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Sustainable aviation fuel won’t be enough to decarbonise aviation, non-profit claims

Sustainable aviation fuel won't be enough to decarbonise aviation, non-profit claims
According to the report, by 2050, bio- and synthetic SAF will make up 86 per cent of aviation's energy demand (Image credit: @scharfsinn86/Adobe Stock)

A new report has found that a number of fuel sources will be required to successfully decarbonise the aviation industry.

The non-profit organisation Clean Air Task Force says ammonia and hydrogen will be crucial for the industry to meet its global 2050 net zero carbon emissions target – alongside sustainable aviation fuel (SAF).

According to the report, by 2050, bio- and synthetic SAF will make up 86 per cent of aviation’s energy demand.

Meanwhile, zero-carbon fuels – ammonia and hydrogen – will make up the remaining 14 per cent.

Thomas Walker, transportation technology manager at the Clean Air Task Force, said: “Decarbonising the aviation industry is in many ways the most difficult challenge facing the transportation sector – in large part because the weight and space constraints of air travel are most cost-effectively met using energy-dense fossil fuels.

“Many countries have made commitments to reduce the industry’s climate impacts by increasing the use of sustainable aviation fuel, but overreliance on this fuel source for decarbonisation is unlikely to succeed in the long-term.

“This is partly due to indirect impacts on land-use change and largely because aviation energy demand could double projected SAF supply by mid-century.

“Our new report evaluates other fuel options that could supplement SAF shortfalls and ultimately finds that a combination of fuels is a plausible decarbonisation strategy for the aviation sector.”

The non-profit’s study states that HEFA (hydro-processed esters and fatty acids), a common form of SAF, are estimated to reduce greenhouse gas emissions by 50 to 65 per cent compared to traditional jet fuel.

However, “exclusive reliance” on bio-SAF to achieve the industry’s climate objectives is “unlikely to succeed” in the long-term due to feedstock constraints and sustainability concerns related to the indirect effect of biofuels production on agriculture and land use.

Comparing projections for sustainable biofuels supply against expected growth in aviation energy demand over the next several decades suggests that, by 2050, aviation energy demand – at an estimated 21.5 quadrillion BTU (quads) – could be double the energy available from projected global biofuels supply.

This shortfall points to the need for other low or zero-carbon aviation technologies – drop-in replacements, including synthetic or e-fuels and even electric aircraft, according to the Clean Air Task Force.

Walker added: “Achieving a multi-fuel future will require a massive amount of low-carbon hydrogen, significant cost reductions and substantial innovation, driven by major strategic changes in the aviation industry and well thought out policies to create the correct incentives.

“Notwithstanding those challenges, this report helps illustrate a potentially viable way forward.

“Remaking the aviation fuel market will be an ambitious undertaking, but if the entire sector rises to the challenge, aviation decarbonisation is possible on a timeline that meets national and international climate goals.”

The Clean Air Task Force claims that to help overcome these challenges and promote the tools and technologies needed to achieve aviation’s sustainability goals, a wide range of policies are needed, such as a clean fuel standard, which would require gradual reductions in the carbon intensity of the transportation fuel mix.

The non-profit says this would include a trajectory to net zero carbon emissions by 2050, “robust and comprehensive” lifecycle greenhouse gas emissions accounting and safeguards against overreliance on unsustainable feedstocks.

Governments should also explore policies that help accelerate full commercialisation of the “critical” technologies needed by investing in research and development programmes, the report outlines.