Can We Make Flying “Green”?

Sabine Hossenfelder

At 3 mins 38 seconds I confused the horizontal with the vertical axis. Sorry about that!

What can we do to reduce the carbon footprint of air travel? In this video we look at battery powered planes, hydrogen powered ones, bio fuel, and synthetic kerosene.

Data about airplane emissions come from Our World in Data…

The figure for the increase of airplane efficiency is from this report:…

The figure for the energy per volume and energy per mass values for different fuels is from this paper:…

Data for the cost of bio jet-fuel is here:…

The paper about the increased efficiency of gene-edited microalgae is this:

The number for the carbon-dioxide emissions of synthetic jet fuel comes from here:…

Numbers for the cost of synthetic jet fuel are from here:…

Market estimates for the increase in air fuel demand are here:…

The recent report from the International Air Transport Association calling for support for synthetic fuels is here:…

00:00 Intro
00:47 How Bad is Flying?
02:30 Electric Planes
06:32 Hydrogen
09:05 Biofuels
13:00 Synthetic Kerosene
16:05 Sponsor Message

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January 24, 2023 6:33 am

There is no climate crisis

So, the question is irrelevant

Steve Case
Reply to  strativarius
January 24, 2023 6:48 am


1. More rain is not a problem.
2. Warmer weather is not a problem.
3. More arable land is not a problem.
4. Longer growing seasons is not a problem.
5. CO2 greening of the earth is not a problem.
6. There isn’t any Climate Crisis.

Dean S
Reply to  strativarius
January 24, 2023 7:44 am

Maybe but taking that approach is almost guaranteed to get peoples back up. And achieve exactly nothing. Head in the sand type stuff. We need to win the argument, not piss people off.

The approach which has worked on my friends who are pretty hard core greenies is to agree with them and then dismantle the arguments which come from that. Easy to do on availability of raw materials, and also Sabine is great at smashing the green fantasies.

Reply to  Dean S
January 24, 2023 8:22 am

Facts can piss people off, it would seem. But at least I’m not disrupting travel or throwing soup around…

Bill Powers
Reply to  Dean S
January 24, 2023 10:13 am

One problem with your approach Dean. You obviously are dealing with people interested in intellectual debate, You must be interacting with people educated before 1990 That would be before the Clinton/Gore “Bridge to the 21st Century” dismantled education and converted our public schools and institutions of higher learning into indoctrination centers.

Reply to  Dean S
January 24, 2023 2:41 pm

huh fundamental mistakes about aircraft is not smashing

May Contain Traces of Seafood
Reply to  Dean S
January 24, 2023 6:21 pm

Sorry Dan, but if you are not prepared to dig your heals in at the start of the logic path you are going to die a death of compromise.

Case point: Net Zero.

Why are we getting dragged into debates about the need for nuclear power in order to reach Net Zero when we should be asking why New Zero is even an objective.

Frankly (and Hi Frank!) I don’t want nuclear power to help me reach Net Zero, I want nuclear power to lower my power bills.

CO2? Pump that stuff out. We need to keep the Oxygen levels under control or we will have giant insects! 😛

Leo Smith
Reply to  strativarius
January 24, 2023 8:16 am

There is a fossil fuel crisis however, so the question will be relevant in due course.

Reply to  Leo Smith
January 24, 2023 8:23 am


Bill Powers
Reply to  Leo Smith
January 24, 2023 10:23 am

You can view anything as a crisis if you deploy a Central Authority to ban legitimate solutions. Nuclear Power anybody?

How about we combine nuclear power in Africa with lifting restrictions on DDT.
Water and sewage treatment, Electricity grids oh my! What a wonderful world it could be.

Although a down side would be reduced need for telethons, which provides a lot of meaningless pandering and self congratulation among we the fortunate pretending we are doing something to help the less fortunate. Oh! And the mosquito net industry would go the way of the buggy whip.

