“Green aviation” can be more than a flight of fancy – let’s help it achieve lift-off

Co-authored by Jennifer Ozimkiewicz and Matthias Berninger

In fiction, examples of limitless energy sources abound. Think of the aptly named “unobtanium” in Avatar, Stephen King’s “Source”, or Douglas Adams’s “Infinite Improbability Drive”, which is powered by the concept of improbability itself. And while such “wonder fuels” are and will remain a pipe dream, the search goes on to shift our energy dependence away from finite fossil fuels, and towards cleaner, more sustainable energy supplies.

Renewable energy sources like wind and solar power have seen huge amounts of investment, expanded much faster than predicted, and will help dramatically reduce carbon emissions. Bayer’s shift to renewable energy sources through our partnership with Cat Creek Energy, for instance, will reduce our carbon footprint by 370,000 tons each year. Imagine this effect replicated across companies and sectors.

However, not all sectors can benefit equally from the shift to renewable energy – aviation being one of these.

The reason for this lies in power density and is well described by the energy and environment researcher Vaclav Smil. While electrification can allow cars, trucks and even some ships to draw on wind, solar and hydro-based power, battery-powered flight may take decades to fully materialize (and it is uncertain if it will ever be viable for long-haul journeys). We need a faster solution, given that the aviation industry is responsible for an estimated 2.5% of global carbon emissions and 4% of human-caused warming to date. There are many promising innovations under development that could offer such a solution (hydrogen, e-fuels, or torrefaction-based fuels, which my colleague Juergen Eckhardt recently highlighted). However, our topic today is sustainable aviation fuel (SAF) – a technology we feel is an essential part of the route to net-zero.

The new generation of SAF benefits farmers while lowering the aviation industry’s carbon emissions  

SAF differs fundamentally from conventional jet fuel in that they are made from plant or animal materials, rather than fossil fuels. While SAF is currently produced from a variety of materials (ranging from cooking fat to municipal waste), the next generation would be made from biomass-based diesel – which includes plants, algae, crop residues, animal waste and forestry residue – and non-human waste like product packaging and food leftovers. SAF’s carbon-reduction potential varies according to its type, with some potentially capable of yielding an 85-95% reduction in the aviation industry’s carbon emissions, and some virtually carbon-neutral, given that the carbon dioxide absorbed by plants or algae during their growth phase is roughly equivalent to the amount produced when the fuel is used. They can also help the agricultural sector reach its own sustainability goals: turning “wet wastes” like manure and sewage sludge into fuels keeps methane gas out of the atmosphere, for instance.

The SAF type about which we and Bayer are currently most excited is the category called “intermediate oilseed cover crops” – like CoverCress

(developed through advanced breeding and genome editing by the company CCI, in which we own a majority share and partner with Bunge and Chevron). Crops like these are grown in a double-cropping system over the winter in rotation with corn and soybeans. As a result, they neither create new demand for agricultural land, nor do they displace food crops. At the same time, they provide farmers with a much-needed additional source of revenue while also helping improve soil health and reduce erosion. And there are more benefits: due to the improved profile of the CoverCress plant, once crushed for oil, the leftover meal can also be used as a high-quality animal feed.

In this way, SAF crops can benefit farmers and mitigate the environmental impact of aviation without jeopardizing, but instead enhancing, food security.

In light of projections that under current conditions, emissions from international aviation could quadruple by 2050 (vs. 2015 levels), it will be crucial to support and scale up the production and use of SAF. Here’s how.

Ambitious targets must set the scene for a secure SAF market

SAF currently contributes just 0.2% of jet fuel used worldwide. While they are a “drop-in” solution (they can be used immediately, without any new or adapted technologies), current regulations state that SAF must be blended with conventional, fossil-based jet fuel, and can only form a maximum of 50% of the mixture used to fuel an aircraft.

Under current conditions, neither production nor uptake are set to accelerate quickly enough: a 2024 World Economic Forum report on SAF estimates that “announced projects [cover] only 30–40% of the aspirational 10% of global fuel supply in 2030” – a figure which falls significantly short of the levels required to meet the decarbonization commitments and aspirations of both industry and governments. While this is in part due to low supply, the major reason for the sluggish uptake is that SAF is expensive – around triple the price of conventional jet fuel. As the same WEF report notes, “people have got used to cheap fossil fuel prices over recent decades […] The free market by itself will not drive a rapid adoption of SAF under these circumstances.” This creates a huge obstacle to widespread use, given that all but the most premium airlines are now low-margin businesses; while demand has rebounded following the pandemic, operating costs have soared in parallel, leaving many airlines struggling (or outright failing) to turn a profit.

Some governments are already seeking to up the ante: the UK has introduced an "SAF mandate", which stipulates that by 2030, 10% of all jet fuel supplied must be SAF, increasing to 22% in 2040. The EU has set itself an SAF-use target of 63% by 2050. Neither of these match the aviation industry’s own aspirations, however. IATA has still set itself the goal of sourcing sufficient SAF to meet 100% of aviation fuel demand by 2050 – and, given that SAF is currently the only viable means for the industry to meet net-zero targets, it is imperative that it is successful.

Governments must support the aviation industry in this ambition by setting equally high targets for SAF usage – thus creating investment incentives for producers and increasing economic certainty along the SAF value chain.

This ambition would need to be set initially at multilateral level: a pledge, for instance, published under the auspices of COP30 in 2025 and committing countries to scaling up SAF production. There are good precedents (the Global Renewables and Energy Efficiency Pledge, for instance). Such a step would kick-start the internationally aligned approach that is needed to accelerate SAF production at scale. In addition, a global pledge should feed into national policies, by proposing a flexible toolbox of measures (such as regulations, mandates, or incentives) from which countries can choose as appropriate. In this way, national policies can then complement global efforts and translate them into effective measures that recognize local conditions and needs.

