Electrofuel
Electrofuels, also known as e-fuels, a class of synthetic fuels, are a type of drop-in replacement fuel. They are manufactured using captured carbon dioxide or carbon monoxide, together with hydrogen obtained from water split by low-carbon electricity sources such as wind, solar and nuclear power.

The process uses carbon dioxide in manufacturing and releases around the same amount of carbon dioxide into the air when the fuel is burned, for an overall low carbon footprint. Electrofuels are thus an option for reducing greenhouse gas emissions from transport, particularly for long-distance freight, marine, and air transport.

The primary targets are methanol, and diesel, but include other alcohols and carbon-containing gases such as methane and butane.

Research
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 under President Obama’s Secretary of Energy Steven Chu, is the Department of Energy’s (DOE) attempt to duplicate the effectiveness of the Defense Advanced Research Projects Agency, DARPA.  
Examples of projects funded under this program include OPX Biotechnologies’ biodiesel effort led by Michael Lynch and Derek Lovley’s work on microbial electrosynthesis at the University of Massachusetts Amherst, which reportedly produced the first liquid electrofuel using CO2 as the feedstock.

The first Electrofuels Conference, sponsored by the American Institute of Chemical Engineers was held in Providence, RI in November 2011. At that 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 are beyond proof-of-principle, and are working to scale up cost-effectively. Porsche is currently considered to be the leader on these projects with their estimated cost per gallon of efuel at forty-five dollars per gallon.

Electrofuels have the potential to be disruptive if carbon-neutral electrofuels are cheaper than petroleum fuels, and if chemical feedstocks produced by electrosynthesis are cheaper than those refined from crude oil. Electrofuels also has significant potential in altering the renewable energy landscape, as electrofuels allows renewables from all sources to be stored conveniently as a liquid fuel and reducing curtailment.

, prompted by the fracking boom, ARPA-E's focus has moved from electrical feedstocks to natural-gas based feedstocks, and thus away from electrofuels.

In 2021, Audi announced that it was working on e-diesel and e-gasoline projects. British company Zero, which was founded in 2020 by former F1 engineer Paddy Lowe, has developed a process it terms 'petrosynthesis' to create sustainable fuel and has set up a development plant in Bicester Heritage business centre near Oxford. 

In 2023, a study published by the NATO Energy Security Centre of Excellence, concluded that e-fuels offer one of the most promising decarbonization pathways for military mobility across the land, sea and air domains.

Controversy 
Some current processes that claim to produce electrofuels are powered by electricity generated by non-renewable fossil fuels; academics have acknowledged the necessity of these methods in the early stages of electrofuel production despite their counterintuitive nature.

By 2021, the European Federation for Transport and Environment, an advocacy group, advised the aviation sector needs e-kerosene to be deployed as it could substantially reduce their climate impact, and similarly for shipping. It also stated that electrofuel usage in cars emits two significant greenhouse gases beyond the  captured for the production: methane (CH4) and nitrous oxide (N2O); local air pollution was still a concern, and it was five times less efficient than direct electrification.

The eFuel Alliance, another advocacy group, states that "the perspective of the lack of efficiency of Electrofuels is misleading as what is critical for global energy transition is not the degree of efficiency of electricity’s end usage, but rather how efficiently electricity can be produced from renewable energies, and then made usable".

Classification 
Europe defines a class of electrofuels called "Renewable Liquid and Gaseous Transport Fuels of Non-Biological Origin" (RFNBO), chemically the same as e-fuels in general, but with stricter requirements. The power must be made by new renewable unsubsidized power plants located in the same bidding zone as the e-fuel facility, power production and e-fuel production must occur simultaneously, and carbon sources must be certain types.

Applications 
Electrofuels are largely seen as a supplement and eventual replacement for fuels used in transport, such as jet fuel, diesel fuel, and fuel oil. The most basic electrofuel is hydrogen produced from water, though it is hampered by difficulties in effective storage and transportation. Hydrogen is often further processed into methane or syngas via reaction with carbon dioxide produced through a variety of renewable means, which can then be processed further to produce the more easily handled gasoline, kerosene or diesel liquid fuels through the Fischer–Tropsch process. Catalytic synthesis routes have been used to produce methanol as an e-fuel from syngas produced in this way.

Projects 

In September 2022, the Finnish company Q Power sold P2X Solutions a synthetic methane production unit to be delivered in 2024 in Harjavalta, Finland, next to its 20 MW green hydrogen production plant. Ren-Gas has several synthetic methane production projects in Tampere, Lahti, Kotka, Mikkeli and Pori in Finland. 

Towards the end of 2020, Porsche announced its investment 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, based on wind power and producing ~130 m3 of eFuel per year in the pilot phase, scaling to 55,000 m3 per year by the mid-2020s, and 550,000 m3 after another two years, to be exported through its port. As of 2023 this facility can successfully produce 34,340 gallons a year with commercial applications coming later down the line.

See also

References

External links
  
 eFuel Alliance

Alternative fuels
Renewable fuels
Synthetic fuels
Aviation fuels