Fresno Bee: A $2 billion power plant in Kern County using notoriously dirty coal and petroleum coke conjures images of soot pouring into a brown skyline — an idea seemingly dead on arrival in one of the nation’s worst air basins. But it may become a model for clean energy instead. Forget the smoke. Imagine 2,600-degree heat in a sealed chamber vaporizing coal and petroleum coke — hard, black leftovers from refineries — to extract a highly prized fuel: hydrogen. Using the dregs of …