In Indian cities, an auto-rickshaw or cargo three-wheeler earns money only while it is moving. Waiting four hours to recharge, or queuing at a battery swap station, eats directly into a driver's income.
Lithium-ion batteries have become the default way to shift solar power into the evening, but they wear out with heavy cycling and are usually built for two to four hours of output.
Europe is wasting a growing share of its renewable electricity because there is nowhere to put it when the wind blows hardest. Lithium-ion batteries empty in a few hours, which is not enough for a calm, grey week in winter.
Finland now has so much wind power that electricity is sometimes almost free, and sometimes very expensive. District heating networks still burn wood chips, gas and oil to keep homes warm through the winter.
Millions of European homes keep a large cylinder of hot water in a cupboard, slowly losing heat all day. Switching such homes to heat pumps often means fitting an even bigger tank, and many flats simply have no room.
