The most energy-efficient and cost-effective process for producing a high volume of hydrogen gas with minimal environmental impact for industrial applications like fuel cell technology is water electrolysis using renewable energy sources.Water electrolysis involves splitting water H2O into hydrogen H2 and oxygen O2 using an electric current. When powered by renewable energy sources like solar, wind, or hydroelectric power, this process can be both energy-efficient and environmentally friendly, as it produces no greenhouse gas emissions.There are two main types of water electrolysis technologies: alkaline electrolysis and proton exchange membrane PEM electrolysis. Both methods have their advantages and disadvantages, but PEM electrolysis is generally considered more efficient and has a faster response time, making it more suitable for integration with renewable energy sources.In summary, water electrolysis powered by renewable energy sources is the most energy-efficient and cost-effective process for producing hydrogen gas with minimal environmental impact for industrial applications like fuel cell technology. However, it is essential to continue researching and developing new technologies to further improve efficiency and reduce costs.