If pure hydrogen fuel is used, the only by-product of the process at the point of use is water. And, excitingly, if the hydrogen itself is produced from a carbon-neutral source such as solar or wind power, we have the potential for carbon-neutral and emission-free energy. Our cars, buses, mobile phones, laptops, home generators, powerstations and so on could be clean ... and quiet!
The system they use is durable and compact and provides a consistent driving character regardless of the environment or climate, so consumers experience no major compromises in terms of practicality and performance compared to conventional petrol and diesel-powered vehicles.
Hydrogen gas is a common industrial gas that is colourless and odourless. Some 35 million tonnes are produced globally every year, about one per cent of the amount of oil produced globally in 2001. Consequently, extensive safety protocols already exist and work is also under way to produce internationally standardised handling procedures for everyday situations. All fuels, including those suitable for use in fuel cells such as hydrogen, require careful management to control the risks.
As a fuel, hydrogen gas is energy dense. This means that, as with many commonly used fuels, such as petrol and natural gas, there is a danger to health and property in the event of uncontrolled combustion or explosion. All fuels require the application of fuel-specific safety controls, and hydrogen is no exception. The main difference between hydrogen gas and petrol is in its behaviour when released to the air. Hydrogen gas disperses rapidly and fires burn out quickly, dissipating heat only very locally.