Germany’s federal and state governments, with backing from industry, have agreed a roadmap that commits to the development of e-fuels – also described as power-to-liquids (PtL) – for the aviation sector. E-fuels can potentially deliver net zero emissions and are considered a critical technology for producing large volumes of sustainable aviation fuel (SAF) at scale with limited environmental impact. For aviation to achieve net zero emissions by 2050, the bulk of SAF will likely have to come from e-fuels. However, the technology is currently only at pilot scale and e-fuels are very expensive to produce, reports Susan van Dyk. Produced from carbon dioxide and hydrogen, e-fuels will also have to comply with strict sustainability criteria to be CO2 neutral, and these metrics will need to be clearly defined. The PtL roadmap sets out measures for commercialising the technology, as well as establishing sustainability criteria and binding targets to achieve a market ramp-up of e-fuels.
Commercial production of SAF is currently limited to the HEFA technology, based on hydrotreated fats and oils. Other SAF technologies, such as gasification-based SAF and alcohol-to-jet, are currently being scaled up, and commercial facilities are under construction. However, these technologies are based on land-based feedstocks or available in limited quantities, such as used cooking oil or municipal solid waste. E-fuels, on the other hand, are produced from air and water with unrestricted potential for fuel production at a large scale while having a minimal environmental impact and potential net-zero CO2 emissions.
Dr.-Ing Ulf Neuling, Renewable Fuels Group Leader at the Hamburg University of Technology and a joint author on several studies on e-fuel technologies, indicates there are still some technical challenges remaining for commercial production of e-fuels to take place, such as the syngas production required for e-fuel synthesis. Not all the different technologies involved within the overall e-fuel production process are at the same technology maturity level, he points out, and the integration of the entire process at an industrial scale must still be demonstrated. “So far, not a single drop of PtL kerosene is produced commercially,” stated a recent study co-authored by Neuling.
A significant challenge for commercialising e-fuel technology is the current high cost of production. One study investigating the techno-economics of e-fuels showed it is much greater than other types of SAF. E-fuels are very expensive and cannot currently compete with other SAF technologies, confirmed Neuling. However, based on the significant role e-fuels are expected to play in the future, their development and scale-up is critical. Hence the requirement for policies that specifically target the development of e-fuels, as demonstrated by the German PtL-Roadmap. The need for e-fuel specific policy is also acknowledged in the proposed ReFuelEU Aviation initiative, where a dedicated sub-mandate for e-fuels is being considered.
The price of the renewable electricity for hydrogen production is the most significant component of e-fuel production costs, and as these costs are expected to continue decreasing, e-fuels could reach cost parity with other SAF once it has been scaled up, stated Neuling. However, it is obvious technology development must take place now to reach the large volumes of SAF that will be required for the sector towards 2050. As e-fuels require renewable electricity, investment in the transformation of the electricity grid infrastructure is also a critical but long-term effort.
Policies for technology commercialisation require a supply-side push as well as a demand-side pull effect. The roadmap addresses these challenges, outlining supply-side measures for the development of e-fuel technology, both for individual components of the production system as well as their integration on an industrial scale. It recognises that demonstration and pilot plants are needed as trials have only been carried out under laboratory conditions. According to the roadmap, the role of the German Federal Transport Ministry is to establish a platform for the development, testing and demonstration of different power-to-liquid production processes, while at the same time, the Federal Environment Ministry will set up demonstration plants. The roadmap indicates a focus on establishing and building up crucial industrial expertise within Germany with the aim to become a technological leader in the production of e-fuels for aviation.
On the demand side, the roadmap supports the market ramp-up of the technology, with binding targets for the use and sale of e-kerosene as a binding minimum quota on aviation fuels sold in Germany. Targets will be combined with a purchase obligation to secure demand and investment certainty for market players despite the higher costs of the fuels. Aviation sector participants in the roadmap indicated their commitment to the market ramp-up of e-fuels with Peter Gerber, President of the German Aviation Association (BDL) and CEO at Brussels Airlines, stating: “We want to participate in the construction of industrial plants for the production of sustainable aviation fuels, for example in the form of purchase guarantees.”
Critical considerations for airlines are the provision of sustainable e-fuels in sufficient quantities and at competitive prices and a regulatory system that is competition-neutral, they say. Environment Minister Svenja Schulze said a gradually increasing statutory sub-quota for PtL kerosene planned by the federal government would significantly boost its production from 2026 onwards while creating the necessary investment security.
The goal of the roadmap is to create the basis for producing at least 200,000 tons of sustainable e-kerosene annually by 2030 for the German aviation sector.
The goal of the roadmap is to create the basis for producing at least 200,000 tons of sustainable e-kerosene annually by 2030 for the German aviation sector. This corresponds to a third of the current fuel requirements for domestic German air traffic. Andrew Murphy, Aviation Director at Transport and Environment (T&E), considers this a realistic and achievable target and believes the German government and business have shown the ability to cooperate towards achieving this goal. Federal Economics Minister Peter Altmaier has indicated support for the market ramp-up through various funding programmes and the design of the regulatory framework to contribute to the development of hydrogen technologies and global climate protection.
The potential of e-fuels to have net-zero CO2 emissions is the central rationale for their production. The prospective emission reductions of fuels must be calculated based on a life-cycle assessment of the entire production pathway. This process has two critical sustainability metrics, the source of the carbon dioxide and the source of electricity used for electrolysis to produce hydrogen, said Keith Whiriskey, Deputy Director of the Bellona Foundation and co-author of ‘The Power to Liquids Trap’ report published in 2017. According to Whiriskey, people often ignore the source of electricity or carbon dioxide. “There is a lot of hype around e-fuels. It’s like alchemy, and very attractive to say you can turn air into fuels,” he said.
