
Jet fuel from thin air: Aviation's hope or hype? - theklub
https://www.bbc.com/news/business-49725741
======
jbaumg
I am involved in this project. The aim is to built a demonstration plant to
show the feasibility of the process and to develop a blueprint for larger
plants that can produce sustainable jet fuel economically. Producing
sustainable fuels is always more expensive than fossil fuels. However,
upcoming legislation and taxation (at least in the EU) will change this
equation.

Someone mentioned an efficiency of around 50% in a post here and resulting
pricing, that's a fairly good estimate of the overall process and what is
discussed as achievable cost for renewable synthetic fuels in general. The
process is in this demonstration plant is Fischer-Tropsch. Using CO2 from an
industrial point source is more efficient; however, it has potential
legislative issues when it comes to certification of sustainable fuels,
emission certificate trading... it's a fairly complicated topic. In addition,
worldwide potential for lowest renewable energy costs does not correlate
necessarily with existing CO2 point sources. That's why direct air capture
makes a lot of sense.

Whether CCS is a better solution depends on renewable electricity pricing vs.
the CCS costs, public acceptance and feasibility at the location of a plant.
These vary strongly depending on where you are in the world. In many parts of
Europe there is strong opposition to it as it may prolong the exploitation of
fossil sources.

~~~
mogadsheu
Finally, an expert! I’m not, although I’ve been involved in energy for a while
now.

I believe the Germans made synfuels towards the end of WWII using Fischer
Tropsch when they were running low on conventional fuels. What tech is new
about this project, besides the energy source?

~~~
jabl
They made synfuels from coal, which contains a lot of, uh, coal. So no need to
capture it from the air. They didn't worry about CO2 pollution back then.

~~~
dredmorbius
For fuel synthesis, you have two principle processes: carbon sourcing, and
actually sythesizing the fuel.

Once you've got the coal sourced, most of the rest of the WWII process is
directly applicable to modern carbon-capture methods.

------
leoedin
The jet fuel part of this is a distraction from the important (and hard) part
- turning electricity into usable liquid fuel.

Electrolysis is easy enough, and there's plenty of places with enough water.

Then you have hydrogen. Hydrogen is not nice to work with, store or use, so
you want to turn it into something else a bit nicer.

The problem is, almost all practically usable liquid or gaseous fuels contain
carbon. Where do you get that from?

The obvious answer is the atmosphere. That's also the premise of carbon
sequestration. The problem is that CO2 isn't actually particularly abundant.
It's currently hovering around 400 parts per million - that's about 0.04% of
air. To make a kg of hydrocarbon you need to process an awful lot of air to
get enough CO2. That all takes energy. A lot of energy. Suddenly your round
trip efficiency is practically zero. If these guys have cracked that problem,
it would be fantastic. I hope they have, but I suspect they haven't.

~~~
thisisbrians
I came here to say essentially this. To your point about how low (in
percentage terms) the concentration of CO2 is, direct carbon capture from the
atmosphere still seems a fool's errand to me. The only way I see carbon
capture being at all viable for this purpose in the short term is to scrub the
waste gasses from industrial processes where carbon-containing compounds are
extremely concentrated.

~~~
Robotbeat
Cement (of certain types) relies on direct carbon capture from the atmosphere
to complete curing (although conventional cement only carbonizes through a
finite depth during its expected lifetime), so it's definitely possible. It
just takes a lot of energy.

About 2 MWh (thermal, or ~7GJ) per tonne of CO2 captured (not counting storing
that CO2) to regenerate the chemical CO2 capturing agent. Here's a review:
[https://www.sciencedirect.com/science/article/pii/S095965261...](https://www.sciencedirect.com/science/article/pii/S0959652619307772)

(As an aside, a gallon of gasoline emits about 10kg of CO2, so to capture that
CO2 from a gallon of gasoline would require about 20kWh worth of
electricity.... Typically, a gallon of gasoline gives you about as much range
as 10 kWh in an electric car, so you can go 2 times as far in an electric car
just using the energy it'd take to capture the CO2 from a gasoline car. And
that doesn't count the electricity required to refine/crack the gasoline from
crude.)

And also, on board the International Space Station, CO2 is captured from the
atmosphere regeneratively. Capturing CO2 in this way takes less energy at the
higher concentrations on board ISS, but is still possible.

As an aside: Much of the ISS's CO2 is converted into a hydrocarbon (methane)
using hydrogen (from water and solar electricity) and, amusingly, vented to
space as a waste product. The point is to recover the oxygen (again, in the
form of water) from the CO2.

