Clean Coal | Clean Coal Knowledge Centre
Environmental Issues related to the utilization of coal
Air Pollutants
There are several classifications, or ‘families’ of air pollutants. Of particular interest are:
There are several classifications, or ‘families’ of air pollutants. Of particular interest are:
- criteria air contaminants
- toxic pollutants
- greenhouse gases
Criteria Air Contaminants (CACs)
In Canada, the recognized criteria air contaminants are: ammonia (NH3), carbon monoxide (CO), lead, nitrogen oxides (NOX), ozone, total particulate matter (TPM), particulate matter less that 10 microns (PM10), particulate matter less than 2.5 microns (PM2.5), (sulphur oxides (SOX), and volatile organic compounds (VOCs).
In Canada, the recognized criteria air contaminants are: ammonia (NH3), carbon monoxide (CO), lead, nitrogen oxides (NOX), ozone, total particulate matter (TPM), particulate matter less that 10 microns (PM10), particulate matter less than 2.5 microns (PM2.5), (sulphur oxides (SOX), and volatile organic compounds (VOCs).
Toxic Pollutants
Toxic pollutants are sometimes referred to as hazardous air pollutants or as toxic substances. A subset of the toxic pollutants is comprised of some of the heavy metals, such as lead, mercury, cadmium compounds and chromium compounds. Mercury is of particular concern with respect to coal combustion.
Mercury is a constituent of coal in trace amounts. That is, the mercury concentration in coal is often measured in units of parts per million or less. However, because of the large volumes of coal combusted annually around the world (approximately 60 Mt tonnes in Canada alone in 2005), the releases of mercury to the atmosphere are considerable.
Although mercury occurs naturally in the environment, scientists estimate that, currently, half of the mercury entering the global pool on an annual basis is from anthropogenic sources.
In Canada, the Canadian Council of Ministers of the Environment (CCME) and the Province of Alberta have established actions to directly address mercury emissions from coal-fired generating stations. See here for information on the CCME Canada-wide Standards for Mercury or here for information on Alberta Environment’s mercury regulation.
Toxic pollutants are sometimes referred to as hazardous air pollutants or as toxic substances. A subset of the toxic pollutants is comprised of some of the heavy metals, such as lead, mercury, cadmium compounds and chromium compounds. Mercury is of particular concern with respect to coal combustion.
Mercury is a constituent of coal in trace amounts. That is, the mercury concentration in coal is often measured in units of parts per million or less. However, because of the large volumes of coal combusted annually around the world (approximately 60 Mt tonnes in Canada alone in 2005), the releases of mercury to the atmosphere are considerable.
Although mercury occurs naturally in the environment, scientists estimate that, currently, half of the mercury entering the global pool on an annual basis is from anthropogenic sources.
In Canada, the Canadian Council of Ministers of the Environment (CCME) and the Province of Alberta have established actions to directly address mercury emissions from coal-fired generating stations. See here for information on the CCME Canada-wide Standards for Mercury or here for information on Alberta Environment’s mercury regulation.
Greenhouse Gases
Using an internationally agreed-to format, Environment Canada's Greenhouse Gas Inventory monitors six gases: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), sulphur hexafluoride (SF6), perfluorocarbons (PFCs) and hydrofluorocarbons (HFCs). Water vapour, too, is considered a greenhouse gas.
Using an internationally agreed-to format, Environment Canada's Greenhouse Gas Inventory monitors six gases: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), sulphur hexafluoride (SF6), perfluorocarbons (PFCs) and hydrofluorocarbons (HFCs). Water vapour, too, is considered a greenhouse gas.
The greenhouse gases are so-called because their accumulation in the earth's atmosphere is believed to cause the "greenhouse effect" on the earth's climate. This greenhouse effect is explained in the following graphic.
While some measure of the greenhouse effect is necessary to sustain life as we know it on earth, evidence suggests that increasing concentrations of greenhouse gases in the atmosphere are leading to an increase in average temperatures around the planet. The Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (2001) states "emissions of greenhouse gases and aerosols due to human activities continue to alter the atmosphere in ways that are expected to affect the climate."
This affect on our climate has been dubbed "global warming". A more appropriate term is "climate change", because while some regions around the globe may experience higher temperatures others may experience a cooling trend.
Carbon dioxide (CO2) is the greenhouse gas of prime concern with respect to human activities. As coal consists predominantly of carbon, carbon dioxide is an unavoidable byproduct of coal combustion. And, with the large amounts of coal burned around the world to produce electric power and to fuel other industries, coal combustion is the largest anthropogenic source of CO2.
For links to external sites dealing with environmental air quality and related issues click here.
This affect on our climate has been dubbed "global warming". A more appropriate term is "climate change", because while some regions around the globe may experience higher temperatures others may experience a cooling trend.
Carbon dioxide (CO2) is the greenhouse gas of prime concern with respect to human activities. As coal consists predominantly of carbon, carbon dioxide is an unavoidable byproduct of coal combustion. And, with the large amounts of coal burned around the world to produce electric power and to fuel other industries, coal combustion is the largest anthropogenic source of CO2.
For links to external sites dealing with environmental air quality and related issues click here.