Posted on 07/29/2016 8:50:46 AM PDT by Red Badger
Simulated sunlight powers a solar cell that converts atmospheric carbon dioxide directly into syngas. Credit: University of Illinois at Chicago/Jenny Fontaine
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Researchers at the University of Illinois at Chicago have engineered a potentially game-changing solar cell that cheaply and efficiently converts atmospheric carbon dioxide directly into usable hydrocarbon fuel, using only sunlight for energy.
The finding is reported in the July 29 issue of Science and was funded by the National Science Foundation and the U.S. Department of Energy. A provisional patent application has been filed.
Unlike conventional solar cells, which convert sunlight into electricity that must be stored in heavy batteries, the new device essentially does the work of plants, converting atmospheric carbon dioxide into fuel, solving two crucial problems at once. A solar farm of such "artificial leaves" could remove significant amounts of carbon from the atmosphere and produce energy-dense fuel efficiently.
"The new solar cell is not photovoltaic—it's photosynthetic," says Amin Salehi-Khojin, assistant professor of mechanical and industrial engineering at UIC and senior author on the study.
"Instead of producing energy in an unsustainable one-way route from fossil fuels to greenhouse gas, we can now reverse the process and recycle atmospheric carbon into fuel using sunlight," he said.
While plants produce fuel in the form of sugar, the artificial leaf delivers syngas, or synthesis gas, a mixture of hydrogen gas and carbon monoxide. Syngas can be burned directly, or converted into diesel or other hydrocarbon fuels.
The ability to turn CO2 into fuel at a cost comparable to a gallon of gasoline would render fossil fuels obsolete.
Chemical reactions that convert CO2 into burnable forms of carbon are called reduction reactions, the opposite of oxidation or combustion. Engineers have been exploring different catalysts to drive CO2 reduction, but so far such reactions have been inefficient and rely on expensive precious metals such as silver, Salehi-Khojin said.
"What we needed was a new family of chemicals with extraordinary properties," he said.
Salehi-Khojin and his coworkers focused on a family of nano-structured compounds called transition metal dichalcogenides—or TMDCs—as catalysts, pairing them with an unconventional ionic liquid as the electrolyte inside a two-compartment, three-electrode electrochemical cell.
The best of several catalysts they studied turned out to be nanoflake tungsten diselenide.
Amin Salehi-Khojin, UIC assistant professor of mechanical and industrial engineering (left), and postdoctoral researcher Mohammad Asadi with their breakthrough solar cell that converts atmospheric carbon dioxide directly into syngas. Credit: University of Illinois at Chicago/Jenny Fontaine
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"The new catalyst is more active; more able to break carbon dioxide's chemical bonds," said UIC postdoctoral researcher Mohammad Asadi, first author on the Science paper.
In fact, he said, the new catalyst is 1,000 times faster than noble-metal catalysts—and about 20 times cheaper.
Other researchers have used TMDC catalysts to produce hydrogen by other means, but not by reduction of CO2. The catalyst couldn't survive the reaction.
"The active sites of the catalyst get poisoned and oxidized," Salehi-Khojin said. The breakthrough, he said, was to use an ionic fluid called ethyl-methyl-imidazolium tetrafluoroborate, mixed 50-50 with water.
"The combination of water and the ionic liquid makes a co-catalyst that preserves the catalyst's active sites under the harsh reduction reaction conditions," Salehi-Khojin said.
The UIC artificial leaf consists of two silicon triple-junction photovoltaic cells of 18 square centimeters to harvest light; the tungsten diselenide and ionic liquid co-catalyst system on the cathode side; and cobalt oxide in potassium phosphate electrolyte on the anode side.
When light of 100 watts per square meter - about the average intensity reaching the Earth's surface - energizes the cell, hydrogen and carbon monoxide gas bubble up from the cathode, while free oxygen and hydrogen ions are produced at the anode.
"The hydrogen ions diffuse through a membrane to the cathode side, to participate in the carbon dioxide reduction reaction," said Asadi.
The technology should be adaptable not only to large-scale use, like solar farms, but also to small-scale applications, Salehi-Khojin said. In the future, he said, it may prove useful on Mars, whose atmosphere is mostly carbon dioxide, if the planet is also found to have water.
"This work has benefitted from the significant history of NSF support for basic research that feeds directly into valuable technologies and engineering achievements," said NSF program director Robert McCabe.
"The results nicely meld experimental and computational studies to obtain new insight into the unique electronic properties of transition metal dichalcogenides," McCabe said. "The research team has combined this mechanistic insight with some clever electrochemical engineering to make significant progress in one of the grand-challenge areas of catalysis as related to energy conversion and the environment."
