Hacker News Reader

Comment by simonhorlick | Hacker News Reader

I don't understand how this is sustainable. The fuel is still being combusted and releasing CO2 isn't it?

It's greenwashing, they are hoping we won't pay too much attention to air travel as it's clearly impossible to switch the whole fleet to SAF.

For the UK we would need to switch half of our agricultural land to growing feedstock in order to switch to SAF.

https://eandt.theiet.org/content/articles/2023/02/uk-would-h...

It may not scale, but it's not greenwashing - for it to be green washing, you'd need either claims of lower co2 to be false, or pretend that this solves the issue completely.

Lufthansa, at least - when I checked - made no such claim. I reviewed their compensaid site thoroughly (afraid it's just greenwashing), and their communication seems very honest.

"Net zero by 2050" sounds like greenwashing to me.

My dictionary defines greenwashing as "misleading or deceptive publicity disseminated by an organization so as to present an environmentally responsible public image".

This is exactly what this industry is doing.

Exactly. Biofuels can be very useful, but only by also drastically reducing overall energy consumption. Flying uses a lot more energy than trains.

Is that if we wanted to produce all of our aeroplane fuel here though? Presumably we don't do that at the moment.

Here in the US, we have a corn-farming industry that has captured the Agriculture department and can block passage of essential legislation. To be expected: legislation proposed in Congress that all US jet fuel henceforth contain X% bio-product.

> Whereas fossil fuels add to the overall level of CO2 by emitting carbon that had been previously locked away, SAF recycles the CO2 which has been absorbed by the biomass used in the feedstock during the course of its life.

Source: https://www.iata.org/en/programs/environment/sustainable-avi...

I guess it's reasonable to claim that it's sustainable if it's part of a cycle rather than just being a source of CO2 dug straight out of the ground. We still have a way to go with carbon capture but this feels like an improvement over the current fuels.

“Sustainable” as a marketing word was likely chosen to refer primarily to itself, i.e. the production of the fuel itself is sustainable compared to drilling for a known finite resource (crude oil). However, it is ecologically sustainable in that we are using material already making the rounds as opposed to unsequestering carbon sinks only to immediately burn.

There are other benefits, CO2 is not the only greenhouse gas around, and conventional Jet-A releases non-CO2 emissions into the atmosphere. SAF has stricter requirements as to what sort additives are allowed based on each chemicals specific burn profile.

In theory, its sustainable, because the fuel is being created from CO2 captured from the air by photosynthesis - so burning it doesn't add to the overall atmospheric CO2. Unlike fossil fuels where you are digging up CO2 and adding it to the atmosphere.

In practice it's rather more complex than that.

> its sustainable, because the fuel is being created from CO2 captured from the air by photosynthesis

An essential detail: the CO2 would have been back in the atmosphere soon, regardless of its use. We need less CO2 in the atmosphere, regardless of who, what, when, or how it got there or how it's removed.

The method of capture doesn't matter. Atmospheric carbon capture devices would be just as good, if they worked efficiently.

If you capture CO2 in a way that would keep it from the atmosphere long-term, then releasing it again is obviously not a good idea.

If you grow corn, you capture CO2. But the corn will soon die and (if I understand correctly) release the CO2 again, so you might as well use the corn for your fuel and release the CO2 that way.

However: If you plant a field with corn for fuel instead of with longer term carbon capture options (e.g., certain types of trees), it seems like a loss. It's better than digging up CO2 that's already stored long term (fossil fuels) and adding it to the atmosphere, but that's not good enough. We need to get CO2 out of the atmosphere.

Yeah we need to capture CO2 and NOT try and use it for short term gains. We need to capture it and lock it away to never be used.

It is releasing co2, but in case of SAF, that co2 was captured first by plants or other methods - so it's considered close to carbon neutral.

Similarly, burning wood/biomass for heating is considered roughly carbon neutral, as opposed to coal or natural gas.

Climate change isn't a simple product of CO2 emission. It's a result of fossil carbon that was outside of the earth's carbon cycle for millions of years being reintroduced to the system.

Biofuels made from plants are rereleasing carbon that the plants collected. They're more or less carbon neutral, assuming the existence of more plants growing. Biofuels won't help remove the excess carbon from the atmosphere, but they certainly can help mitigate the rapid bleeding by cutting down on fossil fuel use.

This is especially important for aviation, where the usage of batteries is almost certainly impossible for practical use.

Of course, the ideal thing to do is remove carbon from the atmosphere and not use it. But getting to net zero first is necessary.

Even plants breathe CO2, that alone does not make the fuel unsustainable.

It’s not - you can switch a small portion of fuel demand in a sustainable manner. The SAF plants are built purely on economics underpinned by tax credits. The larger issue is that once you get past a certain volume number, the marginal feedstock is soybeans (in the US at least) which for a variety of reasons is structurally more expensive than oil - this is never going to be economic and is a taxpayer funded boondoggle, I wish that weren’t the case

Reply on news.ycombinator.com