Lab Turns Hard-To-Process Plastic Waste Into Carbon-Capture Master (phys.org) 26
An anonymous reader quotes a report from Phys.Org: What seems like a win-win for a pair of pressing environmental problems describes a Rice University lab's newly discovered chemical technique to turn waste plastic into an effective carbon dioxide (CO2) sorbent for industry. Rice chemist James Tour and co-lead authors Rice alumnus Wala Algozeeb, graduate student Paul Savas and postdoctoral researcher Zhe Yuan reported in the American Chemical Society journal ACS Nano that heating plastic waste in the presence of potassium acetate produced particles with nanometer-scale pores that trap carbon dioxide molecules. These particles can be used to remove CO2 from flue gas streams, they reported.
"Point sources of CO2 emissions like power plant exhaust stacks can be fitted with this waste-plastic-derived material to remove enormous amounts of CO2 that would normally fill the atmosphere," Tour said. "It is a great way to have one problem, plastic waste, address another problem, CO2 emissions." A current process to pyrolyze plastic known as chemical recycling produces oils, gases and waxes, but the carbon byproduct is nearly useless, he said. However, pyrolyzing plastic in the presence of potassium acetate produces porous particles able to hold up to 18% of their own weight in CO2 at room temperature. In addition, while typical chemical recycling doesn't work for polymer wastes with low fixed carbon content in order to generate CO2 sorbent, including polypropylene and high- and low-density polyethylene, the main constituents in municipal waste, those plastics work especially well for capturing CO2 when treated with potassium acetate.
The lab estimates the cost of carbon dioxide capture from a point source like post-combustion flue gas would be $21 a ton, far less expensive than the energy-intensive, amine-based process in common use to pull carbon dioxide from natural gas feeds, which costs $80-$160 a ton. Like amine-based materials, the sorbent can be reused. Heating it to about 75 degrees Celsius (167 degrees Fahrenheit) releases trapped carbon dioxide from the pores, regenerating about 90% of the material's binding sites. Because it cycles at 75 degrees Celsius, polyvinyl chloride vessels are sufficient to replace the expensive metal vessels that are normally required. The researchers noted the sorbent is expected to have a longer lifetime than liquid amines, cutting downtime due to corrosion and sludge formation.
"Point sources of CO2 emissions like power plant exhaust stacks can be fitted with this waste-plastic-derived material to remove enormous amounts of CO2 that would normally fill the atmosphere," Tour said. "It is a great way to have one problem, plastic waste, address another problem, CO2 emissions." A current process to pyrolyze plastic known as chemical recycling produces oils, gases and waxes, but the carbon byproduct is nearly useless, he said. However, pyrolyzing plastic in the presence of potassium acetate produces porous particles able to hold up to 18% of their own weight in CO2 at room temperature. In addition, while typical chemical recycling doesn't work for polymer wastes with low fixed carbon content in order to generate CO2 sorbent, including polypropylene and high- and low-density polyethylene, the main constituents in municipal waste, those plastics work especially well for capturing CO2 when treated with potassium acetate.
The lab estimates the cost of carbon dioxide capture from a point source like post-combustion flue gas would be $21 a ton, far less expensive than the energy-intensive, amine-based process in common use to pull carbon dioxide from natural gas feeds, which costs $80-$160 a ton. Like amine-based materials, the sorbent can be reused. Heating it to about 75 degrees Celsius (167 degrees Fahrenheit) releases trapped carbon dioxide from the pores, regenerating about 90% of the material's binding sites. Because it cycles at 75 degrees Celsius, polyvinyl chloride vessels are sufficient to replace the expensive metal vessels that are normally required. The researchers noted the sorbent is expected to have a longer lifetime than liquid amines, cutting downtime due to corrosion and sludge formation.
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Generating power from wood chips is stupid, but to be fair, one of the biggest practitioners is the UK, which is no longer in the EU.
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Trees are mostly carbon neutral. Unless you are very careful about the type of tree you plant, it will likely die before 2100 and release most of the CO2 it contained back into the atmosphere. There is a good reason that trees managed to exist for billions of years before complex life.
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Unless you are very careful about the type of tree you plant, it will likely die before 2100 and release most of the CO2
There are plenty of tree species that live far longer than 80 years and many that take a very long time to decay.
Even if we harvest forests, there are far better ways to use the wood than chip it, ship it to the other side of the world, shove it into a boiler, and send it up a smokestack.
An accurate heuristic to recognize a wasteful boondoggle is to look at who is paying for it. If greedy profit-seeking capitalists invest their own money, it likely makes financial sense. If taxpayer euros are paying for i
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wow, a tree hugging conservative. Once more conservatives embrace things they opposed. Add that to the list. Remember when conservatives said companies should have the freedom to be racist in hiring? That was back when they thought successful companies would try to exclude minorities. Nowadays they are mad that companies voluntarily try to hire minorities. .. I wonder what the ulterior angle is.
Now conservatives are pro-environment
Carbon capture tech (Score:3, Interesting)
Carbon capture is starting to have technological solutions. There's also a 2nd method [semanticscholar.org] that's very close to first customer deployment that works but is slightly more expensive.
