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This article was published on December 3, 2021

United dragged by Twitter over greenwashing with its ‘100% sustainable fuel’ flight

Misleading marketing alert

United dragged by Twitter over greenwashing with its ‘100% sustainable fuel’ flight
Ioanna Lykiardopoulou
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Ioanna Lykiardopoulou

Ioanna is a writer at TNW. She covers the full spectrum of the European tech ecosystem, with a particular interest in startups, sustainabili Ioanna is a writer at TNW. She covers the full spectrum of the European tech ecosystem, with a particular interest in startups, sustainability, green tech, AI, and EU policy. With a background in the humanities, she has a soft spot for social impact-enabling technologies.

Wednesday was a “historic” day for aviation, United Airlines claims.

Boeing 737 MAX 8 flew from Chicago’s O’Hare International Airport and headed to Reagan National Airport in Washington, DC, marking the “world’s first passenger flight using 100% sustainable aviation fuel (SAF).”

At first glance, the statement seems very impressive, but a closer look reveals that it might be an exaggeration. And yes, the Twitterverse has something to say about United’s greenwashing technique.

We’ll turn to Twitter’s snarky comments soon, but first things first: What’s this sustainable aviation fuel (SAF) United is boasting about?

SAF is a clean substitute for fossil jet fuels. Rather than being refined from petroleum, SAF is produced from sustainable feedstock such as cooking oil, solid waste from homes, and even food scraps.

This 2-minute explainer video from the International Air Transport Association (IATA) lays out everything you need to know much better than I ever could:


So SAF is indeed a sustainable alternative and has the potential to cut down 80% of CO2 emissions produced by conventional jet fuel.

Then why Twitter is attacking United Airlines for greenwashing?

1. The plane didn’t actually use 100% SAF

And it’s clear enough if you read the press release, as some of Twitter’s users did.

In fact, one engine was running with 100% SAF and the other with traditional jet fuel.

That’s because the US Federal Aviation Administration (FAA) allows for a 50% total of SAT to be used during a flight, United explains.

For this reason, SAF is basically employed by airlines as a drop-in fuel that gets blended with the conventional one at a 50-50 ratio. United decided to fly its plane with one SAT-powered engine and one fossil fuel-powered to demonstrate that “there are no operational differences between the two.”

That’s definitely an admirable experiment, but Twitter folks are right to call United’s statement misleading, even if they’re not in the aviation industry.

2. SAF is sustainable but not 100%

Naturally, many Twitter users asked not only how SAF is made, but also how sustainable it really is. One wondered, “What is sustainable fuel for planes? Curious…”

Indeed, SAF focuses on this type of feedstock to make its lifecycle as green as possible. However according to IATA, “there are emissions produced during the production of SAF, from the equipment needed to grow the crop, transport the raw goods, refine the fuel and so on.”

But when Twitter user Michael Polanyi, Policy and Campaign Manager at Nature Canada, asked about the greenhouse emissions involved in the production of SAFs, United offered no reply.

3. SAF isn’t easily scalable

Actually, that’s the comment I would have posted on Twitter.

United’s flight is meant to demonstrate the “scalable uses of SAF by all airlines in the future”, but that’s easier said than done.

According to IATA, current volumes of SAF represent less than 1% of the total jet fuel demand. And scaling up the volume is actually a very big challenge.

A recent paper by the International Council on Transportation (ICCT) has focused on the EU to estimate SAF feedstock availability to meet the growing aviation demand. 

Here are two alarming conclusions:

Taking into account sustainable availability and an optimistic assumption for the deployment rate of novel conversion technologies, we estimate that there is a resource base to meet approximately 5.5% of the European Union’s projected 2030 jet fuel demand using advanced SAFs.

Even with strong policies in place, the limited availability of the best-performing feedstocks suggests that SAF production alone cannot achieve the EU aviation sector’s long-term GHG reduction obligations. 

And that’s for the EU alone. I don’t even want to imagine the numbers if the same study was applied to the US.

Besides the production challenges, there’s one more important factor to consider: the elevated cost of SAF. According to IHS Markit, SAF prices are about five times higher than prices for conventional jet fuel. 

So what does that mean for us, the customers? That’s right: higher prices.

Either way, I’m actually in favor of SAF and support any green initiative aiming to help us tackle climate change. But the truth is that alternatives such as SAF are like using a bandage for a wound that requires stitches.

I believe the following tweet perfectly summarizes the situation and gives us some food for though. I don’t know who Timlagor is but they make an interesting point:

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