Conservatives have long argued that requiring our modern technological society to conform to standards that would reduce harm to the environment would force us to lose all that modern technology. According to them, the only way to reduce the harms modern life causes to the environment is to live the way our ancestors did in the 19th century, and they count on people weighing the convenience of modern technology against being able to live sustainably, and always choosing the former. That is, 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 that technology came about from bright ideas somebody came up with, and humans are still thinking. New ideas have helped dirty technologies to become cleaner and more efficient, such that keeping the technology does not require ruining the environment. The development of hybrids and fully electric cars, as well as LED lighting, are examples of this.
Now, with the mother of all environmental crises looming over us while most people continued their habits in denial means we have to stop using fossil fuels as quickly as possible in order to avoid catastrophe. While the use of solar and wind make it imaginable to eliminate the use of fossil fuels in powering our homes, and even our cars, there is one type of modern transportation that presents a formidable challenge in eliminating—or even reducing—its fossil fuel dependency. This is jet transportation, which is responsible for producing as much as 3.5% of the world’s greenhouse gas emissions. The per-passenger fuel burned in a single flight from New York to London exceeds the annual fuel use of most individuals in the developing world. Yet, modern people, used to being able to go virtually anywhere in the world less than a day or two, are not going to give up flight as a means of transportation. How can we address this problem?
Unfortunately, the likelihood of transforming air transport through use of electricity, as is currently happening with ground transportation, is somewhere between very small and nonexistent. Even the most high-tech of batteries lacks the energy density of jet fuel. The only hope (at least in the short term—which is about all we have right now) is to find a way to make jet fuel not from petroleum but from renewable resources. We have already been doing this with other fuels—ethanol from corn or agricultural waste added to gasoline, and diesel fuel from used cooking oil. The idea is to leave the ancient fossil fuels in the ground while using fuels that have just recently been through the planet’s carbon cycle. If it’s done properly, 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 pursue this goal. President Biden has set as a goal for the US to produce 3 billion gallons of SAF by 2030, and 35 billion gallons by 2050. In 2021, the biofuels industry has only produced 33 million gallons of SAF, so there’s a long way to go. However, one flight from Chicago to Washington, DC, in December 2021 was the first passenger flight to be fueled entirely by SAF. This is a hopeful sign that this strategy will work.
Producing jet fuel from biomass is unlike the idea behind putting ethanol in gasoline because you can’t just add ethanol to jet fuel and expect it to have equal energy density (it doesn’t) or even to be compatible with a jet system that has been optimized for a specific formulation of jet fuel. Simple fermentation will not produce a substitute for jet fuel. Multiple processing strategies for converting waste cooking oil and other biomass feedstocks into SAF are being pursued, and it is expected that not all of them are anticipated to be successful. However, in order for us to be able to continue flying without contributing to the destruction of the planet’s climate, at least one (and, hopefully, a few) have to be successful.
Sources:
Science
Chemical & Engineering News
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