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
(See details on Coal)

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

(See details on Oil)

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

(See details on Natural Gas)

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

(See details on Nuclear)

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

(See details on Wind)

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

(See details on Biomass)

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 [18].  CO2 is also emitted – at about the same level of fossil fuel plants. However, biomass is widely recognized as a “green” energy source due to the fact that biomass releases carbon dioxide that was captured during its own growth, thus being essentially “carbon neutral” [19].

Geothermal

(See details on Geothermal)

Geothermal energy is a clean, sustainable energy source with very low emissions.  Geothermal power plants emit little carbon dioxide, very low amounts of sulfur dioxide, and no nitrogen oxides.  In comparison to traditional fossil fuel plants, a steam geothermal plant emits almost 50 times less carbon dioxide, nitric oxide, and sulfur.  A binary geothermal plant emits no emissions at all due to its self-contained cycle [20]. Due to this, electricity produced from US geothermal resources, compared to conventional coal-fired plants, annually offsets the emission of 4.1 million tons of carbon dioxide; 80,000 tons of nitrogen oxides; and 110,000 tons of particulate matter [21]. 

Furthermore, geothermal energy greatly minimizes the amount of resulting solid waste and land required for energy production [22].  An entire geothermal field uses 1-8 acres per megawatt versus 5-10 acres per megawatt for nuclear operations and 19 acres per megawatt for coal power plants.  Also, unlike coal power sources, geothermal power does not require huge acreages for mining fuel and does not produce waste heaps or disturbed surfaces [23].

Solar Power
(See details on Solar Power)

Solar power plants consume no fuel and produce no air or water pollution while they silently generate electricity [24].  Thus, unlike fossil fuels, there are no concerns regarding emissions; unlike wind power, there are no concerns regarding noise pollution.  However, there are environmental impacts of solar power associated with manufacturing, installing, and ultimately disposing of the solar systems [16].  That is, energy is required to manufacture and install solar components, and any fossil fuels used for this purpose generate emissions.  Furthermore the manufacturing of PV cells often requires hazardous materials such as arsenic and cadmium [16].

Lastly, concerns exist regarding the quantity of land required for utility-scale solar power plants (approximately 0.4 square miles for every 20-60 megawatts generated).  Despite this, generating electricity from coal still requires as much or more land per unit of energy delivered if the land used in strip mining is taken into account [16].

Hydropower, Wave Power & Tidal Power
(See details on Hydropower or Wave and Tidal Power)

Hydropower offers many advantages over other energy sources including the fact that it is fueled by water, and thus does not pollute the air like fossil power plants.   However, recently hydropower has come under criticism for the impact that dams have on fish populations and water quality and flow [25].  Other concerns have arisen from observations that if a large amount of vegetation is growing along the riverbed when a dam is built, it can decay in the lake that is created, causing the buildup and release of methane, a potent greenhouse gas. Furthermore, hydropower has been accused of altering ecosystems and affecting the wildlife and people who depend on those waters [26].

Wave and tidal power are relatively new technologies and are only recently being applied on a larger scale.  Thus the full environmental impacts may not yet be realized.  Like hydropower, wave and tidal power utilize no fuel (other than the water itself) and thus do not pollute the air.  However, concerns may arise from the fact that obtrusive objects (i.e. the turbines) are being submerged in bodies of water and thus may have some effect on the water ecosystem.

Environmental Policy

Jump to: The Clean Air Act; Emissions Trading; or The Kyoto Protocol

The Clean Air Act

The Clean Air Act, passed in 1963 and amended in 1967, 1970, 1977, and 1990, has changed the nature of emissions in the US in a number of ways.  The Act serves as the first major federal involvement in air pollution.  Whereas the original act empowered  federal officials to intervene in interstate air pollution matters only at the request of state governments, the amendments of 1977 and 1990 greatly increased the role of the federal government [2].  Since 1977 (and amended in 1990), the EPA is able to enforce national air quality through the creation and utilization of National Ambient Air Quality Standards (NAAQS). These standards are aimed at protecting ecosystems, including plants and animals, from harm, as well as protecting against decreased visibility and damage to crops, vegetation, and buildings [27]. 

Emissions Trading

The 1990 Clean Air Act amendments and the 1995 Acid Rain Program established an emissions trading (or cap and trade) program.  The program serves as an administrative approach to control pollution by providing economic incentives for achieving reductions in emissions (primarily emissions of SO2).  Under the program, the EPA sets a limit on the amount of a pollutant that can be emitted. Companies and other groups that emit the pollutant are given allowances (or credits) which represent the right to emit a specific amount [28].  The total amount of allowances cannot exceed the cap, limiting total emissions to that level. Companies that pollute beyond their allowances must buy credits from those who pollute less than their allowances. This transfer is referred to as a trade. In effect, the buyer is being fined for polluting, while the seller is being rewarded for having reduced emissions. The more firms that need to buy credits, the higher the price of credits becomes – which makes reducing emissions cost-effective in comparison [28].

Under the SO2 program, an allowance authorizes a utility or industrial source to emit one ton of SO2 during a given year or any year thereafter.  At the end of each year, the source must hold an amount of allowances at least equal to its annual emissions, i.e., a source that emits 5,000 tons of SO2 must hold at least 5,000 allowances that are usable in that year.  However, regardless of how many allowances a source holds, it is never entitled to exceed the limits set under the Acid Rain Program. Allowances are fully marketable commodities. Once allocated, allowances may be bought, sold, traded, or banked for use in future years [29].

