Activated Carbon Injection (ACI) is state-of-the-art technology for mercury control

WILSONVILLE, Ala. — Larry Monroe pointed to a set of eight manhole cover-size plates mounted on the exhaust vent to limit mercury emissions from Gaston 3, a coal-burning power plant that feeds electricity to a half-dozen southern states.

Gaston 3 and plants like it, the backbone of the U.S. power industry, are the focus of a furious debate over mercury pollution -- how much and how fast the nation should move to regulate a toxic metal capable of causing severe neurological damage, especially to fetuses and young children.

Each of the plates at Gaston 3 houses an injector that squirts activated carbon dust into Gaston 3's flue gas.activated carbon manufacturerParticles of mercury cling to the carbon, which is then trapped by filters and discarded as toxic waste.

"The equipment is really small and simple, but we still don't know everything about the unintended consequences," said Monroe, emissions control research manager for Southern Co., the owner of Gaston 3. "Using it is like taking your car in for repairs. You're always worried [that your problems] will cascade."

Activated Carbon Injection (ACI) is state-of-the-art technology for mercury control, and at Gaston 3 it removes, on average, 80 percent of the mercury from the plant's stacks. Plant managers say the system would do better with more elaborate equipment.

What's best timeline?
But the Bush administration and its industry allies say research gaps and equipment shortages make it virtually impossible for plants using ACI or anything else to achieve the targets mandated by the Clean Air Act — a 90 to 95 percent reduction in mercury emissions by 2007.activated carbon south africa

Instead, the Bush administration has used a different section of the act to propose a new target of a 29 percent reduction by 2007 and an industry-wide reduction of 70 percent by 2018. That prescription is scoffed at by environmentalists, who say ongoing tests at Gaston 3 and elsewhere show the Bush targets are far too modest.