Empirical electrical modeling for a proton exchange membrane electrolyzer

The hydrogen (H₂) economy is a proposal for the distribution of energy using hydrogen as an energy carrier (due to its high mass energy density) for reducing green house gas emissions. Energy conversion from renewable energy (RE) sources with suitable energy storage can play an important role in the development and operation of RE systems. The integrated intermittent RE system, (e.g. wind, solar energy systems) based on energy storage in the form of electrolytic H₂, is considered a promising alternative to overcome the intermittence of the RE sources. In comparison to commonly used battery storage, H₂ is well suited for seasonal storage applications due to its inherent high mass energy density. PEM based electrolysis has many advantages as compared to conventional alkaline based electrolysis e.g. smaller dimension and mass, lower power consumption, intrinsic ability to cope with transient electrical power variations, high degree of purity of gases and possibility of getting H₂ compressed at higher pressure within the unit and more safety level. In this work, PEM electrolyzer model has been developed. Input current-voltage (I-V) characteristic of electrolyzer has been modeled by using the experimental analysis under steady state conditions at room temperature. The model is developed by using electrical equivalent circuit topology by considering useful power conversion and losses. Electrolytic H₂ production rates are found out with respect to the input current and power. These experimental results are verified with the theoretical results and the relative errors are <;2%. The electrolytic H₂ production rate increases linearly with current, but variation of electrolytic H₂ production rate with the input electrical power is nonlinear (i.e. logarithmic). These are verified through the developed model also. This model will help to analyze energy system behavior where is stored in the electro- ytic H₂ form.