A contract of cleanliness.

• Author: Stricker, Julie
• Position: Construction of a coal power plant in Alaska

The time has come for Interior's experimental Healy Clean Coal Project to show what it can do.

It has been a long, rocky road for the Healy Clean Coal Project.

The experimental, 50-megawatt electric plant was billed as a showcase for innovative technology that would reduce air pollution while burning the high-moisture, ultra-low sulfur coal mined at Usibelli Coal Mine in Healy to provide much-needed energy for the state's Interior.

The project is part of the U.S. Department of Energy's Clean Coal Technology Program, a joint government-industry partnership with more than $6.5 billion invested nationally in new technologies to increase electricity generating options while curbing the release of acid rain pollutants.

The program began in 1986 and uses cutting-edge technology designed to reduce nitrogen oxide emissions from existing boilers by 75 percent, and from new boilers by 90 percent. It is designed to remove 90 percent of sulfur dioxide and virtually all fly-ash particles before flue gases are released.

The 50-megawatt electric plant was built on Golden Valley Electric Association property in Healy, adjacent to GVEA's existing 25-megawatt facility.

The Blueprint

Ground-breaking for the $267 million facility, owned by the Alaska Industrial Development and Export Authority, was in May 1995. According to the original blueprints, the plant was expected to finish its demonstration testing phase late in 1998 so GVEA could take over commercial operations in 1999. That hasn't happened.

Early tests were promising, says Dennis McCrohan, deputy director of project development and operation for AIDEA. The plant is living up to expectations regarding emissions reductions, but "we have had somewhat more problems on the combustors than we anticipated. In our view, certainly no unsolvable problems have turned up."

The plant uses a slagging combustor technology in which pulverized coal is injected into a combustion chamber developed by TRW Combustion Business Unit, where it is partially burned and the ash it contains is converted into molten slag, which is drained off the walls. This removes as much as 90 percent of the fly ash before the fuel reaches the main boiler. This process also minimizes the formation of nitrogen oxides, a major pollutant.

At the entrance to the boiler, limestone is injected into the combustion gases to react with and to help remove sulfur dioxide, another pollutant A spray dryer absorber, developed by Joy Technologies, removes...