Electrofuels are hydrocarbons that are artificially synthesized from hydrogen and carbon dioxide. Carbon dioxide can be extracted from ambient air (direct air capture), from point sources such as power plants (carbon capture and utility), or from biomass. To maximize climate-friendly production, atmospheric capture by biomass or direct air capture are preferred. When using biomass, CO2 can be obtained as a by-product from the production of biogas or bioethanol, which then needs to be separated and purified. Hydrogen is produced through water electrolysis using renewable electricity, ensuring CO2-neutral e-fuels.
To produce e-fuels, a synthesis gas of hydrogen and carbon monoxide is converted into hydrocarbons. This synthesis can utilize various processes, including Fischer-Tropsch Synthesis and the Mobile Process (Methanol to Gasoline). E-fuels are secondary energy sources, enabling the use of electric energy to produce fuels with high energy density, storage, transport, and combustion properties. They are chemically identical to their fossil counterparts, allowing their use in existing vehicle fleets and infrastructure such as sea transport, pipelines, tankers, and filling station networks, while avoiding the difficulties of handling hydrogen.
For e-fuels to be competitively priced, two prerequisites are essential: high full-load hours and cheap electricity costs. According to a 2018 study by Agora Verkehrswende, plant complexes for e-fuel production require significant investment, leading to high fixed costs. At least 3,000-4,000 full-load hours per year are needed to reduce costs. The synthesis of e-fuels is electricity-intensive and characterized by conversion losses, making cheap renewable electricity crucial.
The study recommends producing e-fuels in sunny and windy regions rather than using renewable electricity from offshore wind turbines in regions like the North Sea or Baltic Sea. Regions such as North Africa and the Middle East, utilizing PV systems, could achieve production costs as high as €11 cents per kilowatt-hour (€ct/kWh), equating to 0.96 euros per liter or 3.63 euros per gallon by 2030 (3.94 US-$ per Gallon based on calculations from 26 May 2024 without taxes). Iceland, utilizing its existing geothermal energy resources, was also identified as a notable location. Similar findings were reported in a 2018 report by Prognos AG, the Fraunhofer Institute for Environmental, Safety, and Energy Technology, and the German Biomass Research Center (DBF). Their data suggests that by 2050, with production in the MENA region and utilizing the Fischer-Tropsch process, manufacturing costs could range from at least €0.70/L to €1.30/L (2.88 US-$ per Gallon and 5.34 US-$ per Gallon based on calculations from 26 May 2024), excluding taxes, depending on various parameters.
A primary source of funding for research on liquid electrofuels for transportation was the Electrofuels Program of the Advanced Research Projects Agency-Energy (ARPA-E), headed by Eric Toone. ARPA-E, created in 2009, aims to replicate the effectiveness of DARPA. Projects funded under this program include OPX Biotechnologies' biodiesel effort and Derek Lovley's work on microbial electrosynthesis at the University of Massachusetts Amherst, which reportedly produced the first liquid electrofuel using CO2 as a feedstock.
The first Electrofuels Conference, sponsored by the American Institute of Chemical Engineers, was held in Providence, RI, in November 2011. At this conference, Director Eric Toone stated that "Eighteen months into the program, we know it works. We need to know if we can make it matter." Several groups have moved beyond proof-of-principle and are working to scale up cost-effectively. Porsche is currently investing in electrofuels, including the Haru Oni project in Chile, creating synthetic methanol from wind power. In December 2022, Porsche and Chilean company Highly Innovative Fuels opened the Haru Oni pilot plant in Punta Arenas, Chile, producing approximately 130 m3 of eFuel per year in its pilot phase, with plans to scale to 55,000 m3 per year by the mid-2020s and 550,000 m3 after another two years. As of 2023, this facility can successfully produce 34,340 gallons a year.
ARPA-E’s focus shifted from electrical feedstocks to natural-gas based feedstocks in 2014 following the fracking boom. In 2021, Audi announced its work on e-diesel and e-gasoline projects. British company Zero, founded in 2020 by former F1 engineer Paddy Lowe, developed a process termed 'petrosynthesis' for sustainable fuel and established a development plant in Bicester Heritage business center near Oxford. In September 2023, Stellantis (brands including Alfa Romeo, Peugeot, Opel, Citroen, and Chrysler) announced approval for the use of electrofuels in 28 million vehicles in Europe, following extensive testing in collaboration with Saudi Aramco. Stellantis anticipates saving up to 400 million tonnes of CO2 by 2050. A 2023 study by the NATO Energy Security Centre of Excellence concluded that e-fuels offer one of the most promising decarbonization pathways for military mobility across land, sea, and air.
Due to high energy losses when converting electricity into electrofuels and then into mechanical energy, cars with internal combustion engines using electrofuels need 3-5 times more electricity than battery electric cars.
Proponents of electrofuels for internal combustion engine vehicles criticize the focus on energy conversion efficiency, arguing that regions with high renewable energy potential but lower local electricity demand can favorably export that energy as liquid carriers. The eFuel Alliance states that focusing on the efficiency of electricity's end usage is misleading; instead, the efficiency of renewable energy production is critical for global energy transition. Studies supporting this view suggest that by utilizing favorable locations with very high renewable energy potential, internal combustion engine vehicles can achieve similar efficiency to battery electric vehicles.
Proponents of battery electric vehicles acknowledge that converting electricity into hydrogen, synthetic hydrocarbons, or other chemical energy carriers can be reasonable in certain regions or periods, particularly for sectors like aviation, maritime transportation, or the steel and chemical industries, which lack mature and efficient alternatives. Through cogeneration, electrofuels can be reconverted into electricity, with the opportunity to use waste heat for building heating. Even when charged with electricity from synthetic methane, battery electric vehicles remain significantly more efficient than internal combustion engine vehicles.
Some current processes claiming to produce electrofuels are powered by electricity generated by non-renewable fossil fuels. By 2021, the European Federation for Transport and Environment advised that the aviation sector needs e-kerosene to substantially reduce its climate impact, and similarly for shipping. They also stated that electrofuel usage in cars emits methane (CH4) and nitrous oxide (N2O) beyond the CO2 captured for production, and local air pollution remains a concern.
Europe defines a class of electrofuels called "Renewable Liquid and Gaseous Transport Fuels of Non-Biological Origin" (RFNBO). These are chemically identical to e-fuels in general but have stricter requirements regarding power source and production timing.
In September 2022, the Finnish company Q Power sold P2X Solutions a synthetic methane production unit, scheduled for delivery in 2024 to Harjavalta, Finland, adjacent to its 20 MW green hydrogen production plant. Ren-Gas has several synthetic methane production projects underway in Tampere, Lahti, Kotka, Mikkeli, and Pori in Finland.