May, 2022

The Latest in Sustainable Aviation Fuel

Tech Innovations

First, what is sustainable aviation fuel, exactly?  Sustainable aviation fuel is still jet fuel -  the same kerosene that has been burning in airplane engines for decades. The difference is that sustainable aviation fuel is created from renewable sources, in contrast to conventional petroleum-based fuels. SAF can be derived from renewable crops, as well as from waste products such as vegetable oil and recyclable cooking oil, even algae and captured carbon dioxide. It ends up being the same hydrocarbon mixture called kerosene that we know as jet fuel, however. Recent months have seen important progress in the use of SAF: 

  • In March Delta Airlines struck an agreement with Gevo, Inc. to buy 75 million gallons of SAF per year for the next seven years.  Also in March, Airbus flew an A380 for three hours powering one of its Rolls-Royce engines entirely with SAF made from cooking oil and other waste fats.
  • In May United Airlines announced it will purchase up to 52.5 million gallons to use toward every flight departing from Amsterdam’s Schiphol Airport over the next three years. The fuel is from SAF producer Neste, for whom it will be the largest purchase agreement by a passenger airline in history.
  • A SAF program in Dallas Ft Worth International airport is also underway, and it is the first to test a circular economy project in aviation. If you find yourself at Dallas Fort Worth (the fourth busiest international airport in the world!) and stop for a burger, some of the cooking oil from your meal could end up being turned into renewable fuel for your flight. The airport now collects nearly 32,000 pounds of cooking oil each month and stores it in tanks until it can be hauled off and refined into sustainable aviation fuel. The program estimates that every gallon of oil creates around 0.8 gallons of SAF.

Airlines have actually been tinkering with SAF for many years - KLM operated the first commercial flight that used a blend of biofuels and regular jet fuel in 2011. Even before that, in 2008, test flights were flown by  Virgin Atlantic and Air New Zealand.  

Beyond creating SAF from cooking oils, there is another type of SAF in development that uses renewable energy to extract hydrogen from water and then mix it with carbon dioxide taken directly from the air, such as through direct air capture. The result is a synthetic liquid fuel with a potentially endless supply. 

So what’s the holdup? Why isn’t SAF more widely used? The reason is that SAF is still two to six times more expensive than traditional jet fuel.  To solve this the world needs more production facilities for low-cost biofuels, and more support the development of the synthetics, which require renewable energy sources. 

There’s a movement afoot to help address this at scale, though too: Breakthrough Energy Catalyst is a program within the larger Breakthrough Energy network founded by Bill Gates that is  investing in clean technology projects to help to bring down their price and make them more widely available. In addition to direct air capture, green hydrogen and long-duration energy storage, SAF is a focus area.

If you’re interested in tracking sustainable aviation fuel news, we suggest following news from the International Air Transport Association (IATA) and Breakthrough Energy Catalyst.

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