A lack of European raw materials for sustainable jet fuels will limit the extent to which European aviation can reduce its greenhouse gas emissions from 2035. That is one of the main conclusions of a new study by Royal NLR and Delft University of Technology. The shortfall means that greenhouse gas emissions will only decrease by 40% in 2050 compared to a situation where only fossil petroleum aircraft are used. Sufficient availability of sustainable fuels can result in a two-fold reduction in greenhouse gas emissions.
The limited availability of European raw materials required for the production of sustainable aviation fuels, also known as “sustainable aviation fuels” (SAF), is a barrier to achieving the blending targets proposed by the European Commission in the medium and long term. “While the results show that the availability of raw materials is sufficient to meet the targets up to and including 2030, from 2035 we see a significant and growing gap between supply and expected demand,” says Johan Kos, project manager and lead author of the project. examination. These conclusions apply to two situations examined in the study. In one of them, aircraft powered by green hydrogen will be deployed on short and medium distances from 2035. Otherwise, such aircraft will not be deployed, and additional aircraft on SAF will be used instead.
Potential for new aircraft
The study is called TRANSCEND and is carried out within the ‘Technology Evaluator’ of the European Clean Sky 2 research program and NLR’s own Climate Neutral Aviation programme, in collaboration with TU Delft. Started in 2019 and recently concluded, TRANSCEND explored new propulsion technologies and alternative fuels for aviation up to 2050 as promising solutions to contribute to climate-neutral aviation. The study modeled the introduction of hydrogen-powered aircraft in flight segments of up to 300 passengers on flights of up to 3,700 kilometers. The study shows that in 2050, these hydrogen-powered aircraft will ensure that global aviation CO2 emissions during flights are 16 to 20% lower than in the same transport scenario using only SAF-powered aircraft. The total energy consumption ‘good to wake up’  and fuel costs for airlines are also lower in a hydrogen-powered aircraft situation than in a SAF-only aircraft situation.
Climate effects other than CO2 emissions, such as the influence of water vapor and soot, have not been studied. “The full contribution to global warming is significantly greater than CO2 emissions alone,” says Herma LAAMA-De Walle, program manager for Climate Neutral Aviation. “One of our recommendations is therefore to carry out thorough studies in the near future”, adds Kos, “to be able to make a more complete estimate of the possible contribution of hydrogen-powered aircraft and SAF to climate-neutral aviation.”
To enable a fair comparison, efficiency gains through innovative aircraft technology for both hydrogen and SAF powered aircraft have been modeled in the same way. Efficiency improvements must be achieved through further development of aircraft and engine technologies. The aerospace industry must research and then further develop these technologies. In addition, the authorities must develop the necessary regulations to certify and use hydrogen-powered aircraft commercially. “Due to the need for security around the rules and the time it takes to develop aircraft and infrastructure, these rules must be in place within five years at the latest,” emphasizes Kos.
In the aforementioned cases studied in TRANSCEND, net CO2 equivalent emissions decrease by only 40% in 2050. This is compared to a reference scenario that includes efficiency improvements from innovative aircraft and propulsion technology, but assumes that these units are fully petroleum fueled . is driven.
Balance between supply and demand
Based on the lack of European raw materials for the production and availability of SAF, one of TRANSCEND’s recommendations is that policy makers and industrial parties should ensure sufficient availability of sustainable biomass, residual streams and renewable electricity that can be used for the production of green. hydrogen and SAF. In addition, the researchers explicitly recommend politicians, universities and research institutions to periodically monitor and reassess important variables that affect the balance between supply and demand. “Examples are the energy efficiency of new aircraft, transportation developments and associated fuel needs, availability of sustainable biomass, residual and green power, and factories to make green hydrogen and SAF,” says Kos. “Because it is not possible to scale up raw material availability and fuel production from one day to the next, it is crucial that we anticipate supply and demand gaps in time so that we can act on them in time. In this way, we ensure that aviation can make its contribution to climate neutrality.”
TRANSCEND has studied several scenarios regarding the share of the total amount of raw materials available for aviation. The results in this text are valid for an aviation share of 10%. This means that 90% of the total amount of raw materials available is used for other sectors. Improvements in engine and aircraft technology – as developed and explored in the European Clean Sky 2 program – have been modeled from 2030 onwards. Hydrogen powered units are modeled based on the latest available knowledge and feedback from an expert workshop. In the modelling, these aircraft, with a maximum of 300 seats, will be introduced on flights up to 3700 kilometers from 2035. The demand for alternative fuels (i.e. green hydrogen and SAF) has been studied for flights departing from EU and UK airports, in transport scenarios derived from the first assessment of the Clean Sky 2 Technology Evaluator. Estimates of the availability of these fuels are based on the expected availability of raw materials in the same countries, supplemented to a limited extent by imports from neighboring regions. The choice of raw materials and production methods for SAF from sustainable biomass or waste streams is chosen to maximize the reductions of CO2 equivalent emissions during the life cycle. Therefore, most SAF is produced via the Fischer-Tropsch process. The amount of synthetic SAF is based on the amount of green hydrogen left over after the use of green hydrogen for hydrogen-powered aircraft.
TRANSCEND’s final report, containing nine strategic recommendations, is available for download. The project’s website provides access to published reports and articles.
 Well-to-wake energy is the total amount of energy required to perform a flight, including the energy required to produce the fuel.