Environmental Impact of Energy Production

In our modern society, energy—especially in the convenient form of electricity—is critical to our quality of life. No matter how our electricity is generated—gas, coal, nuclear or even wind—there is some impact on the environment. This interactive web page allows you to compare the environmental costs associated with each fuel option.

Move your mouse over the fuel sources to the right to compare the amount of pollution produced by traditional electric plants to that of wind power. This chart shows the offset from Cape Wind in one year of operation (all values in tons).

CO2	Carbon dioxide is the primary gas involved in global warming. Rising global temperatures are expected to raise the sea level, change precipitation and alter other climate conditions.
NOx	Nitrogen oxides contribute to the formation of smog, acid rain and toxic chemicals by reacting with other compounds in the air. NOx emissions also contribute to the deterioration of water quality by increasing nitrogen loading.
SO2	Sulfur dioxide contributes to respiratory illness and aggravates existing heart and lung disease; damages trees, crops, stone and other materials; increases acidity in soils, lakes and other bodies of water; and increases visibility impairment. Sulfur dioxides form particulates that can be transported over long distances and deposited far from the point of origin.
CO	Carbon monoxide causes harmful effects by reducing oxygen delivery to the body’s organs and tissues; it also contributes to the formation of smog.
VOC	Volatile organic compounds contribute to the formation of ozone, which causes respiratory problems in people susceptible to asthma. Ozone also contributes to smog and increases plant vulnerability to disease, pests and harsh weather. Many forms of VOCs have been determined to be hazardous air pollutants that contribute to detrimental health effects such as cancer.
PM	Particulate matter has been linked to increases in respiratory problems including asthma, chronic bronchitis and decreased lung function. Particulate matter contributes to visible haze and soot, which stains and damages stone and other materials.

Other sources of electricity

Although hydro- and nuclear-power do not produce any smokestack emissions, they both incur significant environmental costs.

Hydropower

The most obvious impact of hydro-electric dams is the flooding of vast areas of land, much of it previously forested or used for agriculture. The size of the reservoirs created can be extremely large. The La Grande project in the James Bay region of Quebec has already submerged more than 10,000 square kilometers of land. If future plans are carried out, the eventual area of flooding in northern Quebec will be larger than the country of Switzerland. Many rare ecosystems are also threatened by hydro-electric development.

Recent studies of large reservoirs created behind hydro dams have suggested that decaying vegetation, submerged by flooding, may give off quantities of greenhouse gases equivalent to those from other sources of electricity. If this turns out to be true, hydro-electric facilities such as the James Bay project in Quebec that flood large areas of land might be significant contributors to global warming.

Bacteria present in decaying vegetation can also change mercury, present in rocks underlying a reservoir, into a form which is soluble in water. The mercury accumulates in the bodies of fish and poses a health hazard to those who depend on these fish for food. The water quality of many reservoirs also poses a health hazard due to new forms of bacteria which grow in many of the hydro rivers.

Large dams and reservoirs can have other impacts on a watershed. Damming a river can alter the amount and quality of water in the river downstream of the dam, as well as prevent fish from migrating upstream to spawn. Silt, normally carried downstream to the lower reaches of a river, is trapped by a dam and deposited on the bed of the reservoir. This silt can slowly fill up a reservoir, decreasing the amount of water that can be stored and used for electrical generation. The river downstream of the dam is also deprived of silt which fertilizes the river's flood-plain during high water periods.

Nuclear power

The environmental costs of nuclear power starts with the mining of uranium to fuel the plants. The mining process is similar to coal mining, with both open pit and underground mines. It produces similar environmental impacts, with the added hazard that uranium mine tailings are radioactive. Groundwater can be polluted not only from the heavy metals present in mine waste, but also from the traces of radioactive uranium still left in the waste.

Accidents like the one in 1979 at the Three Mile Island nuclear power plant, along with many subsequent close calls, exposed the risk of nuclear plants. A severe nuclear accident has the potential to do catastrophic harm to people and the environment. A combination of human and mechanical error could result in an accident killing several thousand people, injuring several hundred thousand others, contaminating large areas of land and costing billions of dollars.

Nuclear plants pose a security risk. Not only can the radioactive material can be used to make nuclear weapons, but even its release is catastrophic. Government studies report that radioactive material released from either the reactor or the onsite spent fuel can kill and injure tens of thousands of people living within 500 miles and render large regions uninhabitable for long periods.

Nuclear reactors also produce radioactive waste. This waste is being stored at the nuclear plants where it is produced, most commonly in a large steel-lined pool. As these pools fill up, the waste material is stored in large steel and concrete casks. In addition to the spent fuel, the plants themselves contain radioactive waste that must be disposed of after they are shut down.