For the first time, scientists have successfully produced hydrogen directly from seawater without desalinating the water beforehand. These results, published in Small, have the potential to kickstart a green hydrogen industry free of some environmental and financial costs associated with conventional methods.
The researchers, led by Nasir Mahmood, PhD, a vice chancellor’s senior research fellow at the Royal Melbourne Institute of Technology (RMIT), successfully split and harvested hydrogen from seawater while bypassing the expensive desalination process that other hydrogen generation methods require.
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Typically, hydrogen is pulled from seawater in a process called electrolysis, which uses electricity to split water into hydrogen and oxygen. This process is performed with an electrolyzer. The downside of electrolysis is that (1) the reaction catalysts are expensive and (2) are energy- and water-intensive. Additionally, electrolyzers produce toxic chlorine as a byproduct. “The biggest hurdle with using sweater is the chlorine,” Mahmood said. “If we were to meet the world’s hydrogen needs without solving this issue first, we’d produce 240 million tons of chlorine each year—which is three to four times what the world needs in chlorine. There’s no point replacing hydrogen made by fossil fuels with hydrogen production that could be damaging our environment in a different way.”
To address this challenge, Mahmood and his team developed specialized catalysts designed to work specifically with seawater. Compared to other catalysts, these new catalysts are more efficient, stable, and cost-effective. “Our approach focused on changing the internal chemistry of the catalysts through a simple method,” said co-author Suraj Loomba. He explained that because they are easier to manufacture and cheaper to produce, these catalysts can also be scaled up.
The technology has the potential to lower the cost of electrolyzers significantly, which may enable the Australian government to meet their goal of green hydrogen at $2/kilogram—a figure that would make green hydrogen competitive with hydrogen sourced from fossil fuels.
The next step for the researchers is to develop a new type of electrolyzer that uses a series of catalysts to produce large quantities of hydrogen efficiently.
