Evaluation of CO2 liquefaction processes for ship-based carbon capture and storage (CCS) in terms of life cycle cost (LCC) considering availability

Abstract

This study compared four liquefaction systems based on the life cycle cost (LCC) analysis, in order to select the optimal CO2 liquefaction system for ship-based carbon capture and storage (CCS). Three open processes and one closed process were considered: the Linde Hampson system, the Linde dual-pressure system, the precooled Linde Hampson system, and the closed system. The design parameters including pressure, temperature and refrigerant type were determined through repeated simulations or process optimizations. LCC analyses were employed for the evaluation of the four systems, considering the capital expenditure (CAPEX), the operational expenditure (OPEX), and the unavailability cost. The results showed that the OPEX value was the most dominant cost, accounting for over 80% of the LCC. The CAPEX and unavailability cost took 11% and 9%, respectively. The Linde Hampson system and Linde dual-pressure system showed higher CAPEX and OPEX values than those of the other systems. The closed system showed the lowest LCC while the precooled Linde Hampson system had only slightly higher values than the closed system. A sensitivity analysis was conducted to reveal the influence of several factors. LCC was re-estimated depending on different liquefaction conditions, disposal amounts, cooling water temperatures, electricity prices, CO2 trade costs, and uncertainty of the employed methodology. The LCC results had approximately 7% uncertainty, caused by the unreliability of the method for CAPEX estimation.