An IATA report to compare leading decarbonisation roadmaps for the aviation sector has found significant differences regarding how technologies and solutions may evolve in the transition to net zero. Although all roadmaps assume sustainable aviation fuels will be responsible for the greatest amount of CO2 reductions by 2050, their role varies from 24% to 70%. This, says the report, reflects the uncertainties regarding potential supportive government action, the level of investments, cost of production and profit potential, as well as access to feedstocks. This first analysis undertaken to provide a holistic review of 14 major global and regional net zero CO2 emissions by 2050 roadmaps was undertaken by IATA in collaboration with the Air Transport Action Group, the International Council on Clean Transportation, the Mission Possible Partnership and the Air Transportation Systems Laboratory at University College London.

The report, ‘The Aviation Net Zero CO2 Transition Pathways Comparative Review’, compares the selected roadmaps in terms of their scope, key input assumptions, modelled aviation energy demand, respective CO2 emissions and the emissions reduction potential of each mitigation lever or pathway, namely new aircraft technologies, zero-carbon fuels, SAF and operational improvements.

The possible pathways to net zero CO2 emissions by 2050 differ significantly depending on the key assumptions of the roadmap authors regarding how technologies and future fuels may evolve, so the resulting role of particular levers will be more or less important, finds the study led by IATA’s Dr Bojun Wang. In addition, the roadmaps analysed adopted different demand modelling approaches. Some used a top-down approach with pre-determined aviation demand growth rates, and the transition measures were applied on top of this growth as ‘gap fillers’ to reduce the emissions to net zero by 2050, while others used a bottom-up approach where demand growth is modelled to reflect the impacts of different transition measures on demand. This makes it difficult for stakeholders and policymakers to compare the transition pathways and levers of action to achieve net zero, points out the report.

Given that currently there are only a few new aircraft projects under development and the fleet replacement rate is generally low, most of the roadmaps assume, on average, about 1.0% per year improvement in energy efficiency from now until 2050, measured in megajoules per revenue passenger kilometres, although some have more aggressive assumptions, with one forecasting a 2.2% per year fuel efficiency improvement from new types of aircraft introduced from 2035.

All roadmaps assume that energy intensity reduction from operational efficiency gains will be lower than that of technology efficiency improvement, on average 0.1% to 0.2% per year, although one has a greater 0.5% assumption based on higher load factors and traffic efficiency improvements.

If putting the technology and operational levers together for all roadmaps, the total efficiency improvement is about 1.0% to 1.5% per year in most roadmaps.

Sustainable aviation fuel produced from biomass resources (bio-SAF) and those synthetic fuels produced from CO2 and electricity (power-to-liquid or PtL) are assumed to deliver the highest emissions savings in the energy transition of the aviation sector to reach net zero by 2050. SAF volumes only reached 0.5 Mt in 2023 and all roadmaps indicate that to reach the 2050 target, the share of SAF in total aviation energy demand must be at least 5-6% by 2030. ICAO recently set an aspirational goal of achieving a 5% reduction in carbon intensity from international aviation by 2030, and the ICAO LTAG S3 models the highest share of SAF at 21% by 2030 for international aviation.

The report notes that for the higher 2030 SAF use estimates, the speed with which infrastructure can be ramped up is also a key constraint for SAF production, given that the number of SAF facilities planned to be built by then may not meet the high SAF demand.

By 2050, SAF is expected to account for 65% to 100% of the total energy demand for aviation, depending on whether any other clean energy sources, such as green hydrogen-powered aircraft, are considered in the given roadmap.

How fast SAF can penetrate the global aviation energy supply depends on feedstock availability and production costs relative to fossil jet fuel, says the report, and with SAF currently about two to six times more expensive, future prices of SAF remain “highly uncertain”. PtL fuels are assumed to be available only from the mid-2020s or 2030 in the majority of roadmaps. Demand for SAF is projected to accelerate significantly from 2030 to 2050 across all the roadmaps. However, the shares of bio-SAF and PtL in the total SAF consumption vary widely by the corresponding model assumptions.

Hydrogen-powered aircraft, with a limited range, are largely assumed to enter the market in the mid-2030s, while battery-electric aircraft coming in around the same time but serve even shorter-range markets. The estimated emissions savings from these aircraft vary greatly across the roadmaps, depending on whether a strong pro-hydrogen policy is adopted and on whether there is a rapid decline in renewable energy prices that enable swifter uptake of these technologies.

With the exception of one US roadmap, all the global roadmaps suggest the aviation sector will need help from market-based measures (MBMs), such as ICAO’s CORSIA scheme and the EU ETS, and carbon removals to address residual emissions in 2050. “Even if carbon removal technologies are considered an ‘out-of-sector’ mitigation measure, it is still both urgent and critical to develop these technologies as CO2 will be needed as feedstock for producing PtL fuels,” says the report.

IATA’s own roadmap mid-scenario models gross CO2 emissions of 1115 Mt in 2050, which after the implementation of the technology, operational and SAF levers, leaves residual emissions of 465 Mt CO2 to be mitigated by MBMs and carbon removals. This is the largest of all the roadmaps, with the exception of ICAO’s LTAG S2 scenario of 495 Mt from international aviation. The lowest on a global basis, 70 Mt, is forecast in ICCT’s Breakthrough scenario.

Concluding, the authors say: “By comparing these roadmaps, this report is instrumental in helping airlines better understand the potential of reducing CO2 emissions by different mitigation measures. Given that most of the transition measures for the aviation sector are not yet readily available, we believe there will not be a universal path to help the aviation sector reach net zero by 2050.”

