The work systematically evaluates working-fluid choices and advanced cycle architectures for extracting power from LNG’s cold-temperature range up to ambient conditions. Using modeling and optimization, the researchers pinpoint a standout configuration: a two-stage Rankine cycle with reheating, designed to better match temperature levels during heat addition and expansion.

To explore the design space, the team screened 30 single-working-fluid options and 49 binary mixtures, then compared four enhanced configurations incorporating reheating, regeneration, and Kalina-cycle integration. The calculations were performed in Aspen HYSYS, while a Python genetic algorithm searched across pressures, temperatures, and fluid compositions to maximize net output.

Because LNG storage centers around roughly −162 °C, each kilogram retains about 830 kJ of cold energy available for conversion. The central challenge is that regasification heat transfer is often too limited or poorly aligned with conventional cycle temperature profiles, leaving much of the potential unexploited.

Among single-fluid systems, hexafluoroethane (R116) performed best in the upper cycle, while ethane (R170) was strongest in the lower cycle. Together, these selections delivered 7.5 MW of net power with a thermal efficiency of 24.1%.

Binary mixtures improved performance stability and nudged output higher. The best conventional two-stage baseline combined R116 in the upper cycle with an optimized R1150/R23 mixture in the lower cycle, achieving about 7.7 MW—roughly 2.6% above the top single-fluid design.

The largest gains emerged from reheating. In the optimal scheme, R116 drives the upper-cycle expansion, while an R1150/R170 mixture operates in the lower cycle. Expansion is split into two turbine stages, separated by additional heating, which raises effective operating pressure and preserves usable heat for the downstream stage.

This reheated architecture produced 9.2 MW of net power at an LNG capacity of 216 tonnes per hour. The improvement corresponds to roughly 22% over the best single-fluid case and 19% over the best mixed-fluid baseline, while regeneration and Kalina integration offered little net advantage due to reduced effective heat transfer between stages.

Overall, the findings emphasize that maximizing cold-energy recovery requires optimizing the entire thermodynamic system, not just individual components. For real LNG terminals, the authors highlight reheating as the clearest pathway toward additional low-carbon electricity generation.

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Subject of Research: Cold energy recovery from LNG using advanced binary working fluid power cycles

Article Title: Enhancements and optimization of LNG cold energy recovery via advanced binary working fluid power cycle systems

News Publication Date: 11-May-2026

Web References: https://doi.org/10.48130/een-0026-0007

References: Wong SH, Xiao G, Zhang D. 2026. Enhancements and optimization of LNG cold energy recovery via advanced binary working fluid power cycle systems. Energy & Environment Nexus 2: e014. doi: 10.48130/een-0026-0007

Image Credits: Credit: Shing-hon Wong, Gongkui Xiao & Dongke Zhang

Keywords

LNG cold energy, regasification, binary working fluids, two-stage Rankine cycle, reheating, cryogenic power generation, Aspen HYSYS, thermal efficiency, optimization