So, we want to have a hydrogen fueled future, right? It's a truly clean fuel that doesn't emit CO2 when burned. It would be the perfect replacement for fossil fuels for every type of vehicle from cars to trucks to trains and ships and even airplanes. It would be the perfect medium for storing renewable energy, especially from intermittent sources like solar. A solar generating plant that produced hydrogen could keep sending out power even when the sun wasn't shining. Hydrogen can be made from water, even sea water, which obviously there is plenty of here on Earth, using a process called electrolysis (no, not the hair removal process). It's a process that uses electricity to break water into its component parts: oxygen and hydrogen. But...up to this point electrolysis has been complicated and expensive. At École Polytechnique Fédérale De Lausanne, or ÉPFL in Switzerland, a team headed by Demetri Psaltis has developed a system that may be about to change all of that.
In a conventional electrolysis system, two electrodes, the cathode and the anode are submerged in water and separated by a polymer membrane. An electric current is sent through the cathode. As it passes through the water to the anode, the water molecules to break apart into oxygen and hydrogen. The membrane keeps the two gases from mixing together and making an explosive mixture. Membranes are usually made of Nafion, which is extremely stable and good at conducting ions. But Nafion membranes have some major drawbacks. They are expensive. They have a limited lifetime, and only work in highly acidic solutions, which are toxic and potentially dangerous.
Psaltis and his team have created a system that works a bit differently. Their new system places the electrodes less than a few hundred micrometers apart in a microfluidic device. When the liquid moves between the electrodes above a certain speed, the two gases are pushed in opposite directions. Due to the lift forces caused by the Segré-Silberberg effect the two gases are guided into separate outlets, all without needing a membrane, meaning much lower cost, and a much simpler, much more reliable device.
"Our device has the potential to surpass the performance of a similar water-splitting apparatus that relies on an ion conductive membrane," says Mohammad Hashemi, the first author of a paper on the team's efforts. "This is due to the higher ion conduction in liquid electrolytes than in common solid membranes. As the only dimension that needs to remain small is the inter-electrode distance, it is possible to implement the same concept using high surface area electrodes as side walls of narrow electrolyte channels."
Psaltis and his team are currently working on scaling up the design for higher production rates, meaning that soon, if all goes according to plan, they could potentially change the entire world.
(Sources: phys.org, Wikipedia)