Sustainable aviation fuels offer an opportunity to substantially reduce CO2 emissions from flying, but they are not a universal panacea.
Benefits of using SAFs to reduce emissions
There are obvious attractions to using SAFs as a way of addressing the significant amount of CO2 emissions and GHGs within the aviation industry. In the short-to-medium term, the four types of gas turbine engine used in aircraft are well-known, tried, and tested after 50 years of development and refinement. They have proven to be dependable, viable, and have an enviable power-to-weight ratio. Therefore, coupling this mature technology with emerging SAFs presents a pragmatic and realistic choice for reducing the sector’s CO2 emissions in our current scenario where global aviation is likely to be reliant on liquid fuels for many years to come. As SAFs are functionally equivalent to conventional jet fuel, they are easy to combine with current aircraft as well as the existing supply infrastructure and storage systems.
In addition to the environmental benefits outlined above, SAFs usually contain fewer impurities—most notably sulfur and aromatic carbons—such that existing engines produce significantly less sulfur dioxide and particulate emissions compared to operation with conventional jet fuel. Reductions in these contaminants allows land-based power plants using aeroderivative turbines to significantly increase their maintenance intervals. While additional testing is required, preliminary testing indicated that neat SAFs fuels have the potential to notably reduce engine operating temperatures, increasing power while reducing maintenance requirements.
Finally, SAFs constitute a more diverse (global) geographic fuel supply. This renewable technology presents economic and social opportunities, including rural jobs, associated economic growth, and the potential for poverty and inequality reduction within developing countries in particular.
Risks and challenges to overcome to increase penetration levels
With the first test flight using SAF occurring in 2008, SAF technology is still in its infancy compared to conventional fossil fuel use in aviation. Despite SAF’s potential, there are still some significant barriers to overcome.
- Lack of commercial facilities: Even with six pathways to approval and certification, only the Hydroprocessed Esters and Fatty acids (HEFA) pathway has been used to produce SAF for commercial sale. While technical challenges can be substantial, commercial facilities face challenges with feedstock availability, price volatility of fossil jet, and other traditional business trials. Operating commercial analogues are critical to attract equity investment in the space as well as secure debt financing for the construction and operation of new facilities in the absence of loan guarantees or other government support for development.
- Difficulties in monetizing the benefits of SAF: Feedstock costs and the processing costs of waste feedstocks such as municipal solid waste are generally higher than the cost of crude oil at current market prices. These increased costs result in a product that is generally considered to be between two and seven times more than that of jet fuel derived from conventional fossil fuels. Global blending standards and energy security policies have enabled the construction of several SAF production facilities to date, but construction has been slow given limited commercial opportunity. Recent GHG reduction policies—such as the California Low Carbon Fuel Standard that allow producers to monetize GHG reductions—have been critical in incentivizing the private sector to construct new SAF facilities that are coming on line in 2020 and beyond.
- SAFS have cornered a very minor share of the market: Even with multiple partnerships springing up between the likes of Finnair and Neste, SkyNRG and KLM, United and World Fuels, etc., the growth of SAFs in commercial flights is still very much in the minority. New Scientist’s Adam Vaughan makes the point that roughly 220,000 flights have used SAF since 2008. While this might sound like a lot, it’s quite insignificant when compared with the 39 million total number of flights in 2019.
A call for policy support
Many fledgling industries have received government support to help them progress towards a commercial-scale innovation. Strong support is needed to shift emphasis from carbon-based fuels to sustainable, low-carbon options as soon as possible. An ICCT paper suggests that a precedent for anticipating some of the immediate challenges might be drawn from the journey taken in switching to advanced alternative road fuels. Potential barriers can be overcome through policies and incentives such as mandates, fiscal incentives, sovereign guarantees, decarbonization programs, and grants. Procurement contracts and associated measures can and have helped improve the feasibility of SAF projects and mitigate some of the risks associated with SAF production. It may also help to implement a tax regime and specific financing to help reduce operational costs and boost investment in SAF projects to accelerate projection and deployment.
The incremental gains in technical performance that SAFs can offer on their own are unlikely to increase uptake to the level necessary to address global climate change. Smart policy, regulatory, and economic support for SAF production and use has the potential to unleash immense benefits in combating climate change, creating rural jobs, securing our energy supply, and reducing the impact of waste on our natural environment.
The tragedy of COVID-19 has levied—and continues to levy—untold suffering on humanity and the aviation industry, the true extent of which is still unknown. Amidst the uncertainty there is one certainty: that we will survive. It is our hope that SAF is part of the solution as we emerge stronger and more resilient than ever before.