
In light of the global drive towards carbon neutrality, countries are increasingly focusing on sectoral contributions to emissions in order to realise their respective emission targets. The spotlight has shifted towards hard to abate sectors such as industries and transport. Within the mobility sector, while significant progress has been made on the road transport front, the potential of the aviation sector has often been overlooked. The sector contributes roughly 3 per cent to the global carbon dioxide (CO2) emissions and is responsible for 12 per cent of the emissions originating from the overall transport sector. Soaring fuel prices owing to the Russia-Ukraine war highlights the need for securing alternate sustainable sources of fuels that prevent developing economies from being at the mercy of market determined exorbitant fuel prices.
According to estimates by IRENA, emissions from the aviation sector need to fall by 90 per cent by 2050 in order to limit global temperature rise beyond 1.5º Celsius. Moreover, as of October 2021, members of the International Air Transport Association (IATA) jointly agreed to achieve carbon neutrality by 2050, representing the only global sectoral decarbonization target that has been announced till date.
Beyond tapping the low hanging fruits of improving energy efficiency or fleet renewal, the top contenders for decarbonizing the aviation sector include use of electric propulsion systems, hydrogen fuelled aircrafts and Sustainable Aviation Fuels (SAF). However, once commercially available, electric aircrafts will only be suitable for covering shorter distances and carrying fewer passengers. It is important to note here that roughly 80 per cent of the emissions from this sector result from flights covering more than 1500 km. This highlights the limited impact that electric aircrafts will possibly have on overall emissions. Similarly, in addition to adequate supply of green hydrogen, refuelling infrastructure and storage facilities would be required to make use of hydrogen as a technology option. However, hydrogen as an aviation fuel is still in nascent stages and it will be a while before it is ready for use in both short and long-range flights. This effectively only leaves the option of SAF which can be derived from a variety of feedstock (e.g., jatropha, camelina etc.) and waste (e.g., municipal waste, agricultural residue, used cooking oil etc.).
SAF can be produced using one of the three technologies i.e., hydro-processed esters and fatty acids (HEFA), alcohol to jet or power to liquid (PtL). Amongst these, HEFA is the least expensive option which makes use of vegetable oils and fats. PtL on the other hand involves electrolysis of water to produce hydrocarbons that are in turn combined with carbon monoxide produced from captured CO2. Depending on the feedstock used, SAF can deliver 80 percent reduction in lifecycle emissions in comparison to traditional jet fuels. Moreover, the use of these fuels requires little to no modifications in the current aircraft infrastructure. These can be blended with traditional kerosene with blending rates of up to 50 percent already being certified. However, with SAF accounting for only 0.1 per cent of the jet fuels used globally, it begs the question as to why the shift has not been made.
One obvious barrier is the cost component with some SAF variants costing twice as much as traditional jet fuels when produced from waste products and the costs rising by 6-10 times when produced from synthetic fuels in conjunction with carbon capture . Another issue is with respect to securing adequate supply of feedstock for producing SAF. It is important to note here that not all SAF are of the same quality and they differ in terms of their environmental impacts. The ‘sustainability’ component is determined by well-to-wake emissions that account for lifecycle emissions starting from feedstock extraction to processing and combustion. A case in point is biofuels derived from palm oil that has been unsustainably produced or from crops that result in deforestation and lead to land use changes. In addition, there exists an added issue of competing demand for feedstock catering to different applications in the transport, aviation and maritime sectors, though differing in terms of product quality.

Emissions from the aviation sector need to be viewed from a dual lens – one focusing on domestic aviation and the other on international aviation. It is pertinent to mention here that while the former is included within the Nationally Determined Contribution (NDC) targets submitted by the Paris Agreement signatories, international aviation falls beyond its purview. Dealing with the latter is a bit tricky given how 65 per cent of aviation CO2 emissions exist in international space, and no one country can be assigned responsibility over the same. Though fraught with a few glaring limitations, the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) (2016) launched by the International Civil Aviation Organization (ICAO) is a good starting point. It calls for carbon neutral growth from the aviation sector post 2020 and also contributes towards the goal of augmenting aviation fuel efficiency by 2 per cent every year till 2050.
While biofuels and bioenergy in the context of energy transitions and decarbonization of the mobility sector has been a part of the G20 discourse, the aviation sector has not found a mention till now. Nevertheless, at the country level, member nations such as, Australia, Brazil, European Union, Indonesia, Japan, United States etc. have shown interest in SAF and have or are in the process of formulating policies and schemes to expand their scale. For instance, EU’s “Fitfor55 package” encompasses a ReFuelEU Aviation Initiative that introduces mandates for fuel suppliers to increase the share of SAF and also proposes obligations on airlines for limiting the use of jet fuel. Similarly, US has launched a Sustainable Aviation Fuel Grand Challenge that aims to produce 3 billion gallons of SAF annually till 2030 and also work towards reducing aviation emissions by 20 per cent during the same period.
Leveraging off of this common interest, and also taking note that some of the busiest domestic airline routes in the world are housed within the G20 countries, decarbonizing the aviation sector may be treated as one of the priority areas in India’s upcoming Presidency. In fact, the country has already taken preliminary steps to express its interest in this theme with India opting to co-lead the Innovation Platform on Sustainable Aviation Fuels under Mission Innovation. Furthermore, the country is well positioned to assume a leadership role as far as SAF is concerned by reaping benefits from its low-cost renewable energy and abundant feedstock supplies. The G20 platform may be leveraged to further this agenda on multiple fronts. For one, it may be used to create markets for supplying feedstock and tackling the supply shortfall. For instance, while EU faces shortages of used cooking oil (UCO), one of the primary feedstock that it uses for SAF production, countries like India with an annual consumption of 22-27 million tons of UCO can emerge as suppliers of the same. This of course would first require working out the logistics of its domestic collection systems. Second, under India’s G20 Presidency, the group may wish to develop common standards for SAF feedstock quality for trade which may echo those designed under CORSIA or differ from the same. As an added advantage, SAF offers opportunities that tie up well with priority areas identified by preceding presidencies such as Carbon Capture Utilization and Storage (CCUS) and green hydrogen, which have a pivotal role to play in producing advanced versions of such fuels. However, the uptake of SAF would necessarily need complementary policies at the domestic level in the form of mandates, blending targets, subsidies etc. akin to those already in place for the mobility sector.
Granted that SAF is not the only panacea for aviation sector emissions, similar to other sectors, there are a host of technology levers that need to be tapped for ensuring emission reductions and carbon neutrality. Taking note of the technology readiness levels and varying timelines of commercialization, SAF appears to be the most realistic option that can deliver results in the short to medium term.
(Views expressed are the author’s own and don’t necessarily reflect those of ICRIER)