~~~
Zanni
In case someone else is wondering about the math on the aside about how a
gallon of gas (3.8kg) can emit 10kg of CO2:
[https://www.fueleconomy.gov/feg/contentIncludes/co2_inc.htm](https://www.fueleconomy.gov/feg/contentIncludes/co2_inc.htm)

------
nradov
The US Navy is already experimenting with producing synthetic jet fuel on
aircraft carriers using power from the nuclear reactor. Their concern is with
reducing the logistics chain rather than environmentalism. But if the research
results are made public they could be applied to commercial aviation.

~~~
DuskStar
It would be _really_ interesting to see that getting applied to a fleet oiler
design. A nuclear powered tanker that constantly refills itself for the DDs
and CGs to use...

------
nickcw
Let me get out my back of the envelope for some quick and inaccurate
calculations ;-)

There are 10.3 kWh of energy in a litre of Jet A1 fuel.

Let's assume (generously I think) that the process is about 50% efficient, so
it takes ~20 kWh of electricity to make a litre of Jet fuel.

Assuming (amortized) solar power is the same cost as grid power ~$0.1/kWh then
to make your litre of fuel costs 20 *0.2 = ~$2/litre

According to my research Jet A1 costs about ~$0.50/litre.

So this is a way off at the moment, however if there was tax on fossil fuels
for aviation then this could be competitive.

~~~
markvdb
Depending on how capital intensive the plant is, this might still be cost
competitive with intermittent low, zero or negatively priced green
electricity.

~~~
jblow
Also ... renewables are always going through cycles of high and low
availability. Prices vary across these cycles. If you make your fuel only at
the time during the day when there is the highest delta between supply and
demand, then you pay the minimum electricity cost, and the utilities are glad
to have you there to balance the load.

~~~
ThrustVectoring
Note that this economic strategy is already in place in other industries where
electricity price is a large component of the final cost of goods sold.
Aluminum smelting is a huge example of this.

------
comnetxr
The question should not be whether this is too costly as compared to jet fuel,
but at what carbon price is it cheaper than jet fuel? Once the cost of carbon
is at the long term limit, which is equal to the cost of extracting carbon
from the atmosphere, then these technologies could be much more cost
effective. (But if they aren't, there would be no reason to ban flying, as the
carbon price would pay for the extraction of carbon that flying produces.)

By not account for how much jet fuel costs with increasing carbon pricing, and
by framing the alternative to allowing climate change as banning flying, it
seems like the author has completely missed the story..

------
vilhelm_s
I guess a more low-tech approach would be to fuel jets with ethanol. Googling
a bit now, the U.S. uses about 18 billion gallons/year of jet fuel[1], and
produces 17 billion gallons/year of fuel ethanol [2]. The price per gallon is
about $1.5 versus $1.94 [3,4]; because jet fuel has 46% higher energy density
that means that the cost per Joule would increase by a factor of 1.9.

Obviously this is only a back-of-the-envelope thing, but it seems that even if
we switched to renewable fuels using the technology that are available today,
ticket prices should about double. Historically, that corresponds to going
back to circa-1980 prices[6], which I guess is bad, but not exactly
apocalyptic.

