European regulations for sustainable aviation fuel could steer producers toward routes that are more expensive and require more energy than necessary. This is the conclusion reached by researchers from the Swedish Chalmers University of Technology in a new study on fuels derived from solid biomass residues, including residues from forestry. According to them, current regulations do not align well with the most efficient production method.
More sustainable fuel needed in aviation
The European Union aims to significantly increase the use of sustainable aviation fuel over the coming decades. Since 2025, fuel supplied to European airports must consist of at least 2 percent sustainable aviation fuel. That share will rise to 70 percent in 2050. Within that obligation, a separate target also applies to synthetic aviation fuels.
These synthetic fuels are typically produced using renewable hydrogen and carbon dioxide. In this way, aviation should become less dependent on fossil kerosene, while simultaneously creating a market for new low-carbon fuels.
Three routes to the same fuel
The researchers compared three ways to produce methanol from solid biomass residue streams. Methanol can later be processed into sustainable aviation fuel.
Two routes begin with the combustion of biomass. This produces carbon dioxide, which is subsequently converted into methanol together with renewable hydrogen. The third route uses gasification. In this process, biomass is directly converted into synthesis gas, which can be further processed into methanol.
According to the study, gasification is clearly more efficient. Production costs are around 820 euros per ton of methanol. For combustion routes, the costs range from approximately 1.050 to 1.500 euros per ton. Electricity demand is also about 30 percent lower with gasification.
European classification proves unfavorable for gasification
However, the more efficient route is given a less favorable position under current European regulations. In the study, the two combustion routes are fully classified as RFNBO, renewable fuel of non-biological origin. For the gasification route, this applies to only 55 percent of the methanol produced. The remainder falls under advanced biofuels.
That difference matters, because European targets specifically steer towards the use of synthetic fuels. According to the researchers, this may cause producers to opt for combustion routes that score better from a policy perspective, even though they require more energy and the costs are higher.
Scarce residual streams are coming into view
This also raises the question of how sparingly Europe should handle available biomass residues. In addition to hydrogen, synthetic aviation fuels require a sustainable carbon source. Solid biomass residues can supply this.
The researchers warn that current regulations could increase the demand for biogenic carbon dioxide, precisely because combustion routes fit better within European definitions. As a result, there is a risk of less efficient use of available biomass and renewable energy.
Rules can steer investments
Fuel plants are built to last for decades. If European regulations treat one technology more favorably than another, this can help determine which production chains are actually scaled up.
According to the researchers, this could cause Europe to get bogged down in a system that is more expensive and requires more green electricity and hydrogen than necessary. They therefore advocate for rules that consider not only the legal classification of a fuel, but also the efficient use of energy and raw materials.
Pressure on European fuel regulations is increasing
The study is being released at a time when the debate over sustainable aviation fuel is escalating. Airlines already warned earlier this year that the European obligation for synthetic fuels from 2030 could lead to high costs, as production is still limited. The new study adds a second point to this. The way in which regulations assess different production routes can also have a major impact on costs, resource use, and technology choices.
Source: chalmers.se
Photo: pxhere.com
