Benefits of additional mercury emission abatement of global coal power plants

Motivation Mercury (Hg) and many of its compounds are highly potent neurotoxins, especially to human fetuses and young children. Global anthropogenic mercury emissions exceed natural emissions by far and mostly come from... [ view full abstract ]

Motivation 

Mercury (Hg) and many of its compounds are highly potent neurotoxins, especially to human fetuses and young children. Global anthropogenic mercury emissions exceed natural emissions by far and mostly come from coal-fired power production. Thus, it is imminent to implement regulations for coal power plants where they are insufficient and to change coal sources, pre-treat raw coal or upgrade flue gas control to protect the public from adverse health impacts effectively. This work highlights the most promising options for mercury emission reduction globally.

Methods 

Power-plant-specific emission data from pollution emission registers such as the U.S. American TRI and the European E-PRTR has been merged with a global power plant database containing data from sources such as U.S. Energy Information Administration (EIA) eGrid database, the International Energy Agency's coal power atlas, EU power plant information, and the PLATTS World electric power plant (WEPP) database. Remaining gaps in the emission inventory have been filled with US Geological Survey (USGS) coal data, estimates on coal consumption from published power plant capacity factors and a model for Hg emissions during coal combustion. Potential emission reductions were then estimated by applying models for mercury-removing flue gas cleaning technologies such as activated carbon injection or wet flue gas desulphurization. Impacts on human health and ecosystems before and after additional Hg abatement were quantified by life cycle impact assessment (LCIA) with the ReCiPe Endpoint (E) V1.12 method.

Results and conclusions 

The results of this work highlight the hot spots in global coal mercury emissions and show where reduction of these emissions is most urgent. Especially in developing and newly industrialized economies, there is still a lack of wet flue gas desulphurization systems with particulate removal from flue gas that would decrease the impacts of mercury emissions. India and China are currently introducing and enforcing stricter regulations. The conventional treatment systems for desulphurization are widely used by western countries, which leads to smaller health impacts by mercury in these regions. Switching to low-mercury fuels is another promising option. More advanced treatment specifically addressing mercury such as the injection of sorbents like activated carbon is advisable to further reduce mercury health impacts by up to 80%.