Solar photovoltaic power generation has been increasing by leaps and bounds in the last decade, propelled by dizzying improvements in conversion efficiency and reductions in the cost of PV panels. But it suffers from one drawback that will, in all probability, never be removed: This is its inability to supply power at night, or during spells of bad weather. Despite dramatic advances in battery technology, storing electricity remains prohibitively expensive. By the same token it is only in the past three or four years, after the failure to mass-produce cellulosic ethanol from non-food crops, that people have begun to accept that, as a replacement transport fuel, ethanol too is a blind alley.