Only two U.S. electric utilities are building expensive coal-gasification power plants, while dozens of similar facilities have been scrapped and some remaining projects may eliminate coal in favor of abundant, cheap natural gas.

Duke Energy's 618-megawatt Edwardsport coal project in Indiana and Southern Co's 582-MW Kemper County project in Mississippi are the only "integrated gasification combined cycle", or IGCC plants, under construction out of more than three dozen proposed in the United States over the last decade.

Of the handful of other IGCC projects still in development, two are looking at switching to gas as the primary fuel and dropping coal -- at least for now.

The power industry cited gasification technology as a way to save coal's role as the dominant fuel in electric generation as federal limits on carbon dioxide (CO2) emissions appeared imminent, but the technology was unable to gain traction in the face of high capital costs, carbon legislation delay and rising supplies of natural gas.