Calpine Corp. is planning to shut down its 400-megawatt Clear Lake Power Plant, in Pasadena, Texas, the company said Friday. Calpine said in its second quarter earnings statement the 31-year-old natural-gas-fired plant is being shut down due to its use of older technology, high maintenance costs and a lack of adequate compensation in Texas. The closure will take place no later than 2018, the company said.