The PSC has approvedLouisville Gas and Electric's application to construct a 640 megawatt natural gas power plant at the current site of the gas-fired Cane Run Power Station. The company will also buy existing gas generation in Oldham County.The company already had approval to retire Cane Run, as well as two other coal-fired power plants. The PSC heard the case to add the gas turbines in March. The proposal was opposed by environmental groups, which argued the generation capacity could be replaced with renewable sources and energy efficiency measures.LG&E estimates the nearly $700 million project won’t raise LG&E customers’ rates. Because they’re estimated to use a large share of the power, the project will raise rates about 4 percent for Kentucky Utilities customers. But previously-approved environmental upgrades to two of LG&E's coal-fired plants--Mill Creek and Trimble County--are expected to raise LG&E rates 18 percent by 2016.Will be updated.