[HN Gopher] Fuel out of thin air: CO2 capture from air and conve...
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Fuel out of thin air: CO2 capture from air and conversion to
methanol (2020)
Author : bill38
Score : 67 points
Date : 2022-12-10 18:34 UTC (4 hours ago)
(HTM) web link (research.american.edu)
(TXT) w3m dump (research.american.edu)
| the_third_wave wrote:
| Using such a process on plain air is not likely to ever be
| economically feasible as air only contains a tiny amount of CO2,
| around 400 parts per million. If you want to run such a process
| run it on the exhaust stack of a gas-fired power plant since that
| contains a good amount of CO2. Of course this only makes sense if
| the capture takes less energy than the power plant produces which
| can not be the case since it would violate the second law of
| thermodynamics [1].
|
| [1] https://www.britannica.com/science/second-law-of-
| thermodynam...
| andrewmutz wrote:
| Well the good news is that every year that 400ppm goes up
| sbierwagen wrote:
| >violate the second law of thermodynamics
|
| This is directionally correct, in that coal emissions
| sequestration is unlikely to be economical, but with two
| caveats:
|
| 1) Most coals are not actually pure carbon, they do contain a
| small percentage of hydrogen. If you don't capture the
| resulting water vapor+ then that gives you some combustion
| energy for free.
|
| 2) If you had to spend energy to split the carbon off CO2 and
| sequester the carbon, then yes, it would be a pointless round
| trip. Which is why most "clean coal" schemes just compress the
| CO2 and sequester it underground.
|
| ---
|
| +: Water vapor is itself a powerful greenhouse gas, but it
| varies between 4,000 and 25,000 ppm, so clean coal, which is
| intended to be a short term stopgap measure operated only for a
| few decades until the global PV solar infrastructure is built
| out, shouldn't have time to affect global gas balances.
| acidburnNSA wrote:
| Quick summary: "Given sources of Carbon and Hydrogen plus massive
| energy inputs, you can synthesize hydrocarbons!"
|
| I feel like the headlines always try to pretend you're getting
| energy out of the CO2 rather than putting energy into a
| hydrocarbon energy storage chemical.
|
| Question of course is economics of converting some (hopefully
| clean-ish) energy into stored hydrocarbon chemical bond energy
| and then combusting it in a vehicle vs. just digging up
| hydrocarbons and combusting them.
| DennisP wrote:
| Well we might want to consider the externalities of "just
| digging up hydrocarbons and combusting them."
| acidburnNSA wrote:
| Of course, and we are. But let's not pretend there is free
| fuel floating around in CO2 as part of that consideration.
| mlindner wrote:
| I think the primary idea is that eventually we'll still need
| carbon source inputs for making certain things (fertilizer for
| one, most types of rocket fuel for another) and so this is an
| alternative to that. If we're not getting hydrocarbons from
| fossil fuels, we need to get it from somewhere else for the
| petrochemical industry.
|
| It's also a nice thing to do when the spot price of energy goes
| negative or extremely low when there's tons of surplus
| renewable energy.
|
| I also heard one example assuming a future with nuclear fusion
| being cheap and you put a nuclear fusion plant at larger
| airports to produce jet fuel on-site.
| subradios wrote:
| I think it's totally plausible actually, there's lots of
| stranded renewables and otherwise flared natgas that could be
| used for this process
| mlindner wrote:
| The flared natural gas is happening because it's too
| expensive to ship it away versus what it's worth. I'm not
| sure what you gain by burning the natural gas into CO2, and
| then converting it back into a hydrocarbon again only for it
| to again be marooned...
| PaulHoule wrote:
| Very similar technology is used to turn CH4 to motor fuels
|
| https://en.wikipedia.org/wiki/Gas_to_liquids
|
| they say
|
| https://en.wikipedia.org/wiki/Pearl_GTL
|
| in Qatar makes about 95 million barrels of liquid a year at
| $40 a barrel.
| acidburnNSA wrote:
| There are places you can get energy from to do this for sure.
| But you're still putting energy into an energy conversion,
| _not_ getting energy out of CO2. (Unless you 're doing some
| kind of late stage stellar nucleosynthesis fusion, which...
| you're not)
|
| The headline should be: "Fuel components from air synthesized
| into liquid fuel using energy from some other energy source"
| simondotau wrote:
| An inefficient process is still infinitely more efficient
| than nothing.
|
| I think there's an opportunity to formalise an excess
| energy marketplace, established with an inefficient process
| to get the ball rolling. From there, market forces can
| dictate winners.
