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☁️ "A Bumpy Ride toward Decarbonizing Aviation"

Catalyst with Shayle Kann

Photo by Kvnga / Unsplash

Host: Shayle Kann
Guest: Dan Rutherford | Director of the Aviation & Maritime Programs | The International Council on Clean Transportation
Category: ☁️ Carbon Reduction

Podcast’s Essential Bites:

[4:22] “Aviation is kind of a tricky issue here. The emissions can either look really large or reasonably small, depending upon how you normalize it. But just to give you a few different figures. Airlines emitted about 900 million tons of CO2 […] in 2019. So if aviation was considered as a country, it would be about the sixth largest emitter, so a little bit larger than Germany, somewhat smaller than Japan. Globally that would be about 2.4% of anthropogenic carbon dioxide. But It doesn't account for the climate impact of co-pollutants. So when you burn a gallon of jet fuel at elevation, it has a larger climate impact than if you burn it, say on the road, because you're also emitting things like nitrogen oxides and black carbon and water vapor. So if you look at the total climate impact of flying, it's about three times larger than carbon dioxide alone. And if you put together all of the math, it would be about 3.5% of the total radiative forcing from anthropogenic emissions. But that's on a societal level. If you look at individual fliers, it can be very different. So half of the United States doesn't fly in any given year, and about 90% of the world doesn't get on a plane in any given year. So if you're a frequent flyer, flying is a much larger part of your overall carbon footprint, generally 20% or higher.”

[6:24] “If you look only at CO2 [from aviation], it's about 12% of the transportation inventory. But again, that's not accounting for these other pollutants. And comparing directly cars versus planes gets tricky on a number of levels. So it's not the largest source, but it is one of the fastest growing sources. And by some accounts, overall emissions could triple by mid century, unless additional action is taken to reduce the pollution.”

[8:44] “It's a really interesting time right now. We are starting to see the airlines come out with more net zero commitments. […] We're also starting to see some really interesting short and mid term commitments either on emission reductions, or for the use of sustainable aviation fuels for example. Airbus is looking very seriously at hydrogen fuel designs […]. And we're seeing a number of startups, especially in the electric aircraft space, that are starting to develop products. […] And I would say there's a larger diversity of action right now than I've ever seen. The big question that's maybe hanging over all of this is the cost, because we've all become really used to the idea of catching really cheap flights whenever we want. And the question of who pays for all of this is something that has yet to be resolved.”

[10:33] “Sustainable aviation fuel is sort of a catch all phrase. It's meant to describe drop in alternatives to fossil jet fuel […]. And so these are being generated using a variety of feedstocks. Current uptake is very, very small. It's less than 0.1% of global jet fuel use. But sustainable aviation fuels have a lot of merits in that they're meant to be dropped in. So you can blend them into existing supply and continue to use the same planes and the same engines that are already in service. They're energy dense. So as a sort of a liquid hydrocarbon in essence. They will allow planes to maintain their same range. So you'll be able to take a long haul flight, for example, on a sustainable aviation fuel. And we do believe that they'll be less polluting not just on a CO2 basis, but those other co-pollutants […] we think sustainable aviation fuels can reduce those climate impacts as well. So that's the good news. The limitations are that supplies very low and cost remains really high. So the figure you often hear quoted is three to four times the cost of conventional jet fuel […] today.”

[12:23] “In terms of the buckets, I'd say that there are four main ones. […] The first are what we call waste fats, oils, and greases. So these would be things like used cooking oil or beef tallow or yellow grease. Wastes that can easily be converted into jet fuel, and have good lifecycle emissions. So we do think that once you account for all of the energy used to produce them, and also things like land use impacts, we expect that these fuels can reduce emissions by 40 to 50% on a lifecycle basis. Those are the cheapest and the most available today, but the supply is relatively limited. So we think, overall, maybe about 2% of overall jet fuel use could be met by diverting these waste fogs from existing uses to to aircraft.”

[13:26] “[The] second bucket [is] what we call advanced biofuels. So those would be things like cellulosic fuels or municipal solid wastes. And there's even some technology that can […] exhaust gases from the steel plants into first alcohol and then jet fuel. […] Those are more expensive, the technology is kind of emerging, but the potential supply is much, much larger if […] you can get over the hurdle of developing the technology and making the capital investments. Those fuels can provide even larger reductions, something on the order of like an 80% reduction in lifecycle greenhouse gases.”

[14:37] “[Number] three […] are electro fuels that are synthetic fuels. […] The basic idea is that you capture carbon from some source either directly from the air or from a point source like a landfill, and then you generate hydrogen from renewable electricity, either wind or solar plus an electrolyzer, and then you synthesize a jet fuel out of that. So that's a variety of names: e-fuels, synfuels, e-kerosene. That is an emerging technology. […] Actually there was a plant that opened up in Germany recently that is now producing e-fuels for the first time. Huge potential supply, also quite expensive. So the cost figure that they released was 5€ per liter, which is roughly 10 times the cost of jet fuel in Europe today. […] A little bit more long term, larger potential reductions up to like 99% reductions, essentially a near zero fuel.”

[17:17] “Bucket four is actually […] the cheapest possible fuel, but the one that is most problematic in terms of potential emissions and these are crop based biofuels. So it is possible to use soy or corn or worst case scenario palm as a feedstock to generate sustainable aviation fuels. That is generally considered a rather bad idea, just because anytime that you create a fuel that competes with food, you open up the possibility that you indirectly trigger deforestation in the tropics. And as a result, you can actually produce sustainable aviation fuels that, on a lifecycle basis, emit more carbon dioxide than the base jet fuel. […] There are some policies that unfortunately could push us in that direction if we adopt them.”

[23:10] “Airbus is currently investigating three potential designs that they think could be brought to surface by 2035 that would be powered by hydrogen. And if 2035 seems like a long time from now, I assure you, it's actually almost tomorrow, when you think about a fundamental technology shift for the aviation sector.”

[31:00] “There is the safety question. By all accounts hydrogen is not any [of what] a lot of people think [like] Hindenburg. […] Hydrogen itself is not more dangerous than jet fuel. It is just different. And so you're gonna need to have new standards, new regulations for how to handle the fuel, how to feel at the airport, etc. So, I mean, you don't want to ignore the complexity there.”

[47:47] “About 0.05% [of aviation fuel is sustainable today]. […] Globally, a decade from now [I estimate it to be] 2-3%. […] The airlines are saying something like 60-70% of mitigation in 2050, will come through aviation alternative fuels. […] I won't say it's impossible. The economics of renewable power are rapidly improving and I would expect that we'll also see breakthroughs in direct air capture and probably hydrogen as well. […] It's more about political will and also generating the capital needed for the investments.”

Rating: ⚡⚡⚡⚡

🎙️ Full Episode: Apple | Spotify
🕰️ 48 min | 🗓️ 12/02/2021
✅ Time saved: 46 min

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