Time-shifting storage scheme via electricity price arbitrage: Techno-economic optimization for carbon dioxide compression cost reduction in carbon capture, utilization and storage

Abstract

Global decarbonization policies have heightened the urgency of developing carbon capture, utilization, and storage technologies. Despite advances in capture methodologies, energy-intensive compression of captured carbon dioxide remains a critical bottleneck in reducing overall capture costs. Current optimization efforts primarily focus on internal technical improvements but overlook external operational factors, such as electricity pricing. Fluctuating electricity prices under time-of-use policies directly impact the daily operating costs of the carbon dioxide compression unit. Therefore, this study proposes a time-shifting storage scheme that exploits electricity price variations across different periods to reduce compression costs. Furthermore, the vapor compression refrigeration and organic Rankine cycles are employed to optimize energy utilization. Five simulation cases are conducted. The results show that under design conditions, Case 2 (carbon dioxide is temporarily stored during peak periods) achieves a levelized cost of compression of 12.62 $/tonne, which is 20.68 % lower than conventional compression compared to Case 1 (15.91 $/tonne). Moreover, Case 3 (carbon dioxide is stored during peak and shoulder periods) demonstrates a significantly lower cost of 10.15 $/tonne, indicating a 36.02 % reduction. Integrating two thermodynamic cycles in Case 3 reduced specific energy consumption from 97.44 kWh/tonne to 92.36 kWh/tonne and 93.71 kWh/tonne. The system exergetic efficiency increased from 62.39 % to 65.55 % and 64.87 %, yielding additional cost reductions of 2.36 % and 1.81 %, respectively. In full-chain carbon capture processes where the carbon dioxide compression system accounts for 30 % of the total cost, adopting the time-shifting storage scheme (Case 3) results in a 10.80 % reduction in aggregate costs.