With air travel volumes increasing rapidly, global emissions from aviation industry have also significantly risen over the past half-century. In order to tackle the urgent challenge of reducing aviation sector emissions without constraining economic growth, around the world governments and private actors look for sustainable pathways to decarbonising the industry such as exploring more efficient engines, increased operational efficiencies, and the use of low-carbon fuel alternatives.
What is SAF – sustainable aviation fuel?
In this context, Sustainable Aviation Fuel (SAF) has emerged as one of the credible short to medium-term solutions. SAF, which is chemically similar to fossil-derived kerosene aviation fuel, is produced from a range of sustainable sources from biomass residues using different processes (there are nine approved pathways to date as per ICAO) and can be blended with conventional fossil jet fuel. Some of the most popular pathways include:
Hydroprocessing Esters and Fatty Acids (HEFA): Uses hydrogen in refining a range of vegetable oils and fats to turn into jet-range fuel.
Gas-FT: The first pathway approved by the American Society for Testing and Materials (ASTM) involves the conversion of synthesis gas into liquid fuel.
Alcohol-to-Jet (AtJ): Uses alcohol (ethanol and iso-butanol) to produce alternative jet fuel through the removal of oxygen.
Power-to-Liquids (PtL): Uses green hydrogen from renewable electricity and water to develop synthetically produced liquid hydrocarbons from CO2 captured from industrial activities or direct air capture.
Unlike other solutions, such as hydrogen-powered or electric aircraft, which require significant technological and infrastructure advances over a long development lead time (to around 2035-2040) and are suitable only for shorter routes, SAF has some significant advantages. It is a “drop-in” fuel that can be mixed with traditional jet fuel without requiring any changes in the aircraft or fuel-related infrastructure and is suitable for both short-haul and long-haul flights. Depending upon the feedstock and process, it can reduce carbon emissions by up to 85% as compared to fossil jet fuel over the life cycle of fuel, including production, distribution, transportation, and combustion, although the true net impact on emissions depends on many factors (such as the potential alternative uses of the land used for growing the feedstock).
At the same time, there is no silver bullet for decarbonising the sector. The use of SAF from biological sources cannot remove all emissions, while PtLs are extremely expensive, so SAF is likely to be supplemented by some offsetting. However, given the pressing need for the aviation industry to reduce its carbon footprint, SAF is expected to be the viable approach in the short to medium term. According to IATA, SAF is expected to play the largest role in aviation decarbonisation, up to 65% in achieving a net zero target for Aviation by 2050. Any delay in its adoption will only escalate the offsetting requirements through other means, which still have a long way to go.
Hurdles in the pathway of SAF’s increased adoption
Sector stakeholders, such as airlines, airport operators, and fuel suppliers, have made some initial moves towards accelerating SAF adoption. This includes operating test flights with a blend of SAF and aviation turbine fuel, collaborating with research agencies for research and development (R&D), selecting suitable pathways for SAF production, and conducting studies to evaluate the demand, challenges, and opportunities of supply and infrastructure.
However, amidst this welcome progress, the missing vision in terms of government-mandated SAF targets has, to some extent, held back industry players from making serious commitments towards SAF production and use. There is currently a strong mismatch in the rate of SAF production and the industry’s needs, and feedstock availability is a key challenge in SAF adoption across all markets. Success will lie in the right selection of suitable feedstocks, which would effectively reduce lifetime GHG emissions and ensure the scaling up of SAF production.
For example, crop-based feedstocks can result not only in deforestation but also in competition with food, which is why, in many quarters, they are not considered genuinely sustainable. There is no single feedstock which will be feasible in every geography; therefore, the pathways will be different in different parts of the world.
SAF policy around the world
Globally, some major economies have adopted a proactive approach in defining their vision and roadmap to decarbonise the aviation sector in line with set target timelines. The UK has identified SAF to be a key lever; as per provisional statistics, 26 million litres were supplied in the UK in 2022, a figure which is rapidly increasing. It is set to introduce a SAF mandate in 2025, requiring that by 2030, at least 10% of jet fuel should be SAF. This sends a strong signal to investors about the government’s confidence in this technology and its future.
Further to this, the UK is assessing feedstock availability in the coming years in order to strike the right balance between its ambitious targets and market readiness to set SAF mandates. Alongside bridging the price gap between SAF and conventional jet fuel, it has made the SAF mandate eligible for the corresponding reduction in UK Emissions Trading Scheme (ETS) obligations. This ‘cap and trade’ scheme obliges companies to buy and sell carbon allowance per tonne of CO2 produced per year, those that reduce their emissions can then sell their allowances to more polluting companies.
Likewise, the EU’s SAF mandate would be applicable from 2025 with at least 2% SAF adoption, increasing in five-year intervals to eventually reach a minimum target of 63% by 2050. Using a different approach, the US aims to achieve a minimum of 50% reduction in GHG emissions through SAF. The country has set SAF production targets of close to 11 billion litres per year by 2030, dovetailed with funding opportunities for SAF projects, production scale, and SAF tax credits instead of mandating usage. One common thread across all these economies is the policy push from the government, either on minimum usage or production of SAF.
As a result of governments’ push for SAF adoption, multiple airlines have proactively started planning for SAF procurement in advance. For instance, following the mandates for the European market, the Hungarian airline Wizz Air has invested in a biofuel company which converts sewage sludge into SAF. Similarly, other developments include United Airlines forming a Joint Venture (Blue Blade Energy) to develop SAF using ethanol, Delta Airlines and DG Fuels getting into a partnership, and Shell Oil partnering with multiple operators to push SAF’s development. These early moves are intended to expedite investment in SAF R&D towards different pathways and provide a strong base for the airlines to achieve the requisite availability of SAF by the time mandates kick in.
Excerpt from ‘How can SAF help Indian’s booming aviation sector.’ by Sanuj Mittal, Principal Consultant @ Steer, originally published on Voices of Steer on 18th July 2023.