Using the same infrastructure as fossil equivalents
Electrofuels (e-fuels) are fuels (in gas or liquid form) made by synthesizing CO or CO2, captured from gases emitted by industrial processes or directly from the air (CO2 is about 0.04% of the atmosphere), and hydrogen, obtained from sustainable electricity sources, such as solar & wind. They differentiate from biofuels, which are primarily produced from biomass [Engie, 2022].
By drastically reducing the harmful emissions associated w/ combustion engines, e-fuels play a key role in decarbonization strategies. Thru the creation of a circular carbon cycle, their carbon footprint is a lot lower than oil-based fuels: as the process uses CO2 in production and releases around the same amount of CO2 when burned, they can be considered carbon neutral.
Examples of liquid e-fuels are e-methanol, e-ethanol, e-gasoline, e-kerosene, and e-diesel; of gaseous e-fuels, e-methane & e-ammonia. E-fuels have the advantage of using the same infrastructure as their fossil equivalents (petrol, diesel, kerosene, methanol, natural gas), putting them in competition with biofuels, which offer the same advantage [Engie, 2022].
In addition to being used to H2 transport & storage, e-fuels can be used from heavy-duty long-haul transport decarbonization to green chemistry [Engie, 2022]. They are also a way of recycling & recovering CO2, from which most e-fuels are made. Figure 1 shows different process steps for e-fuels production. Figure 2 shows energy efficiency among different technologies.
While e-fuels can be very low-carbon if made from renewable electricity, they can’t be low-cost at the same time (they reach five times the price of oil products). The e-fuels production process is inherently inefficient, converting at best half of the energy in the electricity into liquid or gaseous fuels [ICCT, 2020].
Figure 1: Process steps for the production of e-fuels
Figure 2: Energy efficiency of different techs
Fossil fuels provide a large amount of energy for a small amount of fuel, but they add CO2 to the atmosphere. E-fuels can be dropped straight into the existing engines of cars, aircraft, commercial, and agricultural vehicles, allowing them to run sustainably in exactly the same way and same performance as they do on fossil fuels, w/o engine modifications [Zero, 2023].
Recently, Germany, w/ its Italian and Polish allies, obtained an agreement authorizing sales beyond 2035 for combustion engine vehicles that use synthetic fuels. The EU must now establish a provision to classify vehicles running on e-fuels as carbon neutral. Berlin hopes that this legislative process will be completed by Fall/2024 [Le Monde, 2023].