Electric buses drive out of a public transportation hub in Shenzhen. More than 16,000 buses — almost none running on diesel or gas — circulate in the Chinese city. (Qilai Shen/Bloomberg News) June 2 at 6:00 AM SHENZHEN, China — A year ago, when D.C. Metro officials unveiled 14 electric buses — a purchase that made the capital one of the largest electric-fleet operators in the United States — this southern Chinese metropolis was already in the middle of a full-blown electric revolution. Today, more than 16,000 buses and 12,000 taxis whir along Shenzhen’s palm-fringed boulevards. How many run on diesel or gasoline? Practically none. How many are made in China? Almost all. Going fully electric “cost a lot of money,” said Zheng Jingyu, the Shenzhen transit official in charge of the overhaul. “But it helps our citizens and helps our air.” Turns out, it also helps China’s competitiveness. […]