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Back to Gas

Utility turbines bridge the capacity gap.

Fortnightly Magazine - December 2008

Carolinas is in the process of retiring two, 150-MW coal-fired units at its Buck Steam Station in Rowan County N.C., and two more 150-MW coal-fired units at the Dan River Steam Station in Rockingham County, N.C. It will re-power each plant with 620-MW gas-fired combined-cycle systems. The Buck Station re-powering will be completed by 2010, with Dan River scheduled to follow a year later.

“We obviously don’t have a high percentage of natural gas in our fuel mix,” explains Marilyn Lineberger, Duke Energy spokesperson. “The Buck plant was the first fossil-fired station built in the Carolinas and it will be the first to be re-powered to combined-cycle operation. Both installations will serve as intermediate units, i.e. , they’ll run more often than a peaking unit, but less than a base-load unit.”

Other measures are afoot that will further change Duke Carolinas’ generation mix and, as a result, its overall carbon footprint.

In May, the company announced it will purchase the entire output of a photovoltaic solar farm to be built in Davidson County, N.C., north of Charlotte. Under agreements signed with SunEdison, the company will receive more than 16 MW of power from the solar farm beginning in late 2010. The agreements run for 20 years.

The utility is also in the process of shutting down four more coal-fired units (net output, approximately 200 MW) at its Cliffside plant on the Cleveland/Rutherford County line in North Carolina and replacing them with a more efficient $1.8 billion, 800-MW supercritical coal-fired unit. The utility says the supercritical unit will be completed by 2011 and lead to the eventual retirement of another 800 MW of coal-fired generation, making the new unit carbon neutral by 2018.

Finally, Lineberger says the utility plans to pursue a nuclear plant that would deliver another 2,200 MW to the service territory; as well as additional renewable, energy-efficiency, and smart-grid initiatives.

“Due to price fluctuation in fuel costs, we don’t want to put all of our eggs in one basket. We haven’t made any final decision on the nuclear plant yet, but we do have these combined-cycle plants,” Lineberger says. “It’s obviously going to take time to reduce our carbon emissions. We view these two natural gas systems as a bridge to a lower carbon future. But coal is still going to be part of our mix. The new technology at Cliffside will be as clean a coal-fired unit as is possible. And at the same time we’ll continue to retire older, less efficient coal units.”

Multiple Regions

Minneapolis, Minn.-based Xcel Energy also is looking to alter its generation mix. By combining a number of gas-fired generation projects in its four service territories with renewable energy initiatives, the utility plans to reduce its carbon footprint and improve its ability to meet the anticipated federal climate policies.

Xcel Energy subsidiaries Northern States Power Co., Northern States Power Co.-Minnesota, Public Service Company of Colorado, and Southwest Public Service Co. operate in eight states, including Minnesota, Wisconsin, North and South Dakota, Colorado, New Mexico, Texas and Oklahoma.

Like other utilities, each is looking to