The salt in seawater is corrosive, which can lead to the production of harmful chlorine gas. However, new electrode technology can extract clean hydrogen fuel from seawater without the need for prior filtration or treatment.
This technology marks a significant advancement in the commercialization of hydrogen as a sustainable energy solution.
“Traditional electrolysis methods can only be performed with pure water, a resource that is increasingly scarce,” said Doug Wicks from the Advanced Research Projects Agency – Energy (ARPA-E) of the U.S. Department of Energy, in a press release. “We no longer have to rely on pure water but instead can use the abundant water resource: the oceans.”
Seawater will become a source of clean hydrogen fuel. (Photo: Tamara Kulikova/Alamy)
This process utilizes a negatively charged cathode and a positively charged anode to separate seawater into four “streams” – oxygen, hydrogen, harmless acids, and alkaline substances. The alkaline stream reacts with CO2 in the atmosphere, forming stable minerals that are returned to the ocean, while the acid stream will also return to the ocean after restoring its original pH by flowing through silica-rich rocks.
Electrolysis of seawater not only produces hydrogen and oxygen but also generates chlorine gas (Cl₂), a toxic substance, due to the presence of chloride ions (Cl⁻) in seawater. This process can corrode the electrodes and quickly damage the electrolysis equipment. According to laboratory test results, Chen and colleagues predict that these anodes could operate continuously for about three years before maintenance is required, meaning they would need to be removed to be re-coated to prevent chlorine buildup.
Pau Farras, a scientist at the University of Galway in Ireland, commented that the three-year lifespan of the selective oxygen anodes is a remarkable outcome. He agrees that this is a promising method for utilizing seawater in hydrogen fuel production. However, Farras emphasized that, although the laboratory results are very promising, it is still necessary to test whether these anodes can maintain similar performance in a natural environment.
The company developing the selective oxygen anodes is set to begin mass production at a facility in California, with an expected output of around 4,000 anodes per year. This project promises significant results, with the potential to eliminate 10 tons of CO₂ and produce 300 kg of hydrogen each day.
