Mercury emissions slashed by Thief

A new weapon has been added to the arsenal of those trying to reduce harmful pollution by cutting mercury emissions from coal-fired power stations.

The US Department of Energy’s National Energy Technology Laboratory has developed new technology to help industry meet Environmental Protection Agency targets of 70% reduction in mercury emissions by 2018.

Conventional technology uses activated carbon to remove the heavy metal from emissions but this is an expensive process, costing between US$500 and US$3,000 per ton.

The new Thief process instead takes partially combusted coal from the boilers and uses it as a thermally activated sorbent to extract mercury from the plants’ flue gases.

This has proved a cheaper and more efficient option, costing an estimated US$90 to US$250 per ton.

“The Thief process serves as yet another step forward in mercury control technology program to make the nation’s air as clean as possible,” said Mark Maddox, DOE’s principal deputy assistant secretary for fossil energy.

During pilot testing that burned low-chlorine subbituminous coal, the Thief process achieved mercury removal rates as high as 93%.

The process has now been patented and licensed to a private company, Mobotec USA, for production.

By Sam Bond

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