'Diamonds from the sky' approach turns CO2 into valuable products

August 19, 2015
Researchers are generating carbon nanofibers (above) from CO2, removing a greenhouse gas from the air to make products. Credit: Stuart Licht, Ph.D.

Finding a technology to shift carbon dioxide (CO2 ), the most abundant anthropogenic greenhouse gas, from a climate change problem to a valuable commodity has long been a dream of many scientists and government officials. Now, a team of chemists says they have developed a technology to economically convert atmospheric CO2 directly into highly valued carbon nanofibers for industrial and consumer products.

The team will present brand-new research on this new CO2 capture and utilization technology at the 250th National Meeting & Exposition of the American Chemical Society (ACS).

"We have found a way to use atmospheric CO2 to produce high-yield ," says Stuart Licht, Ph.D., who leads a research team at George Washington University. "Such nanofibers are used to make strong carbon composites, such as those used in the Boeing Dreamliner, as well as in high-end sports equipment, wind turbine blades and a host of other products."

Previously, the researchers had made fertilizer and cement without emitting CO2 , which they reported. Now, the team, which includes postdoctoral fellow Jiawen Ren, Ph.D., and graduate student Jessica Stuart, says their research could shift CO2 from a global-warming problem to a feed stock for the manufacture of in-demand .

Licht calls his approach "diamonds from the sky." That refers to carbon being the material that diamonds are made of, and also hints at the high value of the products, such as the carbon nanofibers that can be made from atmospheric carbon and oxygen.

Because of its efficiency, this low-energy process can be run using only a few volts of electricity, sunlight and a whole lot of . At its root, the system uses electrolytic syntheses to make the nanofibers. CO2 is broken down in a high-temperature electrolytic bath of molten carbonates at 1,380 degrees F (750 degrees C). Atmospheric air is added to an electrolytic cell. Once there, the CO2 dissolves when subjected to the heat and direct current through electrodes of nickel and steel. The carbon nanofibers build up on the steel electrode, where they can be removed, Licht says.

To power the syntheses, heat and electricity are produced through a hybrid and extremely efficient concentrating solar-energy system. The system focuses the sun's rays on a photovoltaic solar cell to generate electricity and on a second system to generate heat and thermal energy, which raises the temperature of the electrolytic cell.

Licht estimates electrical energy costs of this "solar thermal electrochemical process" to be around $1,000 per ton of carbon nanofiber product, which means the cost of running the system is hundreds of times less than the value of product output.

"We calculate that with a physical area less than 10 percent the size of the Sahara Desert, our process could remove enough CO2 to decrease atmospheric levels to those of the pre-industrial revolution within 10 years," he says.

At this time, the system is experimental, and Licht's biggest challenge will be to ramp up the process and gain experience to make consistently sized nanofibers. "We are scaling up quickly," he adds, "and soon should be in range of making tens of grams of nanofibers an hour."

Licht explains that one advance the group has recently achieved is the ability to synthesize carbon fibers using even less energy than when the process was initially developed. "Carbon nanofiber growth can occur at less than 1 volt at 750 degrees C, which for example is much less than the 3-5 volts used in the 1,000 degree C industrial formation of aluminum," he says.

Explore further: Researcher develops carbon dioxide-free method of producing iron

More information: A new approach to carbon dioxide utilization: The carbon molten air battery, the 250th National Meeting & Exposition of the American Chemical Society (ACS).

Related:

1) S. Licht, "Efficient Solar-Driven Synthesis, Carbon Capture, and Desalinization, STEP: Solar Thermal Electrochemical Production of Fuels, Metals, Bleach" Advanced Materials, 47, 5592 (2011).

2) S. Licht, H. Wu, C. Hettige, B. Wang, J. Lau, J. Asercion, J. Stuart "STEP Cement: Solar Thermal Electrochemical Production of CaO without CO2 emission," Chemical Communications, 48, 6019 (2012).

3) S. Licht, B. Cui, B. Wang, F.-F. Li, J. Lau, S. Liu,"Ammonia synthesis by N2 and steam electrolysis in molten hydroxide suspensions of nanoscale Fe2O3," Science, 345, 637 (2014).

