The production of green hydrogen is highly valued as the process uses electrolyzers and electricity exclusively from renewable sources. Unfortunately, green hydrogen production costs are at least 30% higher than those of blue hydrogen – which uses natural gas. A plentiful supply of cheap hydrogen fuel could have a significant impact on the reduction of carbon emissions.
Researchers at Australia’s RMIT University are working with sound waves to boost the production of green hydrogen, while also reducing the energy input required. The team used high-frequency vibrations to attack individual water molecules during electrolysis. With the use of these vibrations, they managed to split the water molecules to release 14 times more hydrogen compared with standard electrolysis techniques.
“One of the main challenges of electrolysis is the high cost of electrode materials used, such as platinum or iridium,” said Associate Professor Amgad Rezk, the team leader. “With sound waves making it much easier to extract hydrogen from water, it eliminates the need to use corrosive electrolytes and expensive electrodes such as platinum or iridium. As water is not a corrosive electrolyte, we can use much cheaper electrode materials such as silver.”
The use of sound waves has a twofold advantage: it lowers the cost of the production of green hydrogen, while also preventing the build-up of hydrogen and oxygen bubbles on the electrodes, which greatly improves their conductivity and stability. The team expects that this new acoustic platform will prove useful for other applications, especially where bubble build-up on the electrodes is a challenge.
“Our ability to suppress bubble build-up on the electrodes and rapidly remove them through high-frequency vibrations represents a major advance for electrode conductivity and stability,” said Professor Leslie Yeo, one of the senior researchers. “With our method, we can potentially improve the conversion efficiency leading to a net-positive energy saving of 27%.”
The team is now working on integrating the sound-wave innovation with existing electrolyzers in order to scale up the work.