Thermodynamic and environmental analyses of a novel closed loop regasification system integrating ORC and CO2 capture in floating storage regasification units

Regasification systems in Floating Storage Regasification Units (FSRUs) that use the steam generated by the boilers as the heat source (closed loop) in the liquefied natural gas (LNG) regasification process are less detrimental to the marine environment than those systems that use seawater (open loop). Their drawback, however, lies in the significant increase in fuel consumption and, thus, CO2 emissions. The present paper performs an energy, exergy and environmental analysis of a novel closed-loop regasification system for FSRUs that integrates an organic Rankine cycle (ORC) and post-combustion CO2 capture system with a 30 wt% aqueous solution of monoethanolamine (MEA). LNG cold energy is utilised for power generation through the ORC as well as in the processes of CO2 capture, compression, drying and liquefaction. The system proposed is able to meet the electrical power demand of the FSRU without the use of dual fuel engines, while CO2 capture efficiency in the boiler flue gases exceeds 90%. Fuel consumption is cut by 18% in this system in comparison with existing closed-loop regasification systems, and exergy efficiency increases by 14%, while CO2 emissions decrease by approximately 75% compared to open-loop systems commonly installed on board.