Green energy from an old dam

A hydro project that dates to 1919 might help Duke Energy meet its circa-2007 mandate to generate renewable energy.

Duke is in the midst of fortifying its three dams at Lake James, at the top of the Catawba River chain of reservoirs. New earthen and concrete structures on the downstream slopes of the dams will strengthen them against earthquakes.

Work is finished on two dams. But the old powerhouse below the third dam, Linville, had to be removed before work on it starts early this year. A new powerhouse, 200 feet downstream, began generating electricity in November.

The new generators are capable of producing 8.5 megawatts more than the old ones. Duke wants the N.C. Utilities Commission to register the increased capacity as a renewable energy facility under the state's 2007 green-energy law.

The law allows small hydro operations, under 10 megawatts. Larger ones -- Lake James has a total capacity of 31.5 megawatts -- are controversial because they so profoundly disrupt rivers.

It's impossible to say how much help the hydro power would be to Duke in meeting the green-energy standard, spokesman Jason Walls said. The law requires utilities to get the equivalent of 3 percent of their 2012 sales from renewable sources or energy efficiency. But hydros run mostly at peak times, so their actual generation is a sliver of their capacity.

The commission's Public Staff, which represents consumers, has agreed with Duke's request. Commission members haven't yet ruled.