[1]
[https://www.eia.gov/todayinenergy/detail.php?id=31512](https://www.eia.gov/todayinenergy/detail.php?id=31512)
[2]
[https://www.eia.gov/todayinenergy/detail.php?id=32152](https://www.eia.gov/todayinenergy/detail.php?id=32152)
[3] [https://markets.businessinsider.com/commodities/ethanol-
pric...](https://markets.businessinsider.com/commodities/ethanol-price) [4]
[https://www.indexmundi.com/commodities/?commodity=jet-
fuel](https://www.indexmundi.com/commodities/?commodity=jet-fuel) [5]
[https://en.wikipedia.org/wiki/Energy_density](https://en.wikipedia.org/wiki/Energy_density)
[6] [https://www.theatlantic.com/business/archive/2013/02/how-
air...](https://www.theatlantic.com/business/archive/2013/02/how-airline-
ticket-prices-fell-50-in-30-years-and-why-nobody-noticed/273506/)

~~~
throw_into_air
The problem with ethanol is it absorbs water, which at greater altitudes
(lower temperature and pressure) freezes and blocks fuel lines. For that
reason aviation fuels have limits on ethanol content.

~~~
thisisbrians
Could we redesign the fuel system to (safely) remove the water somehow? Or
prevent the fuel from absorbing moisture in the first place?

~~~
selectodude
It would have to be hermetically sealed from creation to combustion at 37,000
feet. I’m sure it’s theoretically possible but so difficult as to be
untenable.

~~~
vilhelm_s
Maybe you could chill it to precipitate the ice just before loading it on the
plane?

------
credit_guy
So, here's how to kill a few birds with one rock. Make jet fuel using nuclear
energy. But nuclear energy is horribly expensive, right? No, _civilian_
nuclear energy is horribly expensive. The US Navy churns out nuclear reactors
at a steady pace, and operate them perfectly safely. They've never had any
incident. If the Congress mandates the US Navy to become net zero carbon
emitter, they can do it. And they also gain additional logistical
simplification. They say that every gallon of fuel sent to the front line in
Iraq costs the DoD $100. Yes, in the oil-soaked Iraq. If you shorten the
supply line, maybe this price goes down to a more reasonable level. Can you
imagine that, instead of getting a war for the exorbitant price of $10
trillion, you can get one for a paltry $1 trillion? We could get 10 wars for
the price of one.

~~~
cameronbrown
> They've never had any incident.

I'm not being conspiratorial here, but if there was an incident, which would
make the navy look vulnerable and weak to both the population and potential
enemies, would we ever know about it?

~~~
maxerickson
A big chunk of incidents would be known to adversaries just by their nature.

------
teekert
"It sure does sound amazing. It sounds like a solution to all of our problems
- except that it's not," said Jorien de Lege from Friends of the Earth.

"If you think about it, this demonstration plant can produce a thousand litres
a day based on renewable energy. That's about five minutes of flying in a
Boeing 747.

"It'd be a mistake to think that we can keep flying the way that we do because
we can fly on air. That's never going to happen. It's always going to be a
niche."

Wow, the Naysayers really know how to build a constructive argument.

------
ajross
This always strikes me as missing the point. The end result is fuel to burn.
It doesn't matter where it comes from, only what the net carbon budget is.
Continuing to burn petroleum in jet engines is _fine_ , as long as it's
appropriately offset. There's absolutely no technical reason to need to bend
over to implement this kind of setup. Spend those dollars on renewables and
sequestering solutions instead, clean up the last 10% of fossil fuel
extraction at the end of the process.

~~~
quickthrower2
Lots of people working on different ideas to help reduce CO2 is probably what
we need though. We don't know what will be the 'winner' yet, but the more
things we try the more likely we are to find the best solution(s).

------
tedmcory77
Sounds very similar to Prometheus Fuels. The AMA thread on here from the
founder was amazing.

~~~
detritus
To save anyone else curious the hardship of searching...

[https://news.ycombinator.com/item?id=19842240](https://news.ycombinator.com/item?id=19842240)

------
mastazi
> "It'd be a mistake to think that we can keep flying the way that we do
> because we can fly on air. That's never going to happen. It's always going
> to be a niche".

Why did BBC include such a strong statement in the article, given that it's
just someone's gratuitous personal opinion?

I know that it's good journalistic practice to include sceptical opinions, but
couldn't they find someone who is sceptical while at the same time being able
to back their opinion with some sort of evidence or arguments?

Edit: it's also possible that this person's contribution was a longer text,
and that it was cut short due to the article length limits. Maybe the original
text included better arguments? It would be unfortunate if that was the case.

