Prospects for renewable jet fuel


Conservatives have long argued that requiring our modern technological society to conform to standards that would reduce environmental damage would force us to lose all that modern technology. According to them, the only way to reduce the damage modern life does to the environment is to live as our ancestors did in the 19th century, and they rely on people weighing the convenience of modern technology against the ability to live sustainably, and always choose first. In other words, in the choice between dirty technology and a clean environment, dirty technology will always win.

Of course, environmentalists, scientists and engineers have demonstrated over the years that this is a false choice. All of this technology was born out of brilliant ideas that someone had, and humans are still thinking about it. New ideas have helped dirty technologies become cleaner and more efficient, so maintaining technology doesn’t require ruining the environment. The development of hybrid and fully electric cars, as well as LED lighting, are examples of this.

Now, with the mother of all environmental crises looming over us as most people continue their habits of denial, we must stop using fossil fuels as soon as possible in order to avoid catastrophe. While the use of solar and wind power makes imaginable the elimination of the use of fossil fuels to power our homes, and even our cars, there is one type of modern transportation that presents a formidable challenge to eliminating, if not reduce its dependence on fossil fuels. . This is jet transport, responsible for the production of 3.5% of global greenhouse gas emissions. Fuel consumption per passenger on a single flight from New York to London exceeds the annual fuel consumption of most people in developing countries. Yet modern people, accustomed to being able to get virtually anywhere in the world in less than a day or two, are not going to give up flying as a mode of transportation. How can we solve this problem?

Unfortunately, the likelihood of transforming air travel through the use of electricity, as is currently the case with ground transportation, is somewhere between very low and non-existent. Even the most high-tech batteries don’t have the energy density of jet fuel. The only hope (at least in the short term, which is pretty much all we have right now) is to find a way to make jet fuel not from petroleum but from renewable resources. We’ve done this before with other fuels: ethanol from corn or agricultural waste added to gasoline, and diesel fuel from used cooking oil. The idea is to leave old fossil fuels in the ground while using fuels that have just passed through the planet’s carbon cycle. If done correctly, no additional carbon dioxide will be released.

The initiative to produce sustainable aviation fuel (SAF) is widespread and there are a number of strategies to achieve this goal. President Biden has set a goal for the United States to produce 3 billion gallons of SAF by 2030 and 35 billion gallons by 2050. In 2021, the biofuels industry only produced 33 million gallons of SAF, so there’s a long way to go. However, a flight from Chicago to Washington, DC, in December 2021 was the first passenger flight to be powered entirely by SAF. This is an encouraging sign that this strategy will work.

Producing jet fuel from biomass is different from the idea of ​​putting ethanol in gasoline because you can’t just add ethanol to jet fuel and expect it to have a density of equal energy (it’s not) or even compatible with a jet system that’s optimized for a specific jet fuel formulation. Simple fermentation will not produce a substitute for jet fuel. Multiple processing strategies to convert waste cooking oils and other biomass feedstocks into SAF are being pursued, and not all of them are expected to be successful. However, for us to continue flying without contributing to the destruction of the planet’s climate, at least one (and hopefully a few) must succeed.



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