[HN Gopher] MIT engineers make converting CO2 into useful produc...
___________________________________________________________________
MIT engineers make converting CO2 into useful products more
practical
Author : rbanffy
Score : 134 points
Date : 2024-11-13 15:42 UTC (7 hours ago)
(HTM) web link (news.mit.edu)
(TXT) w3m dump (news.mit.edu)
| VyseofArcadia wrote:
| Time scale is also something I want to know about. "Can I remove
| CO2 from the air and turn it into something valuable in a way
| that is cost effective?" is one question. Another question is,
| "Can I remove CO2 from the air and turn it into something
| valuable faster than a tree?"
| ben_w wrote:
| As this is more of "can we make carbon sequestering
| commercially viable, or at least less lossy", I'm less worried
| about that and would be more concerned about the global market
| for ethylene being "316.8 Million Tonnes in the year 2023"*,
| compared to the tens of gigatons of CO2 emissions -- though on
| the plus side, I'm optimistic about removing _most_ of those
| emissions and this kind of thing is still fine for the last
| 10%.
|
| As for "less lossy" even if it's not always a commercial winner
| alone: my guess would be there's always going to be an easier
| way to get CO2 than "from the air", unless you're on Venus or
| Mars: take tree (or coal), cut up, put chips in oven, set on
| fire. Much higher CO2 concentration than air, likely to make
| most things that need CO2 much easier.
|
| * https://finance.yahoo.com/news/global-ethylene-industry-
| repo...
| sampo wrote:
| > "Can I remove CO2 from the air and turn it into something
| valuable faster than a tree?"
|
| In some climate zones, grasslands do it better than forests.
|
| https://climatechange.ucdavis.edu/climate/news/grasslands-mo...
| criddell wrote:
| A tree gives you wood. What are the valuable outputs of
| grasslands?
| Kostic wrote:
| Chernozem.
| thechao wrote:
| https://en.wikipedia.org/wiki/Chernozem
| lupusreal wrote:
| Does bamboo count?
| criddell wrote:
| Maybe. I know it actually _is_ grass, but are bamboo
| growths called grasslands?
| nostromo wrote:
| You can make it into a carbon-neutral heating fuel.
|
| You can make paper products including things like cardboard
| and packaging.
|
| You can put livestock on it and produce meat.
|
| Or if you just want to sequester carbon, you can harvest it
| and bury it deep in the ground.
| sampo wrote:
| > What are the valuable outputs of grasslands?
|
| If you use grasslands for grazing cattle you get meat, or
| also wool with sheep. Sequestering carbon into grassland
| soil (or into any soil, really) makes them better at
| absorbing and retaining rainwater, reducing the risks of
| catastrophic floods in the watershed area.
| criddell wrote:
| Good points. I wasn't thinking of second order products.
| Tyr42 wrote:
| Cows?
| undersuit wrote:
| https://en.wikipedia.org/wiki/Cellulose#Commercial_applicat
| i...
| marcosdumay wrote:
| Grass always do it better than trees.
|
| And the GP is quite wrong, because almost everything will be
| more efficient than trees or grass. Machines are just way
| more expensive, that's why nobody ever made them.
| newsclues wrote:
| What is smarter, spending years researching and arguing the
| best way to do this, or using the natural process all over,
| and adapting the best practice locally, to try to solve
| climate change?
|
| Some places can plant trees, others grasslands. Or whatever,
| but it seems like there is a lot of money to create an
| industrial process that can be commercialized instead of just
| doing the work naturally...
| not2b wrote:
| My guess is that it would be much more effective to capture and
| remove CO2 directly at the source, for example at a cement
| plant. While this could be done at a fossil fuel plant as well,
| it seems a lot less attractive: you give back most of the
| energy you just got from burning the fuel.
| Suppafly wrote:
| They should sell it to people for their car tires with a
| specially colored valve cap like they do for nitrogen. It'd be
| stupid, but so is paying extra for a slightly higher nitrogen
| content and people do that.
| jandrese wrote:
| That sort of application is just spitting into the ocean when
| you're talking about global CO2 emissions and sequestration.
| BenjiWiebe wrote:
| Plus it all comes out of the tires in the end anyways.
| danbruc wrote:
| I have not thought about this too carefully so I might be
| overlooking something. With that out of the way, a quick search
| indicates that we burn about 90 % of gas, oil, and coal for one
| purpose or another. Let's round this and pretend we burn it
| all. To undo this we will essentially need the same amount of
| energy again that we got out of it when we burned it, we would
| need to use all the energy coming from fossil fuels to undo
| burning them. Conservation of energy essentially.
