Chrysler and partners test titanium dioxide as power plant mercury remover

Chrysler, Washington University in St. Louis, and the midwestern utility Ameren are exploring use of the pigment titanium dioxide to reduce mercury emissions from coal-fired power plants.

A pilot program kicked off last fall when an Ameren power plant near St. Louis began generating electricity by combusting coal and waste auto paint from Chrysler's St. Louis assembly facilities. Ameren is now analyzing the results of the test run.

One major paint ingredient is titanium dioxide. Although the program's main goal was energy generation from a waste material, officials soon realized that the pigment might have the additional benefit of oxidizing and complexing mercury that is released when coal is burned.

Pratim Biswas, chairman of Washington University's department of energy, environmental, and chemical engineering, is now working with Chrysler to test this pollution-prevention potential of titanium dioxide. Ameren is interested because it will be required under federal regulations to cut mercury emissions from its coal-fired power plants.

Bob McIlvaine, president of the consulting firm McIlvaine Co., says most utilities are looking to activated carbon to abate mercury in power plants, such as the St. Louis facility, that clean up their emissions with dry scrubbers.

But Ken Anderson, Ameren's managing supervisor of air quality management, points out that too much carbon can render power plant waste ash unfit for one of its primary uses-as a cheap replacement for Portland cement in the concrete manufacturing process.

"We believe titanium dioxide has the potential to remove mercury without affecting the quality of the power plant's ash," says Washington University's Biswas.