an estimated 15 L/kg of hydrogen and this is de-ionised water so much processing of the water to be done.
Steam Methane Reforming (SMR)
Conclusion: Based on the Linde facility data, we can infer that water consumed in hydrogen production ranges from 5.85-13.2 L H20 / kg H2. Additional wastewater would also be expected to be generated in the process, but this is not described in the report by Linde.
Autothermal Reforming (ATR) ... Finkel's described preferred option in 2018.
Autothermal reforming is a developmental process for producing hydrogen. The process uses the best features of partial oxidation and SMR [9]. The primary benefit of ATR is that it releases CO2 in a concentrated stream, which allows for easier application of carbon sequestration.Producing hydrogen through the process of ATR requires less heat and water than SMR to drive the reaction. Extrapolation from the Johnson Matthey process estimates 31,000 L/hr of demineralized water is required to produce 6,000 kg/hr of hydrogen [10]. Assuming a 70% efficiency coefficient for the use of water in the process, and production of demineralized water, the total water demand will be equivalent to ~7.4 L H2O / kg H2.
and ElectrolysisProducing hydrogen through the process of electrolysis theoretically requires 9 L of water per kg of hydrogen based on the stoichiometric values. [11].
2H2O→O2+4H++4e-
4H++4e-→2H2
Overall: 2H2O → O2 + 2H2 [12]
However, most commercial electrolysis units on the market today advertise that they require between 10 and 11 L of deionized water per kg of hydrogen produced. Commercial electrolyzer units with published water demands are listed in Table 1. Other companies with commercial electrolyzer units who do not have publicly available water demands include PROTON, McPhy, and Nel. Note that additional water would be required depending on the process of converting surface/tap water to deionized (DI) water.
Water for the Hydrogen Economy, WaterSMART Solutions Ltd.
-5-Additional water will also be required for system cooling. HYRDOGENICS’ PEM electrolyzer requires 15.5
L of tap water per kg of H2 [13]. A schematic of the electrolysis process is included in Appendix A.
from the link I posted above.....
