In the United States, there are approximately 6,997 power plants with a capacity to generate at least one megawatt of electricity (United States Energy Information Agency [EIA], 2013). Each of these power plants may operate one or more electric power generators resulting in an estimated 19,023 individual generators (EIA, 2013). It is estimated that U.S. power plants produced 3.8 billion kilowatt-hours (KWh) of electricity in 2013 (EIA, 2014). Plants combusting fossil fuel (coal, oil, natural gas) supplied approximately 66% of the U.S. electrical energy needs, nuclear power plants provided 19% and renewable energy plants provided another 13% (EIA, 2014).
The public health risks associated with power plants are largely dependent upon pollutants released from the fuel used to generate heat. The primary pollutant emissions from coal combustion include particulate matter, nitrogen oxides, sulfur oxides, carbon monoxide, methane, carbon dioxide, mercury, volatile organic compounds (VOCs), and heavy metals (United States Environmental Protection Agency [EPA], 2013). Natural gas-fired plants also emit nitrogen oxides, carbon dioxide and methane, but in lower quantities than coal-fired power plants. Sulfur oxides and mercury emissions from natural gas combustion are negligible (EPA, 2013a). Nuclear power plants and renewable power plants do not have emissions from combustion; however, nuclear plants discharge large quantities of high temperature water used for cooling. In addition, nuclear power plants generate nuclear waste that is difficult to dispose and remains hazardous for thousands of years (Chapman, 2012).
Here I focus on risks associated with fossil fuel power generation; however, it is important to recognize that risks occur along the entire fuel cycle, from resource extraction to waste disposal. The public and occupational health risk from nuclear power generation is primarily related to radiation exposure during all stages of the fuel cycle (Hamilton, 2011). Secondary health risks include trauma (Hamilton, 2011). Among five renewable energy categories (geothermal, hydropower, photovoltaics, wind, and solar), trauma is the primary occupational hazard during power production operations. Exposure to toxic brines, hydrogen sulfide and radon are also occupational and public health risks at geothermal plants (Hamilton, 2011).
Fossil Fuel Power Benefits and Risks
Fossil fuel power production has allowed unprecedented industrial and population growth from a fairly low dollar cost energy source. Wilkinson et al. (2007) noted that the exploitation of fossil fuels is integral to modern living and has been a key element of the rapid technological, social and cultural changes during the past 250 years. Their review paper noted that 2.4 billion of the world’s population, disadvantaged by a lack of access to clean energy, are exposed to high levels of indoor air pollutants from inefficient burning of biomass fuels.
Community health risks associated with fossil fuel power plants are unique, not because they are the only sources for certain pollutants, but because of the quantities of pollutants emitted. For instance, according to the EPA 2011 national emissions inventory data, fossil fuel power plants accounted for 69% of all anthropogenic emissions of sulfur dioxide (SO2) (EPA, 2014). The majority of power plant SO2 emissions are from coal (98%), further distinguishing them from natural gas-fired and oil–fired power plants (0.7%). Short-term exposure to SO2 has been associated with an array of adverse respiratory effects, including bronchoconstriction and increased asthma symptoms (EPA, 2014). Fossil fuel power plants emit approximately 51% of all anthropogenic mercury emissions, of which coal-fired plants account for 97% (EPA, 2014). Mercury may remain in the atmosphere for long periods of time before depositing into the environment where it can bioaccumulate. Fossil fuel power plants also emit other hazardous heavy metal air pollutants, including arsenic (62%), nickel (28%) and chromium (22%) (EPA, 2014).
Risks to the natural environment from fossil fuel power plants include heavy metal discharges into water and ground water from coal pile runoff; leachate from coal ash landfills; discharges related to equipment maintenance and cleaning; cooling tower blowdown; discharges from wastewater treatment; and heavy metal air emissions that deposit into water and onto land surfaces. EPA surveys of groundwater near ash landfills and surface impoundments have demonstrated that arsenic may exceed human health thresholds by more than four orders of magnitude and poses the greatest risk for heavy metal discharges from coal plants (EPA, 1998). At oil-fired plants, arsenic, vanadium, and potentially nickel, are of greatest concern.
Another risk to the natural environment that does not involve a pollutant discharge is that of water withdrawals for cooling. To generate power, many power plants boil water to generate steam. The steam spins a turbine which generates electricity. After the steam passes through the turbine, it must be cooled to be recycled. To cool this water, power plants pull water from streams, rivers and estuaries for use in cooling towers or heat exchangers. A single power plant is able to pull hundreds of millions of gallons of water for use in cooling. In the United States, fossil fuel power plants account for 91% of all cooling water withdrawals (EPA, 2014). Large water withdrawals from lakes, rivers, estuaries and other water bodies may result in aquatic organisms being impinged on screens meant to filter debris. Small fish and eggs may be entrained, leading to a loss of early life stages needed to maintain healthy populations. A majority of power plants (71%) are also located within two miles of water bodies that are impaired due to excess nutrient loadings or other forms of pollution (EPA, 2014g). Thus, impingement and entrainment may exacerbate the loss of species and critical habitat from pollution.
