Water-splitting system pulls green fuel from seawater

Water-splitting system pulls green fuel from seawaterA prototype that can generate hydrogen fuel from seawater. (Credit: H. Dai, Yun Kuang, Michael Kenney)Researchers have devised a way to generate hydrogen fuel using solar power, electrodes, and saltwater from San Francisco Bay.

The findings demonstrate a new way of separating hydrogen and oxygen gas from seawater via electricity. Existing water-splitting methods rely on highly purified water, which is a precious resource and costly to produce.

Theoretically, to power cities and cars, “you need so much hydrogen it is not conceivable to use purified water,” says Hongjie Dai, professor in chemistry in Stanford University’s School of Humanities and Sciences and co-senior author of the paper. “We barely have enough water for our current needs in California.”

Hydrogen is an appealing option for fuel because it doesn’t emit carbon dioxide, Dai says. Burning hydrogen produces only water and should ease worsening climate change problems.

Dai says his lab showed proof-of-concept with a demo, but the researchers will leave it up to manufacturers to scale and mass produce the design.

Faster splitting without corrosion

As a concept, splitting water into hydrogen and oxygen with electricity—called electrolysis—is a simple and old idea: a power source connects to two electrodes placed in water. When power turns on, hydrogen gas bubbles out of the negative end—called the cathode—and breathable oxygen emerges at the positive end—the anode.

But negatively charged chloride in seawater salt can corrode the positive end, limiting the system’s lifespan. Dai and his team wanted to find a way to stop those seawater components from breaking down the submerged anodes.

The researchers discovered that if they coated the anode with layers that were rich in negative charges, the layers repelled chloride and slowed down the decay of the underlying metal.

They layered nickel-iron hydroxide on top of nickel sulfide, which covers a nickel foam core. The nickel foam acts as a conductor—transporting electricity from the power source—and the nickel-iron hydroxide sparks the electrolysis, separating water into oxygen and hydrogen. During electrolysis, the nickel sulfide evolves into a negatively charged layer that protects the anode. Just as the negative ends of two magnets push against one another, the negatively charged layer repels chloride and prevents it from reaching the core metal.

Without the negatively charged coating, the anode only works for around 12 hours in seawater, according to Michael Kenney, a graduate student in the Dai lab and co-lead author of the paper.

“The whole electrode falls apart into a crumble,” Kenney says. “But with this layer, it is able to go more than a thousand hours.”

Previous studies attempting to split seawater for hydrogen fuel had run low amounts of electric current, because corrosion occurs at higher currents. But Dai, Kenney, and their colleagues conducted up to 10 times more electricity through their multi-layer device, which helps it generate hydrogen from seawater at a faster rate.

“I think we set a record on the current to split seawater,” Dai says.

The team members conducted most of their tests in controlled laboratory conditions, where they could regulate the amount of electricity entering the system. But they also designed a solar-powered demonstration machine that produced hydrogen and oxygen gas from seawater from San Francisco Bay.

And without the risk of corrosion from salts, the device matched current technologies that use purified water. “The impressive thing about this study was that we were able to operate at electrical currents that are the same as what is used in industry today,” Kenney says.

Simple solution

Looking back, Dai and Kenney can see the simplicity of their design. “If we had a crystal ball three years ago, it would have been done in a month,” Dai says. But now that they’ve figured out the basic recipe for electrolysis with seawater, the new method will open doors for increasing the availability of hydrogen fuel powered by solar or wind energy.

In the future, the technology could do more than generate energy. Since the process also produces breathable oxygen, divers or submarines could bring devices into the ocean and generate oxygen down below without having to surface for air.

In terms of transferring the technology, “one could just use these elements in existing electrolyzer systems and that could be pretty quick,” Dai says. “It’s not like starting from zero—it’s more like starting from 80 or 90 percent.”

Research appears in Proceedings of the National Academy of Sciences. Additional researchers from Beijing University of Chemical Technology and Shandong University of Science and Technology contributed to the work.

The US Department of Energy, National Science Foundation, National Science Foundation of China, and the National Key Research and Development Project of China supported the research.

