Environmental Impact

Jump to: Pollution Overview; Coal; Oil; Natural Gas; Nuclear; Wind; Biomass; Geothermal; Hydropower; or Environmental Policy

This section serves as a summary of the major environmental issues associated with the generation of electricity from each energy source.  Detailed information about the history, utilization, and quantities of each energy source can be found on each page dedicated to the energy source. 

Pollution Overview

When fossil fuels are burned to generate electricity, a variety of gases and particulates are formed. If these gases and particulates are not captured by some pollution control equipment, they are released into the atmosphere [1].  The most common forms of air pollution are carbon monoxide, sulfur oxides, nitrogen oxides, particulate matter, and ground-level ozone (also referred to as smog). In the US, carbon monoxide causes about 67% of the measurable air pollution; sulfur oxides and nitrogen oxides about 15%; and particulate matter and the other pollutants making up the balance [2, 3]. 

The Environmental Protection Agency (EPA) has set national air quality standards for six principal air pollutants (also called “criteria pollutants”): nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2), particulate matter (PM), carbon monoxide (CO), and lead (Pb). Four of these pollutants (CO, Pb, NO2, and SO2) are emitted directly from a variety of sources. Ozone is not directly emitted, but is formed when NO2 volatile organic compounds (VOCs) react in the presence of sunlight. PM can be directly emitted, or it can be formed when emissions of NO2, SO2, ammonia, organic compounds, and other gases react in the atmosphere [4].

All criteria pollutants, except for lead, are emitted from the generation of electricity at fossil fuel-based power plants [5].  Of the criteria pollutants, electric utilities contribute the greatest percentage to emissions of sulfur oxides; electric utilities generate 70% of the sulfur dioxide emissions in the US, with most of that coming from coal-fired power plants [2].  However, progress has been made: utility emission levels of SO2 in the US decreased from 17.3 to 11.2 million tons from 1980 to 2000 due to the burning of lower-sulfur fuels, the installation of pollution control devices, and the Acid Rain Program [2].

The EPA reports that national air quality levels have shown improvements over the past 20 years for all principal pollutants, and that since 1970, aggregate emissions of principal pollutants have been cut 48% [4].  While these trends indicate positive environmental progress, about 160 million tons of pollution are still emitted into the air each year in the US alone [4].

Of the abovementioned types of pollution, progress has been slowest for ground-level ozone. Over the past 20 years, there has been some improvement in the Northeast and Pacific Southwestern regions of the US, but the national average ozone levels have been fairly constant throughout the vast majority of the nation [4].

Figure 1 provides emissions data from fuel combustion by electric utilities from 1998 to 2002 (most recent data available) [6].

Figure 1: Emissions from Fuel Combustion by Electric Utilities

Coal
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Smith (2004) states: “Of all fossil fuels, coal has the most harmful immediate and long-term effects on the environment and human health. People who lived in the industrial cities of the nineteenth century knew that coal produced annoying and debilitating smoke, but they could not comprehend the magnitude of coal’s impact on the environment and the human body.  Today we have scientific measurements that show the extent of the distribution. Air pollution, thermal pollution, land devastation, groundwater pollution, acidification of streams and rivers, erosion, subsidence of land caused by underground mines, hazards to miners, and, of course, global warming are all recognized as part and parcel of coal’s utilization” [2].

Because of coal’s negative environmental consequences, Smith argues that although coal reserves may last 2,000 years, utilization of all known reserves would be catastrophic for the environment [2].

Utilizing coal reduces not only air quality, but has many negative impacts on land itself.  The Surface Mining Control and Reclamation Act of 1977 (SMCRA) requires that land be reclaimed after mining operations cease – but its enforcement has been dubbed “spotty” [2].  However, in the cases where SMCRA is successful, once coal is removed from one section, the land is returned, regrated, and replanted.  Due to this, many consider modern mining a “temporary land use.”  Once the coal is removed and the land reclaimed, it can be used for golf courses, wildlife preserves, shopping centers, or just about any other use [7].   

Clean coal technology is a new generation of energy processes that sharply reduce air emissions and other pollutants from coal-burning power plants [8]. The Bush administration’s Clean Coal Power Initiative is providing government co-financing for new coal technologies that can help utilities cut sulfur, nitrogen, and mercury pollutants from power plants by nearly 70% by the year 2018 [8]. Furthermore, clean coal plants have proven to increase coal-to-electricity efficiency, which in turn reduces greenhouse gas emissions [8].

In 2003, President George W. Bush announced that the US will sponsor a $1 billion, 10-year demonstration project to create FutureGen, the world’s first coal-based, zero-emissions electricity and hydrogen power plant.  The prototype plant will establish the technical and economic feasibility of producing electricity and hydrogen from coal, while capturing and sequestering the carbon dioxide generated in the process [9].

In 2002 (most recent data available), coal combustion by electric utilities in the US produced 256,000 tons of carbon monoxide; 4,097,000 tons of nitrogen oxide; 642,000 tons of PM-10 and 535,000 tons of PM-2.5; 9,738,000 tons of sulfur dioxide; and 51,000 tons of volatile organic compounds [6].

