The N.C. Utilities Commission has approved a compromise settlement that allows Duke to increase rates 8 percent over two years. The utility had requested a 12.6 percent increase. Residential customers are expected to pay approximately $3.70 a month more in 2010 and $3.61 more in 2011. The increases will be used partly to pay for Duke’s new coal-fired power plant under construction at its Cliffside facility in Rutherford County. The $2.4 million project has been opposed by numerous environmental groups who contend Duke is not using the latest available technology to reduce emissions. But the utilities commission ruled that Duke Energy’s spending to expand the plant is “reasonable and prudent.” Duke has said the expansion will allow it to shut down older, less efficient plants.