A Study of the Life Cycle Exergic Efficiency of Hydrogen Production Routes in China

Hydrogen is a clean secondary energy source that plays an important role in promoting the region’s low-carbon energy mix transition. Currently, most of the evaluations of hydrogen production technologies in terms of energy consumption focus on energy efficiency, and fewer studies have been conducted at the level of exergy. In this paper, we use the life-cycle approach and the energy quality coefficient method to assess and discuss the exergic efficiency of three technology routes, namely hydrogen production from natural gas, propane dehydrogenation, and hydrogen production from green electricity, which were carried out in China. Hydrogen production from natural gas was found to have the lowest exergic efficiency, with exergic losses mainly from the compression process, high-temperature chemical reactions, and reduced catalyst activity. Propane dehydrogenation was found to be about 16% more exergic efficiency than natural gas to hydrogen, with exergic losses mainly from compression. Hydrogen production from wind power has the highest exergic efficiency, with exergic losses mainly due to the electricity required to run the electrolyzer. By analyzing the changes in energy consumption and exergy consumption of China’s future hydrogen supply, this paper found that the energy consumption per unit of hydrogen production will decrease to 9.2 kg of SC/kg of H2 and the exergy consumption per unit of hydrogen production will decrease to 9.6 kg of SC/kg of H2 in 2030. The exergic efficiency of the hydrogen production process in China will be further improved as the proportion of hydrogen production from electrolytic water in the hydrogen production structure increases.