physico-chemical aspects and carbon footprint of hydrogen production from water and hydrocarbons

Physico-chemical aspects determine the efficiency and competitiveness of hydrogen production technologies. the indicator of water consumption is especially relevant, since water is one of the main sources of hydrogen in almost all methods of its production. the article analyzes comparative water consumption indicators for various technologies based on published research and actual data from production plants. the volume of water consumption depends on the quality of the source water, which should be taken into account when implementing hydrogen projects in order to minimize the negative impact on the environment. based on the operating industrial plant, the material balance of hydrogen production by steam reforming was demonstrated, which made it possible to determine the proportion of hydrogen (48.88 %) obtained from water. currently, the carbon footprint indicator is becoming more important, reflecting greenhouse gas emissions throughout the production chain. according to the results of the total greenhouse gas emissions assessment for hydrogen production by steam reforming (about 10.03 kg co2-eq/kg h2), the carbon footprint of hydrogen from water (4.2-4.5 kg co2-eq/kg h2) and hydrogen from methane (15.4-15.7 kg co2-eq/kg h2) has been determined. consequently, almost half of the hydrogen produced by steam reforming is produced from water, corresponds to the indicators of “low-carbon” hydrogen and can be considered as “renewable” hydrogen. to make management decisions, an objective assessment in terms of energy and water costs is necessary based on a system analysis by the development of hydrogen energy and the growth of global hydrogen production. the impact of these indicators on the water cycle and global water resources will increase.