Synthetic fuels are the missing link between renewable electricity and the sectors where electrification is most needed and yet most difficult. Through power-to-x (P2X) solutions, we can decarbonise transport segments like aviation and marine as well as energy intensive industries like steel production. The potential is enormous, and the possibilities endless. Synthetic fuels are the most prominent long-term solution for transferable energy storage, and they represent a probable pathway for displacing fossil fuels from the transport sector.

This happens through a power-to-x process, e.g. in which hydrogen is produced from water with renewable electricity through electrolysis. This hydrogen could then also be used in other processes, e.g. in the production of ammonia as fuel for the marine sector. The elements for synthetic fuels production are:

• low-cost renewable electricity
• hydrogen (H₂) created by the electrolysis of water
• carbon dioxide (CO₂) extracted from the atmosphere or captured from industry

In a synthesis plant, carbon dioxide and hydrogen can be combined into hydrocarbon products like methane, gasoline, diesel, jet fuel or methanol. Production of synthetic ammonia is a similar process, except that the CO₂ is replaced by nitrogen (N2). Ammonia is an important raw material for fertilisers and a potential low-carbon fuel for shipping.

Synthetic fuels can be used in traditional combustion engines or gas turbines, and can also be blended gradually into the existing fossil fuel mix, displacing an ever-growing portion of the fossil energy.

This minimises the need for renewal of infrastructure and vehicle fleets, massively reducing the overall costs associated with decarbonisation. There are no limitations for the availability of carbon in the form of CO₂ and the distillation curve challenge (as explained in chapter #5) can be avoided. Power-to-x can achieve near carbon neutrality with enough renewable electricity and excess CO₂ as input. Production of synthetic fuels requires carbon capture technologies, and the CO₂ can be separated from large point sources, such as cement and steel production and pulp mills. CO₂ can also be separated from air through what is called Direct Air Capture (DAC) or from the sea. On the other hand, low CO₂ concentrations drive up the size of the equipment and the cost of each tonne of captured CO₂.

A comparison between hydrogen and hydrocarbon-based synthetic fuels show that the latter have properties which make them much more favourable as energy carriers. Using pure hydrogen as an energy carrier will be limited as a result of its poor volumetric energy density and its value chain shortcomings like distribution, storage and end-user applications. To conclude, we believe synthetic fuels will play a crucial role in the energy system of the future. The biggest bottleneck is – and will continue to be for the next decade – the availability of clean and cheap electricity. We must invest significantly in additional renewable electricity production and an accompanying electricity grid. It will also be important, and necessary, to research and develop solutions for lowering the production costs of synthetic fuels.