MIT engineers make converting CO2 into useful products more practical
news.mit.edu
news.mit.edu
https://terraformindustries.wordpress.com/2024/04/01/terrafo...
Their business model may have a slight problem.
Oil is subsidized to a much higher amount by the US government
Take a look at De Luna et al, Science 364 2019 [1]
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.
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.
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.
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.
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.
They've been looking at that for a while, I don't know what issues they encountered.
My point was just about the scarcity of concentrated co2.
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.
Is it considered cheap if the marginal cost of a PV MWh is close to zero ?
So the question is, is this so valuable that it outweighs just selling that CO2 once you've pulled it out of the atmosphere?
If we’re just using our captured CO2 to extract more fossil fuels to burn, thats not nearly as big a reduction in atmospheric CO2.
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...
What makes it valuable is that the co2 is concentrated and under pressure. But pretty much any gas would fit the bill.
And let's not forget, the original article was about MIT scientists making extracting co2 from the atmosphere "more efficient". Which, as you point out, is a rather hopeless quest---in order to get the co2 back out of the atmosphere, you'd need more energy than you got from burning whatever put it there in the first place.
So making any meaningful dent in the atmospheric co2 by extraction/converting a mug's game. You'd need on the order of the entire amount of energy used by the human race during the entire industrial age.
But yeah, it's quite underwhelming.
1 - Wild guess. But it's certainly less than 100%, and certainly not by a lot.
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.
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...
In some climate zones, grasslands do it better than forests.
https://climatechange.ucdavis.edu/climate/news/grasslands-mo...
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.
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.
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.
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...
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.
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?
If you capture the carbon dioxide, then for every supertanker full of oil you burn you need to permanently get rid of a supertanker full of liquid carbon dioxide. This is of course a project of insane scope given that we burn billions of tons every year. So in order to not have to deal with the waste, what if we just turn it into something useful that people will pay for? Because that costs a lot of energy, the energy we just extract. And now you want to put it back in? To get back what you just burned or at least something similar that you could almost certainly produce more efficiently directly from the oil?
That said, it still seems an extremely useful measure, even if we keep using only single-digit percentages for long-use plastics instead of hydrocarbon fuels.
Let's assume that for the next century or so a bunch of applications will continue to require the convenience and energy-density of liquid hydrocarbons. In order to avoid extracting more and further increasing CO2 levels, we'll have to input significant energy to reconstitute them from CO2. Obviously, inputting that energy from more fossil fuels defeats the purpose, but using renewables will work; and now they are even cheaper energy inputs.
The result would be a cycle of newly fabricated hydrocarbon fuels, which can be custom-optimised for each application. No new CO2 would enter the atmosphere and the existing levels would be reduced by the amount of hydrocarbon fuels (and plastics, etc.) fabricated and in existence throughout the entire chain of existence, fabrication, storage, distribution, transport, in-vehicle, right up to the moment it is burned. With cheaper renewable energy inputs and optimized custom fabrication, it would likely get cheaper than the existing drill/pump/transport/refine process. And, it's permanently sustainable, and as liquid hydrocarbon fuel use declines, custom production can be converted to storable materials.
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).
Synthetic hydrocarbons let you use renewable energy shifted in time, space, modality or avoid capital costs.
- applications that can't use batteries, like long distance plane flights
- applications where it's cheaper to spend 6X as much for fuel than it is to buy a new vehicle
- for storage more than a few days
etx
But that is not really carbon removal from the atmosphere, you take some out and later put it back. The article however frames the endeavor as removing carbon from the atmosphere, either the one we are currently burning or even the one we burnt in the past. Carbon removal by definition means we can not burn it later somewhere else, we have to permanently store it somewhere. There is no point in turning the carbon into some high quality product if we then just bury it somewhere, you want something cheap to make and easy to store.
As a non-fossile source for chemicals it makes sense but that is just a small fraction of our problem as we just burn most of the stuff.
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.
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.
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.
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).
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.
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.
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.
Which is why hydrogen solutions for stationary storage could be interesting, but the moment you start transporting them around they become less useful.
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.
If we could get controlled fusion though, we are going to see a massive surge of what you're suggesting.
Edit: just realized that PTFE is Teflon. Makes more sense now.
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.
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.
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?
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.
Housing is also a great carbon sink as the wood used in construction is protected from rotting.
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.
The question is how cheap can we do this process and how fast can we get transportation off of oil.
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.
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.
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?
Negative interpretation: Because of look/appearances/prestige.
It inherently takes more energy to "unburn" co2 than you got from burning it in the first place. We burn co2-producing fuels just because of this fact--they give us tons of energy!
But it would take yet more tons of energy to unburn it. That is just thermodynamics. There is no magic science wand to wave here.
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.
If we could divert enough energy to do that, we could have not put it into the air in the first place!!
We are talking about an absolutely ginormous amount of energy. It would take more energy than the human race has used since the industrial revolution to "pay down the debt" (to use your metaphor).
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.
You are obviously not a golfer.
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.
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.
0: https://www.sciencedirect.com/science/article/pii/S258929911...
For the small amount of CCS we need, oceanic bio CCS is the way to go.
We're better off simply not emitting as much GHGs or digging up any more, and switching to renewables and distributed storage.
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.
That's the exact sort of thing governments are supposed to solve.
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.
repeat
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.