Guardian: High in the stark Nevada desert, a couple of hundred miles north-west of Las Vegas, is the shimmering circular mirage of Crescent Dunes. Ten thousand silvery glass panes, each measuring 115 square metres, surround a tall central tower, which stands like a twinkling needle in the featureless landscape around it. Resembling a fabulous alien metropolis, Crescent Dunes is in fact a highly sophisticated, mile-and-a-half-wide solar power plant the next generation in solar energy, according to Kevin...