Researchers have developed a cheaper and more energy-efficient way to make hydrogen directly from seawater, in a critical step towards a truly viable green hydrogen industry.

The new method from RMIT University researchers splits the seawater directly into hydrogen and oxygen—skipping the need for desalination and its associated cost, energy consumption and carbon emissions.

Hydrogen has long been touted as a clean future fuel and a potential solution to critical energy challenges, especially for industries that are harder to decarbonize like manufacturing, aviation and shipping.

Almost all the world's hydrogen currently comes from fossil fuels and its production is responsible for about 830 million tons of carbon dioxide a year, equivalent to the annual emissions of the United Kingdom and Indonesia combined.

But emissions-free "green" hydrogen, made by splitting water, is so expensive that it is largely commercially unviable and accounts for just 1% of total hydrogen production globally.

Lead researcher Dr. Nasir Mahmood, a Vice-Chancellor's Senior Research Fellow at RMIT, said green hydrogen production processes were both costly and relied on fresh or desalinated water.

"We know hydrogen has immense potential as a clean energy source, particularly for the many industries that can't easily switch over to be powered by renewables," Mahmood said.

"But to be truly sustainable, the hydrogen we use must be 100% carbon-free across the entire production life cycle and must not cut into the world's precious freshwater reserves.

"Our method to produce hydrogen straight from seawater is simple, scalable and far more cost-effective than any green hydrogen approach currently in the market.

"With further development, we hope this could advance the establishment of a thriving green hydrogen industry in Australia."

A provisional patent application has been filed for the new method, detailed in a lab-scale study published in the journal Small.