Once we have valid capture tech and lots of excess energy, we can start removing some of the CO2 from the atmosphere. Current plans are to pump it underground, where heat and pressure will turn it into solid carbonates which are long-term stable. A single dedicated breeder reactor could grab and store a lot of atmospheric carbon over its useful lifetime.
If we can keep a stable civilization long enough to deploy these methods...
Re:Carbon transport tech (Score:4, Insightful)
Like amine-based materials, the sorbent can be reused. Heating it to about 75 degrees Celsius (167 degrees Fahrenheit) releases trapped carbon dioxide from the pores, regenerating about 90% of the material's binding sites.
If they are talking about the reusability of the material, it sounds more like the sorbent is being used to capture CO2 where it's being generated, then transporting to a recycling site where the gas can be released from the material so it can be reused. That still leaves the CO2 to be somehow used or sequestered for this to be helpful.
I don't know if this is more cost effective or easier to retrofit into existing processes than the hydroxide exchange membrane (HEM) mentioned in the previous thread.
New Game-changing Technology Removes 99% of CO2 from the air [slashdot.org]
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That still leaves the CO2 to be somehow used or sequestered for this to be helpful.
That solution has already been sorted, effectively pumping it deep underground. The problem is grabbing it in the first place.
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Carbon capture is starting to have technological solutions. There's also a 2nd method [semanticscholar.org] that's very close to first customer deployment that works but is slightly more expensive.
All we need to do now is make it mandatory. People aren't going to do this out of the kindness of their hearts, not when dumping it is free.
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We know how to break plastics down into useful raw materials for industrial processes. Thermal depolymerization is one way.
https://en.wikipedia.org/wiki/... [wikipedia.org]
Where do we get the heat for this? Nuclear fission
Also: Wind, solar and other renewables.
Fly in the ointment (Score:3)
" Heating it to about 75 degrees Celsius (167 degrees Fahrenheit) releases trapped carbon dioxide from the pores"
Ok, and where does the CO2 go then? Bury it? React it? This all takes huge amounts of energy and resources. Until someone finds a thermodynamically efficient method of splitting CO2 (unlikely) then the best way to get rid of it is growing plants whether that be trees or algae.
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Ok, and where does the CO2 go then? Bury it? React it? This all takes huge amounts of energy and resources. Until someone finds a thermodynamically efficient method of splitting CO2 (unlikely) then the best way to get rid of it is growing plants whether that be trees or algae.
That’s also temporary storage, the vast majority of organically captured CO2 is just released as part of the decomposition process. It’s true the organic material reserves have shrunk and there certainly is room to increase the mass providing a permanent storage of sorts, but something will have to be done to actually reduce CO2 beyond that. One example might be sinking the algae to deep ocean depths where the decomposition process is so long it provides a much larger organic mass for long ter
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Any zooplankton that creates a shell sequesters CO2 when it dies as it eventually turns into limestone.
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There are plenty of holes we can pump it into. Old fracking bore holes, for example.
Re:Fly in the ointment (Score:4, Insightful)
Although it's important to realize the scale of this problem. You need a hole really, really close to your power plant.
Generating a single kwh of electricity emits about a kg of CO2. So a 1000 MW baseload coal plant (large but not super-large) generates a billion kg of CO2 per hour. You're going to have to *ship* that billion kg to your hole -- along with the plastic carrier. It probably makes more sense to recycle the carrier onsite and build a pipeline from your plant to your hole.
For the price of deploying this solution on a major scale, you'd get a bigger immediate bang for your buck by replacing all coal plants with natural gas plants, which generate less than half the CO2 per kwh. Or a mix of renewable and load-following natural gas to fill in for dunkelflaute periods. Substantial, but non-zero reductions buy time for getting to zero.
Re:Fly in the ointment (Score:4, Informative)
Your calculation seems to be off by a factor of 1000. 1000MW = 1,000,000kW, or 1 million kg of CO2, not a billion.
Even then, the entire world only emits about 36 billion metric tons of CO2 per year.
Sources:
https://ourworldindata.org/co2... [ourworldindata.org]
https://www.statista.com/stati... [statista.com]
https://www.carbonbrief.org/gl... [carbonbrief.org]
1 million kg = 1000 tons. 1000 tons/hour for a year, with a bit of down time, is around 8 billion tons/year, which doesn't seem to add up given the global emissions figure.
I'm not sure what the issue is because a quick check suggests that 1kg CO2/kWh is reasonable for a coal plant, but clearly they can't all be emitting 8 billion tons of CO2 a year or the global total figure would be much higher.
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1000 tons of CO2 per hour is roughly around 300 tons of coal per hour which seems a bit high for a 1GW station but even if you halve it the figures still seem wrong.
Here's a radical idea... (Score:3)
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Anyway every little bit helps.
Ive noticed the US food conglomerates have decreased contents of their products in the usual attempt to fool away inflation. SO that means a higher percentage of packaging -- a step in the wrong direction.
From TFA
"To make the material, waste plastic is turned into powder, mixed with potassium acetate and heated at 600 C (1,112 F) for 45 minutes to optimize the pores, most of which are about 0.7 nanometers wide. Higher temperatures led to wider pores. The proces
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