Environmental and economic performance of carbon capture with sodium hydroxide

Carbon capture and utilization processes can lead to the manufacture of carbonates with low, neutral or even negative carbon footprint. In this sense, we consider the utilization of solid sodium hydroxide, NaOH, as an agent for CO₂capture in different conceptual approaches to produce usable carbonates. The experimental background on this application has proven its technical feasibility, although the high cost and carbon footprint of the electrolytic production of NaOH, mainly due to high electricity consumption, are the main barriers for a widespread adoption. However, the use of NaOH has not yet been compared and benchmarked in the current and future scenarios of carbon capture, where the share of renewable sources is progressively increasing in many national electricity mixes and further applications of carbonates are potentially available. To account for these scenarios, we considered different sources of CO₂and NaOH, and the potential utilization of the generated products. Altogether, we evaluated 18 scenarios regarding the impact on life cycle global warming potential and fossil resources depletion, along with the cost of capture. Results show that net emissions savings and potential cost reductions are attainable for both flue-gas and air-based capture processes, provided that the resulting sodium carbonate is used to substitute the current, Solvay-based, production of sodium carbonate.