Artificial lung to remove carbon dioxide—from smokestacks

September 10, 2013
Inspired by how blood vessels are packed in the avian lung and the fish swim bladder, scientists have found the best way to pack tubes in a carbon dioxide capture unit. Credit: ThinkStock/XiaoZhi Lim

The amazingly efficient lungs of birds and the swim bladders of fish have become the inspiration for a new filtering system to remove carbon dioxide from electric power station smokestacks before the main greenhouse gas can billow into the atmosphere and contribute to global climate change.

A report on the , more efficient than some alternatives, is on the agenda today at the 246th National Meeting & Exposition of the American Chemical Society (ACS), the world's largest scientific society. The meeting, which features almost 7,000 presentations on new advances in science and other topics, continues here through Thursday in the Indiana Convention Center and downtown hotels.

With climate change now a major concern, many power plants rely on CO2 capture and sequestration methods to reduce their emissions. Speaking at a symposium, "CO2 Separation and Capture," Aaron P. Esser-Kahn, Ph.D., said he envisions new CO2-capture units with arrays of tubes made from porous membranes fitted side-by-side, much like blood vessels in a natural . Once fabricated to be highly efficient and scalable to various sizes by repeating units, these units can then be "plugged" into power plants and vehicles, not unlike catalytic converters, he explained.

To capture the most CO2, the Esser-Kahn group from the University of California, Irvine, first had to figure out the best pattern to pack two sets of different-sized tubes –– one for waste emissions and the other a CO2-absorbing liquid –– into the unit. "The goal is to cram as much surface area into the smallest space possible," said Esser-Kahn.

They studied the way blood vessels are packed in the avian lung and the fish . Birds need to exchange CO2 for oxygen rapidly, as they burn a lot of energy in flight, while fish need to control the amount of gas in their swim bladder effectively to move up and down in the water. "We're trying to learn from nature," said Esser-Kahn, adding that the avian lung and fish swim bladder are biologically well-suited systems for exchanging gases.

But the blood vessels in the avian lung and fish swim bladder are packed in different patterns. The avian lung consists of a hexagonal pattern where three large tubes form the vertices of a triangle and a small tube sits in the gap, while the fish swim bladder has a squarer pattern where a large and small tube alternate between vertices of a square. It turned out that this tube-packing challenge is a well-studied mathematical problem with nine unique solutions, or patterns, Esser-Kahn said.

The team used computer simulations to predict how efficient gas exchange would be for each pattern. Four were predicted to be highly efficient, including the avian lung's hexagonal pattern and the fish swim bladder's squarer pattern. However, the most efficient pattern was actually one not found in nature: the double-squarer pattern, similar to the squarer one in the fish swim bladder, but with two small tubes alternating with a large tube. Esser-Kahn's team then synthesized miniature units up to a centimeter long and confirmed experimentally that the double-squarer pattern was the most efficient, outperforming the avian lung and fish swim bladder by almost 50 percent.

Now, scientists can conduct further research to improve CO2-capture units' efficiencies by adjusting the sizes of the tubes, thicknesses of the tube walls and membrane materials that make up the tube walls. "Biological systems spent an incredible amount of time and effort moving towards optimization," said Esser-Kahn. "What we have is the first step in a longer process."

Explore further: Aggressive piranhas bark to say buzz off

Related Stories

Aggressive piranhas bark to say buzz off

October 13, 2011

Thanks to Hollywood, piranhas have a bad reputation and it would be a brave scientist that chose to plunge their hand into a tank of them. But that didn't deter Sandie Millot, Pierre Vandewalle and Eric Parmentier from the ...

Cichlid fish: How does the swim bladder affect hearing?

August 8, 2012

In bony fish the swim bladder primarily serves for buoyancy Moreover, in many species it also possesses acoustic functions: it plays a role in sound production and improves hearing in numerous ways. Biologists around Friedrich ...

Underwater CO2 shows potential as barrier to Asian carp

January 23, 2013

As the Asian carp population grows and the threat of the invasive species entering Lake Michigan through one of the Chicago canals is monitored, a University of Illinois researcher believes using two barrier methods is better ...

Nanomaterial to help reduce CO2 emissions

July 9, 2013

University of Adelaide researchers have developed a new nanomaterial that could help reduce carbon dioxide emissions from coal-fired power stations.

Harvesting electricity from the greenhouse gas carbon dioxide

July 23, 2013

A new method for producing electricity from carbon dioxide could be the start of a classic trash-to-treasure story for the troublesome greenhouse gas, scientists are reporting. Described in an article in ACS' journal Environmental ...

Recommended for you

A new form of real gold, almost as light as air

November 25, 2015

Researchers at ETH Zurich have created a new type of foam made of real gold. It is the lightest form ever produced of the precious metal: a thousand times lighter than its conventional form and yet it is nearly impossible ...

New 'self-healing' gel makes electronics more flexible

November 25, 2015

Researchers in the Cockrell School of Engineering at The University of Texas at Austin have developed a first-of-its-kind self-healing gel that repairs and connects electronic circuits, creating opportunities to advance the ...

Getting under the skin of a medieval mystery

November 23, 2015

A simple PVC eraser has helped an international team of scientists led by bioarchaeologists at the University of York to resolve the mystery surrounding the tissue-thin parchment used by medieval scribes to produce the first ...

Atom-sized craters make a catalyst much more active

November 24, 2015

Bombarding and stretching an important industrial catalyst opens up tiny holes on its surface where atoms can attach and react, greatly increasing its activity as a promoter of chemical reactions, according to a study by ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.