Potential and risks of hydrogen-based e-fuels in climate change mitigation

Abstract

E-fuels promise to replace fossil fuels with renewable electricity without the demand-side transformations required for a direct electrification. However, e-fuels' versatility is counterbalanced by their fragile climate effectiveness, high costs and uncertain availability. E-fuel mitigation costs are 800-1200 €/tCO 2 . Large-scale deployment could reduce costs to 20-270 €/tCO 2 until 2050, yet it is unlikely that e-fuels become cheap and abundant early enough.Neglecting demand-side transformations threatens to lock in a fossil fuel dependency if e-fuels fall short of expectations. Sensible climate policy supports e-fuels deployment, while hedging against the risk of their unavailability at large scale. Policies should be guided by a "merit order of end uses" that prioritizes hydrogen and e-fuels for sectors that are inaccessible to direct electrification.

Cost of long-distance energy transmission by different carriers

“…Hydrogen production by water electrolysis has efficiency of about 60-70% depending on the type of the electrolyzer. Efficiency of e-fuel production can be about 40-50%, depending on the type of fuel produced and the specifics of the synthesis system integration (Zang et al, 2021;Ueckerdt et al, 2021). On the consumption side, when hydrogen or e-fuels are converted back into electricity, the conversion efficiency ranges from approximately 30% for internal combustion generators to approximately 60% for large IGCC turbines or fuel cells.…”

Integrated assessment of the role of bioenergy within the EU energy transition targets to 2050

“…However, uncertainty surrounding long-term projections on Europe's access to sustainable biomass may result in lower supply volumes than projected. Acknowledging this, European bioenergy policy should seek to follow a 'merit order of end uses' (Ueckerdt et al, 2021), prioritizing bioenergy to sectors where direct electrification and decarbonization are harder to attain.…”

Production of Gasolines and Monocyclic Aromatic Hydrocarbons: From Fossil Raw Materials to Green Processes

“…In the near future, it seems universally accepted that electrolytic hydrogen produced using renewable energy will be largely available. Researchers have concluded, however, that the use of electrolytic hydrogen to produce biofuels may be a strong limit for the production of biofuels [242]. As we have remarked above, the use of hydrogen produced or co-produced by converting biomass may help, in particular when hydrogen-poor hydrocarbons (as aromatic hydrocarbons) are the target product.…”