To improve the sustainability of transportation, a major goal is the replacement of conventional petroleum-based fuels with more sustainable fuels that can be used in the existing infrastructure (fuel distribution and vehicles). While fossil-derived synthetic fuels (e.g. coal derived liquid fuels) and biofuels have received the most attention, similar hydrocarbons can be produced without using fossil fuels or biomass. Using renewable and/or nuclear energy, carbon dioxide and water can be recycled into liquid hydrocarbon fuels in non-biological processes which remove oxygen from CO 2 and H 2 O (the reverse of fuel combustion). Capture of CO 2 from the atmosphere would enable a closed-loop carbon-neutral fuel cycle.

This article critically reviews the many possible technological pathways for recycling CO 2 into fuels using renewable or nuclear energy, considering three stages—CO 2 capture, H 2 O and CO 2 dissociation, and fuel synthesis. Dissociation methods include thermolysis, thermochemical cycles, electrolysis, and photoelectrolysis of CO 2 and/or H 2 O. High temperature co-electrolysis of H 2 O and CO 2 makes very efficient use of electricity and heat (near-100% electricity-to-syngas efficiency), provides high reaction rates, and directly produces syngas (CO/H 2 mixture) for use in conventional catalytic fuel synthesis reactors. Capturing CO 2 from the atmosphere using a solid sorbent, electrolyzing H 2 O and CO 2 in solid oxide electrolysis cells to yield syngas, and converting the syngas to gasoline or diesel by Fischer–Tropsch synthesis is identified as one of the most promising, feasible routes.