PacifiCorp, the multi-state Rocky Mountain utility that’s been trying to restrict third-party wind and solar contracts under federal PURPA regulations, is now planning a $3.5 billion investment of its own in a wind-powered future.  In a Tuesday filing, the utility owned by Warren Buffett’s Berkshire Hathaway told regulators that it wants to bring an additional 1,100 megawatts of wind power on-line between now and 2020, most likely through power-purchase agreements with projects in Wyoming, where the wind blows strong and steady.