The extraction and combustion of coal negatively impacts the environment, causing water and air pollution, acid rain, mountaintop depletion and acid mine drainage. Harmful emissions from incomplete burning of coal also pose serious environmental hazards to biotic communities due to drastic changes in atmospheric conditions.
Fossil fuels are bio-fuels that formed millions of years ago from the decayed organic remains of prehistoric organisms. Coal, natural gas and oil constitute the bulk of the non-renewable sources of energy that provide usable power to produce electricity, heat households and fuel transportation. However, burning of these materials contribute to global warming and environmental degradation.
Coal particularly affects the air through the various pollutants emitted during combustion. In the United States, typical emission rates include 2,249 lbs/MWh for carbon dioxide, 6 lbs/MWh for nitrogen oxides and 13 lbs/MWh for sulfur dioxide, as reported by the U.S. Environmental Protection Agency. Other pollutants include carbon monoxide and particulate matter. Coal also contains methane, which is a source of greenhouse gas that results in global warming.
Power plants that use coal-fired boilers also contribute to water contamination. Industrial waste water often contain toxic chemicals, such as arsenic, lead and chromium, that pollute waterways. Coal mining may also cause surface and groundwater pollution due to acid mine drainage. Acid rain, which damages ecosystems, is produced when nitrogen oxides and sulfur dioxide chemically combine with hydroxyl compounds. Mountaintop coal mining is a method that denudes forests and bares the upper layer of soil, often resulting in increased runoff.