets made from sawdust and other waste wood. In 2009, just under 1% of all power in the United States was generated by biomass.
Solar
Solar power can be harnessed in two ways: through solar thermal power systems that concentrate sunlight to heat a working fluid to power a turbine to generate electricity, or through photovoltaic solar panels that convert sunlight directly to electricity. In 2009, 808 thousand megawatts of power were generated by solar power plants, only a very small portion of overall power generation. However, this number has been steadily increasing. Solar power has a huge benefit over fossil fuel-fired plants in that there are no by-products of production. While up front capital costs are much larger for solar power plants, the maintenance costs are very low.
The balance of electricity generated in the United States can be accounted for in smaller fuel sources, such as geothermal power, some petroleum sources, and gases such as propane. Through a diverse assortment of power generation methods, the United States meets its energy generation needs. This assortment reduces dependence on one particular fuel source, although coal still makes up by far the largest percentage of the overall power sources in the United States.
Susan Kristoff - Susan Kristoff is mechanical engineer by trade, but has a diverse set of professional and personal interests. The glue that binds all of ...
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