In 2003, the EPA began to administer the NOx Budget Trading Program, the first new emissions trading program to be implemented in ten years. Similar to the SO2 program established in 1995, the new program is a market-based cap and trade program created to reduce emissions of nitrogen oxides (NOx) from power plants and other large combustion sources in the eastern US [30].

According to the EPA, the emissions trading programs established under the Acid Rain Program have reduced SO2 emissions by over 5.5 million tons and NOx emissions by about 3 million tons from 1990 levels.  Furthermore, by 2010 the Acid Rain Program's annual benefits will be approximately $122 billion (2000$), at an annual cost of about $3 billion – a 40-to-1 benefit-to-cost ratio [31].

Since their implementation, the Clean Air Act and Acid Rain Program have greatly contributed to the improvement of air quality throughout the nation.  However, recently more focus has been placed not on national-level environmental policy, but on international-level policy.

The Kyoto Protocol

The Kyoto Protocol (Full Text; Summary) is an agreement made under the United Nations Framework Convention on Climate Change (UNFCCC).  Countries that ratify this protocol commit to reduce their emissions of carbon dioxide and five other greenhouse gases, or engage in emissions trading if they maintain or increase emissions of these gases.  The Kyoto Protocol now covers more than 160 countries globally and over 55 percent of global greenhouse gas (GHG) emissions (full list of signed and ratified countries; map of signed and ratified countries). 

Despite the widespread international acceptance of the Kyoto Protocol, a growing environmental ethic in the US, and the fact that the US is the largest single emitter or carbon dioxide from burning of fossil fuels [32], the US has not ratified the agreement. The US is one of only two countries that have signed but not ratified the agreement – the other being Australia. The Bush Administration cites equity reasons for not signing the protocol, arguing that China, the world’s second-largest emitter of greenhouse gases, is exempted from the requirements of the protocol and thus it would be unfair to limit emissions in the US [33].

Resources

1. EIA. Electric Power Industry Overview.  2000  [cited 2007 27 March].

2. Smith, Z.A., The Environmental Policy Paradox. 4th ed. 2004, Upper Saddle River, NJ: Prentice Hall.

3. GPO, Statistical Abstract of the United States. 1996, Bureau of Statistics; Government Printing Office: Washington, DC.

4. EPA, Latest Findings on National Air Quality: 2002 Status and Trends. 2002, Environmetnal Protection Agency: Washington, DC.

5. EPA. The Plain English Guide to the Clean Air Act: The Common Air Pollutants.  2006  [cited 2007 28 April].

6. EPA. National Emissions Inventory (NEI) Air Pollutant Emissions Trends Data.  2005  [cited 2007 28 April].

7. Chambers, A., Power Primer: A Nontechnical Guide from Generation to End Use. 1999, Tulsa, Oklahoma: PennWell Publishing Company.

8. DOE. Clean Coal Technology & The President's Clean Coal Power Initiative.  2007  [cited 2007 1 April].

9. DOE. FutureGen - Tomorrow's Pollution-Free Power Plant.  2007  [cited 2007 1 April].

10. Pace. Power Scorecard: Electricity from Oil.  2000  [cited 2007 5 April].

11. EPA. Electricity from Oil.  2005  [cited 2007 6 April ].

12. EPA. Clean Energy: Electricity from Natural Gas.  2006  [cited 2007 28 April].

13. EPA. Clean Energy: Electricity from Nuclear Energy.  2006  [cited 2007 28 April].

14. NRECA, NRECA White Paper on Wind Power. 2003, National Rural Electric Cooperative Association: Arlington, VA.

15. BLM. Wind Energy Development Environmental Concerns.  2007  [cited 2007 28 April].

16. USC. Clean Energy: Environmental Impacts of Renewable Energy Technologies.  2005  [cited 2007 28 April].

17. EERE. Biomass Energy or Biopower.  2005  [cited 2007 8 April ].

18. PACE. Power Scorecard: Electricity from Biomass.  2000  [cited 2007 28 April].

19. NREL. Learning About Renewable Energy.  2006  [cited 2007 8 April].

20. NREL. Geothermal Technologies Program: About Geothermal Electricity.  2007  [cited 2007 8 April].

21. EERE. Geothermal Power Plants - Meeting Clean Air Standards.  2006  [cited 2007 28 April].

22. EERE. Environmental Impacts and Benefits of Using Geothermal Energy.  2006  [cited 2007 28 April].

23. EERE. Geothermal Power Plants - Minimizing Land Use and Impact.  2006  [cited 2007 28 April].

24. EERE. PV for Utility Power Production.  2006  [cited 2007 8 April].

25. EERE. Advantages and Disadvantages of Hydropower.  2005  [cited 2007 8 April ].

26. EPA. Clean Energy: Electricity from Hydropower.  2006  [cited 2007 28 April].

27. EPA. Air and Radiation: National Ambient Air Quality Standards (NAAQS).  2007  [cited 2007 28 April].

28. EPA. Clean Air Markets: Allowance Trading Basics.  2007  [cited 2007 28 April].

29. EPA. Clean Air Markets: Acid Rain Program SO2 Allowances Fact Sheet.  2007  [cited 2007 27 April].

30. EPA. Clean Air Markets: NOx Budget Trading Program / NOx SIP Call.  2007  [cited 2007 28 April].

31. EPA. Clean Air Markets: Acid Rain Program 2005 Progress Report.  2007  [cited 2007 28 April ].

32. EIA. Country Analysis Briefs: United States.  2005  [cited 2007 25 April].

33. whitehouse.gov. President Bush Discusses Global Climate Change.  2001  [cited 2007 25 April].