|
| Which makes it obvious that the entire idea is pretty
| pointless, burn fossil fuels to generate energy to then use it
| to unburn fossil fuels. To do it with renewable energy, we
| still need the same capacity as the fossil fuel capacity and
| when we have that - ignoring issues like fluctuations in
| renewable sources - it makes more sense to just use the
| renewable sources directly instead of using them to undo
| burning fossil fuels.
|
| If you want to use the process to pull carbon out of the
| atmosphere, then you first have to replace all fossil fuels
| with renewable ones, then you can use additional renewable
| capacity to remove carbon. Add additional 10 % capacity to the
| world energy capacity to undo one year of carbon emissions
| every decade, at least to a first approximation.
|
| To come back to the initial question, you essentially need an
| industry the same order of magnitude as the fossil fuel
| industry to have a meaningful impact. Not going to happen
| anytime soon.
| TSiege wrote:
| The point that you're missing is that changes this equation a
| bit is that burning fossil fuels wastes most of the energy as
| heat another waste of energy is the amount of FFs we use to
| ship FFs to other places. So together that means we don't
| need the same amount of electric power to do the same amount
| of work. That being said, keeping fossil fuels in the ground
| will always be better than removing CO2 for the reasons you
| said. We also seem to be growing energy demands instead of
| shrinking or stabilizing them which also makes the transition
| harder.
| axus wrote:
| Lots of solar on-site that doesn't need to transfer it's
| power elsewhere could be used; maybe the real winner would be
| 100% solar-powered solar panel factory :)
| toss1 wrote:
| >>we would need to use all the energy coming from fossil
| fuels to undo burning them
|
| This would true if we need to re-create the original molecule
| with it's stored energy (plus losses of course).
|
| However, it seems this is a misapprehension of the task.
| Instead of trying to recover the entire hydrocarbon molecule,
| we're "just" trying to extract or recombine the CO2 reactant.
|
| Without doing the chemistry or the math, it seems likely that
| a variety of methods of either preferentially attracting CO2,
| or combining it into simpler lower-energy-dense molecules to
| be collected, would require less energy as was in the
| original hydrocarbon, often substantially less.
|
| Seems it should be an inequality, not an equality. Or am I
| missing something?
| thinkcontext wrote:
| > To undo this we will essentially need the same amount of
| energy again that we got out of it when we burned it
|
| Amine based carbon capture at the smokestack captures about
| 90% of CO2 with a 20% energy penalty. There's a new natural
| gas turbine design that captures 100% at no energy penalty
| (Allam cycle).
| userabchn wrote:
| Have there been any recent developments in "lab-grown wood"?
| The last time I looked into it there had been some research on
| it (also at MIT), but there didn't seem to have been any
| updates for a few years.
| Clippybara wrote:
| Permeating the PTFE layer with copper electrodes in order to get
| _both_ hydrophobicity and conductivity seems stupidly simple, but
| the best ideas often are. I also greatly admire how their model
| looks like a s 'more lol
| mchannon wrote:
| The writer appears to be under the impression that CO2 is not a
| valuable commodity.
|
| In fact, it is, so long as it's under enough pressure, and in the
| right place. In Montezuma County, Colorado, sits the McElmo dome,
| an ancient underground CO2 well. They pump it out, down a 500
| mile pipeline, to Denver City, Texas, where it gooses oil wells
| into pumping more crude out. Other than making more oil and
| making it cheaper, not really much in terms of greenhouse gas
| contributions- the CO2 starts underground and ends up
| underground.
|
| Kinder Morgan won't just let you back up your truck and buy some
| (it's already spoken for), and even if they would, they'd expect
| you to pay a pretty penny for what we widely consider to be waste
| gas.
|
| I think MIT is doing some good work. Just wanted everyone to be
| mindful of the massive scale under which CO2 is already getting
| bought and sold.
| ulrikrasmussen wrote:
| Isn't it also used as input to basically every e-fuel which can
| replace fossil hydrocarbons?
| analog31 wrote:
| No. The value of commercial co2 is its energy content -- what
| it takes to process it into useful form. There is no useful
| form of co2 for making fuel. The energy has already been
| extracted.
| jvanderbot wrote:
| You're right (current state of the art), but also wrong (in
| the spirit of the question as I read it).
|
| If energy prices go down, e.g., from continuing decline of
| solar, then it may be very cost effective to store energy
| as hydrocarbons which are synthesized from cheap energy +
| CO2. E.g., make natural gas from the air and sell it
| cheaper than it could be extracted and transported.
|
| In this scenario, rather than paying exorbitant fees for
| CO2, the cheap energy could be used to extract it from the
| atmosphere where it is abundant.
|
| Before anyone bites my head off - consider the tyranny-of-
| the-rocket-equation problem of burning gas to transport gas
| from source (wells, refineries, etc) to consumers. Then
| consider that the sun shines most places, and CO2 is
| effectively uniformly distributed. So Synthesis wouldn't
| have to be cheaper at the source if it can beat the price
| at the consumer via avoiding huge distribution costs.
