Cold Energy Recovery from LNG Regasification Process

Energy sector has been getting a lot of attention these past years as the gap between supply and demand of energy is getting bigger day by day. Energy resources must be used efficiently to ensure that there will be a continuous and uninterrupted energy source in the future. This also applies to Liquefied Natural Gas (LNG) which nowadays is one of the widely used sources of energy. LNG must go through regasification process before being used for industrial and domestic purposes. Known to be at a very cold temperature (-162°C), this process normally uses the thermal energy of sea water as heating medium. Unfortunately, this process releases a large amount of energy (about 800 kJ per kg of LNG) as the cold sea water will be discarded back to the sea. This study proposed to recover the large amount of cold energy from LNG regasification process using the Rankine and Brayton power cycles for electricity generation. Aspen Hysys software is used to design and simulate an improved system using the Kelloggs process as the base case. The results show that after simulation and parameter manipulation, the proposed combine cycle has thermal efficiency of 38.8% and thermal efficiency of 65.52% using water and carbon dioxide as the working fluid.