New research at Oak Ridge National Laboratory in Tennessee, USA, has produced a means of scrubbing CO₂ from coal-fired power plant flue gases using soda lime. Flue gases are bubbled through a solution of bis-iminoguanidines, which bind to bicarbonate anions, which then act as sorbents for CO₂ molecules, in a process which the researchers say is 24% less energy intensive than industrial benchmarks. The CO₂ sorption process creates a kind of organic (solid) limestone, which is separated out of the process and heated to 120^oC, releasing the CO₂ again in a pure form so that it can be stored. The big advantage of the process is that, after ten cycles, no absorbent is lost, a significant improvement on processes to date. Senior author of the research paper (published in Chem on 31 January), Radu Custelcean, said the “main advantage of our ‘organic soda lime’ is that it can be regenerated at much lower temperatures and with significantly less energy consumption compared to inorganic scrubbers.”