Sustainable synthetic carbon based fuels for transport

This Royal Society report considers the production and use of sustainable carbon based synthetic fuels

The need to achieve net-zero greenhouse gas emissions from all human activities has never been clearer. One area requiring urgent action is the transition from the use of fossil fuels for transport. Whilst the decarbonisation of electricity is progressing and many transport modes can feasibly be electrified, some transport modes, such as heavy-duty vehicles, aircraft and shipping will require different technological options. Sustainable synthetic fuels offer one solution.

What are sustainable synthetic fuels?

They are carbon based fuels made from non-fossil resources, with energy densities similar to fossil fuels. This means that they can be transported using existing infrastructure and used in existing engines with little or no modification.

The report considers two types of sustainable synthetic fuels: electro fuels (efuels) and synthetic biofuels. Efuels are made by combining hydrogen (from for example the electrolysis of water) with carbon dioxide (from direct air capture or a point source). Synthetic biofuels can be made from biological material (for example waste from forestry) or from further processing biofuels (for example ethanol).

Whilst synthetic fuels can be “dropped in” to existing engines, they are currently more expensive than fossil fuels and, in the case of efuels, could be thought of as an inefficient use of renewable electricity. However, where renewable electricity is cheap and plentiful, the manufacture and export of bulk efuels might make economic sense. 

Key research challenges identified include improving the fundamental understanding of catalysis; the need to produce cheap low-carbon hydrogen at scale; and developing sources of competitively priced low carbon energy are key to the development of synthetic efuels and biofuels. The UK has the research skills and capacity to improve many of these process steps such as in catalysis and biotechnology, and to provide a further area of UK leadership in low-carbon energy.