This will almost certainly be a record-breaking year for the advance of solar and wind power across the U.S. The additions that are in progress or planned are significant enough to boost hopes for emissions-free electrical grids within a generation—if natural gas doesn’t get in the way. It just may. Gas is such a bargain that it’s being viewed less as a bridge fossil fuel, driving the world away from dirtier coal toward a clean-energy future, and more as a hurdle that could slow the trip down. Some forecasters are predicting prices will stay low for years, making it tough forstates, cities and utilities to achieve ... (full story)