Environmental effects of coal

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There are a number of adverse environmental effects of coal mining and burning.

These effects include:

• release of carbon dioxide and methane, both of which are greenhouse gases causing climate change and global warming according to the IPCC. Coal is the largest contributor to the human-made increase of CO2 in the air. ^[1]
• waste products including Uranium, Thorium, and other heavy metals
• acid rain
• interference with groundwater and water table levels
• impact of water use on flows of rivers and consequential impact on other land-uses
• dust nuisance
• subsidence above tunnels, sometimes damaging infrastructure
• rendering land unfit for the other uses.

Contents 1 Mining 1.1 Mine collapses 2 Burning 3 By country 3.1 Australia 3.2 China 3.3 United States 4 See also 5 References 6 External links

[edit] Mining

Coal mining causes a number of harmful effects. When coal surfaces are exposed, pyrite (iron sulfide), also known as "fool's gold", comes in contact with water and air and forms sulfuric acid. As water drains from the mine, the acid moves into the waterways, and as long as rain falls on the mine tailings the sulfuric acid production continues, whether the mine is still operating or not. This process is known as acid rock drainage (ARD) or acid mine drainage (AMD). If the coal is strip mined, the entire exposed seam leaches sulfuric acid, leaving the subsoil infertile on the surface and begins to pollute streams by acidifying and killing fish, plants, and aquatic animals who are sensitive to drastic pH shifts.

Coal mining produces methane, a potent greenhouse gas. Methane is the naturally occurring product of the decay of organic matter as coal deposits are formed with increasing depths of burial, rising temperatures, and rising pressures over geological time. A portion of the methane produced is absorbed by the coal and later released from the coal seam and surrounding disturbed strata during the mining process.^[2] Methane accounts for 9% of greenhouse gas emissions created through human activity.^[3] According to the Intergovernmental Panel on Climate Change, methane has a global warming potential 21 times greater than that of carbon dioxide on a 100 year time line. While burning coal in power plants is most harmful to air quality, due to the emission of dangerous gases, the process of mining can release pockets of hazardous gases. These gases may pose a threat to coal miners as well as a source of air pollution. This is due to the relaxation of pressure and fracturing of the strata during mining activity, which gives rise to serious safety concerns for the coal miners if not managed properly. The buildup of pressure in the strata can lead to explosions during or after the mining process if prevention methods, such as "methane draining", are not taken.^[4]

Strip mining severely alters the landscape, which damages environmental value in the surrounding land. Mountaintop removal to remove coal is a large negative change to the environment. While there are sometimes requirements for remediation of the strip mined area, the remediation is often delayed for decades. One of the legacies of coal mining is the low coal content waste forming slag heaps.

All forms of mining are likely to generate areas where coal is stacked and where the coal has significant sulfur content, such coal heaps generate highly acidic, metal-laden drainage when exposed to rainfall. These liquors can cause severe environmental damage to receiving water-courses.^[5] Coal mining releases approximately twenty toxic release chemicals, of which 85% is said to be managed on site.^{[citation needed]} In modern mining, operations must, under federal and state law, meet standards for protecting surface and ground waters from contamination, including AMD. To mitigate these problems, water is continuously monitored at coal mines. The five principal technologies used to control water flow at mine sites are:

• diversion systems,
• containment ponds,
• groundwater pumping systems,
• subsurface drainage systems,
• subsurface barriers.

In the case of AMD, contaminated water is generally pumped to a treatment facility that neutralizes the contaminants.

[edit] Mine collapses

Mine collapses, or mine subsidences, have a potential for major effects aboveground, which are especially devastating in built-up areas. German underground coal-mining, especially in North Rhine-Westphalia, has damaged thousands of houses, and the coal mining industries have set aside many millions in funding for future subsidence damages as part of their insurance and state subsidy schemes.^{[citation needed]}

In a particularly spectacular case in the German Saar region, another historical coal mining area, a suspected mine collapse in 2008 created an earthquake of force 4.0 on the Richter magnitude scale, causing some limited damage to houses. Previous smaller earthquakes had been increasingly common. Coal mining was temporarily suspended in the area.^[6]

[edit] Burning

Combustion of coal, like any other fossil fuel, occurs due to an exothermic reaction between the components of the fuel source, and the components air surrounding it. Coal is made primarily of carbon, but also contains sulfur, oxygen and hydrogen. The reaction between coal and the air surrounding it produces oxides of carbon, usually carbon dioxide (CO₂ - a major greenhouse gas) in a complete combustion, along with oxides of sulfur, mainly sulfur dioxide (SO₂), and various oxides of nitrogen (NO_x). Because of the hydrogen and nitrogen components of air, hydrides and nitrides, of carbon and sulfur, are also produced during the combustion of coal in air. These could include hydrogen cyanide (HCN), sulfur nitrate (SNO₃) and many other toxic substances.

