Cost-Effective Carbon Capture Using Chemical Compounds
September 22, 2022
Energy Research and Development (500)
Electric Program Investment Charge - EPIC
Keith J. Bein, Ph.D., Anthony S. Wexler, Ph.D.
California’s current portfolio of energy sector decarbonization strategies is not enough to achieve economy-wide net-zero carbon emissions by 2045. Negative emission technologies that physically sequester carbon dioxide from the atmosphere or from sources such as power plants are essential to reaching carbon neutrality. A recent report by Lawrence Livermore National Laboratory suggests that to reach its goals, California must achieve approximately 125 megatons of carbon dioxide equivalents per year of negative emissions. Negative emission technologies include natural solutions such as ecological restoration, bioenergy with carbon capture and sequestration, and direct air capture. The research presented here lies at the nexus of carbon capture and sequestration for fossil fuel and bioenergy, as well as direct air capture, all of which can benefit from development of new and improved carbon dioxide capture compounds. Amine-based chemical absorption post-combustion capture is the most technologically mature approach. However, amines have large regeneration energy, high production cost, and toxic byproducts. Bioinspired phosphoenol compounds derived from Crassulacean acid metabolism show promise as amine alternatives by potentially alleviating these implementation barriers. A novel effort is made here to screen these compounds in terms of their relevant physicochemical properties using a suite of computational chemistry tools to assess their suitability as post-combustion capture solvents in existing process architectures. Group contribution methods show reaction enthalpies within the optimal range and identify core gateway structures while nonreactive molecular dynamics simulations indicate that aqueous solution properties like solubility are comparable to the monoethanolamine benchmark. This is important since the theoretical capture efficiency of phosphoenol compounds is twice that of monoethanolamine, meaning a potentially significant reduction in energy penalty and thus cost. Reactive molecular dynamics simulations accurately describe the reaction thermodynamics and kinetics, and process modeling demonstrates encouraging trends for using these compounds in commercial-scale carbon capture and sequestration.