Making net-zero aviation possible

By Dr Maximilian Held, Energy Transitions Commission and Mission Possible Partnership Lead Aviation Analyst
The role of Sustainable Aviation Fuels as a key solution to a 1.5°C-aligned path for aviation

Global aviation is responsible for about 4% of global warming, and while other sectors are already decarbonising, aviation is still on a massive growth pathway. However, the pace at which the aviation sector is preparing its pathway to a sustainable future is accelerating. Just recently, the International Civil Aviation Organization adopted an aspirational target to reach net zero by 2050. Now that goals are set, the question is: How do we get there? 

Within the last two years, the aviation sector has been turned upside down, with COVID-19 hitting the airline industry hard. While global air traffic has experienced a considerable dent, it is set to rebound to pre-pandemic levels by 2024, with strong growth expectations of about 2-3% per year through 2050. 

At the same time, aviation has increasingly been in the spotlight of climate discussions. In 2021, the International Air Transport Association (IATA) increased their ambition from halving emissions by 2050 to achieving carbon neutrality by then. In October 2022, the International Civil Aviation Organization (ICAO), after years of diligent assessments, also adopted a long-term aspirational target (LTAG) to achieve net-zero emissions by 2050.

Toolkit to decarbonise aviation

Now, the question is: How can we achieve net zero, while enabling a prosperous transition of the whole aviation industry to a greener, sustainable future? 

To curb emissions of the aviation sector, there are five measures which need to be scaled simultaneously with immediate effect: (1) demand-side measures, i.e., reducing air travel, e.g., from behaviour change or a shift of short-haul flights to high-speed rail, (2) fuel efficiency gains, such as those from the use of more efficient turbines, more aerodynamic airframes, or from improved air traffic management, (3) Sustainable Aviation Fuels (SAFs), which can be clustered in biofuels (from feedstocks like used cooking oil, municipal solid waste or agricultural/ forestry residues), and power-to-liquids (PtL), i.e. jet fuel based on renewable electricity and captured CO2; (4) novel propulsion aircraft, i.e. hydrogen, battery-electric and hybrid-electric aircraft, and (5) carbon dioxide removals which are required to counterbalance the residual emissions of SAFs, hydrogen and battery-electric aircraft, but must not replace in-sector decarbonisation measures.

The bulk of emission reductions lies in scaling up Sustainable Aviation Fuels

The Mission Possible Partnership (MPP) – a coalition of the Energy Transitions Commission (ETC), RMI, We Mean Business and the World Economic Forum – estimates that fuel efficiency measures and SAFs could contribute about 85-95% of cumulative emission reductions between 2022 and 2050. Fuel efficiency gains are crucial to reduce the energy demand of aircraft and counterbalance the additional fuel cost.

However, fuel efficiency measures can’t reduce emissions to close to zero whereas SAFs can. Scaling SAFs is one of the main challenges the aviation sector needs to solve within this decade in order to decarbonise. There are three hurdles to be overcome: (1) The initially high green premium of SAFs needs to be bridged by policies, increased R&D and demand signals such as offtake agreements. (2) The low technology readiness level of SAF production, in particular for more advanced biofuels and PtL, needs to be increased by de-risking measures like blended finance or public-private partnerships. (3) Sufficient, affordable feedstock needs to be supplied to the aviation sector – ranging from sustainable biomass to low-cost renewable electricity and captured CO2.

Today, SAFs make up less than 0.1% of global jet fuel supply. SAF production needs to be scaled by a factor of 500 by 2030 to achieve a 13-15% share and by a factor of 5,000 by 2050 to reach 100% of all fossil jet fuel being replaced with SAFs. 

While it is crucial to lay the foundation for the massive scale-up of SAF production in this decade, it is also extremely difficult to achieve. New SAF plants have lead times of about 5-6 years, which leaves us (at the end of 2022) about two years to increase the current project pipeline of 8-9 million tonnes (Mt) SAF to the required 40-50 Mt by 2030. In addition to new plants, existing renewable fuel plants that currently serve the road transport sector could be repurposed to produce renewable jet fuel – which requires incentivisation through the right set of policies such as tax credits for bio-jet fuel rather than bio-diesel. The electrification of cars could accelerate this trend by freeing up ethanol currently used for road transport to produce jet fuel.

What it will take to scale SAFs

The transition of global aviation to net zero will require (a) large quantities of resources such as renewable electricity, green hydrogen, captured CO2, and sustainable biomass, and (b) massive investments across the entire value chain.

Today, global aviation relies almost entirely on fossil fuels. This will change dramatically in a decarbonised world. By 2050, global aviation could be responsible for 5-10% of global electricity demand, 10-30% of global green hydrogen demand, and up to 25% of global sustainable biomass supply. In a world of increasingly fierce competition for such low-carbon resources from multiple sectors, policymakers need to set smart guidelines to determine in which sectors to prioritise these resources. Resource allocation should follow a merit order, i.e., channelling resources to the sectors that offer the largest CO2 reductions, while considering market dynamics and a ranking of preferrable decarbonisation solutions. Take the example of biomass: While there are clear alternatives to biofuels for sectors like trucking or shipping (e.g., battery-electric trucks, or ammonia-powered ships), aviation largely lacks those alternatives, especially for long-haul flights. Therefore, a larger share of the globally limited sustainable biomass supply should be directed to the aviation sector.

To enable the scale-up of those resources and the conversion to jet fuel, MPP estimates that average capital investments of about $40-50 billion per year (on top of a Business-as-Usual scenario) are needed in this decade. Through 2050, average capital investments need to increase to about $175 billion per year for SAF production facilities and corresponding upstream energy requirements, foremost for renewable electricity generation. While this is a massive challenge, the joint action of policymakers, industry pioneers and financial institutions can turn this into an investment opportunity in which the green premium–the cost differential between fossil jet fuel and SAFs–is translated from a burden into a first mover advantage. 

Next destination: 1.5°C

About a hundred years ago, the invention of the aircraft was a game changer – suddenly, the whole world was connected. Our next mission must be to make aviation sustainable. We have three decades to completely transform the way we fly and get us on board a 1.5°C-aligned path. Better start now.


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