Rigorous standards are needed to ensure environmental integrity and build trust

However, in parallel, it will be imperative to secure the environmental integrity and increase the social acceptance of SAF. One of the main concerns around SAF in past years has been the fear that the cultivation of biofuel crops could displace food crops, thus reducing the availability of land for food production, and competing with food crops for resources like water and nutrients. These concerns continue to slow the uptake even of the new and more sustainable generation of feedstocks, despite the fact they do not compete with food crops. To combat this, it will be crucial to build public trust around SAF – first and foremost by implementing harmonized and robust sustainability criteria that ensure the environmental integrity of feedstocks.

The International Civil Aviation Organization (ICAO), the EU and US have each introduced their own sustainability criteria for SAF. While these efforts to create a framework are laudable, the scope and detail of the criteria vary, and a more aligned global approach is needed, to ensure harmonization across all aspects of SAF production and use – including lifecycle greenhouse gas emissions, land use, water use, and social impacts. It would also allow space for evolving with advancements of the SAF sector.

Our hope is that under Brazilian leadership in and around COP30, a global standard will be agreed upon that does not place undue burdens on farmers, while balancing concerns for unintended consequences for food systems and biodiversity with the need to create a reliable framework that boosts SAF volumes. Air travel is global – meaning SAF fuel standards should be, too.

In addition to fostering trust in the SAF sector, a technology-neutral, criteria-based approach will help create certainty for producers. SAF regulation is often restrictive towards certain feedstocks, which can deter producers from scaling up their SAF interests. A 2020 World Economic Forum report noted that “no single sustainable feedstock will answer every need; the industry will need to tap into a range of options” – meaning regulation must spur both environmental integrity and innovation.

Cross-sectoral collaboration can further boost investment in and uptake of SAF

Aviation contributes significantly to most companies’ Scope 3 emissions – the “hidden emissions” in a supply chain. While some companies have already made headway in reducing their Scope 3 emissions (at Bayer, our “Scope 3 decarbonization accelerator” program aims to drive our efforts in this regard), helping reduce the carbon footprint of flying would be a game-changer across sectors and geographies.

For years now, individuals and companies have offset the carbon emissions generated by flying by purchasing carbon credits, using the large and flourishing market that has grown up around the service. Continuing in this vein is one option – it is easy and convenient for companies – but the offsetting sector has come under criticism for a lack of transparency, accountability and standardization.

Instead, we would advocate for a more direct approach: an SAF-focused value chain alliance that allows companies to invest in SAF production and thus boost its uptake among airlines.

Some of these are more sector-specific than others: offtake agreements to produce SAF tend to be between players directly involved in the SAF value chain; industry-led investment funds pool and channel financing into SAF projects to secure priority access for members; and buyers alliances represent a wider range of sectors, including customers of the aviation sector, and allow them to invest in SAF projects so as to offset their aviation-related Scope 3 emissions.

All have unique characteristics and benefits – but the model we at Bayer are currently most interested in is the third option, the “buyers alliance”. There is currently only one major SAF-specific alliance to date – SABA – but it seems to me that such a model offers a strategic and impactful use of company resources. By directly reducing emissions, fostering innovation and technology advancement, supporting job creation in the SAF sector, this approach provides tangible, long-term benefits that extend far beyond the limitations of traditional carbon offsetting.

An additional cross-sectoral measure could be for the aviation industry to support farmers using regenerative agricultural systems that remove carbon and produce lower-carbon intense SAF.

With COP29 agreeing on Article 6 and thus clearing the way for the implementation of cross-border carbon emissions trade, it is conceivable to include carbon farming in the CORSIA framework which commits to offsetting all carbon emissions above 2020 levels. Rewarding farmers for carbon removed with high integrity could strengthen the economics of SAF, as they are integrated in crop rotation regenerative agriculture systems. By now, more than 100 million tonnes of emissions – the emissions increase of aviation since the beginning of this decade – are waiting for credible offsetting solutions. At COP29, it was highlighted that the private aviation industry, which grew by more than 40% between 2019 and 2023, is responsible for 15 million tonnes of emissions. This figure is considerable when viewed on a per-person basis; apart from carefully considering the necessity of trips with private jets, one way to address this would be for this industry to take a leadership role in transitioning to SAF.

A cleaner energy future needs both action and financing

As COP 29 in Azerbaijan has drawn to a close, the big takeaway – and the one that had been anticipated by all participants – was that financing will determine the future of global climate change mitigation efforts. Climate finance for agriculture is below 4% today. Supporting SAF is a fitting illustration of how we can successfully redesign and harness market forces to achieve net zero. By directing funds and regulation to support and scale up the production of SAF, both governmental and private financial mechanisms can help lower costs and make these fuels more accessible to the aviation industry. This will not only promote innovation in fuel technologies but also encourages airlines to transition from conventional fossil fuels to SAF, significantly reducing their carbon footprint.

By 2030, the total number of air passenger journeys is projected to increase to well above 5 billion from the 4 billion today. These market dynamics underscore why we cannot wait for a wonder fuel.

If we want to continue benefiting from the miracle of flight while reaching net zero, we must harness a combination of regulation, stringent standards and pan-industry collaboration to engineer a cleaner, greener energy future. That, to us, seems to be more promising than “flight shaming” in times of a dynamic growth of the aviation industry.