Electricity and the Environment -- Minnesota Pollution Control Agency

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The Minnesota Public Utilities Commission (PUC) requires utilities to disclose environmental information to their customers. The utilities send these disclosures with customer bills twice per year - once prior to the heating season and once prior to the cooling season. This section of the MPCA's Web site is intended to assist the public in understanding the environmental information included in the disclosures.

Coal combustion to produce electricity is the single biggest source of many pollutants in Minnesota. Over half of the electricity generated in Minnesota comes from coal-fired electric power plants. Minnesota receives most of its coal supply by rail from Montana and Wyoming.

Two nuclear plants near the Twin Cities typically account for nearly one-fourth of the state’s electricity production. Recent legislation permits the Prairie Island Plant to store additional nuclear waste onsite, extending the plant’s operation through 2014. The smaller Monticello nuclear plant is currently licensed through September 2010.

Minnesota has numerous wind farms, particularly in the southwest, and generates electricity from other renewable sources as well, including conventional hydroelectric dams, municipal solid-waste and landfill gas, and wood waste. Minnesota ranks among the leading states in renewable energy generation.

2007 Electric Power Generation by Primary Energy Source
(Percentage of Megawatthours)
(Data From Energy Information Administration)

Electric Utility Disclosures

Effects

Key emissions required to be reported in the disclosures affect air quality. The key air emissions discussed below are:

Nitrogen oxides, or NO_x, is the generic term for a group of highly reactive gases, all of which contain nitrogen and oxygen in varying amounts. Many of the nitrogen oxides are colorless and odorless. However, one common pollutant, nitrogen dioxide (NO₂) along with particles in the air can often be seen as a reddish-brown layer over many urban areas. NO_x forms when fuel is burned at high temperatures, as in a combustion process. The primary sources of NO_x are motor vehicles, electric utilities, and other industrial, commercial, and residential sources that burn fuels.

Sulfur dioxide is a heavy, pungent, colorless gas formed primarily by the combustion of coal, oil, and diesel fuels. Elevated levels can impair breathing, lead to other respiratory symptoms, and at very high levels aggravate heart disease. People with asthma are most at risk. Sulfur dioxide also contributes to acid rain, which can damage plants, lakes and buildings.

Particulate matter is the term used for a complex mixture of solid particles and liquid droplets found in the air. Air pollution regulations address two size categories of particles, PM₁₀ and PM_2.5. PM₁₀ refers to particles less than ten microns in diameter (an average human hair is about 70 microns in diameter). PM_2.5 refers to particles less than 2.5 microns in diameter, sometimes referred to as fine particles. Major sources of fine particles in the air are cars, trucks, construction equipment, coal-fired power plants, wood burning, vegetation and livestock operations. In general, large particles come from wind-blown dust and mechanical processes. Fine particles are formed mainly by combustion process. They may be directly released when coal, gasoline, diesel fuels and wood are burned. Small particles can also be formed secondarily when combustion gases like nitrogen oxides, sulfur oxides, ammonia, and organic compounds react in the atmosphere to form particles. Particles pose a health risk because they can pass through the nose and throat and lodge themselves in the lungs. Fine particles more easily penetrate the lungs than large particles, and have been linked with increased hospitalizations and deaths due to heart and lung disease and they also can worsen the symptoms of asthma. People with respiratory or heart disease, diabetes, the elderly and children are the groups most at risk. Fine particles are also major contributors to reduced visibility (haze).

Mercury is an element that is present throughout the environment. Human activities release some of that mercury into the air. This air-borne mercury can eventually contaminate surface waters and soil. In the United States, coal-fired power plants are the biggest source of mercury emissions to the air. Mercury can damage human health because it is toxic to the nervous system (the brain and spinal cord) and particularly the developing nervous systems of fetuses and children 16 years old or younger. Humans are exposed to mercury primarily through the consumption of mercury-contaminated fish. The Minnesota Department of Health issues health advisories regarding consumption of certain types of fish from certain lakes.

Carbon dioxide is the principal "greenhouse gas" linked to global warming. The earth’s atmosphere has a natural greenhouse effect. This effect is being increased by human activities causing the Earth’s average global temperature to rise (called “global warming”). As temperature rises, climates around the world change. Long-term changes in climate can influence the survivability of ecosystems, range of pests, smog formation, intensity and frequency of extreme weather events, and many other phenomena. Carbon dioxide accounts for about three-quarters of the greenhouse gases released in Minnesota and the U.S. The main contributor to carbon dioxide emissions is the combustion of fossil fuels in electric power generation, motor vehicles, and industries.

Electricity and the Environment

Electric Utility Disclosures

Effects

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