Experts warn against hype for deriving green hydrogen from direct seawater electrolysis

At first look, the plan sounds compelling: invent and develop future electrolyzers able to producing hydrogen immediately from unpurified seawater. However a better look reveals that such direct seawater electrolyzers would require years of high-end analysis. Moreover, DSE electrolyzers are usually not even crucial—a easy desalination course of is enough to organize seawater for standard electrolyzers.

In a commentary in Jouleworldwide consultants evaluate the prices and advantages of the totally different approaches and are available to a transparent suggestion.

Contemporary water is a restricted useful resource; greater than 96% of the world’s water is discovered within the oceans. If seawater could possibly be fed immediately right into a future electrolyzer to provide inexperienced hydrogen utilizing renewable energy from the wind or solar, it could possibly be a possible resolution. A whole bunch of thousands and thousands of {dollars} in research funding are spent on this concept, and in 2023 alone, there have been greater than 500 publications (this quantity is rising exponentially) on direct seawater electrolysis.

No want for brand spanking new growth

Nevertheless, a techno-economic evaluation exhibits that this argument collapses as quickly as the prices and advantages are analyzed in additional element.

“There is no convincing reason to develop DSE technology because there are already efficient solutions for using seawater to produce hydrogen,” says Dr. Jan Niklas Hausmann, electrolysis researcher at HZB and lead creator of the Joule commentary. Worldwide consultants from numerous disciplines from famend analysis establishments equivalent to Yale College, universities in Canada, Germany and HZB contributed to the commentary.

It’s already potential to make use of seawater to provide hydrogen. Confirmed processes equivalent to reverse osmosis can be utilized to purify seawater for “normal,” commercially out there electrolyzers. From a thermodynamic standpoint, the purification of seawater wants solely 0.03% of the power required for its electrolysis. That is additionally mirrored within the present value: purifying seawater to provide one kilogram of hydrogen prices lower than two cents. Nevertheless, one kilogram of hydrogen prices 13.85 euros at German filling stations.

Investing cash correctly

The event of recent kinds of electrolyzers that may function steadily in seawater would solely save this low cost purification step. In distinction, the event of DSE electrolyzers is extraordinarily difficult and it’s extremely questionable that they’d ever be capable of match the effectivity and long-term stability of at the moment’s electrolyzers.

Specialists see main challenges right here: Seawater incorporates all kinds of natural and inorganic substances that may trigger corrosion and fouling, affecting all components of the electrolyzer. DSE is at present being marketed as a real-world resolution for hydrogen production—a promise that can not be stored and will swallow up lots of taxpayers’ cash, the researchers warn.

“We can compare this with the direct use of crude oil to run cars,” explains Hausmann. “It is possible to develop such cars, but they would just not be as efficient and long-lasting as ones running on purified petrol. This is despite the fact that the cost of purifying crude oil (via refinery) is up to 16% of the final price of the fuel, which is significantly higher than the relative cost of purifying seawater for electrolysis (<1%)."

Getting electrolysis analysis on monitor to contribute to decarbonization

“Academic research does not necessarily have to lead to immediate solutions. However, if DSE is presented as a quick fix and is pushed or hyped to the detriment of other more promising approaches, it will tie up resources that will be lacking elsewhere for the development of key decarbonization technologies,” explains Dr. Prashanth Menezes, an professional on catalysts at HZB.

“If we want to achieve net zero carbon emissions by 2050, funding must be directed to developments that can quickly contribute to this,” says Menezes.