Hydrogen from Seawater using Solar Energy

Context: 

Researchers from the Department of Physics at IIT-Madras have developed critical components for a highly efficient, cost-effective way to electrolyze seawater to generate hydrogen.

Image Source: The Hindu

Key Features of the Invention:

• Alkaline Seawater Electrolyzer: The team replaced fresh water with alkaline seawater in their electrolyzer, which provides a sustainable and abundant source for hydrogen production. 
• Support material for the electrodes: They used a carbon-based support material for the electrodes instead of metals to almost eliminate the possibility of corrosion. 
• Transition Metal-Based Catalysts: The researchers designed catalysts based on transition metals that enable both oxygen and hydrogen evolution reactions. 
  • These catalysts facilitate the simultaneous production of hydrogen and oxygen, even in the presence of impurities and chemical deposition on the electrodes.
• Cellulose-Based Separator: To prevent crossover of hydrogen and oxygen, the team developed a cellulose-based separator. This economical separator allows the passage of hydroxide ions while minimizing the unwanted mixing of gases, thus improving the efficiency of hydrogen production.
• Direct Utilization of Photovoltaic-Derived Voltage: The optimized parameters of the electrolyzer enable it to directly utilize photovoltaic-derived voltage for seawater electrolysis. 
  • This advancement facilitates the production of green hydrogen and oxygen, making the process more sustainable and environmentally friendly.
• Prototype Performance: The researchers tested two prototypes of different dimensions. 
  • The smaller electrolyzer produced hydrogen at a rate of 250 ml per hour, 
  • While the larger one generated approximately one liter of hydrogen per hour. Additionally, a stack consisting of three cells produced around four liters of hydrogen per hour.

Significance:

• Sustainable Hydrogen Production: The invention enables highly efficient and cost-effective electrolysis of seawater to generate hydrogen, contributing to sustainable energy systems and reducing reliance on freshwater resources.
• Overcoming Limitations of Existing Technology: The team’s approach addresses the energy-intensive nature, expensive components, and freshwater requirement of alkaline water electrolyzers, providing alternative solutions that improve efficiency and cost-effectiveness for seawater electrolysis.

News Source: The Hindu