| SoftTalker wrote:
| Exactly right. FTA: "The electrochemical process that
| converts CO2 into ethylene involves a water-based solution
| and a catalyst material, which come into contact along with
| an electric current"
|
| That "electric current" is the challenge. It _takes_ energy
| to convert CO2 into other chemicals. If that energy isn 't
| carbon-neutral, you're just spinning your wheels.
| pwg wrote:
| > If that energy isn't carbon-neutral, you're just
| spinning your wheels.
|
| True, but the "long term" angle here would be to supply
| that energy from, say, excess solar generation during
| midday after the overnight storage batteries are
| refilled.
| ulrikrasmussen wrote:
| I'm not sure if we are talking past each other, but:
| https://en.wikipedia.org/wiki/Electrofuel
|
| _Electrofuels, also known as e-fuels, are a class of
| synthetic fuels which function as drop-in replacement fuels
| for internal combustion engines. They are manufactured
| using captured carbon dioxide or carbon monoxide, together
| with hydrogen obtained from water split._
|
| It is my understanding that there is actually a shortage of
| concentrated co2 if we want to produce e-fuels as drop-in
| replacements in e.g. planes.
| analog31 wrote:
| All ideas for "fuels" hinge on the future availability of
| an economical energy source, which would have to be
| either solar or nuclear.
| outworlder wrote:
| I wonder what happened to the Navy's attempts at
| synthesize aviation fuel in aircraft carriers. They have
| plenty of power (newer carriers have even more) and
| reducing or eliminating the need of support craft for
| fueling would be a massive bonus.
|
| They've been looking at that for a while, I don't know
| what issues they encountered.
| thinkcontext wrote:
| They couldn't get it to be efficient enough.
| alexose wrote:
| It's not that CO2 isn't valuable on its own, but that other
| carbon-containing molecules are even more valuable (especially
| when factoring in transportation costs). This helps prove out
| the technoeconomics of carbon capture.
|
| Plus, if we wind down oil extraction, we'll need new processes
| to produce all the precursors we use for plastics. A cheap
| pathway to ethylene from captured CO2 and water would be huge.
| euroderf wrote:
| > A cheap pathway to ethylene from captured CO2 and water
| would be huge.
|
| Is it considered cheap if the marginal cost of a PV MWh is
| close to zero ?
| rhelz wrote:
| The application you mention does not rely on the gas being co2
| at all. The gas is being used because it is in a high pressure
| reservoir. It could by any gas. The C02 itself is literally
| free because it is literally in the atmosphere all around us.
| 0cf8612b2e1e wrote:
| CO2 may be everywhere, but it is at a very low concentration.
| Efficiently isolating CO2 from the rest of the gases is a
| limiting factor.
| ewhanley wrote:
| Pressure is only part of the equation. The pressure gets it
| to the field economically and does boos reservoir pressure,
| but co2 injection has more to do with miscibility with
| hydrocarbons at relatively low pressures. Miscibility yields
| viscosity reduction and swells the oil to improve
| displacement and mobility, particularly in heavier crude.
| Couple that with pressure and you can dramatically improve
| recovery factor.
| telgareith wrote:
| That sounds like a lot of it ends bound to, and thus comes
| up with, the oil/crude.
| ewhanley wrote:
| It absolutely does and has to be stripped out in
| processing. It typically gets compressed and reinjected
| over and over again
| alach11 wrote:
| Exactly. And getting back to the original poster's
| comment "the CO2 starts underground and ends up
| underground"... that assumes there are no leaks anywhere
| in the process.
| kaibee wrote:
| > The C02 itself is literally free because it is literally in
| the atmosphere all around us.
|
| Not exactly.
|
| > The concentration of carbon dioxide (CO 2) in the
| atmosphere reach 427 ppm (0.04%) in 2024.
|
| Any process that tries to unmix something is not going to be
| 'literally' free. And given the relative trace amounts we're
| talking here...
| timeon wrote:
| Yes but this is not relevant in context of climate change. It
| does not matter that we can bury some CO2 while more of it is
| added to atmosphere.
| vkou wrote:
| So, capturing CO2 from the air can be used to put out even more
| CO2 into the air. Fantastic.
| marcosdumay wrote:
| Well, netting ~95%1 of the extracted carbon as new release on
| the atmosphere is technically better than 100%. They could be
| using nitrogen instead.
|
| But yeah, it's quite underwhelming.
|
| 1 - Wild guess. But it's certainly less than 100%, and
| certainly not by a lot.
| vkou wrote:
| It can be way worse than 100% if the reduced oil extraction
| costs (or greenwashed accounting from earning carbon
| credits for sequestration) results in more net oil being
| extracted, than there would have been without access to
| CO2.
