A big advance in carbon capture technology could provide an efficient and inexpensive way for natural gas power plants to remove carbon dioxide from their flue emissions, a necessary step in reducing greenhouse gas emissions to slow global warming and climate change.
Developed by researchers at the University of California, Berkeley, Lawrence Berkeley National Laboratory and ExxonMobil, the new technique uses a highly porous material called a metal-organic framework, or MOF, modified with nitrogen-containing amine molecules to capture the CO2 and low temperature steam to flush out the CO2 for other uses or to sequester it underground.
In experiments, the technique showed a six times greater capacity for removing CO2 from flue gas than current amine-based technology, and it was highly selective, capturing more than 90% of the CO2 emitted. The process uses low temperature steam to regenerate the MOF for repeated use, meaning less energy is required for carbon capture.
“For CO2 capture, steam stripping — where you use direct contact with steam to take off the CO2 — has been a sort of holy grail for the field. It is rightly seen as the cheapest way to do it,” said senior researcher Jeffrey Long, UC Berkeley professor of chemistry and of chemical and biomolecular engineering and senior faculty scientist at Berkeley Lab. “These materials, at least from the experiments we have done so far, look very promising.”
Because there’s little market for most captured CO2, power plants would likely pump most of it back into the ground, or sequester it, where it would ideally turn into rock. The cost of scrubbing the emissions would have to be facilitated by government policies, such as carbon trading or a carbon tax, to incentivize CO2 capture and sequestration, something many countries have already implemented.
The work was funded by ExxonMobil, which is working with both the Berkeley group and Long’s start-up, Mosaic Materials Inc., to develop, scale up and test processes for stripping CO2 from emissions.
Long is the senior author of a paper describing the new technique that will appear in the July 24 issue of the journal Science.
“We were able to take the initial discovery and, through research and testing, derive a material that in lab experiments has shown the potential to not only capture CO2 under the extreme conditions present in flue gas emissions from natural gas power plants, but to do so with no loss in selectivity,” said co-author Simon Weston, senior research associate and the project lead at ExxonMobil Research and Engineering Co. “We have shown that these new materials can then be regenerated with low-grade steam for repeated use, providing a pathway for a viable solution for carbon capture at scale.”
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