Facts on EMF
- Background Information
- Why is mercury an issue?
- Mercury in our environment
- Coal-fired electricity generation and mercury
- What is being done to manage mercury?
- Making progress in mercury management
- Improving emission measurements
- Reducing mercury emissions
- Mercury coals burned in Canada
Facts on EMF
- Program Overview
- FAQs
- Laboratory Round Robin
- Sampling and Analysis
- Research and Development
- Contact Us
Program Overview
Mercury Background Information and Frequently Asked Questions
Activities to address mercury in the environment have increased dramatically in response to concerns over its impact on human health.
These efforts are focused on improving our understanding of both human and natural sources of mercury releases, mercury movement through the environment,
its effects on human health and the best ways to minimize these impacts.
The coal-fired electricity generation industry is one of the largest point sources of mercury emissions. The industry is working with governments, researchers,
and other stakeholders to vigorously address the issue. The electricity-generation sector is committed to addressing mercury emissions and is engaged in
many initiatives to achieve that goal.
Mercury is a toxic natural element that enters the food chain from both natural and human sources. Although concentrations of mercury in air are usually low
and of little direct concern, mercury in water, having entered directly from soil or with precipitation, can be converted by microorganisms into its most toxic,
organic form. This compound, methyl mercury, accumulates in fish tissue and becomes more concentrated as it moves up the food chain.
Human exposure to mercury occurs primarily through eating contaminated fish. In sufficient doses, methyl mercury can damage the nervous system, especially in developing
fetuses and young children. The magnitude of exposure depends on the amount of mercury in the fish consumed and the amount of fish consumed. In U.S. regulatory decision-making around mercury,
it was noted that there is a “plausible” link between releases from human sources to the atmosphere and methyl mercury in fish. It is considered “plausible” because science has
established neither the relative contributions of human versus natural sources, nor the pathways mercury follows from source to receptor.
Where it is found:
Products and equipment such as thermometers, dental fillings, electrical equipment, and light fixtures and the in the natural environment.
Releases into the environment:
From natural sources such as soils, oceans and volcanoes,
from human products and equipment,
through processes such as fossil fuel combustion, creation of new reservoirs, incineration of municipal, medical and hazardous waste, and gold and ore mining.
Some mercury can move into the atmosphere and be transported long distances before being deposited on earth. Mercury emitted in one country can therefore be transported and deposited in another.
Coal-fired electricity generation and mercury
Canada has a rich diversity of resources for producing electricity. Although the majority of electricity is produced with hydropower, approximately 19% of electricity
in Canada is produced by burning coal. Coal is an important component of the resource mix; it is an abundant resource and an inexpensive option for producing electricity.
Coal contains trace amounts of mercury, which can be released when it is burned. It is estimated that Canadian coal-fired power plants emitted 2.0 tonnes of mercury to
the atmosphere in 2000, about 25% of Canada’s total(1).
In the United States, coal-burning utilities release about 39 tonnes of mercury every year. Since 2000, Canadian
utilities have been required to report their annual mercury emissions under the National Pollutant Release Inventory (NPRI).
(1) Environment Canada National Pollutant Release Inventory, 2000.
What is being done to manage mercury?
Mercury has been characterized as toxic under the Canadian Environmental Protection Act (CEPA). This requires a management program for emissions from human activities.
The Canadian Council of Ministers of Environment (CCME) is establishing standards for a number of emission sources, including coal-fired electricity generation.
Eastern provinces are signatories to a Mercury Action Plan to reduce mercury emissions under the Conference of New England Governors and Eastern Canadian Premiers.
Canada is a signatory to a North American Regional Action Plan (NARAP) under the Commission for Environmental Co-operation. The United States Environmental Protection Agency
must propose a Draft Rule for control of mercury emissions from coal-fired power plants by December 2003, with the final form being completed and circulated to stakeholders i
n December 2004.
Making progress in mercury management
Setting emission standards for this sector, developing implementation plans and measuring their efficacy is impeded by continuing uncertainties in key areas
of mercury management: emissions measurement, availability of technologies for removing mercury and the variability in the presence and behaviour of mercury. The
electric power generation sector is engaged in a number of activities to try to reduce these uncertainties.