Reply to  Leo Smith
January 24, 2023 2:20 pm

Seems to me there was a “fossil fuel crisis” many, many years ago, yet we are still discovering new resources. The “crisis” results from dumb/stupid/evil decisions by persons like ‘Brandon’.

Reply to  strativarius
January 24, 2023 2:41 pm

Matches my immediate reaction to the headline: “Why would we want to?”

January 24, 2023 6:53 am

Boeing and Airbus are looking at H2 as a fuel. Eviation is testing a battery powered plane. True believers want to eliminate that CO2 stuff.

John XB
Reply to  antigtiff
January 24, 2023 7:22 am

H2 + O2 = H2O which is the primary cause of ‘global warming’ as it is the 2% to 4% in Earth’s atmosphere which causes the balance between incoming and outgoing I/R which makes the planet habitable.

Supposedly, according to the climate sensitivity/feed-back thingy, it is the slight increase caused by CO2 that is causing more H2O into the atmosphere causing more warming, causing more H2O, causing more warming and so on… and yikes! Tipping point, eternal feed back, Earth becomes a fireball.

Battery powered plane. Batteries in a electric car add circa 500kg to its weight – battery powered planes wouldn’t get off the ground.

Reply to  John XB
January 24, 2023 7:44 am

Eviation is close to getting off the ground…the tickets may be kinda expensive. Aviation is testing jet engines with a 20% increase in efficiencty and planes that reduce drag by 20%….aviation is not standing still.

Leo Smith
Reply to  John XB
January 24, 2023 8:20 am

H2O turns into clouds that screens out the sun. Contrails etc. You get them with current fuels.
Electric planes perfectly capable of getting off the ground. And even doing a couple of circuits. Just not crossing any oceans.

Harry Passfield
Reply to  Leo Smith
January 25, 2023 3:46 am

I shall always remember the best comment I read about BE aircraft is that their landing weight is the same as their take-off weight.

Reply to  John XB
January 24, 2023 3:58 pm

You misunderstand. The objection to aviation is because it works. If you built a working hydrogen powered plan, it would be banned. Same goes with electric power. E-vehicles are only tolerated because the don’t really work.

Reply to  Hivemind
January 24, 2023 8:10 pm

“E-vehicles are only tolerated because they don’t really work.”

And expensive. If they were cheap and worked they would be banned, probably because of the extra mining required.

Reply to  Mariner
January 27, 2023 4:39 pm

E-vehicles are only for the rich – Value Village Nike’s for everyone else.

Reply to  John XB
January 25, 2023 6:09 pm


Leo Smith
Reply to  antigtiff
January 24, 2023 8:18 am

Both H2 and batteries have sever drawbacks in energy per volume and energy per wight respectively., And hydrogen is very dangerous.
My money is on synthetic kerosene.

Gary Pearse
Reply to  Leo Smith
January 24, 2023 5:26 pm

Maybe we could have a Hindenburg to lift the plane off the ground and also serve as an external gas tank for the the H² burning engines! Or a chain of Hindenburgs suspending a long cable for an airplane to zipline from NYC to London!

I maybe shouldn’t be saying this. It might be picked up and run with by chartreuse sociological engineers to burn up trillions more cash. To them, an idea is a bankable feasibility study.

Joseph Zorzin
Reply to  antigtiff
January 24, 2023 9:18 am

H2 as fuel for air travel – sounds great- what could go wrong with that? /sarc

Last edited 13 days ago by Joseph Zorzin
Reply to  Joseph Zorzin
January 24, 2023 4:00 pm

Try this video.

January 24, 2023 6:55 am

none of the reference links work for me …..“page not found”

John XB
Reply to  DMacKenzie
January 24, 2023 7:23 am

Cause: climate change.

Peta of Newark
Reply to  DMacKenzie
January 24, 2023 8:18 am

They been truncated somehow with those dot dot dots at the end.
I obviously haz the luck of the irish. The only one I clicked was the Nature one about algae and it works.
Until you get the $25 per month paywall…

January 24, 2023 6:59 am
January 24, 2023 7:07 am

Very entertaining and an excellent discussion about the impossibility of flight without anything other than fossil fuels or dilithium crystals.

