Researchers at RMIT University have developed a cheaper and more energy efficient method of producing hydrogen directly from the sea.
In a decisive step towards a truly viable green hydrogen industry, a new method splits the ocean directly into hydrogen and oxygen. The new process deals with desalination and the costs, energy consumption and carbon emissions that come with it.
The new method is detailed in a laboratory-scale study published in the Wiley Journal.
Hydrogen has long been seen as the clean fuel of the future and a potential solution to the most pressing energy problems, especially for the most difficult-to-decarbonize sectors such as manufacturing, aviation and shipping.
Today, almost all of the world’s hydrogen comes from fossil fuels, and its production is responsible for some 830 million metric tons of carbon dioxide per year, which is equivalent to the annual emissions of the UK and Indonesia combined.
However, the release of free “green” hydrogen, made by splitting water, is so expensive that it is commercially unviable and accounts for only 1% of global hydrogen production.
Dr Nasir Mahmood, Principal Researcher at RMIT, says green hydrogen production processes are expensive and rely on fresh or desalinated water.
We know that hydrogen has immense potential as a clean energy source, especially for many industries that cannot easily switch to renewable energy.
But to be truly sustainable, the hydrogen we use needs to be 100% carbon-free throughout its production life, and not deplete the planet’s precious freshwater resources.
What is this method?
“Our method of producing hydrogen directly from seawater is simple, scalable, and far more cost-effective than any other green hydrogen production method currently on the market. With further development, we hope this can stimulate the establishment of a green hydrogen industry in Australia.”
Making it green uses an electrolyser that sends an electric current through the water to split it into its elements of hydrogen and oxygen.
Difference: catalyst for marine
Currently, these electrolyzers use expensive catalysts and consume a lot of energy and water: it takes about nine liters to produce one kilogram of hydrogen. In addition, the production is toxic: they do not produce carbon dioxide, but chlorine.
Mahmood continues: “The biggest obstacle to using marine chlorine is that it can be produced as a by-product.” If we wanted to meet the world’s hydrogen needs without first solving this problem, we would produce 240 million tons of chlorine per year, that is, three or four times more than what the world needs in chlorine. There is no way that fossil hydrogen is made from fossil fuels to replace the production of hydrogen, which can harm our other environments.
“Our process not only releases carbon dioxide, but also does not produce chlorine,” he added.
The new method devised by a team from RMIT’s multidisciplinary Materials for Worlds Energy and Environment (MC2E) research group uses a special type of catalyst developed to work specifically with marine organisms.
The study, in which PhD student Suraj Loomba participated, focused on the production of stable, high-efficiency catalysts that could be manufactured cost-effectively.
“Our approach was to change the internal chemistry of catalysts through a simple method, making it easy to produce them on a large scale so they could be easily assembled on an industrial scale,” Loomba said.
Mahmood added: “These new catalysts (nitrogen-doped porous nickel-molybdenum phosphide) require little energy to operate and can be used at room temperature. Although other experimental catalysts have been developed for seawater splitting, they are complex and difficult to scale.
Mahmood explained that the technology promises to significantly reduce the cost of electrolysis, enough to meet the Australian government’s goal of producing green hydrogen at 2 AU/kilogram, to make it competitive with hydrogen from fossil fuels.
RMIT researchers are working with industrial partners to develop aspects of this technology. The next part of the research is the development of a prototype electrolyzer that combines a series of catalysts to produce large amounts of hydrogen.
A provisional patent application has been filed for the new method.
This looks very good for areas where there is a lot of solar or wind power with easy access to the sea. This situation can be competitive with respect to the production of fossil sources. An impressive investment must be made for the power and performance of the system. But does it take decades to turn a profit?
The work of the RMIT group appears to be the most successful and innovative hydrogen production system and process we have seen so far. Low temperature, relatively low power, and no visible water is certainly a big step.