Like all-electric vehicles, fuel cell electric vehicles (FCEVs) use electricity to power an electric motor. In contrast to other electric vehicles, FCEVs produce electricity using a fuel cell powered by hydrogen, rather than drawing electricity from only a battery.
Hydrogen can be used to fuel cars in two ways. The first is through hydrogen fuel cells, which work in a similar fashion to Lithium-ion battery EVs.
However, while the energy in batteries is stored via a chemical reaction, the energy in hydrogen cells is stored in hydrogen gas.
Hydrogen gas is stored in a tank that feeds fuel cells, each made up of negative and positive terminals (anodes and cathodes) separated by an electrolyte. Oxygen is taken from the air and pumped into the cathode, while hydrogen flows to the platinum anode terminal that acts as a catalyst, splitting positive hydrogen ions from the gas.
These ions flow through the electrolyte to the cathode to build a positive charge. As the separated electrons cannot flow through the electrolyte, they flow around an external circuit, generating a charge used to power an electric motor.
And what about emissions? As the hydrogen ions come into contact with the cathode, they combine with the oxygen to produce water that then flows out of the car’s exhaust.
Using hydrogen for combustion
Hydrogen can also be used as a direct replacement for petrol or diesel in a specialized or converted internal combustion engine. In this case, pressurized hydrogen gas is directly injected into an engine’s combustion chamber and combustion takes place like a normal ICE.
Using hydrogen like this isn’t common, as it’s not as energy-dense as petrol. But burning hydrogen does produce fewer emissions, with water as the main by-product, and fewer toxic NOx gases coming from heat produced by the engine.