It only takes five of these bad boys to clean the entirety of the Shams 1 concentrating solar power plant in the desert near Abu Dhabi every three days. That's a lot of cleaning: there are 258 048 mirrors at the plant, measuring 1.5 m by 1.3 m each, covering a total of about 2.5 square kilometers. The mirrors concentrate the sun's heat onto a liquid inside a tube, which is then used to make steam that turns a turbine to make electricity. According to Alawi Al Jafri, who took me and a gaggle of press around the plant on Sunday, they like to keep the mirrors to 85 percent reflectivity, though it could drop much lower and still function well. It turns out, he says, that there isn't much of a difference in output between clean and somewhat dirty mirrors, but when they get extremely dusty (which happens quickly in the windy desert of the UAE) and the reflectivity drops very low the efficiency comes down dramatically.
Watch the trucks in action:
Photo and video: Dave Levitan