Analysis of the Cascade Utilization System of LNG Cold Energy and Geothermal Energy
[1]QU Huige,AN Chunguo,ZHAI Meiyuan,et al.Analysis of the Cascade Utilization System of LNG Cold Energy and Geothermal Energy[J].Journal of Zhengzhou University (Engineering Science),2026,47(5):50-57.[doi:10.13705/j.issn.1671-6833.2026.05.004]
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Journal of Zhengzhou University (Engineering Science)[ISSN
1671-6833/CN
41-1339/T] Volume:
47
Number of periods:
2026 Issue 5
Page number:
50-57
Column:
Public date:
2026-09-09
- Title:
- Analysis of the Cascade Utilization System of LNG Cold Energy and Geothermal Energy
- Keywords:
- LNG cold energy; geothermal energy; Rankine cycle power generation; HYSYS; exergy analysis
- CLC:
- TE09
- Abstract:
- To enhance the comprehensive utilization efficiency of cold energy at liquefied natural gas (LNG) receiving terminals, this study focuses on the Hainan Yangpu LNG receiving station and a cascade utilization system that integrates LNG cold energy with geothermal energy was proposed. The system aimed to achieve stepwise conversion and utilization of energy at different quality levels. The LNG gasification process was divided into four temperature stages, each matched with a Rankine cycle operating under corresponding conditions to recover waste heat for power generation. Meanwhile, geothermal steam was introduced as a high‑temperature heat source to drive the Rankine cycles, and after heat release, it was reinjected into the geothermal reservoir to ensure sustainable geothermal resource development. In addition to power generation, the system integrated a distillation‑based seawater desalination unit, utilizing waste heat from the Rankine cycles for seawater desalination, thereby enabling combined cooling, heating, and power generation. Process simulation of the system was conducted using HYSYS software, with an LNG inlet temperature of −162 ℃, a gasification pressure of 0.1 MPa, a geothermal steam temperature of 115 ℃, a pressure of 0.1 MPa, and a cooling water temperature of 25 ℃. Based on the simulation, exergy analysis was performed for each Rankine cycle subsystem and the overall system to evaluate energy utilization efficiency and exergy loss distribution. The results indicated that the system achieved a net power output of 25 372.1 kW, a freshwater production rate of 2 781.5 kg/h, and an overall exergy efficiency of 47%. The power generation contributions of the four temperature‑stage Rankine cycles accounted for 60.9 %, 23.2 %, 4.6 %, and 11.3 % of the total power output, respectively. Exergy loss analysis revealed that heat exchangers were the primary source of exergy loss in the system, with exergy losses significantly higher than those of pressure equipment, making them the most concentrated points of energy loss. By coupling geothermal energy with LNG cold energy through Rankine cycles for efficient power generation, the system not only improved overall energy utilization efficiency but also effectively mitigated the low‑temperature marine environmental pollution caused by the direct discharge of LNG cold energy.
- References:
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Last Update:
2026-09-04