Reply to  Margaret
January 24, 2023 8:10 am

I’m givin’ ya all the power I can, Margaret. I’ve realigned the dilithium crystals and I can only get warp 8.5 out of her…


Gunga Din
Reply to  Bob Tisdale
January 24, 2023 10:43 am

If I was a CliSy scientist against air travel, I’d write a paper about airline routes from CA to points east are the cause of the “atmospheric rivers” that (only recently in the MSM) are plaguing California!
(Of course such a paper would need to ignore history (The Pineapple Express) and all the other airline routes around the world where there are no “atmospheric rivers” but I might make a few grant bucks.)

Reply to  Gunga Din
January 24, 2023 4:03 pm

The modern scientific method. Start with the conclusion and create the facts you need out of that.

January 24, 2023 7:08 am

Dr. Hossenfelder covered the cost of various synthetic liquid fuels except for hydrogen. The energy cost to liquify a given amount of hydrogen is about equal to 40% of the energy content of the hydrogen involved for medium sized liquefaction plants. Another challenge.

January 24, 2023 7:09 am

I am proud of the many thousand tons of precious, life-giving, beneficial trace gas CO2 that I have contributed to the atmosphere and hope to contribute many thousand tons more.

Reply to  Shoki
January 24, 2023 4:04 pm

As long as the greens don’t get to you first. They’ll make Pol Pot’s Killing Fields look like a fairy tale.

January 24, 2023 7:10 am

Yeah. Let’s get right to discarding the fuels which have given the world many advances over the last 100+ years.
There is no need to invent new fuels for anything. Its all a game of smoke and mirrors to gain power over the folks who are still dumb enough to believe in “climate whatever”.
Just sayin’.

Reply to  guidvce4
January 24, 2023 8:45 am

I’m all for inventing new fuels – as long as they are better.
Any new energy source or fuel needs to be shown to have advantages economically and environmentally. CO2 isn’t a pollutant so it doesn’t factor into the determination.

John XB
January 24, 2023 7:16 am

Before answering the question in the headline, I would like to know why we would want to?

Also I would like to see evidence that it isn’t already.

January 24, 2023 7:20 am

So why is a large jet spraying tons of water at 35,000 ft considered “green” ?
The water is a greenhouse gas and would generate lots of clouds (contrails) …

E. Schaffer
January 24, 2023 7:31 am

“and it creates clouds at high altitude that trap heat. But in this video we’ll focus on carbon dioxide because that is the biggest issue”

Funny! It is exactly to opposite. CO2 emissions (from aviation) are really a negligible thing, while those aviation induced cirrus are the big deal. Don’t need to take my word, you can also go with the IPCC..

“The potential effects of contrails on global climate were simulated with a GCM that introduced additional cirrus cover with the same optical properties as natural cirrus in air traffic regions with large fuel consumption (Ponater et al., 1996). The induced temperature change was more than 1 K at the Earth’s surface in Northern mid-latitudes for 5% additional cirrus cloud cover in the main traffic regions.”

or NASA..
“This result shows the increased cirrus coverage, attributable to air traffic, could account for nearly all of the warming observed over the United States for nearly 20 years starting in 1975.:”

Since she would spare out the interesting story, I stopped watching the video. Not worth the time. Other than my article on the issue..

Reply to  E. Schaffer
January 24, 2023 9:06 am

Condensation trails. Water, the elixir of life, and a warm and comfortable home.

Reply to  E. Schaffer
January 27, 2023 4:46 pm

warming over the US has been fairly flat for the last couple of decades – has air travel been constant?
Probably not – but airliners have gotten much more efficient – maybe we could look at the amount of fuel used by airlines flying over the US.

Rud Istvan
January 24, 2023 7:34 am

The obvious answer is no, nor should we try.