Explore further: Ionic liquid catalyst helps turn emissions into fuel
More information: Nanostructured transition metal dichalcogenide electrocatalysts for CO2 reduction in ionic liquid, Science, science.sciencemag.org/cgi/doi/10.1126/science.aaf4767
Journal reference: Science
$74.99 seems like a good price. However, this is at a time when the need for tungsten is down due to the evolution of the light bulb to LEDs. The question is how much tungsten is required for a solar panel? How much tungsten will be needed for, let’s say, a 30 acre solar cell farm? What will that cost? If I were a lawmaker giving out research grants, I would make sure all of the math was done to know the costs for the final product. I am sure the run-of-the-mill lawmaker is only thinking about how to line their pockets and not the practical matters of costs. They would sell their mothers down the river if it lined their pockets.
Typical solar cells are very, very thin. The frame is thick, but the actual cells, the blue areas, are thinner than your average window pane. The substrate is a fragile glass, and the actual 'cell' part is just a film on the glass. So any tungsten used would have to be very thin as well. Tungsten is heavy, just very slightly less heavy as gold................
Maybe, but can you power your car with beans?
I am still waiting for algae oil and new advances in energy storage.
Algae for me seemed to be the perfect answer. Then I learned that Exxon pulled back after four years (and $100 million) when it realized that algae fuel is “probably further” than 25 years away from commercial viability. Doggone!
If works, the space industry is going to beat a path to their door.
Mars!..............................
Nice proof of concept
BUT
My take is you could spend one million dollars on the solar cells described here and due to the very low CO2 content in the air it would take one year before you got enough hydrogen gas from this million dollar array to produce one kilowatt of electricity.
Thus not an investment that can pay off.
Trees are slow users of CO2 and much better at this game
Not enough CO2 content in the air to make these solar cells pay off. They will produce hydrogen gas too slowly and good luck gathering the hydrogen gas from an array of these newly invented solar cells.
What you have is a proof of concept and did the taxpayers get dinged for it?
YES!!!! TAXPAYERS GOT DINGED!!
“......was funded by the National Science Foundation and the U.S. Department of Energy. A provisional patent application has been filed.”
You may have missed the irony and sarcasm of my comment.
I got it. I thought it was funny btw.
No the did not invent wood they make syngas the very same stuff the German’s used in WW2 to make diesel and jet fuel on a massive industrial scale. The reaction is named after the two Germans who invented it Fischer - Tropsch which the South Africans use every day to make literately millions of gallons of synthetic diesel.
Syngas is the base material for a number of very valuable and important industrial chemical synthesize reactioins done at refineries world wide in megagram quantities everyday. The break through would be having a process that does not use precious metal catalysts to generate usable quantities of syngas for the direct synthesis of diesel, jet fuel or petrol. The Fischer - Tropsch process doesn’t care if that syngas came for coal, biomass, this solar process it only cares what the H2/CO ratio is which determines if you get heavy paraffin wax, or light alkeanes. If they have a way to take atmopheric CO2 and water plus sunlight and make syngas cheaply it would change the world.
The chemistry to make synthetic fuels via Fischer - Tropsch syngas is well established and commercialized on a global scale. The Chinese use coal, the south Africans also use coal, there is a plant going up in Louisiana that will use shale gas, Qatar uses methane.
The average insolation on the surface of the earth on a cloudless day in the temperate regions is 800 w/m^2, over an 8 hour day about 7 Kwhr of energy would be expected to fall on every sq meter of earth.
Petrol has a HHV of 34 kwhr the max theoretical efficiency is around 90% for photosyntetic reasons so 6 sq meters of surface area would produce a gallons worth of fuel energy per day. The tropics have significantly higher insolation numbers almost 1000 w/m2 and 12 hour day light hours.
Every second of every day more solar energy falls on the surface of the earth than every gallon of fossil fuel humanity has ever burned in all of human history by a couple of orders of magnitude the amount of energy falling on the surface of the earth is staggering.
Actually no syngas is used in massive industrial quantities worldwide everyday to make synthetic diesel, jet fuel, and petrol. it is also used to make synthetic lubricants on a massive scale, you can walk into Wal-Mart right now and buy Pennsoil Ultra Syn oil that is made from natural gas that is steam reformed to syngas then via Fischer–Tropsch GTL reactions to long chain lubricant molecules. They charge $9 a quart for this premium syngas sourced lubricant.
Syngas is a valuable industrial feed stock used around the world in mind boggling quantities on a daily basis. producing it from air water and solar energy is indeed a breakthrough one that if they can scale up would have immediate commercially significant applications in the petrochemical industrial complex.
And if I could gather all the gold dissolved in the oceans, I would be rich beyond my wildest dreams. There is an entropy problem.
Japanese scientists already have a method of gathering uranium from seawater that is close to being economically viable at $200 kg for UOX. no entropy problems there its a matter of ion exchange with a floating polymer that can be reused again and again they have already done limited production runs on the process. the same kind of ion exchange can be done with other heavy metals gold being one of them the issue is and always will be how expensive the recovery process is vs the commodity value of the metal the energy ROI is positive for uranium by a few.orders of magnitude due to the density of nuclear vs chemical Gibbs energies. The next metal coming out of seawater will be lithium and magnetism for high energy batteries may research universities are working on seawater lithium recovery.
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