Estimation of chain availability for ship-based carbon capture and storage (CCS) chain

Abstract

This study designed a ship-based CCS chain and estimated the availability of the chain to investigate which would be critical components in the chain and to suggest improvement methodology for chain design. Three central variables in the chain were analyzed and determined: $CO_2$ liquefaction pressure, $CO_2$ liquefaction system (process), and cargo volume of temporary storage tank. Seven liquefaction pressures were suggested between the triple point (5.18 bar, $-56.6\^circ C$) and the critical point (73.8 bar, $31.1^\circ C$) of $CO_2$ with increments of 10 bar, and compared them in terms of life cycle cost (LCC) to determine the optimal pressure. Four liquefaction systems were proposed and analyzed using LCC in order to select the optimal $CO_2$ liquefaction system. (The Linde Hampson system, the Linde dual-pressure system, the precooled Linde Hampson system, and the closed system.) LCCs of the chains with different cargo volumes were estimated to determine the optimal cargo volume of temporary storage tanks. The optimal liquefaction pressure was 15 bar $(-27^\circ C)$, which had an appropriate pressure, temperature, and density. The closed system showed the lowest LCC among the four suggested $CO_2$ liquefaction systems. The optimal cargo volume of the storage tanks was the identical volume of $CO_2$ carrier. The availability of the chain with three selected design variables was estimated. The results showed that the most significant factor in the chain was the preventive maintenance for the liquefaction system. Although this preliminary study has some uncertainty, it provides meaningful information for a decision-maker to progress to the next step.