Design and Economic Evaluation of Low Voltage DC Microgrid based on Hydrogen Storage

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ABSTRACT This study provides designing and techno-economic analysis of a low voltage (48 V) DC microgrid for domestic load application. In present DC microgrid, photovoltaic (PV) is considered as main power generator to deliver the load demand while fuel cell (FC) and battery are considered as backup power sources. To establish a 48 V DC bus, suitable DC-DC converter having wide input voltage range (22–65 V) is designed to stabilize the variable output voltage of PV and FC generators. The converter efficiency was found to be ≈ 87%. A techno-economic study is also carried out to assess the levelized cost of electricity in microgrid using different energy storage systems, i.e. battery and hydrogen. Lead-acid and lithium-ion are considered as battery storages while high-pressure cylinder and metal hydride storages are considered for hydrogen storage. It is found that PV-battery is most economical configuration; however, PV-FC-battery is better choice for high reliability of overall system. PV-FC-battery configuration has lower cost of electricity as compared to PV-FC alone system. In battery storage system, lithium-ion battery shows faster charging/discharging and efficient operation as compared to lead-acid battery application. In hydrogen storage system, if high-pressure hydrogen is considered, the levelized cost of electricity is reduced significantly as compared to metal hydride storage. However, metal hydride is much better choice for hydrogen storage as compared to the high pressure considering the safety concern.