Source: Erin I. Garcia De Jesus for Stanford University

Related Books

List Price: $59.95
Sale Price: $59.95 $53.22 You save: $6.73


List Price: $20.00
Sale Price: $20.00 $13.33 You save: $6.67


List Price: $58.00
Sale Price: $58.00 $55.89 You save: $2.11


enafarzh-CNzh-TWnltlfrdehiiditjakomsfaptruesswsvthtrurvi

LATEST VIDEOS

What Is The Future Of Climate Change?
by Simon Donner
You would think with all the chatter going on about climate that we’d all have a good understanding on the elements of…
Why Marianne Williamson's Candidacy for President Is Important
Why Marianne Williamson's Candidacy for President Is Important
How do you know something exists if you never hear about it? How do you know about the truth, which is often "the other…
Would You Eat Meat Grown From Cells In A Laboratory? Here's How It Works
Would You Eat Meat Grown From Cells In A Laboratory? Here's How It Works
by Leigh Ackland
For many of us, eating a meal containing meat is a normal part of daily life. But if we dig deeper, some sobering…
Climate System “Getting Unhinged” as Massive Heat Wave Causes Record Melting of Greenland Ice Sheet
by Democracy Now!
The massive heat dome that shattered all-time temperature records across much of Europe last week has settled in over…
Why We're Heading For A Climate Catastrophe
by BBC Newsnight
Scientists say the world is completely off track.
A Climate Reckoning In The Heartland
by CBS News
"A historic flood in March 2019 left much of America's heartland under water. Partiularly hard-hit were Midwestern…
What Would Happen If Antarctica Melted?
by Put Put 1
"What Would Happen If Antarctica Melted?
Dr. Peter Wadhams: Arctic Research & the Methane Risk
by UPFSI
Peter Wadhams is back on ScientistsWarning.TV with a comprehensive analysis of the reticent approach that part of the…

LATEST ARTICLES

What Is The Future Of Climate Change?
by Simon Donner
You would think with all the chatter going on about climate that we’d all have a good understanding on the elements of…
People Of Color Don’t Get Credit For Climate Concern
People Of Color Don’t Get Credit For Climate Concern
by U. Oregon
While their contributions to the climate change movement remain largely unrecognized, people of color are just as…
New Research Shows That Antarctica's Largest Floating Ice Shelf Is Highly Sensitive To Warming Of The Ocean
New Research Shows That Antarctica's Largest Floating Ice Shelf Is Highly Sensitive To Warming Of The Ocean
by Dan Lowry
Scientists have long been concerned about the potential collapse of the West Antarctic Ice Sheet and its contribution…
It'll Be Hard, But We Can Feed The World With Plant Protein
It'll Be Hard, But We Can Feed The World With Plant Protein
by Richard Trethowan
A UN report released last week found a quarter of the world’s carbon emissions come from the food chain, particularly…
Underground Water Sources For Billions Could Take More Than A Century To Respond Fully To Climate Change
Underground Water Sources For Billions Could Take More Than A Century To Respond Fully To Climate Change
by Mark O. Cuthbert, et al
Groundwater is the biggest store of accessible freshwater in the world, providing billions of people with water for…
Why Is The Australian Energy Regulator Suing Wind Farms?
Why Is The Australian Energy Regulator Suing Wind Farms?
by Samantha Hepburn
The Australian Energy Regulator (AER) is suing four of the wind farms involved in the 2016 South Australian blackout -…
Groundwater Reserves In Africa May Be More Resilient To Climate Change Than First Thought
Groundwater Reserves In Africa May Be More Resilient To Climate Change Than First Thought
by Mark O. Cuthbert and Richard Taylor
Groundwater reserves in Africa are estimated to be 20 times larger than the water stored in lakes and reservoirs above…
Australia Urgently Needs Real Sustainable Agriculture Policy
Australia Urgently Needs Real Sustainable Agriculture Policy
by InnerSelf Staff
Australia has made a global commitment to “sustainable agriculture”, an endeavour seen as increasingly crucial to…