MILWAUKEE, Jan. 21, 2002 -- Wisconsin Electric-Wisconsin Gas (WE-WG) and ADA Environmental Solutions (ADA-ES) are releasing preliminary findings from one of the nation's first full-scale tests of carbon injection to control power plant mercury emissions.
The findings are being presented Jan. 21 at the FOMIS Mercury Emissions Workshop in Florida and Jan. 23 at the Electric Utilities Environmental Conference in Arizona. The testing was conducted at WE-WG's Pleasant Prairie Power Plant (P4) near Kenosha, Wis.
At this time, the research team can conclude the following from the preliminary results:
* It is possible to design, build and operate equipment at a scale capable of treating very large power plant flue gas volumes.
* Mercury removal rates during the short-term tests at P4 ranged from 40 to 60 percent depending on the amount of sorbent injected.
* Continuous injection over a two week period showed that the upper limit for mercury removal at P4 appears to be between 60 and 70 percent. However, beyond 50 percent removal, the mercury reduction benefit of increased sorbent injection begins to rapidly decrease.
* Plant operators did not note adverse impacts on electrostatic precipitator (ESP) performance attributable to sorbent injection during the test period.
* Preliminary test results indicate that the injection of even small amounts of activated carbon will prevent P4's fly ash from being beneficially re-used in concrete and will result in landfilling the fly ash.
* Injection rates required to get 50 to 60 percent removal were significantly lower than expected.
* Spray cooling, by water injection to lower flue gas temperature, did not improve mercury removal at P4.
Long-term testing is needed to fully assess the cost and performance of the technology as well as its impacts on the operation of the entire generating plant.
"We're encouraged by the results," said Kristine Krause, vice president of Environmental for Wisconsin Energy Corp. "We look forward to completing the remaining phases of this program and assessing the impacts of the technology on our overall operations. The P4 mercury research is an essential part of the company's integrated plan for reducing emissions and improving air quality."
"This mercury control test is a significant step in demonstrating that activated carbon injection can effectively reduce elemental mercury, the most difficult form to capture, which is produced from western coals," said Dr. Michael Durham, president of ADA-ES. "But we must learn more about how this technology works over time and with other coals and other plant configurations."
Sorbent injection is the most mature of all mercury specific control technologies. Pilot scale testing under actual flue gas conditions, but at reduced scale, was conducted at P4 in June of 2000. The full-scale demonstration, where sorbents were injected into one-fourth of a 600 MW unit under normal operating conditions, was conducted in the fall of 2001. The full-scale test provided information about the capabilities and limits of this developing technology.
The tests at P4 are very important because the plant burns a low-sulfur, western coal. The EPA acknowledged in its decision to develop regulations for reducing mercury emissions from utility coal-fueled boilers that mercury emissions from utilities that burn low sulfur, western coals -- like WE-WG -- will be most difficult to control.
The P4 research is also important because the plant configuration is representative of a large number of power plants across the country. P4 has an ESP in place to capture and collect ash particles. Ninety percent of all the coal-fueled power plants in the United States control particulate emissions with ESPs and test results will provide needed information on the potential use of this mercury-specific technology at other power plants.
The type of particulate control equipment is a key parameter defining both the amount of sorbent that is required and the ultimate limitation of the amount of mercury that can be removed using sorbent injection methods.
Final results on the P4 research will be available later this year. The project was done in collaboration with the U.S. Department of Energy's National Energy Technology Laboratory (NETL) and the Electric Power Research Institute (EPRI).
The majority of the $6.8 million program's cost is being picked up by NETL. About a third of the costs are being covered by WE-WG, EPRI, ADA-ES, Alabama Power, PG&E National Energy Group, Ontario Power Generation, First Energy, TVA, Kennecott Coal, and EPA.
Wisconsin Electric-Wisconsin Gas, the principal utility subsidiary of Wisconsin Energy Corp., serves more than one million electric customers and more than 960,000 natural gas customers throughout Wisconsin and Michigan's Upper Peninsula. Visit the company's Web site at http://www.WE-WG.com . Learn about Wisconsin Energy Corp. by visiting http//www.WisconsinEnergy.com
ADA-Environmental Solutions, LLC (ADA-ES) is an environmental technology and specialty chemical company headquartered in Littleton, Colo. The company offers proprietary products and systems that mitigate environmental impact while reducing operating costs.