The CCC (cryogenic carbon capture) process provides energy- and cost-efficient carbon capture and can be configured to provide an energy storage system using an open loop NG (natural gas) refrigeration system. This system stores energy during non-peak times by liquefying and storing natural gas to be used as a refrigerant. This investigation compares four different natural gas liquefaction processes simulated by Aspen HYSYS as incorporated as part of the CCC-ES process. In these processes, LNG vaporizes in the CCC process and the cold vapors return through the LNG heat exchangers exchanging sensible heat with the incoming flows. Aside from this difference, this investigation uses process designs similar to traditional LNG processes. The simulations meaningfully compare these alternative liquefaction options, eliminating differences in assumptions and process details inherent in comparing processes simulated by different authors or different codes. The comparisons include costs and energy performance with individually optimized processes, each operating at three operating conditions: energy storage, energy recovery, and balanced operation. Given similar quality turbomachinery, efficient heat exchangers in particular reduce energy input requirements and maximize energy savings and capital costs, including heat exchangers used to cool compressed gases. (C) 2015 Elsevier Ltd. All rights reserved.