But the large new NASA grant to Boeing for a full scale flying demonstrator with a radical new wing concept does make sense. IF Boeing can engineer it with advanced materials, then combine it with the 787 carbon fiber body, it has the potential to reduce fuel consumption about 30%. That changes aircraft economics significantly.

Frank from NoVA
Reply to  Rud Istvan
January 24, 2023 7:50 am

One could make a valid Constitutional argument that NASA has no business funding Boeing’s research into radical new wing concepts or anything else for that matter. I’m sure many here will object to this, but that’s how we got to the point where most of what the Federal government does on an ongoing basis, including spying on us, is unconstitutional

Curious George
Reply to  Frank from NoVA
January 24, 2023 9:03 am

What a progressive idea. Ban whatever works!

Frank from NoVA
Reply to  Curious George
January 24, 2023 9:38 am

Perhaps you could elucidate on what you think is working?

Reply to  Curious George
January 24, 2023 1:10 pm

Not being wrong once in a rare while can hardly be called working.

Rud Istvan
Reply to  Frank from NoVA
January 24, 2023 10:13 am

It is NASA’s wing concept. They are paying Boeing to engineer and produce a full scale ‘commercial’ plane using it so it can be flight tested. There only so much you can do with models before the engineering has to hit the runway.

Frank from NoVA
Reply to  Rud Istvan
January 24, 2023 11:40 am

Even worse. If it’s such a great idea, Boeing should conceive, engineer and produce it at their own expense. The fact that they haven’t means it’s either a bad concept and/or it’s economically unviable, at least under current conditions. Geek’s like us might be intrigued by some or even much of what NASA does, but once the camel has its nose under the tent, there’s no principal to stand behind in opposition to their forays into data tampering and GCM-based alarmism, etc. Goes for the rest of the government’s agencies and departments, as well.

Reply to  Frank from NoVA
January 24, 2023 2:29 pm

A man after my own heart.. ooops…should probably rephrase that.

Reply to  Frank from NoVA
January 24, 2023 2:27 pm

The Feds have to keep that 10% recycling.

Reply to  Rud Istvan
January 24, 2023 8:54 am

Since NASA is funding research, then any advantages to wing design and material advancement is in the public domain, right?

Frank from NoVA
Reply to  Brad-DXT
January 24, 2023 9:35 am

If not in the public domain, at least in the PRC’s domain, less 10% for the Big Guy.

Joseph Zorzin
Reply to  Rud Istvan
January 24, 2023 9:22 am

B2 bombers made with advanced materials are litterly worth their weight in gold.

joe x
January 24, 2023 7:45 am

from an abc report.
“On the day ABC News visited, Alice’s batteries had just arrived and engineers in hazmat-like suits were working to fit the behemoth batteries onto the left and right side of the plane. The batteries will be 50% of the takeoff weight and make up the fuselage of the plane near where the wings attach.”

“While not a long distance plane, 440 miles fits the needs of many regional airlines around the world. Charging the plane will be similar to charging a Tesla. While passengers are boarding, the plane will be plugged in and able to do most of a flight off of just a 30 minute charge.”

“The aircraft’s first flight took place at Grant County International Airport (KMWH) in Moses Lake, Washington, on September 27. Alice was airborne at around 7:10 AM PST, and flew for approximately 9 minutes and 3 seconds at an altitude of around 3,500 feet.”

why only 9 minutes and only 3500ft?

batteries=50% of take of weight.
9 passengers and 2 pilots.

scale this up to 100 passengers, baggage and cocktails and get back to me.

i would love to the data collected during this flight.

Leo Smith
Reply to  joe x
January 24, 2023 8:25 am

The batteries will also be 50% of the LANDING weight.
Batteries will work, just not for very long.
Current technology will give about an hours flight and probably the optimal speed would be around 450mph, so allowing for reseves that about a 250 mile range to be safe.

