Mercury legislation, of varying strengths, exists in a number of countries, such as Canada, China and the US, and will likely become more widespread with ratification on the UN Minamata Conventions, according to a new report from the IEA Clean Coal Centre.
In some cases, it is easy for coal-fired power plants to comply, as existing flue gas controls have a co-benefit effect of also reducing mercury emissions. For example, electrostatic precipitators (ESPs), fabric filters, selective catalytic reduction (SCR) for NOx and flue gas desulphurisation (FGD) for SO2 systems all capture mercury to some extent.
Once ratified, signatory countries to the new UN Minamata Convention will need to install BAT/BEP (best available technologies and best environmental practice) on all new coal-fired plants and establish a national action plan on how to control emissions from existing plants. So, a market is emerging for specific control technologies that can reduce mercury emissions by 90% or more.
Growth in the mercury control market is due to:
- The impetus: legislation requiring mercury control.
- The challenge: the effectiveness and applicability of mercury controls vary with coal characteristics, as well as regional, technological and economic restrictions.
- The market variability: markets will emerge relatively independently as countries move forward in a region-specific manner.
Mercury control technology
There are two main types of mercury-specific flue gas treatments: activated carbons and sorbents. They facilitate the capture of mercury in solid form in existing or add-on particulate control devices.
Oxidants, whether chemical (such as halogens) or electrochemical (such as ozone or plasma charging) can increase the solubility of mercury to enhance its capture in either particulate control devices or, more effectively, in FGD systems.
Deciding what technology is most appropriate at a plant is site specific. It depends on the coal characteristics (sub-bituminous and lignite coals are more challenging than bituminous and anthracite coals), the existing plant configuratio, and the level of mercury reduction required.
Regional variation in mercury control regulation
Legislation requiring mercury control first appeared in Canada and North America, so this is where the international market is currently focused. As it matures, new markets may emerge in other regions: for example, China has mercury emission limits for coal-fired plants that can be met by most modern plants with standard control equipment. But, it is likely that requirements for more specific mercury control may appear at some plants.
However, China is unlikely to purchase technologies from abroad that could be produced in a more economic fashion at home. So, China could end up being a net exporter of mercury control systems to other regions in the future.
The EU does not have emission limits for mercury, but it does have annual mercury monitoring requirements. BAT reference documents are being finalized, which include a summary of applicable techniques and technologies for mercury control.
Mercury emissions from the coal sector in Europe have declined impressively since the 1980s and the current and impending legislation will maximise the continued co-benefit reduction of mercury with SO2 and NOx controls. If mercury legislation does appear in the EU in the near future it will probably be on a case-by-case basis at plants that demonstrate a mercury emission issue.
India has minimal emission requirements for coal-fired plants. However, there are rumours that the Indian Government intends to ratify the Minamata Convention and set emission reduction targets or controls for mercury. For India, a multi-pollutant approach, targeting the reduction of particulates, SO2, NOx and mercury simultaneously through maximised co-benefit effects would make the most economic sense.
This is an interesting time in the mercury control market. North America has largely decided how to achieve mercury control and is well on track to comply with its strict emission limits. Conversely, countries such as China and members of the European Union are seeing significant reductions through co-benefit effects of existing flue gas cleaning systems. Whether a new mercury-specific control technology market emerges in these latter regions will depend on the level of commitment each makes under the new Minamata Convention. If controls are deemed necessary, China may well step in to design and supply its own technologies to the global market. Europe, on the other hand, is more likely to buy existing technologies off the shelf, should further mercury reductions be legislated.
Written by IEA Clean Coal Centre. Written by Jonathan Rowland.
Read the article online at: https://www.worldcoal.com/power/06022015/global-market-for-mercury-control-equipment-in-coal-fired-power-industry-coal1854/