When was your first exposure to Sustainable Aviation Fuel (SAF), and what were your first impressions?
My first personal exposure to alternative fuels was in the 90s, not SAF as we know it today, but in working with synthetic fuels in general. I was involved from a very technical standpoint, understanding the combustion process when burning something other than standard kerosene. The SAF work, as we know it today, began around 2004-2005 when manufacturers started collaborating with ATAG (Air Transport Action Group) to prepare for carbon regulations. This coincided with discussions around the Kyoto Protocol, which later morphed into the Paris Accords. It was around this time that we began more in-depth work on SAF's viability and its potential as a solution for reducing carbon emissions.
The first real discussions between manufacturers and the Federal Aviation Administration took place in 2005, with CAAFI (Commercial Aviation Alternative Fuels Initiative) officially forming in 2006. In the early years, we focused on foundational work—understanding how SAF could fit into jet fuel specifications, and what kind of testing needed to be done. I joined CAAFI’s leadership team as an advisory board member in 2007-2008 and took a more formal role in 2012.
Why is the current use and trajectory of petroleum-based jet fuels unsustainable?
If we agree that increasing CO2 levels in the atmosphere is unsustainable, then it's crucial to find ways to avoid adding more carbon to aviation operations. There are multiple ways to achieve this, but one of the key solutions is introducing lower-carbon synthetic aviation fuels like SAF. In addition to operational changes, infrastructure updates, and technological advancements, market-based measures are also part of the overall strategy. Sustainability itself is a complex topic, and definitions can vary depending on whom you ask. However, the most significant contribution SAF offers is the reduction of carbon emissions, which is the most impactful from an environmental perspective. That said, SAF also addresses other sustainability concerns, but the carbon aspect is the primary focus for the aviation industry.
The supply of SAF is still minimal compared to the global demand for jet fuel. This year, the aviation industry will likely exceed 100 billion gallons of jet fuel production, but SAF will account for less than 1% of that. Despite more than a decade of work, we're still in the early stages of this journey compared to the petroleum industry, which has been around since the 1880s. The primary challenge is cost—petroleum is cheap to extract and use because the environmental costs are not factored in. SAF, on the other hand, is currently more expensive. However, there are promising developments that could drive down the cost, eliminate blending requirements, and open the door for broader use of SAF in the future.
Can you tell us about the alternatives to jet fuel that are currently available?
Jet fuel is primarily composed of hydrocarbons, and synthetic fuels aim to replicate this structure using different sources. Instead of pulling hydrocarbons from petroleum, we can recycle hydrocarbons already present in the environment. This includes fats, oils, greases, starches, and sugars—resources that nature gives us. These feedstocks come from various sources, like oil seeds, animal fats, sugarcane, sugar beets, and lignocellulose (the structural component of most plants).
In essence, we harvest these materials, convert them into jet fuel, and repeat the cycle without the need to extract more hydrocarbons from the ground. Other sources, like waste from industrial processes or even municipal solid waste, can also contribute to SAF production. This recycling of hydrocarbons reduces reliance on petroleum and helps foster a circular economy.
What potential regulatory measures or policy incentives could help support the adoption of SAF?
While we're still in the early days of SAF development, policy can play a key role in closing the cost gap between SAF and petroleum-based jet fuel. SAF is currently 1.5 to 2 times more expensive than traditional jet fuel, and policy interventions could help bridge that difference by providing incentives or imposing carbon costs on petroleum. Governments often play a role in supporting emerging industries, and this is no different for SAF.
That said, the real challenge lies in reducing the cost of SAF through innovations like using waste streams with negative costs—such as landfill waste. By finding ways to lower the feedstock cost, we can make SAF more competitive with traditional jet fuels.
What advancements in SAF technology do you see making a significant impact in the next few years?
Most of the SAF produced today comes from fats, oils, and greases, which are chemically similar to jet fuel. However, as we move toward using more complex feedstocks like lignocellulose, the process becomes more challenging. Advances in the conversion of lignocellulose and other plant-based materials hold significant potential for SAF production, but the chemistry is more difficult to manage.
There’s also exciting work being done with algae, which has the potential to produce much higher yields of oil per acre than traditional crops. Beyond biological feedstocks, researchers are exploring ways to capture CO2 directly from the atmosphere or industrial sources and convert it into hydrocarbons, a concept known as e-fuels. These advancements could significantly expand the range of SAF production options in the future.
