Hydrogen Production Plant Retrofit Towards Green H2: an Isolated Microgrid Highly Integrated with Battery Storage, Wind and Solar Sources

Given the climate change being observed in the past few decades, sustainable development and the use of renewable energy sources are urgent. In this scenario, hydrogen production through electrolyzers is a promising renewable source and energy vector because of its ultralow greenhouse emissions and high energy content. Hydrogen can be used in a variety of applications, from transportation to electricity generation, contributing to the diversification of the energy matrix. In this context, this paper presents an autonomous isolated microgrid system for generating and storing electrical energy, to be exclusively used for feeding an electrolyzer hydrogen production plant, which has been retrofitted toward green hydrogen production. The experimental verification was performed at Itaipu Parquetec, which consists of an alkaline electrolysis unit directly integrated with a battery energy storage system and renewable sources (e.g., photovoltaic and wind) by using an isolated DC microgrid concept based on DC-DC and AC-DC converters. Experimental results revealed that the new electrolyzer DC-DC converter increases the system’s overall efficiency in comparison to the legacy thyristor-based power supply system, and autonomously control the energy supply to the electrolyzer under optimized conditions with extremely low output current ripple. Another advantage of the proposed DC microgrid is its ability to proper manage the startup and shutdown process of the electrolyzer plant under generation outages. This paper is the result of activities carried out under the R&D project of the ANEEL program No. PD-10381-0221/2021, entitled Multiport DC-DC Converter and IoT System for Intelligent Energy Management, which was conducted in partnership with CTG-Brasil.