Carbon dioxide can be 'captured from the air with 97% efficiency', study finds
New technologies can capture carbon dioxide directly from the air with up to 97% efficiency, a study has shown.
Researchers at the Paul Scherrer Institute PSI and ETH Zurich investigated different technologies to remove CO2 directly from the air.
The researchers cautioned that such technology would not remove the need to cut carbon emissions, but would instead work alongside carbon reduction to help countries hit their climate goals.
Direct air carbon capture and storage (DACCS) is a fairly new technology for removal of carbon dioxide from the atmosphere.
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The research was published in Environmental Science and Technology.
Carbon dioxide is absorbed from the atmosphere and then either buried or used in carbon-based fuels.
The researchers analysed five different ways to capture CO2 from the air and their use at eight different locations around the world.
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To separate CO2 from the atmosphere, air is first passed over a so-called absorbent with the help of fans. This binds CO2 until its capacity to absorb the greenhouse gas is exhausted.
Then, in the second, so-called desorption step, the CO2 is released from the absorbent again – but the technology requires large amounts of heat (and therefore energy).
"The use of this technology only makes sense if these emissions are significantly lower than the amounts of CO2 it helps to store," said Tom Terlouw, who conducts research at PSI's Laboratory for Energy Systems Analysis and is first author of the study.
The researchers focused their examination on a system from Swiss company Climeworks.
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The PSI team analysed the use of the technology at eight locations worldwide: Chile, Greece, Jordan, Mexico, Spain, Iceland, Norway and Switzerland.
For each location, they calculated the overall greenhouse gas emissions over the entire life cycle of a plant.
The researchers found a huge variation in efficiency (from 9 to 97 percent) in terms of actual greenhouse-gas removal through the use of DACCS.
"The technologies for CO2 capture are merely complementary to an overall decarbonisation strategy – that is, for the reduction of CO2 emissions – and cannot replace it," said Christian Bauer, a scientist at the Laboratory for Energy Systems Analysis and a co-author of the study.
"However, they can be helpful in achieving the goals defined in the Paris Agreement on climate change, because certain emissions, for example from agriculture, cannot be avoided."
The researchers believe that the net-zero emissions target can only be achieved with the help of suitable negative-emissions technologies.
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