Improving emission measurements
For a number of years, companies have been working to improve emission estimates. This requires an understanding of the mercury content in coal and what
happens to that mercury when the coal is burned. Activities to improve this understanding have been confounded by the variability in the levels of mercury
found in coal and its complex chemistry.
The coal mercury content can vary dramatically across coal types and within a single coal seam. Likewise, the chemical form in which mercury is emitted can be highly variable,
depending on coal and ash characteristics, especially the sulphur and chlorine content, as well as operating conditions. Mercury emissions can occur in three forms – particulate mercury,
oxidized or reactive (ionic) mercury, and elemental mercury. The particulate mercury is a very small
fraction of the total mercury. The ratio of ionic mercury to elemental mercury depends upon the factors noted above. The form of the emissions is a key factor in
determining viable management options.
Mercury is difficult to measure in coal-fired electricity generation stack gases because its concentrations are so low – near the minimum level for detection.
For much the same reason, laboratory analyses for mercury in coal or ash samples frequently produce inconsistent results. The Ontario Hydro Method for measuring mercury emissions in combustion gases (“stacks”) has been recommended by regulators across North America,
but it is relatively expensive to be considered as a long-term measurement tool. Because of the low mercury concentrations variable results are produced during repeated tests,
and present only a single point value (“snapshot”) as opposed to continuous measurements. \Coal-fired utilities in Canada continue to invest substantial resources in measuring stack gases.
Continuous Emissions Monitoring systems (CEMs) are available, but their long-term reliability has not been demonstrated for the low mercury concentrations produced by coal-fired plants. Companies
have been investing in research to address these measurement issues, testing coal, ash and stack gases. Activities in these areas will increase significantly with the launch
of an intensive three-year Canadian Electricity Association Mercury Program for Coal-fired Electricity Generators.
Electric utilities have been actively taking steps to reduce mercury emissions as part of ongoing integrated air emission management programs.
Many of the pollution control devices installed to capture other emissions (e.g. sulphur dioxide, nitrogen oxides, particulate matter and carbon dioxide) do
capture some particulate and ionic mercury. It has been estimated that 40 percent of the mercury in coal is removed from coal-fired boilers in Canada in this fashion(1).
However, a recent U.S. modeling study regarding the four most significant air pollutants from electric power generation has shown that "a mercury reduction strategy by
itself would not significantly reduce emissions of the other three pollutants"(2).
The technology receiving the most attention for mercury removal is Activated Carbon Injection (ACI). It is still under study in various programs in the U.S. and elsewhere:
the final test results on commercial volume emissions are expected in late 2003. Installing ACI technology or adjusting air pollution control systems can be effective in
capturing mercury in its ionic form. Neither of these options, however, captures elemental mercury effectively.
Regional differences in the mercury content of coals used in Canada and the lack of technical solutions for reduction in elemental mercury emissions mean there
is currently no commercially demonstrated technology that can achieve uniform reductions in mercury emissions from all coal-fired boilers(3). CEA members are monitoring and
investing in a variety of U.S. mercury research programs including control technologies and their application to Canadian plants. The U.S. government is spending many millions
of dollars on mercury research, including pilot programs for a variety of mercury capture technology options. Important commercial demonstration projects will be completed in 2003.
(1) Smith, Ian in Record of the Meeting of the Multi-Stakeholder Advisory Group and the Mercury CWS Development Committee, June 4-5, 2001
(2) U.S. EPA, Analysis of Emissions Reduction Options for the Electric Power Industry, March 1999
(3) U.S. EPA Notice of Regulatory Finding
Mercury coals burned in Canada
As the mercury content in coals burned varies widely across Canada, so do the mercury emissions. Canadian utilities use medium and low sulphur sub‑bituminous, high‑ and medium‑sulphur bituminous coals, and lignite. The low sulphur sub-bituminous and lignite coals used frequently in Alberta and Saskatchewan respectively tend to produce emissions high in elemental mercury, which are difficult to control. There are more options available for the management of emissions where coals producing higher ionic mercury emissions are used.