Alder Fuels gets 100%


Dr Derek Vardon, chief technology officer, Alder Fuels, has all the experience and qualifications you would expect. The PhD graduate and Navy veteran has more than 40 peer-reviewed papers and eight years at the Department of Energy’s National Renewable Energy Laboratory to his name. 

But he also has an amazing talent for explaining technical issues in simple terms. “You can thank my grandmother who always wants to know what I am doing,” he says. “I practice with her.” He has had some exciting research to share with her recently.  

Alder Fuels wants to take sustainably-sourced organic waste and create Alder Greencrude. They can use a wide range of feedstocks, such as left-over wood waste, regenerative grasses and even nut shells. Their proprietary process (liquefaction of lignocellulosic biomass) is well-proven. Alder is focused squarely on woody waste and regenerative grasses for the short to medium term because they exist in abundance.

Alder Greencrude, which is effectively a low-carbon substitute to fossil crude, can be used to make a variety of renewable products. This includes producing Sustainable Aviation Fuel (SAF) in existing biorefineries and fossil-fuel refineries with only minor adjustments needed. 

Because the feedstocks are also low cost, once scaled, the cost of Alder Greencrude should be competitive with fossil crude oil. That is before accounting for the net positive environmental impacts (or future carbon taxes on fossil fuels).  

Vardon and his colleagues recently created 100% SAF that has the same (or better) characteristics than traditional fossil Jet A. By mixing SAF produced from Alder Greencrude with a percentage of traditional HEFA-SAF from World Energy, made from used cooking oil and waste fats (you can find out HEFA-SAF is made here) they now have a formula for 100% biogenic, sustainable jet fuel. 

Alder Fuels worked with Washington State University, World Energy, Honeywell UOP, and the US Department of Energy’s National Renewable Energy Laboratory on this pioneering project. “You can think of jet fuel like a deck of playing cards,” is how Vardon explains it. “To have a full hand you need four types of suits – the four types of molecules in drop-in ready jet fuel. HEFA-SAF has two, Alder Greencrude has four. By mixing them you have a winning hand.” 

The big issue with 100% SAF usage is the O-ring seals inside engines. Aromatics in the fuel (one of the card suits in Alder SAF) make these swell. However, aromatics also create soot and contrails. 

Alder’s research shows that cycloparaffins (circular molecules) can also make seals expand without the same issues. Cycloparaffins and aromatics are not produced when HEFA-SAF is refined. Vardon says that although it may take time to certify SAF with no aromatics at all, the proportion of aromatics can be cut significantly. Airbus, Boeing and other manufacturers have pledged that their aircraft will be able to use 100% SAF by 2030. 

Alder’s latest tests showed that the 100% SAF – what the company calls Alder SAF100 – had a lower freezing point (-53.8°C), a higher heat of combustion and sufficient seal swell. The results were checked by Honeywell UOP and the National Renewable Energy Laboratory. 

“This could be a game changer with Alder SAF100 (pictured left) because you have a drop-in fuel that performs better than fossil jet (pictured right) on key performance and environmental criteria,” says Vardon.

Alder is now working on scaling production. In January, the Department of Energy selected Alder for a $2m grant to start commercialisation of Alder Greencrude with a much larger award forthcoming once certain development milestones are reached. The company’s existing shareholders include Honeywell UOP, United Airlines Ventures, Directional Aviation and Avfuel. 

Alder also needs to have its SAF pathway approved by regulatory fuel body ASTM. Vardon says that the company is likely to use an existing annex and they are excited by the chance to continue collaborating and demonstrating positive results. 

“We want to get this right from an environmental perspective, but we also want to share our iterative development process so others can learn from it,” says Vardon. “We need this ecosystem to succeed if we want to have a chance of decarbonising vital parts of our transport infrastructure by 2030. We have come through a critical milestone and we want to keep up the positive momentum.” 

Vardon and his colleagues are continuing to look at different sustainable feedstocks that may have the potential to deliver incredibly low-carbon – even carbon-negative – results. This could give him even more developments to discuss with his grandmother very soon.  

Image: Alder SAF100 (left) vs. traditional fossil-based jet fuel (right). Photographer: Werner Slocum from NREL


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