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Electricity Production in the 50 U.S. States
There are many different ways to view and understand the environmental impacts of electricity production in the United States. Consumers who are interested in understanding exactly where their home's electricity comes from, adjusting how much electricity is used in the home, choosing to change how the electricity is produced, or offsetting environmental impacts through green credits may find the Power Profiler tool (published by the EPA) to be particularly helpful.

Businesses seeking to use best practices for greenhouse gas accounting or to consider other air quality impacts may find it useful to evaluate emissions by eGrid subregion rather than by state.

Concerned citizens who want to learn more about how their state contributes to air pollution and other environmental impacts or to advocate for different methods of electricity and power production in their state may find this series of web pages and information helpful. Click on the map above to see how your state chooses to generate electricity and the environmental consequences that result.

Electricity Production in the United States
In 2014, the production of electricity in the United States continued to be dominated by the use of coal, at approximately 38.7% of the total electricity produced. Natural gas comes in second to coal, at 27.5%, followed by nuclear energy at 19.5% and renewable forms of energy (including hydroelectric and wind energy) at 13%. While coal has the reputation for being the dirtiest choice in producing electricity, no method is without its environmental consequences. When it comes to producing electricity, the impacts on the environment are greatest on air quality, including greenhouse gas emissions which contribute to global climate change.

Coal leads the way in air pollution and greenhouse gas emissions. In fact, burning coal for electricity produces almost a quarter (25%) of total greenhouse gas emissions in the United States every year. To understand how coal pollutes the air, consider a typical 500MWh coal plant that serves approximately 140,000 people. In a single year, such a plant alone produces 10,000 tons of sulfur dioxide (leading to acid rain), 10,000 tons of nitrogen oxide, 3.7 million tons of carbon dioxide, 500 tons of small particles, 720 tons of carbon monoxide, 125,000 tons of ash, and over a hundred pounds each of arsenic, mercury, and lead. While coal is the largest offender to air quality, other forms of producing electricity are not without consequences.

Natural gas, when used to produce electricity, is far cleaner than burning coal. Burning natural gas produces negligible amounts of sulfur dioxides, particles and particulates, mercury, and other toxins commonly emitted by coal-fired plants. Burning natural gas also emits less than half of the carbon dioxide that burning coal emits, resulting in far fewer greenhouse gas emissions during the actual production of electricity. However, the extraction and transport of natural gas results in the release of ozone and particulates, as well as methane (which is a far more potent greenhouse gas than carbon dioxide).

Renewable forms of energy (e.g. hydroelectric, wind, solar) produce negligible air pollution compared to non-renewable forms of energy. However, hydroelectric energy is a major player in greenhouse gas emissions. The greenhouse gases generated from decomposing vegetation and soil in flooded areas created by dams for hydroelectric energy can produce up to 0.5 pounds of carbon dioxide per kilowatt-hour (kwh) of electricity produced, compared to 0.6 to 2 pounds for burning natural gas and 1.4-3.6 pounds for burning coal. Solar energy and wind energy produce no air pollution or greenhouse gases during the production of electricity; however, solar energy can produce between 0.08 and 0.2 pounds of carbon dioxide equivalent gases for every kwh of electricity produced, as a result of manufacturing, transport, installation, decommissioning, and dismantling of solar panels and related equipment. Burning biomass such as wood and agricultural products for electricity is complicated in terms of environmental impacts, and whether or not air pollution or greenhouse gas emissions are significant depends on alternative fates for that biomass (i.e. what would have happened to it had it not been used to generate electricity).

Nuclear energy is far cleaner than coal during the actual production of electricity. Nuclear power plants do not release carbon dioxide and other greenhouse gases. However, the mining of uranium and production of fuel for nuclear power plants does release significant amounts of such gases. Nuclear energy also uses a great deal of water and water that is released back into the environment is generally hotter than when it started and has a range of ecosystem consequences. The hard-to-quantify impacts of low level radiation, radioactive waste, past and possible future accidents, and potential terrorist activities associated with nuclear power plants also muddy the waters with regard to the overall, long-term environmental cleanliness of nuclear energy.

While air pollution and greenhouse gas emissions are important and significant with most methods of producing electricity, other environmental impacts come into play as well. For example, most forms of producing electricity withdraw large volumes of water from the environment. Much of this water is returned to the environment, although often hotter and more contaminated than when it entered the power plant. However, a significant volume of water is also consumed in the condensation of steam for nuclear, natural gas, and coal based energy sources as well as for other purposes in certain types of solar energy (e.g. centralized solar concentrator plants). In the case of hydroelectric energy, huge volumes of water are withdrawn from the environment to produce energy, but how much water evaporates and is actually consumed in the process varies widely.

Land usage is also a concern with certain forms of electricity production, particularly renewables like wind, solar, and hydroelectric energy. While fossil fuel power plants (e.g. coal and natural gas) use relatively little land, certain forms of extraction such as surface strip mining for coal can destroy huge swaths of land, destroying habitat and permanently disrupting ecosystems.