Washington, DC - A licensing agreement recently signed by the U.S. Department of Energy and Johnson Matthey, an international specialty-chemicals company, will contribute significantly to the reduction of mercury and other trace elements emitted from coal gasification and coal-fired power plants, while helping to meet ever-stringent clean air regulations.
The agreement between Johnson Matthey and the Office of Fossil Energy's National Energy Technology Laboratory (NETL) paves the way for the company to demonstrate a mercury-reduction process patented by two NETL researchers and to ultimately commercialize the process. Johnson Matthey plans to demonstrate the process at larger bench- and pilot-scales to the point that it can be commercially sold to utility and related industries.
"Our mercury-reduction research efforts are geared toward meeting the goals of the Clean Air Mercury Rule and Energy Policy Act, as well as the President's Global Climate Change and Clear Skies Initiatives," said Tom Shope, Acting Assistant Secretary for Fossil Energy. "This licensing agreement goes a long way toward meeting the Department's mercury-reduction goals and ultimately contributing to the near-zero emissions power plant of the future, FutureGen," he added.
Energy Department research in trace-metal capture has focused on developing low-cost, efficient mercury-removal techniques to meet a national goal of 90 percent mercury emissions capture from U.S. coal-fired plants by 2010. The U.S. Environmental Protection Agency's Clean Air Mercury Rule requires an overall average reduction of nearly 70 percent by 2018, but many states are proposing their own more-stringent regulations.
The process, patented as a "Method for High-Temperature Mercury Capture from Gas Streams," enables scientists to remove mercury from high-temperature gases by using metal sorbents to capture the mercury, as well as the trace elements arsenic and selenium. Once they capture the trace elements, the sorbents can be regenerated and used again in gas streams, primarily from coal gasifiers, coal-fired electric plants, and ore smelters.
Since the Energy Department envisions the increased use of gasification, and a concurrent increase in trace element emissions over the next 20 years, the Department wants to ensure that technologies are in place to meet existing and future regulations.
The key to this new technology is that it has successfully removed mercury from fuel gases at high temperatures. Prior research had shown little progress in removing mercury from high-temperature gas streams because the adsorption of mercury on a sorbent typically decreases as temperature increases. As a result, nearly all of the mercury in coal ends up in the flue and fuel gases. The carbon-based sorbents typically used appear to be unsuited for capturing mercury contained in high-temperature fuel or flue gases.
In early tests, this patented process overcame obstacles related to heat and was able to perform at variable temperatures. Such successes at high temperatures preserve the high-temperature efficiency of gasifying systems, such as integrated gasification combined-cycle plants.
The licensing agreement between NETL and Johnson Matthey builds on a successful and ongoing Cooperative Research and Development Agreement between the two organizations.