A new technology may not only lower the cost of hydrogen production but also offer a potential solution to growing global water shortages.
Using a combination of seawater, metals, and sunlight, researchers in the United States have developed a method to produce both cost-effective green hydrogen and clean drinking water. Their innovation could make the production of this climate-friendly fuel more efficient while simultaneously addressing the escalating scarcity of freshwater worldwide. And because the system runs on renewable energy, it’s also entirely carbon neutral.
At the heart of this breakthrough is a combination of solar cells, heat recovery, and electrolysis, the most common method of hydrogen production. This process uses electricity to split purified water into its components: hydrogen and oxygen. When the electricity comes from renewable sources, the resulting product is known as green hydrogen.
However, current production costs remain high, in part due to the substantial water requirements. According to a recent study published in the journal Energy and Environmental Science, producing just one kilogram of hydrogen requires at least nine kilograms of water. This raises concerns, as freshwater is becoming increasingly scarce, explains study lead Dr. Lenan Zhang from Cornell University in New York. His team’s solution: seawater, an abundant and free resource, alongside sunlight.
Electricity and Heat from the Sun: How the Tiny Prototype Works
To harness both sunlight and seawater efficiently, the team developed a compact prototype measuring just 10 by 10 centimeters. A built-in silicon-based photovoltaic panel generates the electricity needed for electrolysis. Like conventional solar panels, only a portion of sunlight is converted into electricity; the rest is typically lost as waste heat. However, Zhang explains that this prototype cleverly recycles that heat to evaporate seawater. As the water vaporizes, salt is left behind, and the resulting steam condenses into fresh, clean water, which is then fed into the electrolyzer. Here, precious metals like iridium and platinum act as powerful catalysts in the hydrogen production process.
According to the researchers, the prototype currently produces 200 milliliters of hydrogen per hour. When scaled up, it could generate nearly 36 liters of hydrogen and 1.2 liters of drinking water per square meter, per hour.
Over the next 15 years, the researchers estimate their technology could reduce the cost of green hydrogen from the current $10 per kilogram to just $1. In addition, Zhang sees potential for integrating the system into solar parks — not only to produce hydrogen and water, but also to cool down photovoltaic modules, boosting their efficiency and lifespan.
Photo: Richard Davies