| ticviking wrote:
| The big thing here is in theory we could put something
| like a nuclear plant(which people are afraid of) in a
| remote area and produce fuels we are already equipped to
| use from that pretty major energy source.
|
| Combine that with Solar storage and geo-thermal storage
| using that and maybe we will continue to have enough
| movable energy to have long distance travel that isn't
| wind driven.
| PaulHoule wrote:
| There is even talk of using a nuclear heat source to
| drive petrochemical transformations in China as well as
| the US
|
| https://www.osti.gov/biblio/23032635
| Animats wrote:
| Yeah, these articles are consistently vague about the energy
| inputs and outputs of the process.
|
| This isn't even a closed cycle. It uses up potassium hydroxide.
|
| Electrolyzing water into hydrogen and oxygen is more promising,
| if you like that sort of thing. Once you have hydrogen, you can
| make hydrocarbons, if you want to. That's good to have as a
| technology for when we use up all the natural hydrocarbons and
| still want to make plastics. As an energy storage system, it
| sucks.
| bparsons wrote:
| There are a million ways to produce smaller amounts of energy
| from larger amounts of grid energy. This isn't really useful.
| Gibbon1 wrote:
| Yeah it's like the old snark about investing. It's being easy
| to make a million dollars. Just start with two million dollars.
|
| The gross thing about this stuff is it's predicated on the
| average person not being able to do the engineering and
| accounting calculations to realize it's all lies.
| 0xf00ff00f wrote:
| Does anyone know whatever happened to Prometheus Fuels?
| mgiampapa wrote:
| Still burning money, but looking for things where green
| premiums can be paid like for woke Zero Net Carbon aircraft.
| tjkrusinski wrote:
| It was anecdotal, but I met someone who worked with folks who
| worked there, there's a lot of smoke and mirrors and they don't
| really have what they say they have. Unfortunate as it looked
| really promising.
| AtlasBarfed wrote:
| The low temp requirements look promising, but wake me up when the
| cost of the system at scale is known.
|
| Obviously things like long haul aviation need synthfuels, but I
| wouldn't hold my breath that this will be the magic bullet for
| keeping the ICE relevant in the next century.
| rootusrootus wrote:
| Given how inefficient ICE is to begin with, I can't imagine
| something like this being used for any transportation that can
| be easily electrified. This is really for niche cases like air
| travel, I assume.
| subradios wrote:
| ICEs are incredibly efficient. Electricity is only efficient
| if you only care about kwh delivered to the car doing to the
| wheels. The efficiency of getting kwh from the grid to the
| car puts it well worse than most battery setups.
| tuatoru wrote:
| Methanol is a feedstock for lots of industrial chemicals too.
| pfdietz wrote:
| Methanol can be turned into gasoline by the ExxonMobil MTG
| process.
|
| https://www.exxonmobilchemical.com/en/catalysts-and-
| technolo...
| PaulHoule wrote:
| This is not really new, lots of people are writing papers on
| different paths to this.
|
| There was a huge interest in synthesizing motor fuels from coal
| or natural gas up to 1980, it makes for depressing reading
| because the Fischer-Trospch chemistry for building up
| hydrocarbons from hydrogen and carbon monoxide has awful
| economics. For anything else people would be happy that iron
| works as a catalyst but they scoured the rest of the periodic
| table looking for something better and didn't find it. You have
| to run the reaction at low temperatures otherwise you get
| nothing but methane, but under those conditions reactions that
| build up and break down hydrocarbons are closely balanced so
| you have a huge machine which makes a trickle of fuel so the
| capital costs are high.
|
| Looking at the history you'd think somebody would tell the
| airplane engineers that they should just go clean sheet and
| figure out how to fuel airplanes with hydrogen or methane but
| they are so used to being coddled (like that time the FCC
| couldn't make them upgrade their broken altimeters or how they
| are just barely starting to remove lead from GA fuel after all
| these years) that they are sending chemical engineers on what's
| been a lost cause for more than a century.
| gumby wrote:
| I've seen a bunch of these over the years; still waiting for one
| that will get traction. The changing cost of oil (mainly making
| externalities fiscally concrete) may change the equation.
|
| The most interesting I ever ran across was people doing
| artificial photosynthesis to produce H2 and combustable oil, e.g.
| Nate Lewis' group at Cal Tech. Same problem: contemporary
| economics.
|
| I'm glad people are still working on these problems.
| [deleted]
| nix23 wrote:
| >still waiting for one that will get traction.
|
| There is one, got traction since millions of years..it's called
| trees:
|
| https://www.britannica.com/science/methanol
|
| >>wood alcohol, or wood spirit
| gumby wrote:
| Unfortunately it consumes a tree, which takes a while to
| replace. Better to be able to build a facility that can
| produce what you need on a continuous basis.
