EU aviation fuel rules may raise costs and energy use, scientists warn

European Union (EU) rules designed to accelerate the shift to sustainable aviation fuel (SAF) could unintentionally make fossil-free aviation fuels more expensive and energy intensive, according to new research from Chalmers University of Technology.

The study found that current EU regulations favour production pathways that consume more electricity and resources, even when more efficient alternatives are already technically available.

The findings were published as renewed geopolitical tensions, including the US and Israel’s war on Iran and concerns over oil market volatility, sharpen focus on Europe’s efforts to scale up domestic fossil free aviation fuel production.

Under the EU rules introduced last year, aviation fuel suppliers must ensure that at least 2 per cent of fuel supplied at EU airports is SAF. The requirement will rise steadily to at least 70 per cent by 2050. Half of that volume must come from renewable fuels of non-biological origin (RFNBO), a category that includes synthetic fuels made from renewable hydrogen and captured carbon dioxide.

Researchers at Chalmers said the regulations currently favour indirect and less efficient fuel production systems.

“Regulations influence not only industry’s investments in technology, but also which research and development priorities are pursued,” said Henrik Thunman, professor of energy technology at Chalmers and co-author of the scientific article. “Instead of driving innovation towards the most efficient solutions, we risk locking ourselves into less resource efficient production methods.”

The researchers analysed three different pathways for producing synthetic methanol, a fuel molecule that can later be converted into sustainable aviation fuel. Two methods relied on biomass combustion, where carbon dioxide is captured from flue gases and combined with hydrogen produced using electricity. The third pathway used biomass gasification, in which heated biomass is converted directly into synthesis gas containing both carbon and hydrogen.

According to the study, the gasification route performed significantly better. “The gasification pathway proved to be the most resource-efficient option in our analysis, with up to 46 per cent lower production cost and 30 per cent lower electricity demand than the two combustion based alternatives,” said Johanna Beiron, researcher in Physical Resource Theory at Chalmers and lead author of the article.

However, the researchers said EU regulations largely exclude gasification based fuels from the RFNBO category because the process directly uses biomass derived carbon and energy. In contrast, fuels made through combustion pathways qualify if the carbon dioxide is captured after biomass is burned for another purpose, such as in combined heat and power plants.

The study warned that this approach could increase pressure on limited biomass resources while also raising overall energy demand.

“One purpose of the RFNBO classification is to stimulate increased generation of renewable electricity and reduce dependence on biomass,” the researchers noted. “But the current framework risks driving a less energy efficient use of biomass instead.”

Beiron said it was “surprising” that the EU rules did not create stronger incentives for the most efficient technologies, including gasification and electrification of district heating systems.

Thunman said parts of the regulatory framework may need revision if the EU hopes to meet its long term climate and industrial goals.

“Better coordination is needed between climate targets, resource efficiency and industrial feasibility,” he said. “The current uncertainty makes it difficult to make rational investment decisions for the large-scale expansion of sustainable aviation fuels in the coming years.”