Economic Feasibility of Power Generation by Recovering Cold Energy during LNG (Liquefied Natural Gas) Regasification

Abstract

Liquefied natural gas (LNG) has emerged as the leading option for global natural gas trade. Imported LNG must be regasified at the receiving terminal. The practice of using seawater as the heat source for regasification is a sheer waste of the available cold energy in LNG. In this study, power generation from LNG cold energy is investigated to reverse this wastage. We have developed a superstructure for this power generation process (PGP) that includes direct expansion of LNG and organic Rankine cycle (ORC) with simultaneous selection of the working fluid components and their compositions. Using a simulation-based optimization paradigm, the economic viability of the PGP is investigated by maximizing its net present value (NPV). Our results show that although a PGP with both direct expansion and ORC has a higher exergy efficiency, its NPV is nearly 64% lower than that of a PGP with ORC only. We present case studies for various combinations of process parameters and found that LNG regasification pressure has the maximum impact on NPV of the PGP followed by LNG feed temperature and composition. The maximum-NPV PGP uses only ORC and produces a net power of about 0.5–12.9 kW/tLNG after satisfying the power demand of the LNG regasification process. The NPV is about $6.87–2.45 million; thus, power generation by recovering cold energy in an LNG regasification terminal is economically viable. We also present a robust process design strategy to handle uncertainties in LNG composition.

Reducing Power Use in the Cold Section of LNG Plants

“…A simulation-based optimization (SBO) framework based on a metaheuristic solver such as particle swarm optimization (PSO), simulated annealing, or genetic algorithm has been commonly used in the literature. ,,− In particular, the PSO algorithm has proven useful in several works. ,, It maintains an evolving swarm (population) of particles (potential candidate solutions), which moves toward better and better solutions, as new particles are added at every iteration. PSO transitions gradually from search space exploration to search space exploitation by manipulating a parameter called damping factor.…”

Uncertainty and Risk Evaluation of Deep Geothermal Energy Source for Heat Production and Electricity Generation in Remote Northern Regions

“…Furthermore, Organic Rankine Cycle has been capable of generating electricity from even lower temperature sources. For example, power generation from waste energy during the process of liquified natural gas regasification was achieved with a source temperature of 100 to 30 • C (e.g., [136,137]). Thus, Organic Rankine Cycle can be a promising technology for northern regions.…”

Energy, Exergy, and Economic Analysis and Multiobjective Optimization of a Cascade Coupling System Driven by Low-Grade Waste Heat in Hot Summer and Cold Winter Areas of China

“…Global energy consumption will grow continually at a rate of 1.3% every year until 2040, which will continue to increase the energy pressure globally . Therefore, improving the energy utilization efficiency is considered as a significant issue .…”

“…Global energy consumption will grow continually at a rate of 1.3% every year until 2040, which will continue to increase the energy pressure globally. 1 Therefore, improving the energy utilization efficiency is considered as a significant issue. 2 In China, the rapid industrialization process produces more and more low-grade waste heat, and the recovery rate is just 30%.…”