|
| Interestingly I had to reword my comment (plant->facility and
| evergreen-> continuous) to avoid looking like I was trying to
| pun. Natural metaphors are a deep part of our thinking about
| the world.
| pstuart wrote:
| Bamboo seems like an intriguing alternative to trees.
| greenyoda wrote:
| Also, this Wikipedia article specifically discusses the use
| of methanol as a fuel:
| https://en.wikipedia.org/wiki/Methanol_fuel
| Archelaos wrote:
| Or wood gas. At the end of WW2 there were about 500,000
| vehicles with wood gas generators in use in Germany to make
| up for the lack of other fuels.[1] But under today's
| conditions, this possibility does not seem to make economic
| sense.
|
| [1] See: https://en.wikipedia.org/wiki/Wood_gas
| 0xf00ff00f wrote:
| I like this one: https://www.aircompany.com/products/air-vodka/
| bryanlarsen wrote:
| Terraform industries used to claim that their natural gas would
| be cheaper than local natural gas in 2027. They now say that
| the IRA has moved that timeline up to 2024.
|
| https://terraformindustries.com/
| selimthegrim wrote:
| Lewis retired last month I believe.
| narrator wrote:
| The problem is energy conversion efficiency. Sure you can make
| synthetic jet fuel from solar panels, water and CO2 but the
| efficiency is miserable[1]. It's something like 4% efficient
| and the metal catalysts sometimes aren't cheap. I guess it's
| important to start somewhere and work on efficiency
| improvements until it makes economic sense.
|
| [1]https://www.cell.com/joule/fulltext/S2542-4351(22)00286-0
| SamBam wrote:
| As solar becomes cheaper and cheaper, low efficiencies may
| still be worth it. We're never going to power a 747 on solar,
| but if the energy in the fuel comes from the sun, even if 90%
| of that is "wasted," it's still greener.
| mschuster91 wrote:
| Doing the process with standard technology will always be a
| PITA, partially because catalytic agents tend to not just be
| expensive but primarily sourced from questionable or enemy
| nations.
|
| I think the eventual answer will be in genetically engineered
| microbes or plants, if only because it is easier to scale up
| vats with microbes and nature already has figured out
| synthesis paths for ages.
| eganist wrote:
| > When air was bubbled through potassium hydroxide dissolved in
| ethylene glycol and the CO2-loaded solution subsequently
| hydrogenated in the presence of H2 and a metal catalyst, complete
| conversion to methanol was observed at 140 degC.
|
| Am I missing something? Isn't the need for hydrogen gas here a
| constraint?
|
| It's either gonna be refined (steam reforming) or split from
| water.
| retrac wrote:
| The point is that methanol is a liquid which you can pour into
| a tank like regular gasoline and will run with many existing
| engine designs. It is also useful for a variety of industrial
| purposes. Similarly, methane can be piped in existing natural
| gas infrastructure and burned in existing boilers. Hydrogen, by
| comparison, is hard to store, harder to work with, and lower
| density.
|
| There is no readily available carbon-neutral substitute for
| aviation fuel, gasoline, artificial fertilizers, or even
| natural gas. Synthesis from carbon-neutral power would provide
| it. Germany liquefied coal into methane and methanol at an
| industrial scale during WW II due to lack of oil imports. This
| is the same idea, just switching the heat and CO2 and H2 to a
| different source besides coal.
|
| It's also possible to synthesize ammonia (fundamental to
| synthetic fertilizers and all kinds of chemistry) from H2 + N2
| + C02 + heat in the presence of a catalyst.
| pfdietz wrote:
| Why is hydrogen itself, turned into ammonia, not a substitute
| for use of fossil fuels to make artificial fertilizers. Sure,
| urea contains carbon, but there are plenty of N fertilizers
| other than urea.
| kyleyeats wrote:
| Ethanol is a carbon-neutral substitute for gasoline, no?
| coderenegade wrote:
| It can be, but methanol is produced catalytically, unlike
| ethanol, which is made via fermentation and competes with
| crops for arable land. You can make ethanol catalytically
| as well, but afaik it typically involves making methanol
| first. Methanol has slightly less energy density, but it
| has the advantage of burning cleaner than any other fuel
| (no carbon-carbon bonds, so no soot), and it's easier to
| crack using waste heat, which is a pathway to more
| efficient engines (you can boost the LHV of the fuel by
| around 20% this way).