4) S. Licht, B. Cui, J. Stuart, B. Wang, J. Lau," "Molten Air Batteries - A new, highest energy class of rechargeable batteries, Energy & Environmental Science, 6, 3646 (2013).

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36 comments

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Kedas
not rated yet Aug 19, 2015
It feels like they 'forgot' to tell something....
grondilu
not rated yet Aug 19, 2015
That's great. So, what's the catch?
Da Schneib
4.9 / 5 (7) Aug 19, 2015
This is how we'll fix global warming, looks like. I hadn't heard they'd made cement, but I'd heard about the fertilizer before. So that's three important products that can be made from sunlight and CO₂. Excellent.
DavidW
1.4 / 5 (10) Aug 19, 2015
That's great. So, what's the catch?


That the material will get used to cage animals for us to kill for fun, taste, and unneeded nutrition.
betterexists
1.3 / 5 (3) Aug 19, 2015
Excerpts:
Within 10 years, Atmospheric CO2 levels can be Decreased to those of Pre-Industrial Revolution times with $1000 Cost per 1 TON of highly valued C Nanofibers produced meanwhile.
Carbon Nanofiber at 1 volt -- 750° C, far less than 5 volts -- 1,000° C for Aluminum Production
(Like Diamonds falling from the Sky) Dangerous Atmospheric CO2 is now CONVERTED Directly into the highly-valued Carbon Nanofibers - Washington Univ.
Not Forgotten....Embryo hasn't yet grown into Infant and then into an Adult ready to yield the next generation Baby!
Eikka
5 / 5 (10) Aug 19, 2015
I don't think the value of carbon nanofibers will remain at over $1000 per ton when they're produced in the billions of tons required to reduce atmospheric CO2.

You will have literal mountains of it.
Egleton
not rated yet Aug 19, 2015
Huge!
MR166
5 / 5 (1) Aug 19, 2015
Well they are not really saying how much power the process needs and the "Diamonds from the Sky" headline does not give me a warm and fuzzy feeling.. Voltage is a meaningless term all by itself. Having said that, if one can produce a valuable product from otherwise wasted energy and make a profit I am all for it.
Zzzzzzzz
3.5 / 5 (8) Aug 19, 2015
10% of the Sahara is a LOT of real estate - a quick look at Google Earth makes me say about the size of Nevada ..... could be done in the Sahara itself if some of those countries would collaborate, and if too much sand shifting & blowing around doesn't ruin it..... we are talking LOTS and LOTS of mirrors.....10 years to capture the CO2, but I'll bet more than 10 years to build it and get started - better get cracking - need the business case first, and a market for the product.... lots to do
antigoracle
1 / 5 (3) Aug 19, 2015
Pie in the sky.
NoTennisNow
5 / 5 (4) Aug 19, 2015
Come on people, once again the balance of plant and total energy required to process the atmosphere has been overlooked. This is an insult to all chemical engineers (and maybe a few mechanical engineers as well). The Scripps estimate for the atmospheric CO2 content for July 2015 is 401 ppm. Processing one million cubic feet of atmosphere will thus have 401 cubic feet of CO2 or about 45.8 lbs (1 atm. and 20 C (68 F). This requires processing one million cubic feet of dry air, or 75,325 pounds of air). The costs of equipment scales with the amount of gas process SOME BODY PLEASE PUT COMMON SENSE INTO THESE CLAIMS (sorry for the shouting folks)
NoTennisNow
1 / 5 (1) Aug 19, 2015
Yes The process might be sweet, but with limited applications.
Steve 200mph Cruiz
5 / 5 (2) Aug 19, 2015
Screw Keystone, this is what we should do
NoTennisNow
1 / 5 (2) Aug 19, 2015
The uninformed always shout the loudest.
tpb
5 / 5 (3) Aug 19, 2015
Please,
To reduce the atmospheric CO2 in half at $1000 a ton would be about $300 trillion in revenue, or about four times the total GDP of the world in carbon fibers. Not likely.
I can't even imagine the cost of thousands of square miles of molten carbonates and mirrors at 750 degrees C. Or the machinery necessary to scrape the carbon off the electrodes, or to replace the electrodes as they corrode.
Truly pie in the sky.
jeffensley
not rated yet Aug 19, 2015
Low-voltage for the electrolysis, but picturing fairly high voltage to keep the molten carbonate bath at 750 degrees C. Yes, the sun can do SOME of that but not all... especially if these are to operate at night. Sounds great on the surface but we don't know what will happen if we create a large-scale albedo increase and retain/radiate this amount of heat on a scale like this. I like the thinking though... the carbon-fiber market should grow (making everything from vehicles to structures more efficient) as the process of making it continues to get cheaper.
jeremy_h
not rated yet Aug 19, 2015
Imagine you want to offset all coal plant's CO2 emissions using this process, then you would need to put the same amount of energy than a coal plant to get the carbon dioxide back into carbon (coal is C + O2 = CO2 and this process is CO2 = C + O2), plus efficiency losses.
So you would need a plant able to produce an energy equivalent to all the coal power plant in the world just to offset them.
Seems counter-productive to me but might be useful on a small scale, though.
stripeless_zebra
not rated yet Aug 19, 2015
Now I'm really worried about the coming Global Cooling!
NoTennisNow
1 / 5 (1) Aug 19, 2015
No. The coal plant CO2 emissions are on the order of 10 to 14 percent (if memory serves) or 100,000 to 140,000 ppm vs 401 ppm. Even at this concentration CO2 scrubbing is very expensive. Some utilities are looking at (or are constructing coal gasifiers that have a much higher CO2 concentration. Another commenter might want to see what is going on in Mississippi with Southern Company. That project might be doing some CO2 reclamation