|
| Not to mention the energy costs of actually pulling carbon
| out of the air. Often, getting 1kg of CO2 out of the air
| ends up costing so much energy that you end up emitting
| more than 1kg of it.
|
| If sequestration weren't a fairy tale that will keep us
| distracted for another few decades while we continue to
| ruin our environment, people would be doing it, not talk
| about doing it.
| hn_throwaway_99 wrote:
| It the example you give, CO2 gas is _not_ really a valuable
| commodity. _Pressure_ is the valuable commodity in that
| example, and so it 's kind of irrelevant when discussing carbon
| sequestration solutions.
| alach11 wrote:
| That's not correct. If pressure was all that mattered, we'd
| just run compressors on nitrogen (or formation gas). CO2 has
| properties that make it especially favorable for flooding.
|
| https://en.wikipedia.org/wiki/Carbon_dioxide_flooding
| outworlder wrote:
| Has to be both. A random gas might interact with the oil
| being pumped. Why don't they just use compressed air? There
| must be a reason why CO2 is desirable for that application.
| eppp wrote:
| So CO2 is magical here or would a reservoir of highly
| pressurized atmosphere be just as valuable? I think you are
| missing where the value is in this situation.
| regularfry wrote:
| Strongly suspect you don't want pressurised oxygen-
| containing-atmosphere in that situation.
| guiriduro wrote:
| Well, it uses PTFE which is a kind of PFAS which doesn't have a
| clear future and shouldn't be scaled up for good reasons, e.g. :
| https://www.gmp-compliance.org/gmp-news/restrictions-for-ptf...
| idunnoman1222 wrote:
| Only carbon matters
| outworlder wrote:
| Interesting. PTFE tubes are used for 3D printers (although it's
| a small quantity and they aren't consumable), but I didn't know
| it was so much more harmful than other plastics.
|
| Edit: just realized that PTFE _is_ Teflon. Makes more sense
| now.
| travisporter wrote:
| But isn't copper quite expensive? I didn't see them address this
| jandrese wrote:
| Depending on how long the electrodes last the cost of the
| system will probably be dominated by the electricity, not the
| raw materials used in the construction. I have not done the
| chemistry, but my gut feeling is that breaking all of those O2s
| off of the CO2 and all of the O2s off of the H2Os is going to
| be the expensive part of this process.
| kokanee wrote:
| Electrochemical cells (especially PEM electrolyzers) are
| notorious for containing materials far more expensive than
| copper (noble metals). But they pay for themselves much more
| quickly than you might think, if you can get offtakers to
| actually purchase and use the resulting products.
|
| The biggest challenge facing these climate tech industries
| right now is the chicken-and-egg problem. You can't make
| anything cheaper than the centuries-old fossil-based
| competition unless you do it at scale; you can't scale it
| without offtakers; offtakers won't participate unless it is
| cheaper than the status quo.
|
| There are compounding issues with expensive infrastructure
| upgrades (e.g. airplane or maritime engines that need to be
| upgraded to handle new fuels; pipelines or fuel trucks that
| need to be build to handle hydrogen, etc) that further push out
| the break even date. And then you have oil & gas companies
| inserting themselves into these efforts in order to greenwash
| their businesses, causing many would-be supporters to oppose
| entire clean technologies due to the perception that green tech
| startups are in bed with the fossil industry.
| outworlder wrote:
| > The biggest challenge facing these climate tech industries
| right now is the chicken-and-egg problem. You can't make
| anything cheaper than the centuries-old fossil-based
| competition unless you do it at scale; you can't scale it
| without offtakers; offtakers won't participate unless it is
| cheaper than the status quo.
|
| That's the exact sort of thing governments are supposed to
| solve.
| regularfry wrote:
| It's also a marketing problem. As long as the product is a
| commodity, it's a margins game. As soon as you can
| differentiate it somehow there's room to be more expensive
| and still sell the product.
|
| Just as an example that might be incredibly terrible for
| other reasons, I can imagine Ikea selling, say, furniture
| with plastics made from this particular ethylene source.
| They might explicitly mark it up somehow saying "this chair
| directly offsets a week's worth of car driving", or
| whatever, and done right, with the right choice
| architecture, people might be willing to pay _considerably
| more_ for it than stock.
|
| I am, as you can probably tell, no marketer. But part of
| the answer has to be to get it out of the commodity bucket.
| jandrese wrote:
| The article annoyingly failed to close the loop from the
| $1,000/ton figure at the top and do the math on the economic
| efficiency potential of this approach. How much electricity is
| required to sequester each ton of CO2 using this method, assuming
| you can amortize the construction costs over some long duration?