Further, acid rain may occur when the sulfur dioxide produced in the combustion of coal, reacts with oxygen to form sulfur trioxide (SO₃), which then reacts with water molecules in the atmosphere to form sulfuric acid (see Acid anhydride for more information). The sulfuric acid (H₂SO₄) is returned to the Earth as acid rain. Flue gas desulfurization scrubbing systems, which use lime to remove the sulfur dioxide can reduce or eliminate the likelihood of acid rain.

However, another form of acid rain is due to the carbon dioxide emissions of a coal plant. When released into the atmosphere, the carbon dioxide molecules react with water molecules, to produce carbonic acid (H₂CO₃). This, in turn, returns to the earth as a corrosive substance. This cannot be prevented as easily as sulfur dioxide emissions can, because carbon is the main component of coal, and this resultantly means that a person cannot as easily reduce carbon dioxide emissions caused in the oxidation of coal, as they can with the aforementioned use of lime to reduce sulfur dioxide emissions.

Emissions from coal-fired power plants represents one of the two largest sources of carbon dioxide emissions, believed to be the cause of global warming. Coal mining and abandoned mines also emit methane, another purported cause of global warming. Since the carbon content of coal is higher than oil, burning coal is a serious threat to the stability of the global climate, as this carbon forms CO₂ when burned. Many other pollutants are present in coal power station emissions, as solid coal is more difficult to clean than oil, which is refined before use. A study commissioned by environmental groups claims that coal power plant emissions are responsible for tens of thousands of premature deaths annually in the United States alone. Modern power plants utilize a variety of techniques to limit the harmfulness of their waste products and improve the efficiency of burning, though these techniques are not subject to standard testing or regulation in the U.S. and are not widely implemented in some countries, as they add to the capital cost of the power plant. To eliminate CO₂ emissions from coal plants, carbon capture and storage has been proposed but has yet to be commercially used.

Coal and coal waste products including fly ash, bottom ash, and boiler slag, contain many heavy metals, including arsenic, lead, mercury, nickel, sulphur, vanadium, beryllium, cadmium, barium, chromium, copper, molybdenum, zinc, selenium and radium, which are dangerous if released into the environment. Coal also contains low levels of uranium, thorium, and other naturally-occurring radioactive isotopes whose release into the environment may lead to radioactive contamination.^[7][8] While these substances are trace impurities, enough coal is burned that significant amounts of these substances are released, resulting in more radioactive waste than nuclear power plants.^[9] Mercury emissions from coal burning are concentrated as they work their way up the food chain and converted into methylmercury, a toxic compound^[10] that may affect people who frequently consume freshwater fish affected by mercury pollution from nearby coal-fired power plants.^[11] Ocean fish account for almost all of most people's exposure to methylmercury;^[11] the sources of ocean fish methylmercury are not well understood.^[12]

[edit] By country

[edit] Australia

Main article: Coal mining in Australia

Main article: Effects of global warming on Australia

[edit] China

Please help improve this section by expanding it. Further information might be found on the talk page or at requests for expansion.

Coal provides most of China's current power, both for residential electricity and industry. China is hoping to move to nuclear power as it is cleaner and can deliver large amounts of power with a small amount of input fuel.

See also: Coal power in China

[edit] United States

By the late 1930s, it was estimated that American coal mines produced about 2.3 million tons of sulfuric acid annually. In the Ohio River Basin, where twelve hundred operating coal mines drained an estimated annual 1.4 million tonnes of sulfuric acid into the waters in the 1960s and thousands of abandoned coal mines leached acid as well. In Pennsylvania alone, mine drainage had blighted 2,000 stream miles by 1967.

In response to negative land effects of coal mining and the abundance of abandoned mines in the USA, the federal government enacted the Surface Mining Control and Reclamation Act of 1977, which requires reclamation plans for future coal mining sites. Reclamation plans must be approved and permitted by federal or state authorities before mining begins. As of 2003, over 2 million acres (8,000 km²) of previously mined lands have been reclaimed in the United States.

[edit] See also

• List of environmental issues
• Algal fuel

[edit] References

[edit] External links

• World Coal Institute - Environmental Impacts of Coal Mining
• MSNBC report on coal pollution health effects in the United States