The Aviation Industry’s Quest for Zero Emissions: Challenges and Opportunities

The aviation sector, as a consumer-facing industry, has long been a high-profile contributor to global carbon emissions. It accounts for around 1 billion tonnes of CO₂ per annum or over 2 percent of the world’s entire CO₂ emissions. And with the demand for aviation fuel expected to more than double by 2050 compared to pre-COVID levels, the industry is facing an unprecedented challenge to reduce its emissions to zero while meeting the growing demand for air travel. However, this challenge can be met by innovation, policy support, and collaboration across the aviation value chain, as found in a new expert-led, industry-wide report Voices from the Sky, says Milica Folić, Product Line Director at Topsoe.

While improving fuel efficiency, technological innovations, and better Air Traffic Management (ATM) logistics can contribute to reduced emissions, they will not be enough to meet the reduction targets required for a sustainable aviation sector. Decarbonizing the industry will require the widespread adoption of sustainable aviation fuels (SAF) by 2050. With the current use of SAF still quite low, the journey ahead needs to accelerate. SAF provided only 0.1 percent to 0.15 percent of total aviation fuel in 2022—upscaling is happening, but SAF production needs to be ramped up if the aviation industry is to reach its emission reduction goals and SAF mandates.

The aviation industry is stepping up to address this challenge and to meet the numerous proposals, commitments, mandates, and targets emerging from governments, industry bodies, and policymakers. The response can be seen already. For instance, in 2022, the International Air Transport Association (IATA) estimated that SAF production had topped 300 million liters during the 12 months, marking a 200 percent increase on the 2021 production figure of 100 million liters and dwarfing 2019’s 24 million liters. However, despite this growth, reaching the 2050 goals will require an estimated 450 billion liters of SAF to be produced annually.

To meet these ambitious targets, the industry must take a holistic approach, combining operational efficiency improvements in airports and routes, advancements in aircraft design and technology, sustainable aviation fuel usage, and market-based measures such as carbon pricing and offsetting. Additionally, regulation and policy will play a crucial role in reducing emissions.

In a recent industry report from Topsoe, Voices from the Sky, 13 experts from across the aviation industry were asked to discuss the key drivers and challenges facing the adoption and growth of SAF and to provide an authoritative summary of the SAF landscape.The experts in the report identified eight key challenges facing the adoption and growth of SAF. The challenges span the entire air transport value chain. The challenges include: feedstock availability, production capacities, approval requirements, legal frameworks, open and informed dialogue, diversity of innovation, enabling technologies, and price competitiveness.

The report, which features the views of SAF specialists from companies and organizations such as Norwegian, SkyNRG, Southwest Airlines, the ICF, and Sasol, provides a wide perspective on how the industry can ensure faster production upscaling and adoption of SAF but also highlights that no single technology or pathway can meet the EU’s plan for 70 percent SAF blends in tanks by 2050 or the USA’s 35-billion-gallon production forecast for the same year.

It is believed that current and future production pathways, improved collection and distribution of waste products, and capacity increases in renewable energy such as solar farms can help deliver the ambitions of both regions. With initiatives like the USA’s Inflation Reduction Act and the EU’s RefuelEU formalizing requirements in law, there is strong political will to see SAF go mainstream.

The experts also discussed whether Power-to-X (PtX) would be a significant part of the supply chain. While PtX is promising, the experts believe it cannot stand alone in the short term and will not be the dominant pathway to decarbonization. They also noted that while battery-powered light aircraft already exist, a battery-powered passenger jumbo jet is still many decades away.

SAF will be crucial. Currently, there are seven approved pathways to produce SAF (and two co-processing pathways). The pathway using esters and fatty acids – HEFA-SPK process – is the main one producing commercially at scale right now. The report also showed agreement among experts that HEFA-SPK will be the main pathway for the next decade. A hydroprocessed renewable fuel from a diverse set of feedstocks, HEFA-SPK offers drop-in compatibility with the global fleet, volume potential on the way to net-zero by 2050, and easy transport and distribution with existing infrastructure.

The same can be said about FT-SPK, which was already approved as synthetic aviation fuel in 2009. The FT step of the FT-SPK process is also mature as a technology but scale and cost upstream remain more challenging than with HEFA-SPK. Nonetheless, both HEFA-SPK and FT-SPK fuels can today be blended with conventional jet in quantities of up to 50 percent.

In the FT-SPK process, syngas (originating from coal, natural gas, or biomass or captured CO₂ and hydrogen) is catalytically converted to a liquid hydrocarbon fuel blending component in the FT reactor. Originally done at large scale with feedstocks such as gasified coal, the transition to smaller scale, starting from gasified biomass or captured CO₂ and green hydrogen, has required both maturing the upstream technologies and a smaller-scale solutions for FT.

Fischer Tropsch synthesized kerosene with aromatics (FTSPK/A) was approved by ASTM for incorporation into ASTM D7566 in November 2015. FT-SPK/A is a variation of the FT process where a fully synthetic alternative aviation fuel containing aromatics is produced.

However, achieving the necessary production capacities and adoption of SAF long-term will require a mix of feedstocks and diversification of process pathways. More investment is being directed towards pathways like Methanol-to-Jet (MTJ) and gasification combined with the Fischer-Tropsch process, which uses feedstock such as agricultural and forest residues, as well as municipal solid waste.

But investment and incentivization must increase further. Private sector investment, for instance, is expected to play a critical role in this effort, but for that to happen, governments must help de-risk investment in SAF technology through further legislation and incentivization. This will help to accelerate the deployment of new technologies and enable the scaling up of production.

Despite the clear need for investment in SAF production, there are barriers to progress, including a mismatch of timelines for incentives and production – one of the eight key challenges highlighted by experts in the Voices from the Sky report. Production plants typically operate on an investment horizon of at least a decade, while government incentive schemes tend to be shorter and subject to political change. This misalignment can lead to uncertainty and risk for investors in SAF production technologies. A business case built on current incentives may become unviable if the policy framework is canceled or changed, creating instability that makes it challenging to invest in newer technologies.

To address this issue, stronger homogenization of laws could be targeted, so that policy incentives, offtake agreements, and investment horizons match. It is a tricky ask but it would help enable the required investments for keeping SAF supplies on track to meet emission reduction goals in just a few decades. Added stability would provide investors with greater certainty around the long-term financial viability of SAF production projects. As we face the challenge of decarbonizing the aviation industry, eliminating unstable legislation and incentive frameworks is crucial for achieving our goal of reducing emissions.

To deliver this, technology and innovation, legislation, blending mandates, incentivization, a focus on cost reduction and absorption, infrastructure, de-risking investment, and even structural and cultural changes within companies will be necessary, the report concludes. With such a broad request list, it will require a collective effort across the aviation industry, from innovation and specialization to knowledge and best-practice sharing. By taking a holistic approach and embracing the adoption of sustainable aviation fuels, the industry can pave the way for a more sustainable future while meeting the growing demand for air travel.

The Voices from the Sky report is available here.