The energy conversion efficiency of the electricity-hydrogen-electricity conversion is only 315-40%”
Hydrogen energy is used in long-term energy storageFig.1 Composition of hydrogen power system.
Hydrogen has the potential to be used in the power system. Theoretically, it can also be used for energy storage and power generation in the power system through the conversion process of electricity-hydrogen-electricity. In terms of energy storage, hydrogen can be used as an energy carrier for long-term energy storage, or as a substitute for transmission for long-distance transportationIn terms of power generation, hydrogen can be used to generate electricity through fuel cells or gas turbines, for grid balancing (peak shaving), as a distributed power source, etc. The development stage of hydrogen power system is still early, and energy efficiency is the main bottleneck. According to the estimation of 70-80% working efficiency of ALK electrolyzer and 45-50% working efficiency of PEM fuel cell, the energy conversion efficiency of electricity-hydrogen-electricity conversion is only 315-40%；If system losses during the storage and transportation phase are taken into account, the actual energy efficiency of a hydrogen power system may be lower. Fig. 2 Application of hydrogen energy in power system.
Hydrogen cogeneration
Fig.3 Combined heat and power for fuel cells.
Hydrogen can be used in the building sector to help reduce emissions. In 2020, China's heating, domestic hot water, cooking, and household electricity accounted for nearly 20% of the final energy consumption. Fuel cell cogeneration: The system has excellent energy efficiency, and the United States and Japan are the first to promote. Fuel cell cogeneration is the collection of heat generated by fuel cells, significantly improving the energy efficiency of the system. Panasonic fuel cells have an energy conversion efficiency of 56%, while the energy efficiency of combined heat and power is as high as 95%.
Natural gas hydrogen blending applications: economy and safety need to be demonstrated. Theoretically, hydrogen can be blended into domestic natural gas in a certain proportion to utilize existing gas facilities and stoves** and be used.