Fuel cells are devices that convert chemical energy directly into electrical energy, water and heat. In most hydrogen fuel cell cars, the fuel cell provides electrical energy that drives electric motors to provide propulsion.
Hydrogen fuel cell technology specifically is becoming increasingly important as more manufacturers commit to developing this type of power-train and traditional 'Oil companies' like 'Shell' commit to providing hydrogen fuel as part of their 'standard' filling station provision.
Like electric cars, hydrogen powered fuel cell electric vehicles (FCEVs) are are classed as ultra low emission vehicles (ULEVs) since the only substance to come out of the exhaust is water vapour.
FCEVs have an on-board battery for temporary energy storage, and as such are similar in use to plug in hybrid vehicle (PHEV), the fuel cell performing the role of a PHEV's small internal combustion engine (ICE.)
In terms of tailpipe emissions Hydrogen powered vehicles are definitely 'green', as the only emission from the fuel cell vehicle is water vapour. Hydrogen Fuel Cell powered vehicles are therefore a technology that can be used to improve air quality.
Today, most hydrogen is generated using fossil fuels (typically by reforming natural gas), though an increasing amount is being made using renewable electricity (via electrolysis). Emissions generated during hydrogen production (from natural gas) are generally less than burning petrol or diesel in an internal combustion engine.
Hydrogen fuel cell vehicles are potentially somewhat less efficient overall when compared to a Battery Electric Vehicle (BEV). Electricity taken from the national grid and stored in a battery involves fewer steps than using the electricity to first generate hydrogen, which is then used to generate electricity in a fuel cell. Once it’s in the vehicle, hydrogen has an efficiency of around 60% – much better than the circa 20% efficiency of a petrol or diesel engine, but lower than the 75% for a BEV.
While fuel cell production costs remain high, current FCEVs have significant performance advantages over BEVs: the range of most FCEVs is around three times that of the average BEV and refuelling times are significantly shorter.
One of the FCEV commercial conundrums today is that vehicle ownership is limited to 'leasing' the Hydrogen Fuel cell.