jeremy_h
not rated yet Aug 19, 2015
Thanks for the feedback, NoTennisNow.
When I said it could be useful on a small scale, I thought of making some nanofibers from any CO2 sources where cost is not the major issue, such as in aerospace, but I agree with you that scrubbing coal's emissions this way is still expensive.
betterexists
not rated yet Aug 19, 2015
The conversion process, called STEP (for Solar Thermal Electrochemical Process), is powered by sunlight, heat, and a small electrical kick. The researchers simply run a current between two electrodes in a crucible filled with molten lithium carbonate, which melts at 723°C, and a few types of metal. To start the process, the molten lithium carbonate absorbs CO2 from the air. The electrical current then busts apart the CO2 molecules through a process called electrolysis, and the carbon atoms swarm to the negatively charged electrode. Ordinarily, the carbon just forms useless gunge—which makes this form of carbon capture a sure loser. But the researchers found that if they seasoned the lithium carbonate with just the right metals, they could form more valuable carbon nanotubes instead.
betterexists
not rated yet Aug 19, 2015
"It's clearly interesting and exciting research, but it's a first step," cautions James Tour, a nanoengineering and materials scientist at Rice University in Houston, Texas, who is not part of the study. "There's still a lot of work to be done." STEP's coulombic efficiency (a classic measure of chemical yield used to determine how efficiently the product is made) hovered around 95%, meaning that in STEP's case, 95% of the current worked toward producing the carbon nanofibers, and only 5% powered other side reactions.
betterexists
not rated yet Aug 19, 2015
10% of the Sahara desert is more than twice the area of California—that's a lot of molten lithium.
betterexists
not rated yet Aug 19, 2015
James Tour says STEP can't yet produce usable nanofibers. "It's like when you shear a sheep and you get wool," he says. "Those little wool fibers that first come off its back—you can't make a blanket out of that. You have to somehow get it spun into long fibers that you can then put into a machine to get a wool sweater or blanket." Until scientists learn to spin STEP's carbon nanofibers into long commercially usable fibers, he says, it's too early to hail the process as a breakthrough.
Da Schneib
5 / 5 (2) Aug 19, 2015
Every little bit helps.

