Princeton, NJ-based NRG Energy Inc. said Friday it has begun commercial operations of its repowered 550 MW natural gas-fired combined-cycle generating plant at El Segundo, CA. The El Segundo Energy Center includes fast-start capability, allowing the plant to deliver more than half of its capacity in 10 minutes of start-up time and the balance in less than an hour. The new facility meets the state's and the South Coast Air Quality Management District's air quality standards, and it will use 30% less gas per megawatt than the original steam boilers at the site.