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.
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?
Once you've got the coal sourced, most of the rest of the WWII process is directly applicable to modern carbon-capture methods.
I can imagine! Considering lots of the co2 in air has fossil fuel origin, not putting the co2 capturing at a high volume co2 source seems rather dim. Regulators gonna regulate!
Maybe site the direct air capture in the middle of a german industrial city with coal plants all around...
Say, an average price of base load electricity of 43.26EUR/MWh in Germany in 2018 (and that is a very pricey market - country which has a shitload of renewable power) - will result, at 50% efficiency, of energy feed costs of 3.07EUR per gallon of fuel. That's only 1.7x the actual cost of jet fuel in EU as per IATA (https://www.iata.org/publications/economics/fuel-monitor/Pag...).
You should add the capital cost of device itself, but if it's used round the clock, it shouldn't add so much. And if it's not, electricity can be almost free because a lot of the time, renewable power is in excess and can be purchased from the high voltage grid for very cheap (if we are speaking of high throughput industrial units which will probably have hundreds of megawatts connected, and will plug into high voltage grid directly).
All in all, it may get fuel 2x more expensive but it's not such a big deal.
But then, it's also arguable that PV hydrogen is itself a "carrier" for PV electricity. So then the alternative is batteries. As much as I love electricity, I doubt that battery technology will ever achieve the energy densities of hydrocarbon fuels.
Straigh molecular hydrogen is brutally difficult to work with. It is hard to store (high pressures and/or low temperatures), bulky, embrittles metals, and is violently explosive.
Synthetic analogues of fossil fuels (kerosene, petrol) are chemically virtually identical to what we've been using for the past century of powered flight (and should actually be cleaner/purer). There are few unknowns, safety is quite high, and the storage, handling, and combustion properties are well-understood and excellent for the application.
Powering FT fuel synthesis via photovoltaic or other solar processes could certainly work.
Is it planned that the plant will be able to take advantage of low spot prices?
After all, there isn't so much special about Jet A: I figure a PT-6 could run just fine on automotive diesel.
Aircraft, not so much. Liquid hydrocarbons have amazing energy density, both by weight and volume, and in aircraft that matters a lot.
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.
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...
(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.
If we can figure out how to extract atmospheric CO2 and convert it into hydrocarbons efficiently, crude oil won’t be bart of the equation any longer — our atmospheric carbon supply will be part of a closed loop. As a lay person, that’s an awfully appealing prospect.
I wonder how many kWh it takes to pump, transport and process a gallon of gasoline when sources from crude.
But what if it's a device that already exists that moves through air with great speed, filtering through huge amounts of air? Like, say, a jet engine?
The point of this device is to take energy available on the ground and store it for use in the air, and use a storage method with a tremendous amount of energy per unit weight (hydrocarbons).
The tech works quite well though, CRI in Iceland makes methanol (a viable liquid fuel) from CO2 and electrolyzed H2 semi-commercially, taking advantage of cheap and abundant geomthermal electricity.
Would replacing air with wood as the input alleviate the problem? (Trees, in effect, turn atmospheric carbon into hydrocarbons using solar energy.)
There has been some speculation that people could cultivate vats of algae illuminated by blue LEDs emitting light in the optimal photosynthesis spectrum. But this is probably only feasible with effectively limitless supplies of electricity.
If the jet's fuel tanks get filled about 200 times per year, then you need to cut down about 30,000 mature trees per year to supply the carbon to keep it supplied with fuel. This probably adds up to a few thousand acres of forest to continuously meet the needs of a single jumbo jet.
Isn’t biofuel precisely this?
Thinking laterally, instead of processing a lot of air, can't we just engineer a gaseous molecule that is good at capturing CO2 and can precipitate conditionally.
Imagine something like a buckyball that would let in a CO2 molecule. While it's sufficiently hot it stays under its gaseous form. Then once cold it falls to the ground.
You then release a lot of this engineered molecule in the atmosphere where it will come into contact and absorb the CO2 then fall to the ground where you can collect it efficiently by scrubbing it of surfaces like soot for processing and recycling.
If it is bio-safe and sufficiently stable you can even let it accumulate naturally in the water where you will retrieve it even more efficiently once it's concentrated enough. That's what we do in Rouen now and everyone is fine with it /s.
Did you know that there are massive streams of CO2 available for the taking?
Aside from the distance from civilization, you've got water, power, and air movement all right there.
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.
What does work is building the plant in a wind/solar abudant location and co-siting with large, behind-the-meter wind/solar plant. Not only do you get electricity at cost, but you cut the grid costs and taxes away too.
There's non subsidized power plants now being built for southern california, in India and in the UAE where the price for power sold to the grid is 2 to 3 cents per kWh ($0.025 to $0.030 per kWH).
I'm not so sure about it. I believe that transmission of electrical energy is cheaper than transmission of fuel. So it would be better to collocate synthesis with airports where planes are refueled.
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..
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, which I guess is bad, but not exactly apocalyptic.
" jet fuel has 46% higher energy density"
That's why. Few things matter more when lifting things into the air than weight.
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?
"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.
The problems with petroleum (and natural gas) are twofold. One is the carbon emissions, but the other is the fact that supplies will eventually run out, and have to be substituted by something. And as we try to pursue every last fraction of petroleum, the environmental costs will rise -- increasingly hard-to-access, high-risk, or heavy-treatment options. Think deep water, Deepwater Horizons, and tar sands and fracking.
Hydrocarbons are great fuels, and for some applications, especially powered flight, there's virtually no other viable alternative. Keep in mind that the aeroplane and automobile both appeared at virtually the same moment -- the principle requirements for each were high power-to-weight engines and energy-dense fuels. Sorting out the mechanical and aeronautical problems were relatively straightforward.
(Lightweight sturctural aluminium also helped markedly, and also became available largely through the same related set of technological processes providing Otto-cycle engines and petrol-based fuels.)
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.
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.
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!
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.
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.
Honestly this feels like it's a feel-good piece "look, we're doing our part!" when the technology is still a long ways away. Better than saying that the airlines are working on teleportation, but I don't know by how much.
This is the same people that have faith in that technology in renewables can improve to one day surpass nuclear.