Why dis advances like this? Every bit of carbon fiber production we displace with this kind of technology helps in multiple ways. To really get an idea, look first at carbon fiber production, then at expected carbon fiber requirements, then at other technologies the carbon fiber displaces, then add the amount the infrastructure adds to carbon in the atmosphere back in, amortized over the lifetime of production from one plant. The benefits multiply quite quickly, particularly when you start talking about things as basic as cement and fertilizer and building materials. Think of the trees we won't have to cut down and all the carbon they'll eat.

What are you afraid of? Seriously.
DavidW
1 / 5 (2) Aug 20, 2015
Every little bit helps.

Why dis advances like this? Every bit of carbon fiber production we displace with this kind of technology helps in multiple ways.

What are you afraid of? Seriously.


That we save a few lives now only to loose all life here later due to missing the most basic truth of all throughout the entire process of making discoveries and deploying them.

We have a very long history of developing solutions for "good" and then misuse them, accidentally or on purpose. Given that most people agree that life is most important in life is the most important truth in life when asked, but that few accept this in practical terms on a day to day basis we have good reason to have serious concern with anything from anyone that does not put this truth first as the reason and foundation for a discovery. Even then, what is discovered is usually deployed by others that may not have a solid base for logical moral thought by willfully choosing to ignore this truth.

NoTennisNow
1 / 5 (1) Aug 20, 2015
Once again folks you need to consider the entire enchilada. Take concrete for example. Fossil fuel is used to produce it. So you have CO2 emissions from that process,not to emission that CO2 is emitted from the conversion of limestone (CaCO3) to (CaO). Just 'google concrete produstion CO2 as the search term.

antialias_physorg
3.7 / 5 (3) Aug 20, 2015
This is how we'll fix global warming, looks like.

Not sure about that.

a) it's not a fix (it doesn't address the source of the CO2 problem). It's a band aid to buy us some time - at best. Note that with roughly 3% of the Sahara covered in 20% efficient solar panels we could supply the world with energy. Seems like a better way to deal with the CO2 problem.
b) 10% of the Sahara is mighty big.
antigoracle
1 / 5 (1) Aug 20, 2015
What are you afraid of? Seriously.

Think of all that carbon fibre filling up landfills and our oceans.
NoTennisNow
1 / 5 (1) Aug 20, 2015
Put simply, "this dog won't hunt".
gergroeneveld
not rated yet Aug 22, 2015
Sucking CO2 out of the air will take lots and lots of energy. However if the source is a B-IG-CC power plant, producing 21% of its syngas as CO2, with a water shift reaction up to 37%, then there is a good source of ready available CO2, which comes at a gate cost of about $35/ton.
With stainless steel at prices of a $4/kg, bottom price of carbon fibre will not be lower than a $3000/ton, still a pretty good ROI.
Once fabrication technique of carbon fiber is optimized (now still quite complicated and labor intensive), it will be cheaper than than stainless steel and 5 to 10 times lighter. And that could reduce transport energy quite a bit.
NoTennisNow
1 / 5 (1) Aug 22, 2015
Somebody do the economics of this. You can't just take commodity prices and wave your hands.
Osiris1
1 / 5 (1) Aug 23, 2015
One problem, ANYTHING planted in the Sahara will be stolen by and run for the Islumic State...the Daesh! So said installation will have to be garrisoned by hundreds of thousands of troops. Millions of troops if they are Arabs who live there. Remember it only takes a hundred Daesh to scare the bejabbers out of fifty thousand Sunni Iraqis, for example. Those scared desert rabbits..or rats..will run like striped butt apes, throwing away their weapons, abandoning their airconditioned well armed tanks, stripping off their uniforms to be butt nekkid so they can run faster.
NoTennisNow
3 / 5 (2) Aug 23, 2015
Osiris1 Go take a flying whatever and keep crap like this to another forum
docile
Aug 23, 2015
This comment has been removed by a moderator.
NoTennisNow
3 / 5 (2) Aug 23, 2015
Just because you might be right doesn't mean this is the forum for such rants.

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