InsideClimate: Congressional lawmakers from both parties are taking a step to catalyze the nation's clean energy economy: After 32 years of restricting a crucial investment tool to expanding fossil fuels, they're pushing to open it to renewables. Legislation is moving through both houses to tweak the tax code to let clean energy developers form a master limited partnership, or MLP, a type of publicly traded company structure not subject to corporate taxes. For three decades, coal, oil and gas companies have used...