Reply to  Leo Smith
January 24, 2023 9:08 am

What do you do if you have an emergency and must land immediately? Todays planes dump fuel to lose weight for landing. Can’t do that with a battery. You are only allowed a couple overweight landings before undercarriage must be replaced.

James Snook
Reply to  Leo Smith
January 24, 2023 9:11 am

Current Regulations in the USA require a passenger aircraft to have sufficient fuel on landing to have taken a 30min diversion, or to reach an alternative airport 90 miles away.

Reply to  James Snook
January 24, 2023 2:32 pm

Watch the film “Scully”.

Reply to  sturmudgeon
January 24, 2023 4:16 pm

Sully didn’t crash due to a lack of fuel.

Reply to  James Snook
January 24, 2023 6:32 pm

Leo — it’s worse than that. FAA part 121.639 requires fuel to the destination, an instrument approach there with a missed approach, fuel to the most distant of possible alternate airports, an instrument approach at the alternate, plus an additional 45 minutes of fuel on top of all that. I think this is the rule that commercial air carriers have to abide by. I believe the 30-minute requirement has narrow applicability in this case. I could be wrong, but that’s my reading of it.

Reply to  wxobserver
January 25, 2023 11:07 am

Cornell Law School’s Legal Information Institute has a nice reference to the fuel requirements for flight in VFR conditions (visual flight rules). I didn’t look through IFR (Instrument Flight Rules) yet, but thought it would be nice to put out the requirements for the systems. I think it will kill the use of batteries as “fuel”.

  1. for the rules of flight during the day…you need to be able to have enough fuel capacity to get you 30 minutes of flight time past your first point of destination.
  2. for the rules of light at night…that requirement is 45 minutes.
Reply to  Leo Smith
January 24, 2023 1:17 pm

Which means that landing gear will have to be much stronger, and hence much heavier, than the land gear on equivalent range fossil fuel powered planes.

January 24, 2023 8:22 am

Carbon dioxide emissions are not a bug, they’re a feature.

Anyone who claims otherwise is a fool and/or a charlatan.

Rod Evans
January 24, 2023 8:26 am

If adding CO2 to the atmosphere can be shown to be a net benefit and further show CO2 produces a ‘greener’ planet then yes flying can be defined as a ‘green’ activity.
The only downside for me, is the spreading contrails that give us hazy sunless skies in the summer when we want blue skies as a preference..

Last edited 13 days ago by Rod Evans
Curious George
Reply to  Rod Evans
January 24, 2023 9:08 am

The Green movement wants to stop greening the planet 🙂

January 24, 2023 8:46 am

We could probably make all the jet fuel we need with plant oils, but if you can generate all your electricity from renewables and convert all cars to electric, then the air transportation won’t matter. Of course, the greens won’t be happy until they have completely shut down all fossil fuel production, which is the same as saying they won’t be happy until they have completely destroyed modern civilization.

Dave Andrews
January 24, 2023 9:01 am

Most people watching this excellent video will probably think of aeroplanes such as they fly on going for holidays whilst not appreciating the amount of freight carried by both scheduled and specialist freight flights from airports.

According to IATA air cargo transports over $16 trillion worth of goods a year, approximately 35% of world trade by value.

In the UK, Heathrow is the largest ‘port’ by value with a network of 350 destinations worldwide.

These transports weigh a lot more than people going on holiday – will these flights ever be powered by hydrogen?

Last edited 13 days ago by Dave Andrews
January 24, 2023 9:03 am

We can make it “Green”, yes, unreliable.
We can make it “green”, too, carbon-based, reliable energy.

Randle Dewees
January 24, 2023 9:22 am

Sabine is one of the better YT commentators on technical subjects. But, like almost all of them she plays the tribute game to Green/Carbon/Whatever as part of any presentation that has a connection to climate politics. She’s not dumb, it seems she doesn’t court being marginalized (de-monetized) by YT. I find the prevarication tiresome. I do sometimes detect a bit of cynicism in her delivery.

