Coal combustion is currently responsible for 46% of total global emissions of mercury to the atmosphere from human activities with over half of this contribution arising from coal combustion in power plants and industrial boilers. Mercury is the element of ‘greatest global concern’, according to the United Nations Environment Programme (UNEP) and, in response to increasing global concentrations of mercury, UNEP plans to finalise and ratify a new global legally binding instrument on mercury by 2013.

This report summarises current and impending standards globally and regionally which apply to mercury emissions from large-scale coal-fired power plants. At the moment there are a few international treaties and action plans which mention mercury but none requires action to be taken at the installation level. The only countries which currently have legislation which applied directly to mercury emissions and which require specific action to be taken are Canada and the USA. Canada currently has the Canada-wide Standards which set capped emissions and reduction targets on a provincial basis. Compliance requirements at the plants affected vary from the installation of mercury-specific control technologies (such as activated carbon, ACI) to plant closure or fuel switching to gas or biomass. The new Mercury Air Toxics Rule (MATS) in the USA sets challenging emission limits on a heat input basis which aim to reduce emission concentrations from all plants to the level achieved by the top 12% performing units in the country. This, in combination with the Cross-State Air Pollution Rule (CSAPR) for SO2, NOx and other pollutants, means that the coal-fired capacity in the USA faces a challenging period of compliance. Table 12 shows the current (base capacity) installation of various control technologies on the US coal-fired station fleet and shows how this is likely to have changed by 2015. There is clearly going to be a high demand for dry scrubbers, FGD upgrades and sorbent injection systems over the coming years.