Oil

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Burning oil to generate electricity produces significant air pollution in the forms of nitrogen oxides, and, depending on the sulfur content of the oil, sulfur dioxide and particulates.  Furthermore, the process creates emissions of carbon dioxide and methane, heavy metals such as mercury, and volatile organic compounds [10]. In addition, oil wells and oil collection equipment are a source of emissions of methane, a potent greenhouse gas. The large engines that are used in the oil drilling, production, and transportation processes burn natural gas or diesel that also produce emissions.  Utilizing oil also contributes greatly to water resource deterioration, solid waste generation, and land resource use leading to the destruction of habitats for animals and plants [11].  The EPA provides a detailed summary of the environmental impacts of using oil to generate electricity.

In 2002 (most recent data available), oil combustion by electric utilities in the US produced 14,000 tons of carbon monoxide; 130,000 tons of nitrogen oxide; 17,000 tons of PM-10 and 13,000 tons of PM-2.5; 343,000 tons of sulfur dioxide; and 4,000 tons of volatile organic compounds [6].

Natural Gas

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There are numerous environmental benefits to natural gas in comparison to other fossil fuels; primarily it is more clean and efficiently utilized [7].  In fact, it is the cleanest burning of any fossil fuel, producing primarily carbon dioxide, water vapor, and small amounts of nitrogen oxides.  Natural gas plants produce none of the solid waste associated with coal units, less than 1% of the sulfur dioxide and particulate emissions, and 85% less nitrogen oxide than a coal plant with pollution control equipment [7].  Furthermore, in comparison to other fossil fuel plants, the burning of natural gas in combustion turbines requires very little water and thus does not contribute as greatly to water resource deterioration [12].

In 2002 (most recent data available), natural gas combustion by electric utilities in the US produced 88,000 tons of carbon monoxide; 270,000 tons of nitrogen oxide; 12,000 tons of PM-10 and 11,000 tons of PM-2.5; 8,000 tons of sulfur dioxide; and 7,000 tons of volatile organic compounds [6].

Nuclear

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Nuclear power’s major advantage is a lack of harmful air emissions; nuclear power plants do not emit carbon dioxide, sulfur dioxide, or nitrogen oxides [7, 13]. However, fossil fuel emissions are associated with the uranium mining and uranium enrichment processes as well as the transport of the uranium fuel to the nuclear plant [13].  Furthermore, nuclear power plants use very large quantities of water for steam production and for cooling. When nuclear power plants remove water from a lake or river for steam production and cooling, fish and other aquatic life can be affected [13].

Other direct environmental problems associated with nuclear power include the potential for nuclear meltdown, the mining and storage of nuclear fuels, and disposal of nuclear waste [2].  The true environmental costs of nuclear power must consider the entire nuclear fuel cycle from uranium mining at the “front end” of the industry to waste disposal at the “back end.”  Considering the entire fuel cycle leads some to argue that, in environmental terms, nuclear power is the worst energy source utilized. This is because nuclear power plants produce tons of radioactive waste that will be deadly for hundreds of thousands of years [2].  A 1,000 MW reactor will produce about 30 metric tons of spent fuel annually.  Some of the radioactive isotopes decay within a few hours, days or weeks. Others remain radioactive for centuries [7].

Many have argued that providing a viable future for nuclear energy will require policymakers to reform the federal government’s program to manage used nuclear fuel [7].  Yucca Mountain has emerged as a potential location for long-term storage of nuclear waste, but is still riddled with controversy.  For example, in 1998, 219 various organizations asked the DOE to consider the site unsuitable due to the risks associated with the location and the transport of waste to the location [2].

Wind

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The advantages of wind power in comparison to the utilization of fossil fuels are plentiful, including the fact that wind generation produces no air emissions, wind power is received well by the public, wind turbines have a small footprint and can be located on farming or grazing land, turbines can be constructed quickly, there are no fuel costs, wind is the lowest-cost non-hydro renewable energy source, and of course, wind is renewable [14].

However, wind power does have environmental impacts, including noise emitting from the spinning turbine, visual impacts of the turbine, and bird and bat deaths from impacts with the turbine blades [15].  Furthermore, there are environmental impacts of wind power associated with manufacturing, installing, and ultimately disposing of the wind systems [16].  That is, energy is required to manufacture and install wind components, and any fossil fuels used for this purpose generate emissions.

Biomass

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Today, biomass electrical generation is second only to hydropower as a renewable energy source [17].  The technology’s recent rapid development can be accredited to the many benefits of biomass power; primarily that biomass has the potential to greatly reduce greenhouse gas emissions. 

However, whether combusting directly or engaged in gasification, biomass resources do generate SO2, NOx, and CO emissions.  If wood is the primary biomass resource, very little SO2 is emitted.  NOx emissions vary significantly depending on design and control of combustion facilities.  CO is emitted – sometimes at levels higher than coal plants