NOT that long ago, the world wondered whether clean energy could survive without lavish government support. Now the question is how far it can spread. The number of electric vehicles, which breached 1m in 2015, last year reached 2m; countries like France and firms like Volvo are looking ahead to the demise of the internal combustion engine. In electricity generation, too, momentum is with the greens. In June the Chinese province of Qinghai ran for seven consecutive days on renewable energy alone; in the first half of this year wind, solar and hydro generated a record 35% of Germany’s power.
Greater success is breeding greater ambition. California is proposing to reach 60% renewable energy by 2030; 176 countries have clean-energy goals. Hawaii, America’s most oil-dependent state, has pledged to be 100% renewable by the middle of the century. So have 48 poor countries vulnerable to climate change.