| I assume the intended installation is on the exhaust of a fossil
| fuel burning facility, but is it possible to install this next to
| a solar field and generate ethylene from excess mid-day
| production? Large scale carbon sequestration is one of the major
| unsolved problems of the 21st century and we have to expect many
| false starts before the really viable technologies emerge.
| slwvx wrote:
| One place to look for some math on the economic efficiencies is
| the blog of Terraform industries. Here's a start:
|
| https://terraformindustries.wordpress.com/2024/04/01/terrafo...
| jandrese wrote:
| > There is no hand waving about economies of scale or
| subsidies here, though we are eligible for the _full IRA 45V
| green hydrogen tax credit_ , worth $3/kg-H2.
|
| Their business model may have a slight problem.
| bryanlarsen wrote:
| They're saying that they don't need the green hydrogen tax
| credit. The tax credit makes their product profitable
| sooner, but as long as solar keeps following it's cost
| curve for a couple more years they'll be fine without it.
| fao_ wrote:
| > Their business model may have a slight problem.
|
| Oil is subsidized to a much higher amount by the US
| government
| jandrese wrote:
| Yeah, but that subsidy is not likely to disappear in 2
| months.
| marcosdumay wrote:
| Hum... No, the people studying new catalyzer shapes didn't do a
| through market research for a carbon sequestration plant.
| gipp wrote:
| Yeah, figuring out a remotely accurate figure for that is at
| least as hard as the work done here, and requires pretty
| different sets of expertise
| kleton wrote:
| If they are sequestering by reducing (in the sense of donating
| electrons to) carbon, then that will, by thermodynamic
| necessity, require more energy input than oxidizing that carbon
| originally provided. Converting to ethylene, as they mention in
| the article, is such a process.
| szvsw wrote:
| There are plenty of papers which look at precisely the economic
| and carbon tradeoffs of these sorts of processes. It all just
| depends on where you are. When you have a clean grid and a
| cheap grid, these methods become pretty feasible.
|
| Take a look at De Luna et al, Science 364 2019 [1]
|
| [1] https://www.science.org/doi/10.1126/science.aav3506
| bitwize wrote:
| My wife actually has established a cheap, energy-efficient
| facility for converting CO2 into useful materials right in our
| yard.
|
| She planted a garden.
|
| I was thinking about that the other day, how our beautiful trees,
| flowers, and bushes draw a few minerals from the soil, but are
| really mainly knitted together from the components of water and
| CO2.
|
| Yes, yes, I know, planting more trees won't do much about the
| greenhouse gas problem at scale, but the only thing that will are
| the three P's: powerdown, permaculture, population control. I do
| not expect industry to solve the problem industry created in a
| way that doesn't create more problems.
| zelphirkalt wrote:
| > Yes, yes, I know, planting more trees won't do much about the
| greenhouse gas problem at scale, but the only thing that will
| are the three P's: powerdown, permaculture, population control.
| I do not expect industry to solve the problem industry created
| in a way that doesn't create more problems.
|
| But I am always wondering: Couldn't we have planted forests,
| from which we take the grown trees and put them back down under
| the earth, in some old mining facilities or dig some tunnels
| that lead deep down and put that stuff there? Or perhaps build
| lots of long term use furniture from the trees? Anything,
| except burning them or letting them rod? Then we would use
| nature's mechanism for capturing and prevent releasing, by
| putting it deep down, or making meaningful long term use of it.
|
| And couldn't this be done on a bigger scale as well?
| jjmarr wrote:
| > Couldn't we have planted forests, from which we take the
| grown trees and put them back down under the earth, in some
| old mining facilities or dig some tunnels that lead deep down
| and put that stuff there?
|
| This is basically how coal was created in the first place.
|
| https://en.wikipedia.org/wiki/Coal_forest
|
| Assuming carbon in = carbon out, we'd have to plant trees for
| millions of years on virtually all arable land and bury them
| underground to undo our burning of coal, since that's how the
| coal (which is almost pure carbon) was originally created.
| tmtvl wrote:
| The problem is we're putting millions of tons of carbon into
| the air every year and it takes a while for a freshly planted
| tree to reach a ton of carbon stored. So you would need to
| plant millions of trees per year and take care of them for
| years before you can chop them down and bury them.
| zelphirkalt wrote:
| So I guess it is simply too slow, or alternatively, we
| would all be busy in that business and not do anything else
| any longer?
| nostromo wrote:
| Yes, you could grow and bury trees to reverse the carbon
| cycle. Even just leaving the trees standing is a pretty good
| carbon sink.
|
| Housing is also a great carbon sink as the wood used in
| construction is protected from rotting.
| parpfish wrote:
| > I do not expect industry to solve the problem industry
| created in a way that doesn't create more problems.
|
| but it's not one "industry" that has to change their mind,
| this'd create a whole new secondary industry that is able to
| profit from negative externalities made by the former.
