Greater Cincinnati has four coal-fired power plants. Commercial businesses would pay on the order of $14 more every month, according to the report, "Getting the Job Done," released Tuesday.

Ohio's coal-fired power plants emitted more than 8,000 pounds of mercury in 2000 - the most of any Great Lakes state, according to Environmental Protection Agency statistics.

Mercury and other elements were trapped in coal seams when they were formed eons ago and is virtually impossible to separate before combustion.

"We have yet another piece of evidence showing that reducing mercury emissions is a challenge American industry can meet today," said Zoe Lipman, program manager for the National Wildlife Federation. "The technology is available and the cost is reasonable."

The study said the annual cost of controlling mercury emissions in Ohio would be about $287 million a year.

Cinergy spokesman Steve Brash said he doesn't think the study's findings are accurate. One problem, he said, is that it looks at the cost of reducing only mercury in the environment, when Cinergy and other power companies have a multitude of pollutants to consider. Cinergy last month released its long-range plan to spend $1.8 billion over the next four years to come into compliance with new federal rules aimed at reducing the amount of mercury, sulfur dioxide and nitrogen oxide from its smokestacks.

Brash said the energy giant has not studied how much it would cost to reduce its mercury emissions by 90 percent.

"We don't have an estimate, but if we're looking at spending in the neighborhood of $2 billion over four years, that will translate into more than a couple of dollars on an average bill," Brash said.

E-mail dklepal@enquirer.com