| fooker wrote:
| Ethanol can be potentially carbon neutral, given a ton of
| terms and preconditions.
| tuatoru wrote:
| H2 is necessary, yes. It can be provided by electrolysis of
| water, air captured if necessary.
| eganist wrote:
| Yeah that feels like it defeats the point. Not that I know
| the math, but it feels like there's a potential for it to be
| a net contributor of carbon emissions by encouraging more
| steam reforming of cng (and thus more cng pumping) or through
| power consumed to split water--power which invariably will
| come from dirty sources until we've done a better job moving
| away from dirty power.
|
| I'd be curious to see someone graph out where this
| transitions from being carbon positive to being carbon
| negative (or vice versa)
| bryanlarsen wrote:
| Here's a scale model of a methane production plant
|
| https://twitter.com/TerraformIndies/status/1591255472572895
| 2...
|
| If you burn gas to create gas, you end up with less gas
| than you started with. It'd be cheaper to burn dollar
| bills. It only works when the input energy is cheaper than
| the output energy. Right now solar and wind are the only
| energy sources cheaper than fossil energy.
| PaulHoule wrote:
| No, e-Fuels like this are a way to make fuel from carbon
| free sources and that means splitting water to make
| hydrogen and sucking CO2 out of the air.
|
| The navy is interested in making e-fuels from electricity
| on nuclear aircraft carriers since a gallon of jet fuel
| delivered to an aircraft carrier costs a lot more than a
| gallon of jet fuel delivered to a civilian airport and the
| aircraft carrier has to slow down a lot so a tanker it
| refuels from can catch up with it.
| DennisP wrote:
| The point is not to get free energy. The point is to turn
| energy into hydrocarbon fuels that can be used without net
| carbon emissions, especially for vehicles that aren't easy
| to electrify.
| SoftTalker wrote:
| Yes, this sort of thing is best thought of as a different
| sort of battery. You put energy in, and later get energy
| out. It's not a fuel.
|
| If you could do it with solar power, it's sort of like
| free energy but no more than charging batteries from
| solar is. There are still infrastructure costs at
| minimum.
| jalk wrote:
| Potentially also as way of storing excess wind/solar
| generated energy
| pfdietz wrote:
| A problem with ideas like these is that they have to be cheaper
| than burning fossil fuels and then capturing and sequestering CO2
| to compensate. Both schemes capture CO2, so that part of the cost
| cancels out. Sequestering CO2 once you have it shouldn't be very
| expensive, especially if it can be used to stimulate more
| petroleum production.
|
| If you're going to capture CO2 from the atmosphere it may be very
| favorable to do it at high latitude, where air is colder. I
| wonder if this could be sold to Russia as a way for them to make
| money in a post-fossil fuel world.
|
| https://www.cell.com/iscience/fulltext/S2589-0042(22)01836-3
| bryanlarsen wrote:
| Capturing the CO2 is the most expensive part of the process.
|
| Pumping fossil fuels out of the ground and then capturing and
| storing the resulting carbon is likely going to be more
| expensive then capturing carbon, synthesizing the fuel and
| burning the synthetic fuel. But in both scenarios capturing the
| carbon is the dominating cost so they're always going to be
| roughly comparable.
| joe_the_user wrote:
| Who says the fossil fuel carbon will be captured? It's
| certainly not now and who says carbon capture is ever going
| to be enforced?
|
| The only hope I have is that solar energy becomes so cheap
| that it can be profitably used to produce synfuel and so
| drive petroleum from the market. Actual regulation would be
| better but that seems as far as ever.
| Animats wrote:
| Brought to you by the Loker Hydrocarbon Research Institute.
| Mission statement:
|
| _" The final solution to the hydrocarbon shortage will come only
| when mankind can produce unlimited cheap energy as with the
| promise of safer atomic energy and other alternate sources. With
| abundant cheap energy, hydrogen can be produced from sea water
| and then combined with carbon dioxide to produce hydrocarbons. In
| the meantime, however, it is essential that solutions be found
| that are feasible within the framework of our existing
| technological base. The Loker Hydrocarbon Research Institute is
| at the forefront of this effort."_
| yathern wrote:
| Note: This is from 2020
| rqtwteye wrote:
| With enough energy input you can do a lot of interesting things.
| Question is where you get the energy from.
| [deleted]
| mentos wrote:
| From a very high level I wonder if we could use nuclear power to
| drive a CO2 capture mechanism to 'make up' for all the time spent
| burning fossil fuels instead of nuclear?
| bparsons wrote:
| This would be a good investment once the grid is over 100%
| renewable. Until then, just use the renewable power for
| consumption.
