Wonderful Engineering

Scientists Figure Out A Way To Create Hydrogen Fuel From Sea Water

A team of Stanford researchers is looking into a new recipe for hydrogen fuel and has put forth a proof-of-concept. The recipe’s ingredients are saltwater, electrodes, and solar power. The proof-of-concept shows separation of hydrogen and oxygen gas from seawater by making use of electricity. In comparison to existing methods that rely on obtaining hydrogen fuel from purified water, it is very economical.

The process used for breaking up substances such as water into hydrogen and oxygen is known as electrolysis. The technique is hundreds of years old and was first methodized by British legend Michael Faraday. His two laws of electrolysis from 1834 are still guiding scientists of today. When conducting electrolysis, scientists connect two electrodes immersed in water to a power source. Hydrogen can then be collected at the cathode while oxygen is collected at the anode.

This works for fresh water, but the saltwater gets a bit tricky. The saltwater is tricky because it can corrode electrodes during this process using chloride thus greatly reducing the lifespan of the system. Honjie Dai, a professor of chemistry at Stanford, countered this by introducing a change in materials.

The team figured out that if the anode was covered with negative charges, the resulting layer repelled chloride and change the rate of decay in the material that lay under it. The team came up with a nickel foamcore, and on top of that made layers of nickel-iron hydroxide and then nickel sulfide. The foam serves as a conductor while the nickel-iron hydroxide begins the electrolysis.

Without making use of the negative charges on the anode, this system was only good for a total of 12 hours. Michael Kenney, a graduate student in the Dai lab and co-lead author of the paper, said, ‘The whole electrode falls apart into a crumble. But with this layer, it is able to go more than a thousand hours.’

The system works perfectly fine with the normal freshwater, but the problem of resources is what caused the team to use saltwater. Dai said, ‘You need so much hydrogen it is not conceivable to use purified water. We barely have enough water for our current needs in California.’ On the other hand, using saltwater is a promising solution.

Dai further said, ‘If we had a crystal ball three years ago, it would have been done in a month.’ The proof-of-concept brings a myriad of possibilities. For instance, a deep-sea diver could be able to stay under for an unlimited amount of time, so could a submarine. Dai also said, ‘One could just use these elements in existing electrolyzer systems, and that could be pretty quick. It’s not like starting from zero — it’s more like starting from 80 or 90 percent.’

As of now, Dai and his team are focused on improving the proof-of-concept.