Star Tribune: The nations big coal-burning power plants are not ready to become dinosaurs. Utilities are making substantial investments to keep their largest coal generating stations operating for decades and emitting millions of tons of carbon dioxide annually. Upgrades planned or underway at more than 100 Midwestern coal power plants will reduce emissions of mercury or other air pollutants. But they wont affect greenhouse gas emissions that the Obama administration says it will regulate in 2015 to address...