| epistasis wrote:
| There are many many many startups focused on this. If we engage
| in the amount of carbon capture that is predicted to be
| necessary in the second half of the century, we will be moving
| the same order of mass of air-extracted carbon to its fins
| resting place each year that we are currently moving for
| fueling. So a massive massive economy is expected to be built
| around this.
|
| Nuclear power is unlikely to make financial sense as a source
| of electricity for this process. Many of the early pioneers
| were big supporters of nuclear for it last decade, but solar
| photovoltaic has made nuclear obsolete in comparison. I think
| the name of that startup was Carbon Engineering, bawd out of
| Canada... the founder was completely shocked at the advancement
| in solar, and at the time (a few years ago) thought that, by
| 2030, it would be possible to make liquid hydrocarbon fuels out
| of air+solar for roughly the same cost or lower as fossil
| fuels.
| coredog64 wrote:
| Originally, these types of systems relied not only on the
| electricity but also some of the heat output of the nuclear
| plant. If you're having to do both with solar, then the
| efficiency is that much lower.
|
| With that said, according to the abstract, this
| implementation doesn't require excessive heat energy so you
| could probably get away with solar thermal for that bit.
| dotnet00 wrote:
| If we were willing to significantly overbuild nuclear power
| production capability yes, but from what I understand with
| current carbon capture efficiency it's more effective to have
| that nuclear power directly offset current energy consumption
| instead.
| themoonisachees wrote:
| From a logical standpoint carbon capture is a scam [0]. The
| argument is "if you don't have spare energy, why are you
| spending it on carbon capture? And if you have spare energy
| (you don't), why not spend the money you usee to build the
| over capacity to bring clean energy somewhere else?"
|
| That is all assuming your entire power grid is 100% clean (it
| isn't) because otherwise you fall in case 0 where you spend
| energy that could be spent on offsetting non-clean energy
| usage.
|
| [0] https://youtu.be/nJslrTT-Yhc
| bsdetector wrote:
| This videos shows the perverse mindset of climate activists
| that you "have to change your lifestyle" and personally
| suffer to solve the problem. It's a common refrain and
| erroneous, but here particularly so as _only_ carbon
| capture, mechanical or natural, can fully solve the problem
| -- that is, there 's already too much greenhouse effect and
| even an extreme agrarian lifestyle won't solve the problem.
|
| Climate change is a problem nobody can personally solve and
| I think this personal suffering makes them feel like
| they're doing something.
| kbenson wrote:
| It depends on the speed of capture. If you can capture
| faster than conversion reduces, and there are time
| constraints that mean reducing carbon now is better than
| later, then it can make sense.
|
| It's the same as whether you should reduce expenses or
| increase income. Both yield a net increase, but there are
| variables than can make one better than the other in the
| short term. Whichever yields the most benefit for the
| effort is probably the best one, or if one has a time
| constraints and the other doesn't, that might be the best
| one to focus on.
| dotnet00 wrote:
| I wouldn't go as far as to argue that it's a scam, I do
| think it's a complex issue which might require rethinking
| the way we geographically distribute infrastructure.
|
| Carbon capture from the atmosphere is certainly extremely
| inefficient and not too practical (yet, at least), but
| carbon capture straight from large emitters like at
| factories should be much more efficient as it isn't having
| to go through as much air.
|
| Combined with the difficulty of transporting electricity in
| many circumstances, carbon capture solutions which involve
| cleaning up the output from factories using something like
| an on-site small-modular reactor are probably a lot more
| practical. While of course the SMR would be better spent
| replacing a fossil fuel plant in the immediate term, in the
| longer term the output from the factory would also need to
| be cleaned up anyway.
|
| So given enough serious interest in building SMRs/getting
| rid of fossil fuels, the temporary cost of allocating an
| SMR to carbon capture at a factory would be small compared
| to allocating it to replacing a fossil fuel plant (since
| another would be built soon enough to replace the latter).
| fooker wrote:
| The counterpoint is that energy can be difficult to
| transport, but the atmosphere dissipates carbon for free.
| So it might sense to do this where you produce energy, to
| use up extra energy which could be otherwise wasted.
| SamBam wrote:
| Except that energy production is local, while carbon
| capture is global.
|
| If you power a carbon capture device in Greenland using
| geothermal, you can probably get a lot more energy than you
| can reasonably give you the grid. In that case, using the
| rest for carbon capture makes sense.
|
| Further, carbon capture is going to need to be part of our
| future mix, as we'll never be able to be 100% green in the
| reasonable future. It's good to spend a tiny percentage of
| our resources now improving the technology.
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