Membrane-Based Seawater Electrolyzer

by Ghost a year ago 3 min read

A team of scientists have published a new paper in the Journal Nature which details a new way to produce sustainable hydrogen fuel. The process, which uses a membrane-based seawater electrolyzer, is significantly more efficient than traditional methods and could help to reduce our reliance on fossil fuels.

Electrolysis is the process of turning water (H2O) into its constituent components of hydrogen (H2) and oxygen (O) by running an electric current through it.

The Challenge of Electrolysis

Traditional methods of hydrogen production using electrolysis are tough to scale due to the corrosive nature of the ocean/salt water environment, and while the use of desalination can definitely help make the process a little more manageable, the added energy consumption leads to a drastic decrease in efficiency.

Potable sources of water could be a better source for electrolysis, but the vast majority of water on our planet is salty. The ratio is an incredible 97 to 3 salty to fresh water, and of that 3 percent two thirds are locked up in glaciers, icecaps, and snow.

The main obstacle is impurities in seawater, which cause side reactions and corrosion, limiting the durability of the electrodes. Even when the water has been desalinated the extraneous reactions can still take place leading to a breakdown of equipment over time. Costs and infrastructure are major challenges that need to be addressed before electrolysis can become a viable option for sustainable hydrogen production.

The Solution to Corrosion

The team, ". . . developed a system for the direct electrolysis of seawater without side reactions or corrosion" through the use of a membrane which only allows water vapor to transfer through to the other side. The electrodes "are separated by a diaphragm layer and are submerged in a ‘self-dampening’ electrolyte (SDE) comprising concentrated potassium hydroxide solution. Between the SDE and the seawater is a membrane that is impermeable to liquid water but that allows water vapour to pass into the electrolyte."¹

By only allowing water vapor to pass through, the system can run much more sustainably, ". . . only pure water vapor is pulled into the system means that all ions and other impurities in the seawater are kept out. Moreover, the low water-vapour pressure of the SDE drives the diffusion of water across the membrane. As such, no extra energy is required to ensure the entry of water into the system, meaning that our electrolyzer’s energy consumption is similar to that of an industrial alkaline electrolyzer."¹

Additional Use Cases

This technology employed in a similar system could be used to treat waste water in industrial settings, "The strategy could be applied to other non-volatile liquids besides seawater — such as highly concentrated acid, alkali and salt solutions — for use in industrial wastewater treatment. Moreover, it could be used for producing hydrogen at the same time as recovering useful resources such as lithium from water."¹

Scalability

The process is so much more streamlined and cost-effective than traditional electrolysis methods that the potential for widespread use of this membrane-based seawater electrolyzer seems clear. The researchers also mention that additional refinement of the system is possible leading to even more gains in efficiency; couple that with the massive decrease in maintenance costs and we have ourselves a system that can be a game changing addition to renewables.

Conclusion

The ability to produce renewable hydrogen fuel could revolutionize the global energy industry, helping us to transition away from our reliance on fossil fuels and towards sustainable sources like solar and wind. Not only would this be good for the environment, but it could also help to create new jobs and stimulate economic growth in countries around the world. If we can overcome the challenges of scaling up, membrane-based seawater electrolyzers can be a crucial tool in the fight against climate change.

Few papers are able to convincingly achieve scalable and stable hydrogen production from seawater, but the authors’ study has done just that. The elegance of their solution to the detrimental corrosion — a problem that has long tormented the field — will open the way for low-cost fuel production and will hopefully drive change towards a more sustainable world. — Yohan Dall’Agnese, Associate Editor, Nature