|
| capitalism got us into this mess, but it's also the only thing
| powerful enough to get us out.
|
| if we can get tech that allows us to make an _economic_ case
| for reducing atmospheric CO2, it would be far more robust than
| relying on government regulation and /or unpopular moral
| appeals that ask people to sacrifice.
| bluGill wrote:
| Just switch to EVs for transportation and it will be hard for
| the oil industry to keep going. Many wells will be closed
| despite being potentially productive just because there isn't
| enough demand to keep them maintained. Prices are likely to
| go up for plastics if there isn't much demand for oil as fuel
| just to keep all the oil stuff maintained - much of which is
| too big for their needs so the industry faces shutting down
| working refineries and building new smaller ones or operating
| the current ones at low capacity. And of course the plastics
| industry is also interested in going green, so if this isn't
| too much more expensive than oil based plastic they will
| switch anyway.
|
| The question is how cheap can we do this process and how fast
| can we get transportation off of oil.
| hcarvalhoalves wrote:
| A garden actually isn't that great, it has limited CO2 storage
| capacity once it's in balance.
|
| Productive land, specially timber, is a good way of capturing
| CO2, because it will end up stored in products.
|
| We tend to naively think we should reforest land and leave it
| there, and it can be good for other reasons, but is a poor
| strategy for carbon capture. We need to _aggressively_ go back
| to using timber and vegetable fibers as construction material,
| instead of concrete and steel that have an enormous carbon
| footprint.
| bitwize wrote:
| As someone New Orleans-adjacent, I totally support this and
| think timber use would be even better if we perfected
| techniques for strengthening wood through high pressure at
| construction scale.
|
| I for one would love to see wooden skyscrapers with the
| aesthetic of the movie _Her_ that are as strong as their
| concrete-and-steel equivalents.
| rhelz wrote:
| To remove the co2 we put into the atmosphere will always take way
| more energy than we got out of putting it into the atmosphere in
| the first place. That is just thermodynamics.
|
| To remove all the co2 we put into the atmosphere would take more
| energy than we extracted from fossil fuels since the industrial
| revolution. And all that energy would, of course, have to be
| produced in an absolutely carbon-free manner.
|
| So this is and will remain an entirely impractical method of
| combatting global warming. MIT engineers know this. The people
| who funded this research know this. Why are they doing this?
| zelphirkalt wrote:
| Positive interpretation: Because they hope to find a method of
| doing it, that does not require too much energy, so that that
| method can be done using renewables.
|
| Negative interpretation: Because of look/appearances/prestige.
| jgrossholtz wrote:
| From the article : "The work was supported by Shell, through
| the MIT Energy Initiative." Would it only exist to make people
| believe we can burn fossil fuels since a solution is around the
| corner ?
| HappMacDonald wrote:
| Think of carbon in the atmosphere as a debt.
|
| Obviously you cannot effectively pay off debt using the money
| that you borrowed: that just leaves you with a net loss of the
| interest/friction/inefficiency.
|
| But if you can earn enough money to pay down the debt (which
| naturally also requires weaning off of the deficit spending in
| the first place) via other means such as renewable energy
| sources in great excess to the quantity of fossil fuel energy
| we have produced thus far, then figuring out how to pay down
| the debt as efficiently as possible as soon as possible
| absolutely makes sense.
| bluGill wrote:
| The problem is how fast we are adding "debt". The earth is
| naturally slightly CO2 negative without human intervention.
| However currently there are thousands of years to make up for
| every year of CO2 we are adding. I say thousands, but I
| haven't been able to figure out a true number, so thousands
| is conservative, it could be in the hundreds of thousands.
| UniverseHacker wrote:
| Portable, energy dense fuel is incredibly more valuable than
| grid electricity - especially back when most of it was burned,
| before modern battery technology.
|
| It is not obvious to me that the net thermodynamics are
| important here. The only thing that matters is the real world
| cost vs benefits. Carbon free energy is extremely cheap now,
| and getting rapidly cheaper, yet still not very portable.
| tempfile wrote:
| It can never be as practical as leaving it in the fuel it came
| from. This is a waste of time, and only deepens the pit of
| climate catastrophe.
| HappMacDonald wrote:
| Carbon concentrations in Earth's atmosphere are a problem: a
| mess.
|
| Weaning off of fossil fuel use and transitioning to sustainable
| energy production and storage is among the biggest steps to
| stop making more of a mess.
|
| Carbon sequestration is cleaning up after the mess that has
| already been made.
|
| I see no reason to hold off on performing one of these steps
| until after the other has been finished: both should be done at
| the same time.
| tempfile wrote:
| I think the risk that carbon capture gives governments an
| excuse not to properly regulate emissions outweighs the
| possibility they actually succeed in removing carbon from the
| atmosphere.
