Accounting for carbon capture solvent cost and energy demand in the energy system

Abstract: Technical carbon dioxide removal through bioenergy with carbon capture or direct air capture plays a role in virtually all climate mitigation scenarios. Both of these technologies rely on the use of chemical solvents or sorbents in order to capture CO$_2$. Lately, concerns have surfaced about the cost and energy implications of producing solvents and sorbents at scale. Here, we show that the production of chemical sorbents could have significant implications on system cost, energy use and material use depending on how much they are consumed. Among the three chemical sorbents investigated, namely monoethanolamine (MEA) for post-combustion carbon capture, potassium hydroxide for liquid direct air capture and polyethylenimine-silica (PEI) for solid sorbent direct air capture, we found that the production of the compound for solid sorbent direct air capture represent the highest uncertainties for the system. At the high range of solid sorbent consumption, total energy system cost increased by up to 6.5\%, while effects for other options were small to negligible. Scale-up of material production capacities was also substantial for MEA and PEI. Implications of sorbent consumption for carbon capture technologies should be considered more thoroughly in scenarios relying on direct air capture using a solid sorbent.