Nevertheless, added Marie Owens Thomsen, IATA’s SVP Sustainability and Chief Economist: “This report provides airlines, policymakers and all stakeholders with a useful tool to analyse and improve their policy, investment and business choices.

“It is particularly important for SAF, where strong and urgent public policy support is needed to increase production. Without that, no version of roadmaps will get us to net zero carbon emissions by 2050.”

Image: IATA

Christopher Surgenor

Editor

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A new report on sustainable aviation says an annual average investment of $175 billion will be needed from now until 2050 for the air transport sector to meet its target of net zero carbon emissions. It also says the current project pipeline for sustainable aviation fuel must increase five-to-sixfold by 2030, requiring 300 new production plants, and estimates that SAF production levels “need to increase by a factor of 3,000-7,000 within less than three decades”. The report was produced by the Mission Possible Partnership (MPP), a collective of climate action leaders committed to decarbonising the world’s highest-emitting industries, and the Clean Skies for Tomorrow Coalition (CST), a global SAF advocacy group led by the World Economic Forum, reports Tony Harrington. “An unmitigated aviation sector would be responsible for 22% of emissions by 2050,” warned MPP CEO Matt Rogers. Those endorsing the transition strategies outlined in the report include Airbus, American Airlines, Air France-KLM, easyJet, bp and Shell.   

Aviation, which accounts for approximately 3% of global CO2 emissions, is one of seven hard-to-abate industries for which the MPP is developing customised strategies to decarbonise within 10 years. The others are shipping, trucking, steel, aluminium, cement and chemicals, which, together with air transport, produce 30% of global emissions. Predicated on a global carbon budget of 1.5°C, the most ambitious temperature target of the Paris Agreement, the report, ‘Making Net-Zero Aviation possible: An industry-backed, 1.5-degree-celsius aligned Transition Strategy’, calls for immediate action within this decade, and details stepped strategies for the sector to achieve carbon-neutral growth until 2030, a halving of emissions until 2040 and net zero emissions by 2050. It also highlights the implications of the plan on the broader energy system and the airline industry, as well as the capital investments and policy actions required for success.

“Bringing aviation on a path to net zero emissions by 2050 requires a doubling of historical fuel efficiency gains of aircraft, a rapid roll-out of sustainable aviation fuels and the market entry of novel propulsion aircraft (hydrogen, battery-electric or hybrid aircraft) in the mid-2030s,” says the MPP report.  “Currently, about 0.05-0.10 Mt SAF are produced per year, only a tiny fraction of the global fuel demand of about 320 Mt jet fuel. Also, current project pipelines of about 8 Mt are insufficient and need to be scaled up by a factor of 5-6 to supply 40-50 Mt SAF by 2030. That SAF volume could require about 300 SAF plants.”

Further, it adds: “Until 2050, 300-370 Mt SAF could be required to fulfil the jet fuel demand of a net-zero aviation sector. Hence, current SAF production levels need to increase by a factor of 3,000-7,000 within less than three decades.”  

For aviation to fund its transition to net zero emissions, the report estimates average annual investments between 2022 and 2050 of around $175 billion – roughly equivalent to the GDPs of Berlin or Amsterdam – and said 95% of this capital expenditure would be needed for fuel production and upstream assets generating renewable electricity.

“Although average fuel costs are increasing in the net-zero scenario, the cost of flying could remain stable if the higher costs of SAFs compared with fossil jet fuel are counterbalanced by increased efficiency gains,” predicts the MPP. “Hydrogen and battery-electric aircraft can make aviation more efficient starting in the 2030s and could potentially supply up to a third of the final energy demand by 2050.”

The report estimates that by 2050, the aviation sector could account for 5-10% of global demand for renewable electricity and 10-30% of demand for hydrogen. Air transport would also need a substantial share of the feedstocks required to produce SAF, with the MPP estimating demand for up to 25% of global sustainable biomass, and between 600 and 850 Mt of CO2 captured from the atmosphere and transformed into sustainable liquid fuels for aviation. This is contentious, it argues, as demand for such feedstocks is also high for other competing products, such as renewable diesel fuel, which is deemed by many to be a more effective use of scarce ingredients to cut carbon emissions.

The MPP said all sections of the aviation value chain were represented in the report, with signatories including 27 airlines in 19 countries, 1,950 airports in 185 countries, 10 aircraft manufacturers and suppliers, 21 fuel producers and upstream energy suppliers, and five large customers or investment platforms. 

“MPP is mapping critical strategies how to turn the paper goals of annual climate summits into action,” said Rogers. “An unmitigated aviation sector would be responsible for 22% of emissions by 2050. This transition strategy outlines plans and projects that are high on the agenda of ambitious companies, including the ‘nuts and bolts’ of how to build 300 sustainable aviation fuel plants by 2030.”

Johan Lundgren, CEO of easyJet, one of the report’s signatories, said novel propulsion technologies including hydrogen represented the most sustainable solution for short haul airlines. “The adoption of these technologies will help reduce the climate impact of our operations, while preserving the immense economic and social benefits that aviation brings to the world. We therefore support the Mission Possible Partnership Aviation Transition Strategy.”

In addition to the report, the MPP has launched the Aviation Net Zero Transition Explorer, a sectoral interactive tool to provide visual representation of the report, with functionality to adjust key technology and cost drivers to customise decarbonisation scenarios and illustrate how different levels of innovation and climate ambition impact the speed and cost of transition.

Its Aviation Transition Strategy, said the MPP, “provides a shared vision of the industry’s low-carbon future, detailing real economy milestones not just for 2050, but also for the near term.” 

Photo: MPP