A variety of different energy sources can be used to produce hydrogen. Hydrogen is described as an ‘energy carrier’ as it transfers energy from a primary energy source to an application, for example electricity from a wind turbine can be used to generate hydrogen by breaking down water in an electrolyser, and the hydrogen could then be used to produce electricity and heat in a fuel cell.
Currently, the majority of global hydrogen production is produced from natural gas, i.e. from a fossil fuel. One way to produce hydrogen from a low carbon source is to use renewable electricity (e.g. from a wind turbine) to break down water to oxygen and hydrogen in an electrolyser. Other potential low carbon routes for hydrogen production include gasification of biomass and production of hydrogen from natural gas combined with carbon capture and storage.
At present hydrogen is mainly produced for industrial use. Potential energy uses of hydrogen include:
- electricity generation either from fuel cells or through burning the hydrogen in a power station,
- a transport fuel in an internal combustion engine or a fuel cell car,
- a fuel for heating.
Widespread use of hydrogen in transport and other applications could enable significant carbon savings. However, it is important to consider whether the primary energy used to produce the hydrogen could be more effectively employed elsewhere. For instance, using electricity from wind turbines to feed directly into the grid will displace more carbon than using it to produce hydrogen which is then used for electricity generation in fuel cells, because of the inefficiencies of the conversion process.
Hydrogen may also have a role in energy storage. For instance electricity from an intermittent source such as wind could be used to produce hydrogen when the electricity supply is greater than the demand, and this hydrogen could be stored to use as a fuel later.