Objective As the transition to low-carbon and renewable energy accelerates in China, the construction and development of LNG terminals are advancing rapidly. LNG releases significant cold energy during the vaporization process, and optimizing this cold energy aligns with the “dual carbon” strategy. Cold energy power generation is the most viable method for utilizing cold energy. With various technical routes available, selecting the most appropriate option for domestic LNG terminals is essential.

Methods With the cold energy power generation project of an LNG terminal to be built as a case study, the technical routes of single-stage Rankine cycle, parallel double-stage Rankine cycle, and hybrid double-stage Rankine cycle were analyzed. A comprehensive comparison was conducted regarding thermodynamic performance, economical efficiency, reliability, operation, and maintenance to identify the optimal option.

Results Comparative analysis revealed that the hybrid double-stage Rankine cycle system exhibited the highest thermodynamic performance, with an average net output power of 4 037 kW and exergy efficiency up to 29.2％, followed by the parallel double-stage Rankine cycle system. The single-stage Rankine cycle system demonstrated the lowest performance. In terms of economical efficiency, the internal rates of return for the single-stage and hybrid double-stage Rankine cycle systems were similar, at 6.78％ and 6.90％, respectively. The parallel double-stage Rankine cycle system had the lowest internal rate of return, indicating the weakest economical efficiency. In terms of reliability, operation, and maintenance, the single-stage Rankine cycle system was easier to operate and control on-site, offered higher reliability, simplified LNG terminal operations, and occupied less space. In contrast, the hybrid double-stage and parallel double-stage Rankine cycle systems were more complex to operate and required larger areas. For practical engineering applications, it is advisable to adopt the single-stage Rankine cycle for cold energy power generation.

Conclusion Given that the primary functions of LNG terminals are the storage, vaporization, and export of LNG, ensuring the stable operation of cold energy power generation systems, which also function as LNG vaporization facilities, is crucial. Therefore, when selecting a technical route for cold energy power generation, it is essential to consider not only thermodynamic performance and return on investment but also the reliability of the cold energy system and the ease of field operation and maintenance. The research results can provide theoretical reference for the selection of technical routes for cold energy power generation systems at LNG terminals in China.