Frank from NoVA
Reply to  Randle Dewees
January 24, 2023 9:57 am

Agreed. Sort of like having to acknowledge climate alarmism in one’s research in order to get published and maintain funding.

Reply to  Randle Dewees
January 24, 2023 1:21 pm

The EU just passed a new regulation requiring social media sites to remove anything the EU considers to be “misinformation” or face massive fines.

Looks like Cold War was won, by the Soviet Union.

Frank from NoVA
Reply to  MarkW
January 24, 2023 3:11 pm

‘War is the health of the State’.

January 24, 2023 9:24 am

Short answer: no.

Batteries are too heavy. Hydrogen requires heavy tanks and special metals and is just a storage medium, not a primary energy source. CO2 generation for both is moved from the airplane to a ground-based generator.

Airplanes with reduced drag and more fuel-efficient engines will reduce CO2 generation. Anything that adds weight will just increase CO2 generation.

Frank from NoVA
Reply to  fansome
January 24, 2023 10:03 am

Exactly! Trying to extend net zero to flight is just one other indication that climate alarmism has nothing to do with CO2 and everything to do with overturning society and the economy in order to implement global socialism.

David Dibbell
January 24, 2023 9:41 am

“Yes, climate change is an enormous challenge.” (16:08)
No, it is not. It is a fashionable illusion, a misdirection. It makes no sense to do much at all with aviation, except to pursue high efficiency, low weight, low drag. So let’s have the courage to do nothing in response to the unsound climate claims. The industry should stop legitimizing the misguided net-zero movement by pretending to find “solutions” like using hydrogen as fuel.

That said, I enjoyed the author’s mocking of “flight shaming.” Good one.

AGW is Not Science
January 24, 2023 10:32 am

Who cares? Our “carbon footprint” causes no problems and significant benefits.

Stop playing their stupid game.

January 24, 2023 11:33 am

Making aviation green is just virtue signalling and pointless. Aviation’s effect on the environment is negligible.

Reply to  sskinner
January 24, 2023 11:59 am

Given the negligible amount of CO2 in the atmosphere, I suspect all human activities have a negligible effect on the climate. Except the bloviatiations of climate alarmists of course.

January 24, 2023 12:43 pm

I think Sabine made it pretty clear, kerosene is the fuel of choice even with it’s so called short comings, which are minimal.

January 24, 2023 12:55 pm

Instead of asking whether we can make flying “green”, how about asking if we can make greens fly?
Someplace far, far away.

Reply to  MarkW
January 24, 2023 2:17 pm

January 24, 2023 12:57 pm

Anyone who doesn’t believe that the airlines aren’t already doing everything they can in order to reduce their fuel usage costs, knows nothing about capitalism.

January 24, 2023 1:56 pm

Can we make flying Green?

Not a snowball’s chance in Hell with the current definition of ‘Green’ and the dodgy accounting practices that entails back on terra firma-

But you can always count on rebellious youth to see through the hypocrisy and utter BS of their elders from time to time-

January 24, 2023 2:07 pm

Remind me again why people are worried about having more CO2. The more CO2 we have, the better things get. More rain, warmer weather, more vegetable growth, more arable land, and forest, and a longer growing season are all positives.

January 24, 2023 5:36 pm

No. Next stupid f&cking question.

January 24, 2023 5:41 pm
January 24, 2023 10:03 pm

What can we do to reduce the carbon footprint of air travel? 

  1. change wings
  2. change fuels
  3. change engines
January 25, 2023 2:27 am

I loved her saying lorry instead of truck. Very droll.

January 25, 2023 2:52 am

Today is Burns Night. I will be eating a swede with my haggis. Glad to hear that 19 swedes weigh the same as two average Germans.

January 25, 2023 8:29 am

I was expecting the Dambusters theme with that caption pic!

Hatter Eggburn
January 25, 2023 4:14 pm

Go BRICS and stop being a western whatever

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