Scientists Turn Atmospheric CO2 into Coal Flakes

The need to transition to clean energy production free from fossil fuels, is becoming more and more pressing as climate change is impacting our chances of survival on the planet.

At the same time research efforts are also invested in removing from the atmosphere the tonnes of CO₂ that we have already released. Current practices, however, are not widespread because of the costs they involve and because of the difficulty of handling the captured gas and storing it safely.

New technologies, however, are being designed to tackle these issues. In a recent publication, researchers describe the reaction between CO₂ and an aqueous organic sorbent called guanidine. The reaction results in the carbon being transformed into insoluble bicarbonate salt crystals, which can be heated to release the CO₂ for storage and regenerate the sorbent.

This procedure is already applied in scuba rebreathers, in that case with the use soda lime: soda lime captures CO₂ off the breath of a diver, allowing the air to be recycled for re-breathing. The application of a similar procedure for capturing atmospheric CO₂ is particularly attractive because the organic sorbent can be regenerated at much lower temperatures compared to existing commercial inorganic scrubbers, leading to a 24% reduction in energy requirements and a significant decrease in the costs of carbon capture.

In another recent development, scientists reported turning atmospheric CO₂ to solid coal flakes using a liquid metal electrocatalyst. Contrary to previous approaches, the procedure does not involve polluting volatile reagents; additionally, it takes place at room temperature, reducing costs. The resulting carbonaceous materials are neither volatile nor difficult to handle as is liquefied CO₂, and they can be readily used in the production of capacitor electrodes.

The new approaches need to be tested and scaled for industrial application, while detailed engineering and cost analyses for capturing atmospheric CO₂ are already being developed.