E-fuels can only achieve net zero emissions if the CO2 is derived through direct air capture (DAC), and the electricity used is 100% renewable and additional, maintains T&E. Germany currently still derives about 40% of its electricity from fossil sources such as hard coal, lignite and natural gas (source: CLEW). This leads Whiriskey to argue the German grid is not suitable for the deployment of e-fuel technology today as it needs 100% renewable electricity to achieve the full climate benefits. Making e-fuels with electricity derived from coal and natural gas will increase emissions rather than reduce them, he asserts.
A recent study co-authored by Dr Neuling concluded there was not enough renewable electricity in Germany to produce sufficient e-fuels for domestic aviation demand. This challenge is recognised by Hessian State Minister Tarek Al-Wazir, who said the roadmap underlines how central the massive expansion of electricity generation from renewable energy sources inside and outside Europe will be for achieving the Paris climate protection goals. E-fuel technology development will have to go hand in hand with the transformation of the electricity grid.
Whiriskey contends German companies can potentially develop and use PtL technologies in other countries with abundant renewable electricity and then import the e-fuel into the country. Neuling echoes this approach that e-fuels would have to be imported to supply sufficient SAF. However, a cynical Whiriskey added: “German companies want to do this in Germany and get the subsidies, so they have to greenwash the electricity.”
The production of e-fuels outside of Germany is anticipated to some extent by the roadmap. “As the next step, we need an energy and climate partnership with Africa. Africa has the sun, hydropower for production and many young, motivated people,” said Development Minister Gerd Müller. He indicated that through German development cooperation, a reference plant for green hydrogen and synthetic fuels was being built in Morocco.
Using this approach, in January Lufthansa announced investment in a green hydrogen facility in Abu Dhabi, United Arab Emirates, which has abundant renewable potential. Annette Mann, Head of the newly established unit of Corporate Responsibility at Lufthansa Group, is spearheading the Group’s participation in this pioneering project. A memorandum of understanding has been signed by the partners involved, which as well as Lufthansa Group include the Abu Dhabi Department of Energy, Siemens Energy Global, Masdar and Marubeni Corporation, Khalifa University and Etihad Airways.
Apart from the necessity for renewable electricity, the other critical sustainability factor is carbon dioxide origin, either from point source capture or direct air capture. Point sources can be from an industrial source, such as a cement factory (termed unavoidable emissions), or from a biogenic source, such as bioenergy plants. Point source emissions from powerplants based on fossil fuels are considered avoidable and unacceptable, and CO2 capture could support the continued use of fossil fuels. E-fuel production costs will vary depending on the source of carbon dioxide, with direct air capture being more expensive than point source capture. Therefore a company using a point source for CO2 could produce e-fuels at a reduced cost.
However, capturing the CO2 from an industrial smokestack cannot achieve overall net zero emissions of the e-fuel produced from this source. Where CO2 is captured from a smokestack, the carbon accounting becomes critical as “there is a toss-up here about who will claim the decarbonisation,” said Whiriskey. The point source industrial facility and the e-fuel producer cannot both claim the same climate benefits as that would amount to double counting.
Don O’Connor of S&T Squared Consultants and an LCA expert, explained he had run into this problem when carrying out LCA studies for companies. No one wants to take responsibility for the CO2 that is released to the atmosphere when the e-fuels are combusted, he said. If the CO2 was from direct air capture, then the CO2 from the combustion of the fuel would be balanced by the CO2 from the atmosphere, so from an LCA perspective, the net impact will be zero, he explained. CO2 emissions from a biogenic source are not currently counted, and therefore the CO2 emissions from e-fuel combustion do not have to be accounted for. But taking the CO2 from an existing emission source, added O’Connor, leads to the original emitter wanting to claim the reduction. In some cases, industrial facilities may be required under regulatory frameworks to reduce emissions. In that case, the e-fuel combustion emissions have to be included in the LCA for the e-fuel, making the carbon intensity of the e-fuel very unattractive. Overall, he concludes, there is a reduction in GHG emissions, but the reduction belongs to the original emitter and not to the e-fuel.
Whiriskey agrees that it is very common for fuel producers to claim that their e-fuel will reduce CO2 emission by 70-90% regardless of where the CO2 is sourced. For a low carbon (80% reduction) e-fuel to be made from industrial CO2, the e-fuel producer “must shout from the rooftop that no emissions reduction has taken place at the industrial site,” he said. “It should also be made clear that the overall process is not carbon neutral, nor can it be. This is fine when done transparently and one can track the allocation but otherwise the emissions reduction becomes double-counted or simply lost.”
The roadmap recognises the source of CO2 is critical for sustainability of the process. It envisages that initially the carbon for e-fuel production can be obtained from unavoidable sources of CO2 but in the future it should be extracted from the atmosphere using direct air capture.
The climate benefits of e-fuels will depend on clear sustainability metrics and a transparent accounting system to take into account situations that may undermine the overall climate impact of the e-fuel production process. The roadmap indicates an awareness of these challenges and that the regulatory framework implementing its goals should include rigorous sustainability criteria.
It establishes the all-important framework for the development of e-fuels for aviation, and its implementation could play an important role in commercialising e-fuels technology and setting up the conditions for a significant scale-up of production in the future, both in Germany and globally.
“Electricity-based fuels are the impetus for CO2-neutral air traffic,” commented Environment Minister Schulze on the release of the roadmap.
However, unless strict sustainability metrics and transparent accounting is in place, these climate benefits are in danger of not being realised.
Photo (credit ATF Pictures): A Lufthansa A350-900 at Munich Airport. From 1 June 2021, SAFs can be delivered, stored and refuelled at the airport, provided they meet the relevant quality specifications for Jet-A1 aviation fuel. The airport says it expects in the future to see airlines take on PtL blends via its tank farm.