Featured Discovery
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Dr. Bill Koros (right) may well change the way raw materials are converted to usable fuel. The payoff potential of his work is huge: It could someday give America energy independence and make the United States a leading exporter of energy.
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If refineries are to become more energy efficient, they must find new ways to separate components in raw materials. That process today relies on heat and chemical reactions; Koros believes the future lies in breakthrough filtration techniques such as the ones being developed in his lab. “It used to be that if you wanted to purify water, you distilled it,” Koros explains. “That takes a lot of heat. Now, distillation is rarely used to purify drinking water. They use reverse osmosis filters. That’s what we want to do for energy products."
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Fifteen percent of the world’s energy is sunk back into producing more energy. Crude oil and natural gas are good examples – transforming them into usable products carries a high energy cost. Koros, a GRA Eminent Scholar in membrane science and technology at Georgia Tech, believes new methods can cut required energy for production by as much as 90 percent from current refining procedures.
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Membrane filtration requires tremendous changes of scale: Component materials in crude oil or natural gas differ in size by a matter of picometers, or 1000th of a nanometer. Separating components so small requires filters that operate all the way down to a molecular scale. Koros creates such molecular filters out of metal-organic polymers. These polymers are developed into “dope,” and they first take a sludge-like form. Several jars in Koros' lab holds vials of the dope.
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Dr. Ali Rownaghi in the Koros Lab spins the polymer dope into long strands of hollow fiber. Gases travel through the fiber’s center opening and pass between the microfibers it’s made of. The process yields a vast filtration area in a small footprint – one cubic meter of hollow fiber has as much surface area as two football fields. Koros believes only this technology could ever be workable in a real-life setting, because filtration works by pressure. A smaller form factor (hollow fiber) means less pressure – and thus, less energy – will be needed in the filtering process.
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GRA made a major technology investment in the Koros Lab. While other labs around the world work on filtration membranes, only the Georgia Tech lab is making membranes so small. Here, Rownaghi drops the newly spun hollow fiber into a solution for cleaning.
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Lucy Lu inserts the polymer fibers created in Koros’ Lab into small metal shafts, or modules, to be tested. Each polymer is tested for how effectively it filters gaseous mixtures into components. One mixture the lab tests frequently is natural gas, an energy source much friendlier to the environment because it releases only a small amount of carbon dioxide when burned.
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In testing filtration of natural gas, scientists in the Koros Lab want to know if their polymer strands can remove hydrogen sulfide from the gas, leaving only methane. But hydrogen sulfide is highly toxic, so the experiments require a tightly controlled lab with a sophisticated ventilation system. GRA provided matching funds to build this hazardous materials lab at Georgia Tech – the only academic lab of its kind to work on purifying natural gas.
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Koros continues to seek out novel approaches never before tried. In his recent research, he and colleagues heated a hollow fiber created in his lab to 800° C. This process, known as pyrolysis, blasted away everything but the carbon. The resulting carbon sieve can effectively separate propylene from propane, two molecules that differ from one another by just two hydrogen atoms.
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When the hollow fiber filters are perfected, they will likely be used in refineries where raw materials (like crude oil) are separated into their components. But Koros hopes membranes can be developed that will be employed where raw materials are actually harvested, allowing energy companies to filter the product on the spot — and return the unusable portion to the source.
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The hollow fiber’s size also makes it a good candidate for installations at manufacturing plants. Koros envisions using membranes to remove carbon dioxide from factory emissions, reducing pollution and addressing climate concerns.
Mouse-over each image for details about GRA Eminent Scholar Bill Koros' pioneering work
• Photos by Rob Felt except for images 3 (stock), 4 (Gary Meek) and 12 (Dori Kleber)
It's filtration. At the molecular level. And its implications are huge. GRA Eminent Scholar Bill Koros explains why.
GRA's investments in technology give scientists the tools to attract major research funding -- and make surprising discoveries.
