LNG regasification and electricity production for port energy communities: Economic profitability and thermodynamic performance

The integration of electricity and gas systems is a key priority for the energy transition. Alongside electricity, low-carbon energy vectors, such as Liquified Natural Gas (LNG) or hydrogen, are required in future energy systems. Hence, regasification systems, often located nearby port areas, will be strategic assets promoting environmental, social, and economic benefits. This study investigates and compares three integrated configurations exploiting LNG cold exergy for the efficient production of electricity in a port area . In all three configurations, electricity is produced by a gas turbine fuelled with regasified natural gas and different combinations of two bottoming cycles, consisting of a transcritical CO2 Rankine cycle and a natural gas direct expansion cycle. These configurations are compared with a traditional regasification and combined cycle power plant. The study aims at identifying the design of the system that maximizes the second law efficiency and the Net Present Value (NPV) for various relative sizes between gas turbine and regasification capacity, including analyses on Internal Rate of Return (IRR). A sensitivity analysis on the installation of turbine inlet air-cooling taking advantage of LNG cold exergy is also performed. The optimization is performed through Particle Swarm Optimization (PSO) algorithm and Aspen Hysys. Results show that the mutual size between the gas turbine and regasification unit is an important variable that requires careful analysis, as the second law efficiency can vary between 49% and 42% depending on the case. Electric efficiency of the proposed configurations can approach 65%, thus resulting greater than the traditional combined cycle in most of the test conditions. Economic optimizations confirm that the NPV of two configurations is often 10-15 M(sic) greater than the corresponding value of the base case system; however, only a single configuration can increase the IRR by 1-2% in comparison to the case with separate units. These results can guide designers and developers in the definition of the most cost-effective solution of any integrated energy systems including regasification, similar to a port system, which are expected to be key facilities in the future energy scenario.