Transport for LondonHydrogen technology
Hydrogen fuel cell buses
Very simply, a fuel cell works like a battery. As hydrogen gas flows into a fuel cell, the hydrogen combines with oxygen and is converted into water. In the process it produces electricity and this powers the electric motor which drives the vehicle. See a diagram of how fuel cells work (GIF 30KB).
The five hydrogen fuel cell buses being introduced in London will use an electric motor with the hydrogen stored in tanks on the roof. The only emission from a fuel cell bus is water, which forms a vapour cloud as it leaves the exhaust and enters the atmosphere.
Hydrogen internal combustion engine buses
The five hydrogen internal combustion engine vehicles (H2ICE) will use a specialist ICE V10 engine which is powered directly by hydrogen stored in tanks on the roof of the bus.
Using this technology, the hydrogen burns in engines pretty much the same as in traditional petrol/diesel vehicles. But as there is no carbon in the fuel, hardly any emissions are produced. Emissions testing will be done as part of the test and evaluation programme.
Both types of buses will also use hybrid technology to make them as efficient as possible and help them go further before having to refuel.