|
| On top of that, removing diffuse CO2 from the atmosphere
| requires far more energy than the bare minimum (i.e. the
| energy it released as fuel), because it is diffuse. The
| energy harnessed to do this (e.g. electricity from solar)
| would be put to better use doing actual work.
|
| I think we would require an enormous surplus in power
| generation before carbon capture even registers on the scale
| of useful interventions.
| trueduke wrote:
| In mice?
| yarg wrote:
| Worst case scenario, you can always still turn it into wood.
| mempko wrote:
| It's always going to take more energy to convert CO2 to anything
| useful than it is to burn energy and release it as pollution.
| That means to requester all the extra CO2 in the atmosphere will
| require more energy than it took to put it there in the first
| place. Good luck humanity.
| orthecreedence wrote:
| Humans passively polluted the atmosphere. Perhaps they can
| passively clean it up as well. Electric cars that spend 10% of
| their energy on sequestration or something like that. Exchange
| your CarbonBricks for a discount on useless consumer trinkets.
|
| Ultimately, it doesn't matter whether it's distributed or not,
| the real meat is that the energy used to sequester carbon
| _needs to not come from carbon fuels_. Once that can be scaled
| up, we can clean up at least some portion of this disaster.
| hn_throwaway_99 wrote:
| Perhaps someone with more knowledge can comment on why solutions
| like these can't be used to solve the energy storage problem. Is
| it just economics?
|
| That is, renewables are now the cheapest form of energy by a
| significant margin, but they are unreliable with respect to
| timing, so a storage solution is necessary in order to provide
| electricity on cloudy days when the wind isn't blowing, at night,
| etc. Most of the research I've seen into solving the storage
| issue involves batteries or things like pumped hydro. If things
| like solar and wind were "overbuilt", could a solution like this
| be used to create hydrocarbons when there is excess electricity?
| Power prices already go negative in some places when it's
| particularly sunny/windy. If the excess energy at that time could
| be used to make gas that could then be utilized by gas plants,
| well then there is your net 0 storage solution.
|
| I'm assuming solutions like this are uneconomic (and similarly
| with hydrogen plants, e.g. by using the excess renewable energy
| to generate green hydrogen by electrolysis for storage and later
| use), but I'd like to understand better why.
| gbasin wrote:
| yep it should be possible. check this out:
| https://terraformindustries.com/
| rawgabbit wrote:
| There actually have been several solutions and some proofs of
| concept offered. However except for things like batteries, the
| purists object to all of them as green washing. Why, I don't
| know.
|
| Off the top of my head, I believe someone demonstrated you can
| add thermocouples to your water to generate electricity. The
| idea was that during excess electricity generation during the
| day by a homeowner's solar panels, use that to heat up the
| existing water tank. At night, use the thermocouple to generate
| electricity from the hot water. Granted the efficiency is
| abysmal. But 5% of something is better than 0% which is what
| happens when the electricity is thrown away.
| gipp wrote:
| > I'm assuming solutions like this are uneconomic
|
| You kinda answered your own question already, I feel. The
| energy efficiency of cycling a battery (70-90% for grid scale)
| or pumped hydro (70-85%) is simply much, much higher than
| chemical storage. Here's a pretty recent one [1] showing 23%
| efficiency even at lab scale, and as described in the article
| scale is a big drain on efficiency.
|
| [1] https://www.nature.com/articles/s41467-022-29428-9
| jl6 wrote:
| We need massive amounts of medium-term seasonal (3-6 months)
| stable energy storage, and liquid synthetic hydrocarbons are
| not a bad solution. Low efficiency isn't a dealbreaker when
| the inputs are free.
| foota wrote:
| It's essentially just another form of energy storage. I don't
| think there's any deep reason why it is worse than the other
| methods currently available, it's just not cost competitive.
|
| My understanding is that creating hydrocarbons is quite
| difficult and that you lose a lot of energy in the process.
| Otherwise, it would be a very compelling way of storing energy.
|
| I guess for one, you have to get the carbon from somewhere,
| which means either taking sequestered carbon (which is counter
| productive) or capturing it from the air (expensive).
| bluGill wrote:
| We need vast amounts of energy storage is the problem and that
| won't be cheap no matter how you look at it. 20 years ago I saw
| an annalists that suggested the US needs the equivalent of lake
| Superior to get enough hydro storage - that is that much water,
| plus the ability to drain it all in just one day (to where!),
| and then pump it back up the next. Pumped hydro where we can
| use it should be used, but there isn't any place we can put it
| left (and we want to take some of what we have out because it
| is an ecological disaster). Batteries work but are expensive.
| This would probably work as well, but again be very expensive.
|
| Remember you are competing with something we can pump/dig out
| of the ground for nothing anytime you propose storage.
