Solvent-based scrubbing of CO2 from post-combustion exhaust streams are the most mature technologies, and likely the only ones able to be deployed at commercial scale within the next decade, by 2030. The past decade has seen the advancement of 2nd generation amine formulations and process configurations, e.g., CANSOLV and KS-1. These commercial technologies hold considerable promise, in that they are capable of 50% thermodynamic efficiency, with heat rates as low as 2.3-2.4 GJ/tonne CO2, though the total costs of CO2 capture do not yet meet the United States Department of Energy year 2030 $30/tonne CO2 target. Thus, there is a critical need for 3rd generation solvent offerings to further reduce the total costs of capture either by increased efficiency or lower capital costs, preferably both. PNNL has been designing and testing 3rd generation single-component water-lean solvents for the past decade, with a focus on designing materials that have higher efficiency while being able to use of cheaper materials of construction compared to aqueous 2nd generation formulations. We report a new solvent which has a CO2-rich viscosity in operation of ~9 cP, achieves reboiler duties as low as 2.0 GJ/tonne CO2 and total costs of capture 20% lower than the DOE Case B12B baseline. This new low-viscosity derivative is 4% cheaper than our previously developed solvent, EEMPA (the first technology to break below $50/tonne CO2), primarily due to the lower steady-state water content and the viscosity being three times lower. We present here a study that details the solvent design, synthesis, testing, process modeling and technoeconomic assessment of this new derivative for post-combustion CO2 capture with the aim of being the first CO2 capture technology to break $40 tonne CO2 and be on track to meet DOE’s year 2030 target.

Towards $40/tonne carbon capture with chemically resilient water-lean solvents

ACS Fall 2021

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