Dallas Morning News: When private equity titans Kohlberg Kravis Roberts and TPG bought Texas’ largest utility in 2007, the new owners of one of the state’s biggest polluters promised to support legislation to reduce greenhouse gas emissions. FILE 2006/The Associated Press Many of Luminant’s power plants, like this one in Fairfield, Texas, use coal as their fuel. Parent Energy Future has lobbyists working to dilute a provision in the climate change bill that would require utilities to get 25 percent of …