| Renewables when the wind is blowing or the sun is shining are
| very cheap, but as soon as you need storage the costs go way
| up.
| chris_va wrote:
| > Is it just economics?
|
| It's ~75% economics, 25% learning curve.
|
| For hydrogen, you need an electrolyzer, a hydrogen fuel cell
| (or turbine), and storage. The electrolyzer is the main capital
| cost, and it is only running for a fraction of the day (either
| whenever there is curtailed solar/wind, up to 40% of the time
| you have your own captive plant). It needs to be sized for peak
| usage. The storage optimum depends on whether or not there is a
| nearby salt dome, but if not it is extremely expensive per kWh,
| and so days and days of storage are untenable (going directly
| to CH4 changes some of this). Existing fuel cells and H2
| turbines have not yet walked down the learning curve in the
| same way that an NGCC plant has for CH4, but those are running
| 24/7 so the amortization is not as bad.
|
| With a salt dome and captive PV plant, you end up with
| (optimistically) system capital cost that roughly doubles the
| PV capital cost (using US pricing). That means your amortized
| $/kWh rate is about 2x the PV rate. Since PV and NGCC are
| roughly the same $/kWh at the plant, it makes H2 extremely
| uncompetitive unless there is a carbon price or H2 subsidy. At
| $3/kg hydrogen, it's almost just barely within reach assuming
| everything works well. If the cost of electrolysis came down,
| or if H2 were easy to ship globally from high insolation
| regions, that would substantially help the problem.
| cyberax wrote:
| > Perhaps someone with more knowledge can comment on why
| solutions like these can't be used to solve the energy storage
| problem. Is it just economics?
|
| Yes. If you round-trip energy through hydrocarbons, then you
| have to pay the "Carnot tax". Your heat engine will be at best
| around 50% efficient at transforming hydrocarbons into energy.
| This is then compounded with the inefficiency of reducing
| carbon dioxide to get maaaaybe 20% round-trip efficiency.
|
| And all of this with a huge capital cost.
| outworlder wrote:
| The tax is fine _as long as_ it doesn't have to be
| transported, assuming the energy would otherwise be wasted.
|
| Which is why hydrogen solutions for stationary storage could
| be interesting, but the moment you start transporting them
| around they become less useful.
| cyberax wrote:
| I'm not seeing that. Hydrogen requires a ton of very
| expensive infrastructure for storage. Its density is
| impractically low for storage in tanks, it can't be
| liquified under reasonable conditions, and reversible
| hydrogen-binding materials so far have all been duds.
|
| If you happen to have an underground geological storage
| available, then it might be reasonable. Right now, there's
| a demonstrator project for that ongoing in Germany. I guess
| this qualifies as "local"?
|
| So yeah, if you need storage for 3-12 hours of runtime,
| then batteries are fine. Sodium batteries are probably
| going to fit this niche once they become cheaper. Anything
| more than that is a big gaping hole in the renewable story
| with no good solutions.
| fooker wrote:
| It's not quite feasible with solar or wind.
|
| If we could get controlled fusion though, we are going to see a
| massive surge of what you're suggesting.
| chris_va wrote:
| (disclaimer that I do work in a related area)
|
| The novelty of the underlying paper notwithstanding, a quick
| scholar search for "gas diffusion electrodes ptfe copper" will
| show that this is hardly an unexplored space.
| thereisnospork wrote:
| Indeed, this is at least a decade behind the state of the art
| for CO2 electroreduction and adding PTFE to gas diffusion
| electrodes is hardly a novel concept (see: H2 fuel cells which
| likely pre date it's inclusion in CO2 cells). It might be a
| good or even the best implementation of the concept, but if so
| it would be inches, not miles, better.
| newsclues wrote:
| plant trees wait cut them down now you have wood to build stuff
|
| repeat
| rgrieselhuber wrote:
| Trees also convert CO2 into something useful
| ikekkdcjkfke wrote:
| Using quantum technology
| asdf123qweasd wrote:
| What is needed is a Graphene Lightmill, turning driven by light
| alone, capturing CO^2 spinning out graphene as a monofiber, no in
| between steps, no conversions.
| csours wrote:
| I'm very curious about how bioelectrochemistry might be used, eg
| [0]. I dream of artificial lichens on silicone wafers making
| sheets of graphene.
|
| 0:
| https://www.sciencedirect.com/science/article/pii/S258929911...
| trebor wrote:
| Okay, but why not work on making atmospheric methane more
| useful/practical? CO2 is less of a warming influence than
| methane, and there have been huge natural gas leaks (of methane)
| in the last 10-20 years. Even MIT admits that Methane is more
| important: https://climate.mit.edu/ask-mit/what-makes-methane-
| more-pote...
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