Optimal Sizing of a Hydrogen Backup Grid to Support Renewable Generation in Microgrids

Integrating intermittent renewable energy into microgrids poses significant control challenges to maintaining a reliable operation. Indeed, balancing the grid becomes arduous when power generation is only partially controllable. In this context, energy storage systems are beneficial for absorbing power intermittencies, adding the control capabilities needed to secure microgrids' service. In particular, Hydrogen Energy Storage Systems (H
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ESS) are advantageous due to their high energy density and long lifespan. This study proposes a methodology for finding the optimal size of a H
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ESS that supports a microgrid operation. The methodology considers shared assets for electrolyzers and individual fuel cells with heat recovery systems. Thus, it exploits highly efficient processes for hydrogen conversion. A numeric example is presented to explain the sizing methodology in detail and provide practical implementation advice. The results show that a H
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ESS minimizes costs by storing renewable energy production surplus in summer and using it in winter. This seasonal pattern is convenient for H
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ESS since it has lower self-discharging losses than other energy storage technologies.