Guardian: Deep in the deserts of Gansu province, in an area declared off-limits by Chinese state security, is a clean, hi-tech vision of the country’s energy future. Set among the pale yellow dunes are seven banks of dark blue photovoltaic panels that stretch the length of a running track. Together they comprise the biggest desert solar power plant in China and the largest test case of a technology that is about to get a massive boost from the central government. The national …