Can sustainable aviation take off now?

Aviation is already one of the most technology-rich sectors globally. The industry has achieved what seemed unimaginable only a couple of generations ago – flying millions of passengers safely across the world in hours.

The challenge ahead is to reinvent flying and make it compatible with our global net-zero emissions future. Decarbonizing aviation is one of the toughest challenges of the clean energy transition and one that will require many technological breakthroughs and a concerted effort by industry, governments and finance providers.

The aviation industry accounts for 2.5% of global CO2 emissions. And, the impact of flying on climate is not limited to greenhouse gas emissions from burning fuel - the warming impact of contrails is now widely understood to be in the same range as aviation's greenhouse gas emissions. No single technology or solution is going to decarbonize aviation by 2050. Instead, we need the right mix of policy, markets and innovation.

While we develop the nascent technologies needed to build zero-emission aeroplanes, we need new low-carbon fuels that can be used in our current aeroplanes, helping us reduce emissions as much as possible in the coming decades. This is what we call sustainable aviation fuel, or SAF for short, a term that includes many promising emerging technologies that are now ready to scale, but remain more expensive than fossil jet fuel.

On the market side, we need investment and to manage the different risks associated with first-of-a-kind industrial scale projects, which tend to be too risky for traditional debt providers, such as banks. We need to mobilize demand through bankable long-term offtake agreements with clear volume and price obligations to bring down the green premium – the difference in price between sustainable aviation fuel and fossil jet fuel.

A favourable policy environment and targeted public capital deployment are critical to creating the levers and regulations to drive change by de-risking investments in the initial deployment of promising climate technologies – such as sustainable aviation fuel production.

Furthermore, many of the changes will not happen on the aeroplane or even at the airport – they will take place at fuel production facilities and renewable power generation farms. Decarbonizing aviation will require transforming today’s aviation value chain and building up enabling infrastructure in a synchronized and timely manner. This will only be possible through enhanced collaboration and partnerships across the aviation value chain, as well as between companies in the same subsector.

Yet, despite the many challenges, there are promising solutions in development and already being deployed. At Breakthrough Energy, we are laser-focused on driving down the costs of clean technologies. We work with a network of partners, investors and policymakers to support zero-carbon technologies at every stage – from discovery to development to deployment. These partners include the World Economic Forum and the Uplink Sustainable Aviation Challenge, which is helping to bring visibility to the most promising start-ups developing the technologies we will need to make zero-emissions flying a reality.

In the coming years, technology-enabled efficiency gains should be complemented by increasing shares of sustainable aviation fuels. We will need new, low-carbon fuels that can scale quickly and be used in today’s aeroplanes to drive emissions reductions to 2050. But, there are many ways of producing sustainable aviation fuel and this diversity requires a closer look.

Today, practically all the sustainable aviation fuel produced uses hydro-processed esters and fatty acids (HEFA), a mature production pathway that transforms oils and fats into fuels – leading to significant emissions reductions on a lifecycle analysis basis, but with limited scalability. Looking forward, other emerging pathways including advanced biofuels and e-fuels, hold the most promise in terms of emissions reductions, cost-down potential and scalability.

These new pathways are ready to scale, but – as with any emerging climate technology – this initial scaling-up is particularly challenging. Once we can massively scale production and bring down the green premium, sustainable aviation fuel is expected to make the largest contribution towards achieving net zero in the aviation sector by 2050.

Looking further ahead, alternative propulsion technologies – such as electric or hydrogen-powered aircraft – will help us unlock true-zero aviation. While these solutions have a long technology development cycle, once you build in the necessary certification and safety permitting they have the potential to drastically reduce the amount of energy needed to fly, compared to sustainable aviation fuel, and they avoid all types of greenhouse gas emissions, including CO2 and nitrogen oxides (NOx).

In addition to these deep-tech solutions, positive operational changes enabled by digital technologies can help greatly reduce aviation’s non-CO2 effects and can be deployed quickly at a low cost. Breakthrough Energy’s Contrails team, in collaboration with researchers and industry partners, has created software that enables airlines to forecast where high-climate-impact contrails may be most likely to form and plan flight routes that avoid them. This is an easy, short-term way to limit aviation’s climate impact.

It will take a lot of innovation – and investment – as well as collaboration across industry, governments, financial institutions and passengers, but there are pathways that can make flying compatible with a net-zero emissions future and I am confident that we can make sustainable aviation a reality.