Chill sun solar, a facility in Nevada with a generating capacity of 2.25gw, should produce enough electricity to meet 1.7% of California’s annual demand. The 4.1gw Berwick Bank wind farm, off the east coast of Scotland, will provide more energy over a year than could Britain’s two largest gas-fired power stations running full tilt. But none of this will matter until these renewable heavyweights get hooked up to their respective grids.

The grids used by developed countries are not accustomed to rapid change. At the turn of the century a couple of power plants a year might be connected to meet new demand driven by demographic change, to replace plants at the end of their lives or, as in shifts between coal and gas, to compete on price. But the overall rate was typically slow, with net capacity changing little and new plants often using the same connections as old ones.