Sustainably harnessing of LNG cold energy for power generation and wastewater desalination

In utilizing liquefied natural gas (LNG) cold energy, challenges like energy waste and insufficient utilization persist. This study integrates LNG cold energy with power plant waste heat for power generation and wastewater desalination. A data-driven approach employing long short-term memory models was used to predict system performance. Optimization methods, including the Non-dominated Sorting Genetic Algorithm II (NSGA-II) and Particle Swarm Optimization (PSO), were compared. The findings revealed that NSGA-II surpassed PSO, delivering a system net power output of 1201 kW, an exergy efficiency of 54.8 %, and a levelized cost of energy (LCOE) of 0.088 $/kWh. Furthermore, the study proposes eight two-stage power generation cycles for the efficient utilization of LNG cold energy and power plant waste heat. Quantitative comparisons identified the optimal configuration as a tandem Brayton cycle (BC) and organic Rankine cycle (ORC), achieving 1245.2 kW net power, 56.3 % energy efficiency, 48.2 % exergy efficiency, and an LCOE of 0.11 $/kWh. Additionally, analysis of six binary organic working fluids for the ORC recommended CO2/R290 as optimal. Overall, this research provides an economically viable and efficient strategy for LNG cold energy and power plant waste heat utilization, contributing to a sustainable, diversified energy portfolio and ecological well-being.