Power plant expansion behind Duke rate hike

bhenderson@charlotteobserver.comJune 4, 2013 

— To find this rural crossroads a 75-minute drive west of Charlotte, look for the water vapor boiling out of a 555-foot-high smokestack. It’s a landmark in more ways than one.

Duke Energy’s $2.2 billion addition to its venerable Cliffside power plant may be the last coal-fired unit the company builds in the Carolinas, the end of an 86-year line.

Unit 6, which started up Dec. 30, is also a major reason Duke Energy Carolinas customers are being asked to pay higher electric bills for the third time since 2009.

Duke included $863 million of Cliffside’s costs in an overall 9.7 percent request that would raise most residential bills 14 percent.

Duke says Cliffside is a bargain for consumers.

The new addition came in on budget, in contrast to a Duke plant in Indiana that is $1 billion over initial estimates.

“It’s been an engineer’s dream to get a start-up like this,” 36-year Duke veteran Mike Calhoun, Cliffside’s operations superintendent, said Monday during a media tour.

The new Unit 6 and the updated Unit 5 generate more than twice the electricity the plant did before four 1940s-vintage units were shut down, but release 80 percent less sulfur dioxide and half as much nitrogen oxide and mercury into the air. Duke says it is one of the nation’s cleanest coal plants.

But emissions are one reason coal, and therefore Cliffside, remain an environmental target. Greenpeace flew a green blimp emblazoned with protest messages over the plant last August. The plant has been a focus of protests outside Duke’s Charlotte headquarters.

Sulfur dioxide forms haze and nitrogen oxides, ozone. Mercury can contaminate waterways. The new unit alone will also release 6 million tons a year of carbon dioxide, a greenhouse gas, as it gobbles 7,000 tons a day of coal.

Consumers Against Rate Hikes, a coalition of AARP and a half-dozen other groups, says it doesn’t care what fuel Duke burns.

“Our concern is that Duke is going to continue to build unnecessary plants that continue to drive up rates,” said outreach director Bill Gupton of Charlotte. “Anytime a plant is built, you have to look at the costs to build, operate and retire it.”

The coalition says Duke is asking for unfairly higher rates for residents and small businesses compared to other customers. It wants Duke to look harder for ways to shrink bills through energy-efficiency and home weatherization.

What do consumers get for $2.2 billion, which includes financing costs?

A Celtic knot of piping (66 miles of it) and cables (833 miles) encased in 36 million pounds of steel and 81,000 cubic yards of concrete.

An economic engine, through its 128 jobs and property tax revenues. By serendipity, the Unit 6 boiler lies in Rutherford County while its turbines are in Cleveland County.

And enough electricity to supply 660,000 homes, although Duke’s natural gas-fueled plants use a now-cheaper fuel and come online first.

Opened, a four-inch hatch into the unit’s “supercritical” boiler, which runs at a higher temperature and pressure to more efficiently produce steam, reveals the orange glow of burning, talcum powder-fine coal. Throbbing turbines feed a boxcar-sized generator that produces 825 megawatts.

Water to make steam is recirculated in a closed loop. Even so, Unit 6 needs 8,000 gallons a minute of water from the Broad River to replace what escapes from the system.

Both units spray a limestone slurry into flue gases, triggering a chemical reaction that “scrubs” sulfur dioxides and produces marketable gypsum. They also inject ammonia onto ceramic catalysts to catch nitrogen oxides.

Unit 6 catches 99 percent of haze-forming sulfur dioxide, 90 percent of smog contributor nitrogen oxides and 90 percent of its mercury.

Unit 5, built in 1972, has twice been upgraded with emission controls but isn’t designed to capture mercury.

A public hearing on Duke’s proposed rate hike will be held in Charlotte June 26, with testimony before the N.C. Utilities Commission beginning July 8. Duke expects a decision by fall.

Henderson: 704-358-5051 Twitter: @bhender

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