The risks associated with fossil fuel power are not evenly distributed across fuel types or within fuel types. A study of non-climate change-related damages caused by air emissions from 406 coal-fired power plants estimated that 50% of the plants with the lowest damages together produced 25% of the net generation of electricity, while 10% of the plants with the highest damages also produced 25% of the net generation (National Research Council [NRC], 2010). Similarly, a review of 498 natural gas-fired facilities noted that there were major differences in pollution generation. Ten percent of the gas-fired plants accounted for 65% of the damage (NRC, 2010).
Greenhouse Gas Emissions from Fossil Fuel Power Plants
Greenhouse gas (GHG) emissions from power plants have been identified as a long-term risk causing worldwide climate change (Schaeffer et al., 2015). The current and future impact from climate change depends upon a large number of factors, making risk estimation a complex and difficult undertaking. Haines et al. (2000) identified GHG risks to human health that include direct exposure to thermal and weather extremes, and indirect effects that include alterations in vector-borne infectious diseases, water quality and quantity, and changes in agricultural productivity. An example of vector-borne disease risk from climate change includes that of the St. Louis encephalitis virus. The virus, which can cause inflammation of the brain when transmitted to humans, depends on meteorological triggers for virus amplification between mosquitoes and wild birds (Day, 2001). Several researchers reported that climate change has caused an earlier onset of the spring pollen season in the Northern Hemisphere, potentially exacerbating asthma symptoms (D’Amato et al., 2002; Weber, 2002; Beggs, 2004). Other impacts from climate change include regional declines in fish populations (Brooks et al., 2002). Moore et al. (2008) identified potential impacts in marine and fresh water systems that include lower pH, changes to vertical mixing, precipitation and evaporation, and harmful algal blooms.
Forty percent of all greenhouse gases are emitted by fossil fuel power plants (75% of these are from coal-fired plants) (EPA, 2014). As of 2011, fossil fuel power plants in the United States that emit 25,000 tons or more of carbon dioxide equivalent (CO2e) greenhouse gases must report annual emissions to the EPA. The list of chemicals regulated under the program includes carbon dioxide, methane, nitrous oxide, and a number of fluorinated hydrocarbons. Fossil fuel power plants primarily emit carbon dioxide, with smaller quantities of methane and nitrous oxide. While carbon dioxide is the greenhouse gas emitted in large quantities, methane and nitrous oxide have larger global warming potentials (GWP). Methane has a 25 times larger GWP and nitrous oxide has a 298 times larger GWP than CO2.
Compared to other industries, occupational injury numbers and rates in the United States are generally low among power generating facilities. The Electric Power Research Institute (EPRI) collects and publishes information on the number of occupational injuries and illnesses reported by participating power facilities. EPRI reported that the most frequent types of injury (1995-2011) was sprains and strains (38.5%); cuts, lacerations and punctures (15.2%); and contusions and bruises (8.5%) (EPRI, 2013). The greatest occupational risks are associated with fossil fuel power plants. The United States Department of Labor (DOL) shows one fatality per year in 2012 and 2013 among fossil fuel electric power generating plants (DOL, 2014). In 2013, 82% of the approximately 2,200 recordable injuries within the power generation industry occurred at fossil fuel power plants. Nonfatal injury incident rates per 100 full-time employees at fossil fuel power plants was 1.4 in 2013, which interestingly is lower than hydroelectric power generation (2.3), but higher than nuclear power generation (0.2) (DOL, 2014). Illnesses such as respiratory conditions, poisonings from chemicals, and skin diseases are generally low at fossil fuel power plants. Hearing loss, however, represents the highest illness category among fossil fuel plants. In 2013, hearing loss incident rates per 10,000 full-time employees at fossil fuel plants was 20.1, or approximately 55% of all the reported illness incidents (DOL, 2014).
Exposure to coal dust at coal-fired power plants has not resulted in illness rates similar to those in coal mines (DOL, 2014). The reason is not completely understood. While coal ash (material remaining after coal combustion) contains many of the same mineral and metal constituents as coal dust, it does not appear to be as toxic (Borm, 1997).
To address these risks the EPA has proposed a number of regulations to protect the community and natural environment, particularly for coal-fired and oil-fired power plants. Many are the result of continuing efforts that began decades ago to further reduce pollutants associated with a number of potential health effects.
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