Controlling Power Plant Emissions: Control Technology
There are a number of currently available control technologies that coal-fired power plants can use to reduce their emissions of mercury to the atmosphere. For example, controls for sulfur dioxide, oxides of nitrogen and small particles that have already been installed remove some of the mercury before it is released from the stack. The effectiveness of these technologies for mercury removal varies, depending on characteristics of the coal and the configuration of the power plant. In some cases a plant might consider changing the type of coal that it burns in order to get better mercury control from its existing control devices.
Control technologies specifically used to reduce mercury emissions from coal fired power plants have recently begun to be used on some power plants with success. The most highly advanced technology, activated carbon injection has been used on facilities that burn municipal solid waste for the past decade. Particles of activated carbon are injected into the exit gas flow, downstream of the boiler. The mercury attaches to the carbon particles and is removed in a traditional particle control device. Several other control technologies to reduce mercury emissions from coal-fired power plants are being developed and tested but have not yet been deployed at the commercial scale.