Solar Regenerative Hydrogen Fuel Cell Charging System

Due to increasing levels of air pollution from the use of fossil fuels, producing clean renewable energy has become a high priority in society. However, renewable energy like solar or wind energy can only be produced intermittently, and frequently does not align with the energy demand. This has become a significant barrier to the adoption of renewable energy. As a result, additional effort is required to harvest and store excess energy produced during peak production periods to meet the energy demand during off production periods. The objective of this study is to design a solar powered regenerative hydrogen fuel cell charging system that can store excess energy in the form of hydrogen and generate electricity using fuel cell when renewable energy is not available. A group of undergraduate engineering students at the University of California, Merced, designed, integrated, and tested the newly developed renewable energy charging system. This system is comprised of 6 photovoltaic modules rated at 3.0 W each, in-house designed gravity-assisted gas storage tanks, a 1.0 W water electrolyzer, and a 3.0 W fuel cell stack. The integrated system can produce up to 2.5 W to charge a cell phone day or night. During insolation, energy from the photovoltaic modules is used to directly charge the phone and power the water electrolyser for hydrogen generation. The 1.0 W water electrolyzer or electrolysis cell can produce more than 4.0 L of hydrogen under ambient pressure on an average day in Merced, CA. The generated hydrogen fills the storage system during insolation and is released to the 3.0 W fuel cell stack to charge various cell phones at night or during a cloudy day. A DC voltage booster was used to meet the charging requirement for voltage input (4.5 V-5.0 V). In this study, students successfully demonstrated that both solar and hydrogen energy can be used to meet the energy demand for charging a cell phone all year round. This system provides a proof-of-concept study to meet future energy demand with a sustainable solution. Further, various learning outcomes including problem solving, critical thinking, communication, and team work were fulfilled by this in-depth engineering project.