I’m watching a video about Boom Supersonic and somehow I hadn’t previously recognized that their aspirational goal is environmental destruction through high fuel burn while only supporting travel for the rich. They explicitly state they want EVERYONE flying supersonic, but we know that isn’t going to happen. Thankfully, that does limit the impact somewhat, but I don’t think it does enough.
So I started reading their report on fuel consumption (PDF), which affirms what I already thought by stating they are only comparing fuel burn to “premium” fuel burn. Even when biasing things in their favor in this way, it’s 2-3x more fuel per seat. When comparing to the commercial average fuel use per seat, they use 5.3-7.9x more fuel.5
There is an apparent contradiction between their stated goal of overland supersonic flight and part of their fuel burn calculations including accounting for “Flight speed restrictions and routing to avoid sonic boom impacts over land masses, including secondary boom standoff distances”. I think it’s also interesting their study only includes oversea flight paths in its comparison. What happened to the whole point being that you can do overland flight? Maybe they’re just hedging their bets.
I would be remiss if I did not mention they proudly claim “Boom’s sustainability strategy centers on the use of 100% sustainable aviation fuel (SAF) and efforts to rapidly advance and scale SAF production.” Their goal relies entirely on something that doesn’t exist, but they admit it, that’s good.
The real problem is even if SAF exists, using it for a supersonic aircraft while other aircraft aren’t using SAF means burning more fossil fuel. When the fuel you use could’ve fueled flights for 5-8x more people instead, you aren’t actually carbon neutral, you’re offsetting carbon neutrality by using it up, rapidly.
I am also concerned the only specified source of SAF in this document is “using CO2 from the atmosphere and renewable electricity to produce near limitless zero carbon SAF”. That’s the most energy-intensive way to make a fuel, which makes it the most offsetting of clean energy possible. (It also doesn’t meet the definition of zero carbon.)
Again, it is important to note they claim to be funding climate science on the impacts of air travel, and trying to reduce non-CO2 impacts as well. I’m not writing this to say everything they do is wrong, but to highlight the ways in which it is misguided.
Boom achieved carbon neutrality in 2021, and has set itself an ambitious goal to be net zero carbon by 2025.1
I think I should put this quote alongside their decision to start burning tons of methane in 2025: Boom Supersonic to Power AI Data Centers with Superpower Natural Gas Turbines; Adds $300 Million in New Funding. This represents around 14 kilotons of CO2 put into the atmosphere per day, or 5 megatons per year. Nice.
By the way, did you know “carbon neutral” and “zero carbon” are actually different things? Carbon neutral is based on the idea of pulling as much carbon out of the atmosphere as you put in, while zero carbon is to claim putting NO carbon in at all – which is currently impossible.
It’s called Public Relations: Publish good news. Say nothing when there’s bad news. Boom Supersonic stopped published sustainability information in 2023. Their ambitious goal to be zero carbon by 2025 was announced in 2022, as far as I can tell. The document I’m reading is from December, 2022, but I found an article in May making the same claim.
Also I think it’s funny they show how jet engines used a lot more fuel than piston-powered aircraft initially, and then took half a century to use almost the same amount of fuel, implying the switch to supersonics will follow a similar trajectory, when there’s no reason to believe that can happen. Even if true, that would represent a large increase in aviation fuel use, offsetting or even reversing the progress towards clean energy.
Footnotes
- “Notably, Boom achieved carbon neutrality through reduction initiatives and high-quality carbon credits in 2021.” – Measure, Reduce, Offset: How Boom Plans to Achieve Net Zero Carbon by 2025. Carbon credits mostly don’t represent actual carbon sinks, though who knows what “high-quality” means here since they didn’t specify.3
- They claimed part of the zero carbon goal was.. carbon capture. By definition, that isn’t zero carbon, and the company they contracted, Climeworks, partially uses captured CO2 for “climate-friendly products such as carbon-neutral fuels”. This has the same problem as using SAF for supersonics, the energy used to pull CO2 out of the air only to put it right back by burning it would’ve been better spent doing /literally anything else/. Spending energy to cycle the same CO2 that’s already killing the planet is wasteful. (Boom Supersonic Accelerates Towards 2025 Net-Zero Carbon Pledge with Climeworks Deal)
- Nature: Carbon credits are failing to help with climate change — here’s why by Trencher et al4 is a good overview of why carbon credits don’t necessarily mean anything. Only 15% of them achieve their claims. Ironically, it’s easier to access the supplemental materials (PDF) than the article itself.
- Trencher is the one who made it possible to read this, so I’m crediting him instead of the lead author. Suck it, Macintosh. Suck it, pay-for-access science.
- Their paper repeatedly only compares to a hypothetical all-premium seating aircraft, which is where the claim of 2-3x fuel use per seat comes from. Compared to what’s actually flying, they’d use 5.3-7.9x more fuel per seat.
This was originally written and posted on Bluesky, before being cleaned up, reformatted, extended with more information, and a couple minor errors corrected. Its working title was “Boom Supersonic’s goal is implicitly climate accelerationism”, but I thought a less aggressive title would reach more people.
Oops, I spilled my critical thinking
Because they only compared to premium seating, I knew the actual fuel use difference between current aircraft and their proposal was higher, but I didn’t know how much higher. The wording used confused me and I misread it a few times. I won’t say it’s intentional, but I will say that comparing a proposed aircraft to flights that do not exist is misleading. Not even Emirates – with their gaudy gold-trimmed opulance – flies aircraft with only premium seating.
From the Executive Summary (emphasis mine): “This study finds that supersonic air travel on Overture consumes 2-3 times as much fuel per seat than comparable premium class subsonic travel, depending on the routes evaluated, as well as various fuel consumption assumptions related to the subsonic fleet.”
From Section 1 (emphasis mine): “Recently published studies claim that supersonic aircraft result in between 5-9 times3 as much fuel consumption per passenger than subsonic aircraft. However, these claims are based on non-comparable data which do not provide an accurate comparison of supersonic to subsonic aircraft.” You’ll notice they don’t explicitly say they disagree or found a different result, and instead rely on the implication, causing one to assume a difference was found. Technically, their results are different, but not meaningfully different.
In Section 2, the methodology is laid out: Fuel use is based on the ratio of passenger/cargo weight, modified by the cabin floor area dedicated to premium passengers, and divided amongst the seat count within. This is followed by the only specific fuel numbers presented: “Across all aircraft operations considered in this paper, the average subsonic fuel consumption intensity was found to be approximately 0.014 gallons per seat-mile (considering both economy class and premium class seats). The fuel consumption intensity for subsonic premium class seats was approximately three times larger than the average across all subsonic classes of travel, at 0.037 gallons per seat-mile.”
I was very confused why they said “approximately three times larger” when 0.037/0.014 is ≈2.64. I kept re-reading it, trying to find a charitable and consistent interpretation. I now realize they were just rounding aggressively, but I was so confused by this because their choice to round here makes their fuel use look worse. It implies a true fuel use of 6-9x more per seat, when it’s actually 5.3-7.9x more per seat. I thought I read it wrong, multiple times.