Glossary / Cars and engines
Fuel cell
A device that reacts hydrogen with oxygen to produce electricity directly, without combustion. The only exhaust is water.
In 1839 William Grove reported that hydrogen and oxygen in contact with platinum electrodes produce a current[1] — electrolysis of water run in reverse, half a century before the car was invented.
Because no heat engine is involved, it is not bound by the thermal-efficiency ceiling that limits engines. Fuel cells powered spacecraft in the 1960s, and Toyota put the Mirai on sale in 2014. The open problem is producing, transporting and storing hydrogen cheaply.
Related terms
- Lithium-ion batteryA battery that charges and discharges as lithium ions shuttle between the positive and negative electrodes. Used everywhere from phones to electric cars.
- Carnot's theoremThe law that any engine producing work from heat has an efficiency ceiling set only by the temperatures of its hot and cold sides.