Five years ago Texas Utilities Corporation, the state utility, would have derided suggestions that a sale of the company would not get regulatory approval unless it bowed to environmentalists and abandon plans to build more coal-fired power plants. But this is exactly what happened last year.

Texas Corp was sold to a private-equity consortium for $32bn. But only after close consultations with the Environmental Defence Fund and the Natural Resources Defence Council that resulted in a pledge to scrap plans for eight plants.