Tuesday, August 28, 2012

ECO SPECIAL..New material captures CO2 directly from air



New material captures CO2 directly from air 

Finally, a feasible solution to the global warming crisis? Scientists create a material that can capture atmospheric carbon dioxide and then redirect it to fuel producing algae farms 

    Researchers from the Georgia Institute of Technology have advanced the case for extracting carbon dioxide directly from the air using newly-developed super absorbent materials.
The technique might initially be used to supply carbon dioxide for such industrial applications as fuel production from algae or enhanced oil recovery.
But the method could later be used to supplement the capture of CO2 from power plant flue gases as part of efforts to reduce concentrations of the atmospheric warming chemical.
In a detailed economic feasibility study, the researchers projected that a CO2 removal unit the size of an ocean shipping container could extract approximately a thousand tons of the gas per year with operating costs of approximately $100 per ton. The researchers also reported on advances in adsorbent materials for selectivelycapturingcarbondioxide. “Even if we removed CO2 from all the flue gas, we’d still only get a portion of the carbon dioxide emitted each year,” noted David Sholl.
    “If we want to make deep cuts in emissions, we’ll have to do more – and air capture is one option for doing that.”
    Carbon dioxide from large sources such as coal-burning power plants or chemical facilities account for less than half the worldwide emissions of the gas, noted Christopher Jones, a professor at Georgia Tech.
    Much of the remaining emissions come from mobile sources such as buses, cars, planes and ships, where capture would be much more costly per ton.
    Jones is collaborating with a startup company – Global Thermostat – to establish a pilot plant to demonstrate the direct air capture technique.
    The technology for capturing carbon dioxide from the air would be similar to that required for removing the gas from smokestack emissions, though CO2 concentrations in flue gases are dramatically higher than those in the atmosphere.
    Flue gases contain about 15 per cent carbon dioxide, while CO2 is found in the atmosphere at less than 400 parts per million.
    That’s a factor of 375, notes Sholl, who said the difference in capture efficiency could be partially made up by eliminating the need to transport CO2removedfromfluegastosequestration locations.
    “Because the atmosphere is generally consistent, you could operate thecaptureequipmentwhereveryou had a sequestration site,” he said.
    “I don’t think air capture will ever producecarbondioxideascheaplyas capturing it from flue gas. But on the other hand, it doesn’t seem to be wildly more expensive, either.”
    Based on his work with Global Thermostat, Jones believes that the costs of an optimised process will prove to be even lower than the estimates of Sholl’s team.
    “Sholl’s paper is important because it shows that direct capture of CO2 from the air can be up to ten times less expensive than had been estimated by others,” he said.
    “Process improvements based on their initial modelling study could bring costs down even further.”
    “Initial demonstrations of the air capture process will probably be targeted for applications that can use the carbon dioxide for commercial purposes,” Jones said.
    “As the technology matures, we envisionimplementingCO2capture from the air as a climate stabilisation strategy,inparallelwithCO2capture from flue gas and enhanced utilisation of alternative energies.”
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