According to researchers at the Fraunhofer Institute for Systems and Innovation Research (ISI), e-fuels are not suitable for large-scale use in cars and trucks. There are cheaper alternatives, the energy requirement is high and the environmental balance is questionable. In addition, it could become an obstacle to the traffic turnaround, says Fraunhofer ISI after reviewing scientific findings on the subject. In doing so, they are opposing the federal government’s recent decision, according to which e-fuels should play an important role in future in order to achieve climate neutrality in transport.
E-fuels are produced from water and carbon dioxide using electrical energy. The federal government has enforced in the EU that vehicles with combustion engines that are only fueled with e-fuels can also be registered in the EU after 2035. Fraunhofer ISI believes that the short and medium-term use of electricity-based e-fuels in road traffic makes little sense based on the current state of knowledge.
Significantly more power required
Global renewable electricity production would have to be almost doubled compared to today in order to achieve a global share of ten percent of green hydrogen and synthetic combustibles and fuels including e-fuels in 2050. Therefore, the latter would be scarce and expensive for a long time to come, says the research institute in its discussion paper.
Green hydrogen and synthetic combustibles and fuels should be used where there are no other economic alternatives that could be used to achieve greenhouse gas neutrality. These are the steel sector, basic chemicals, refineries and international air and shipping traffic. These areas alone would account for around 15 percent of the final energy requirement in 2045, leaving hardly any usable quantities for road traffic.
“A large-scale use of e-fuels in cars and trucks is not economically expedient. The conversion losses are enormous and alternatives such as direct electrification are up to five times more efficient in terms of electricity use,” write the researchers. E-fuels are expensive and could hardly be paid for by low-income households in the future. In addition, the costs of avoiding CO₂ in cars with e-fuels in 2030 would be around 1,000 euros per ton of CO₂ and thus many times higher than those of electromobility or other climate protection measures.
Problematic climate balance
The researchers also object that the combustion of e-fuels produces nitrogen oxides, carbon monoxide and particulate matter in the engine. As a result, the carbon footprint of e-fuels is problematic. The overall efficiency is low and the energy required for production is high. The strong expansion of electricity generation capacities required for this is associated, among other things, with an enormous need for space and resources for critical raw materials, which has a negative effect on the ecological balance of e-fuels.
From the point of view of “technology openness” it is not necessary to introduce e-fuels in the short term. According to the discussion paper, e-fuels are expected to meet the current fuel standards, so that no further developments are necessary for engines and filling stations. However, synthetic combustibles and fuels are necessary for other fields of application such as international air traffic, so it can be assumed that the development of e-fuels will progress independently of road traffic.
“From the point of view of the current study situation, the promotion of e-fuels in road traffic could have a negative impact on the traffic turnaround, since their use and availability is currently not economically and ecologically expedient,” adds Prof. Dr. Martin Wietschel, Head of the Competence Center for Energy Technologies and Energy Systems at Fraunhofer ISI. Necessary initiatives in the direction of electromobility or other alternative forms of mobility could be slowed down, because for the traffic turnaround to succeed, clear signals as well as planning and expectation certainty are necessary.