NEXT time the lights go out in New York or London, a new breed of power generator could come to the rescue – at a price. These portable fuel cells run silently and produce only water vapour as exhaust. But the first ones to hit the market generate power for only a couple of hours and, confusingly, competing models run on different fuels.
Fuel cells work by combining oxygen with hydrogen and using the energy this liberates to generate an electric current. The oxygen comes from the air, but manufacturers have yet to agree on the best source of hydrogen. One…
