Direct Air Capture of CO2
Researchers at the Tokyo Metropolitan University, Tokyo, Japan have developed a new system for carbon sequestration that may be able to capture and store carbon directly from the air with great effectiveness and efficiency.
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This novel system, described in a study published in ACS Environmental last month, utilizes a liquid sorbent called Isophorone Diamine (IPDA) which is water-soluble. When IPDA comes into contact with CO2 at room temperature, it absorbs the greenhouse gas molecule to form a solid carbamic acid.
The carbonic acid can then be separated out and stored as a solid, or it can be heated to 60°C in order to fully reverse the reaction. Reversing the reaction allows the IPDA to be re-used as a sorbent and controls the release of the CO2 gas to be stored or used elsewhere.
When compared to other established liquid-amine sorbents used for carbon capture, IDPA was far superior, as it was more effective at stripping CO2 from gas streams containing air-level quantities of carbon, more efficient in removing CO2 on a mole-to-mole basis and for a longer duration, and had the added benefit of being completely reusable after a simple heating cycle.
While IDPA performs better than other carbon capture materials in terms of effectiveness, efficiency, and reusability, it still has to reckon with the main issue faced by other carbon sequestration techniques being used: cost.
Problems with Carbon Sequestration
Historically, carbon capture used to occur by injecting CO2 into the earth’s bedrock or water systems. Controversy over whether this method is safe for the local ecosystems has largely been assuaged by experts. Cost, however, is a large barrier, as CO2 companies lack governmental incentives to incorporate carbon capture techniques into their production lines.
The phase-separating system described above will need similar incentives in order to become a viable sequestration method to offset the relatively high cost of the IDPA.
A quick cost analysis reveals that sequestering CO2 in a solid carbamic acid through this phase separation technique, is four orders of magnitude more costly than traditional sequestration methods since it consumes the relatively costly IDPA.
However, because IDPA shows promise for capturing carbon directly from the air and is reusable, then perhaps with some innovations to reduce the cost of producing IDPA, we will see this phase-separating system become commonplace among carbon sequesters in the near future in our quest to reduce greenhouse gas emissions and help curb global climate change.