Tag: seawater

Green hydrogen from direct seawater electrolysis

Green hydrogen from direct seawater electrolysis

At first glance, the plan sounds compelling: invent and develop future electrolysers capable of producing hydrogen directly from unpurified seawater. But a closer look reveals that such direct seawater electrolysers would require years of high-end research. And what is more: DSE electrolyzers are not even necessary – a simple desalination process is sufficient to prepare seawater for conventional electrolyzers. In a commentary in Joule, international experts compare the costs and benefits of the different approaches and come to a clear recommendation.

Fresh water is a limited resource; more than 96% of the world’s water is found in the oceans. If seawater could be fed directly into a future electrolyser to produce green hydrogen using renewable energy from the wind or sun, it sounds like a very good solution. Hundreds of millions of dollars in research fundingare spend for this idea and, in 2023 alone, there have been more than 500 publications (this number is growing exponentially) on direct seawater electrolysis.

No need for new development

However, a techno-economic analysis shows that this argument collapses as soon as the costs and benefits are analysed in more detail. “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 author of the Joule commentary. International experts from various disciplines from renowned research institutions such as Yale University, universities in Canada, Germany and HZB contributed to the commentary.

Proven methods work

It is already possible to use seawater to produce hydrogen. Proven processes such as reverse osmosis can be used to purify seawater for “normal”, commercially available electrolysers. From a thermodynamic point of view, the purification of seawater needs only 0.03% of the energy required for its electrolysis. This is also reflected in the current cost: purifying seawater to produce one kilogram of hydrogen costs less than two cents. However, one kilogram of hydrogen costs 13.85 euros at German filling stations.

Read more on HZB website

Promising material provides a simple, effective method capable of extracting uranium from seawater

Promising material provides a simple, effective method capable of extracting uranium from seawater

  • Uranium can be extracted from seawater simply and effectively using a new material
  • Adding neodymium to layered double hydroxides (LDHs) improved their ability to capture uranium selectively
  • Multiple techniques at ANSTO clarified the octahedral coordination environment, oxidation state and adsorption mechanism

An Australian-led international research team, including a core group of ANSTO scientists, has found that doping a promising material provides a simple, effective method capable of extracting uranium from seawater.

The research, published in Energy Advances and featured on the cover, could help in designing new materials that are highly selective for uranium, efficient, and cost-effective.

Read more on the ANSTO website

Producing hydrogen from seawater

Producing hydrogen from seawater

McGill scientists have identified potential method for producing hydrogen from the oceans.

In her research on bone tissue engineering, Dr. Marta Cerruti has worked for years with graphene, a single sheet of carbon atoms with incredible properties – electrical conductivity and the ability to support tremendous weight. Now, her quest to improve its qualities has opened the door to a possible solution to one of the challenges of producing hydrogen from seawater.

Cerruti, a professor of materials engineering at McGill University, explained that while graphene is structurally sound, “one sheet of atoms is not something you can easily work with.” In fact, piling the sheets up results in, basically, pencil lead.

Searching for a way to make an easy-to-handle structure, Cerruti’s PhD student Yiwen Chen combined graphene with oxygen in a suspension with water to create reduced graphene oxide (GO), a porous, three-dimensional, electrically conductive scaffold. Cerruti suggested a further modification, with GO flakes stacked on the pore walls, “which allowed us to exploit another interesting property of GO – it creates a membrane that allows water through but no other molecules.”

When she canvassed her team for suggestions on how best to test the new scaffold, Gabriele Capilli, a post-doctoral fellow in her lab, suggested seawater electrolysis, a process similar to others he worked on while doing his PhD. It turns out the new GO “selective scaffold” has the potential to improve the process of producing hydrogen from the ocean. The team’s findings were published recently in the journal ACS Nano.

In conventional electrolysis, chloride ions in seawater penetrate the electrode and interact with the catalyst, creating hypochlorite ions, an unwanted byproduct that poisons the catalyst, Cerruti explained. Using X-ray phase contrast imaging at the Canadian Light Source at the University of Saskatchewan, Chen confirmed the GO scaffold had the right structure, with closed GO pores enclosing cobalt oxide nanoparticles as the catalyst. “We saw what we wanted to see.” Electrochemical tests performed in the laboratory of collaborator Thomas Szkopek (electrical engineering, McGill) confirmed the scaffold worked as expected to block unwanted ions.

Read more on the CLS website

Image: Gabriele Capilli, Marta Cerruti, and Thomas Szkopek (l to r), in their lab at McGill University.