2022 Volume 48 Issue 5 Pages 182-189
The power produced from renewable energy sources should ideally be converted into H2 for the purpose of long-term storage and long-distance transportation. In this study, an energy supply chain was considered by assuming that wind turbines whose total output of 3 GW were installed in Yokkaichi city, the electricity generated was calculated based on meteorological data, the obtained electricity was converted into H2 by electrolysis of water and transported to consumers in Yokkaichi city, Nagoya city or Kyoto city after (1) compression, (2) liquefaction, (3) conversion into compressed CH4 or liquefied CH4, (4) conversion into organic hydride, or (5) conversion into NH3. Upon delivery to the consumer, the energy efficiency, CO2 emission reduction effect and number of households and days for which the energy demand of general households could be satisfied were evaluated. In addition, a case of utilizing the cold heat generated from phase change of liquefied natural gas on a liquefaction of H2 as an auxiliary heat source was also evaluated. As a result, the H2 carrier having the smallest energy consumption and CO2 emission in the course of transport was (3) liquefied CH4 after methanation. When the H2 transported to the consumer is used for H2 gas turbine power generation, the CO2 emission for H2 carrier excluding compressed CH4 and liquefied CH4 was 4.29×108 kg/year. In addition, it became evident that the annual energy demand for two-person households could be satisfied for 30.2 households. When the H2 transported to the consumer is used as a fuel for a mobility, the CO2 emission reduction effect became larger in the order of diesel buses, hybrid cars, diesel cars and gasoline cars. Moreover, the energy loss ratio was the smallest in the case of liquefied H2 utilizing the cold heat generated from the phase change of liquefied natural gas irrespective of the transport distance. This is because the energy assist ratio of the cold heat upon phase change of liquefied natural gas to the total energy needed for liquefaction process of H2 was high at 64.3%.
