(60o) Process Development and Analyses for Production of Green Hydrogen Using Liquefied Natural Gas Cold Energy

As the world becomes increasingly aware of the negative impact of traditional energy sources, there is a growing demand for sustainable energy sources. One such technology that has gained attention is the use of liquefied natural gas (LNG) cold energy to generate electricity through an organic Rankine cycle (ORC) system. This system is capable of producing green hydrogen by water electricity, which is generated from the ORC system using LNG cold energy.

In the proposed process of this study, LNG is used as a refrigerant in the ORC system to generate electricity, which is then used to produce green hydrogen through water electricity. The LNG is partially vaporized through heat exchange with the working fluid (WF) of the ORC system and completely vaporized to natural gas (NG) through heat exchange with seawater (SW). The WF of the ORC system is pressured by pump and completely vaporized pump and then completely vaporized through heat exchange with SW. The vaporized WF is used to turn the turbine and generate electricity. The WF in the gas state after passing through the turbine is liquefied through heat exchange with LNG and then circulated through the ORC system to generate electricity. The produced electricity from the ORC system is supplied to the electrolysis stack, and finally, green hydrogen is produced through water electrolysis in the electrolysis stack.

The selection of the WF in the ORC system is critical in the efficiency of the ORC system. In this study, we evaluate the effect of different WFs on the efficiency of the ORC system by proposing three strategies using methane (CH4), ethane (C2H6), and propane (C3H10) as working fluids. A case study is conducted to compare the economics and environmental impact of each strategy through techno-economic analysis (TEA) and life cycle assessment (LCA). By performing these analyses, the contributing factors are investigated from each perspective. Additionally, three strategies are compared to determine the most economically and environmentally viable process.