Sustainable Flights: The Good, the Bad and the Nerdy!


Submitted Liz Clarey - A Pennsylvania voter living in the Czech Republic.


As someone who lives abroad, you probably take a few long-haul trips a year. Maybe more than a few! Airplane travel is responsible for 3% of greenhouse gas emissions. For many people who do fly, those flights make up a sizeable portion of their individual carbon footprint.

The Good:

Even though burning petroleum-based jet fuel is extremely polluting, air travel makes up a smaller portion of our collective emissions compared to other sectors. Moreover, many airlines are in the process of making changes to their aircraft to improve sustainability. The most obvious, of course, is replacing jet fuel with fuels that create lower emissions. Airlines are also working on technologies to make airplanes lighter, more aerodynamic, and more durable. There is some promise that some short-haul flights (which are typically under 3 hours) will be able to run on electricity.

The biggest project, of course, is creating sustainable aviation fuels, or SAFs. Most companies are looking at drop-in fuels, which are alternative fuels that can work with existing jet-engine technology. To do this, most SAFs need to be blended with traditional jet fuel. While the ratio varies, most combinations are 50% SAF and 50% jet fuel. SAFs are often created from biofuels made from waste and by-products.

The Bad:

While ideas are promising, many emissions-free solutions for long-haul air travel are several years from fruition. No 100% SAFs have been approved. And unfortunately, right now, SAFs only account for .1% of the fuel used by the commercial aviation industry. However, like other green technologies, the science is improving each day.

The Nerdy:

This is for all of the chemistry nerds out there!

So, the SAF with the lowest lifetime greenhouse gas emissions is called HEFA (hydro-processed esters and fatty acids). To create HEFA fuel, scientists remove oxygen molecules from unused vegetable oils, waste fats, and grease. They then treat the mixture with hydrocarbons to transform it into burnable hydrocarbons appropriate for jet engines, et voila - low-emissions fuel!

Additionally, a bioenergy company in California creates jet fuel from the trash in landfills. This type of SAF is called “Fischer-Tropsch-SPK.” This solution creates not only low-emissions fuel but also removes methane-producing waste from landfills. It’s an exciting solution and one to look out for. 

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