------
perfunctory
Whatever happened to Prometheus? I haven't heard anything since their launch
[0]. The website doesn't have any updates [1]. Complete radio silence.

[0]
[https://news.ycombinator.com/item?id=19842240](https://news.ycombinator.com/item?id=19842240)

[1] [https://www.prometheusfuels.com/](https://www.prometheusfuels.com/)

------
eternalny1
I envision a future (not too far away) where we can literally turn anything
into anything else reasonably efficiently.

CO2 in the atmosphere with hydrogen and oxygen from water, waste into each of
its base component atoms, whatever into whatever else.

Something like global recycling of everything, if that makes any sense.

------
tito
On Saturday, Elon Musk said that SpaceX will use direct air capture to make
fuel from air on Earth:
[https://youtu.be/sOpMrVnjYeY?t=3852](https://youtu.be/sOpMrVnjYeY?t=3852)

In partnership with Climeworks, one of the leading DAC companies, I just
launched a campaign on Kickstarter using carbon materials to make a bracelet
made of captured atmospheric carbon dioxide. Check out the video!
[https://www.kickstarter.com/projects/go-negative/negative-
br...](https://www.kickstarter.com/projects/go-negative/negative-bracelet-
captured-carbon-dioxide)

------
tengbretson
Sounds like some kind of Fischer–Tropsch process. Starting with CO2 sounds
like it would require an obscene amount of electricity though.

~~~
Analemma_
> Starting with CO2 sounds like it would require an obscene amount of
> electricity though.

It could still be worth it, depending on how/when it was made and how it
interacted with the grid. There's an increasing problem right now of too much
solar supply during the day and not enough power storage; projects like this
could be used to soak up excess power and it would still come out carbon-
neutral.

~~~
MrBuddyCasino
Germany is paying other countries to absorb spikes. Anything that creates
value instead looks like a win to me.

------
perfunctory
In the synthetic fuel world, how much renewable energy capacity would we need
globally? We need to replace all current electricity generation with
renewables, then we need to add more to power electric cars, and then some
more to produce synfuel. That sounds like a lot of capacity.

------
Swivekth18
"This demonstration plant can produce a thousand litres a day based on
renewable energy. That's about five minutes of flying in a Boeing 747"

------
rpmisms
Why not just process biomass?

~~~
dredmorbius
There isn't enough.

Even for aviation alone, which is about 6% of US fossil fuel consumption,
using a process Boeing had lauded as a "breakthrough" a few years ago,
essentially using a salt-water pickleweed (halophytes), you'd need the entire
states of Kansas and Oklahoma, plus considerable chunks of Nebraska and
surrounding states, to meet present US demand.

We use _a lot_ of fossil fuels. Mind-boggling amounts. And those accumulated
slowly over immensely long periods of time, though that's due to
inefficiencies both in what ancient biomass was kerogenised in the first
place, and the losses in keroginisation (essentially: petroleum formation).
Jeffrey S. Dukes, "Burning Buried Sunshine" (2003), lays this out for coal,
oil, and gas.

For petroleum, we're presently burning about 5 _million_ years of accumulated
fossil biomass every year. Or, alternatively, we burn through a full ancient
year's biomass accumulation every 6.3 seconds.

All biomass, roughly, equates all human and livestock feed, plus some
construction materials waste-streams (mostly wood and forestry products). When
you say "use biomass", you're really saying "go through the leftovers of
humans and livestock". And quite simply, there's not all that much there.
Maybe 5-10% of current total energy use _if_ you could _efficiently_ capture
the entire wastestream (and keep in mind that it is _very_ widely distributed.

In practice, you could probably power waste water treatment plants off of
captured biomass, with some surplus left over. But not much more than that.

------
bassman9000
_" It sure does sound amazing. It sounds like a solution to all of our
problems - except that it's not," said Jorien de Lege from Friends of the
Earth._

 _" If you think about it, this demonstration plant can produce a thousand
litres a day based on renewable energy. That's about five minutes of flying in
a Boeing 747._

This is the same people that have faith in that technology in renewables can
improve to one day surpass nuclear.

