While green hydrogen may be one of the pillars upon which a net zero carbon emissions future will be built, the expenditure required for its production means that is largely commercially unviable, meaning that it currently only accounts for approximately 1% of the total hydrogen production globally; with the rest of the world's hydrogen currently utilizing fossil fuels in its production, making hydrogen that is not green responsible for about 830 million tons of carbon dioxide emissions per year, approximately equivalent to the annual emissions of the UK and Indonesia combined.
With green hydrogen being touted as a future fuel for the masses and a potential solution to critical energy challenges, especially for industries that are harder to decarbonize like manufacturing, aviation and shipping, making green hydrogen more financially attainable is a priority.
One such method that may make green hydrogen a commercially viable option for the masses could involve its production directly from seawater.
Currently, green hydrogen production relies on fresh or desalinated water. it is understood that we cannot be cutting into the world's freshwater reserves for its production, especially to the levels that will be required to meet our future energy needs. Therefore, methods of producing green hydrogen from seawater may provide the perfect solution.
In a new method developed by the Materials for Clean Energy and Environment (MC2E) research group with the Royal Melbourne Institute of Technology (RMIT) University, researchers have found how to split seawater directly into hydrogen and oxygen, skipping the need for desalination and its associated cost, also avoiding the associated energy consumption required in the desalination process and carbon emissions. This method is thought to be a far simpler, more scalable and cost-effective way of producing green hydrogen than any other that is currently on the market.
Currently, the manufacture of green hydrogen requires an electrolyser to send an electric current through water to split it into its component elements of hydrogen and oxygen. Said electrolysers currently use expensive catalysts and consume a lot of energy and water though, to the extent where it can take about nine litres of water to make one kilogram of hydrogen. They also have a toxic output of chlorine, which is recognized as another significant hurdle to using seawater in the production of green hydrogen. For example, if the world's hydrogen needs were met without solving the issue of chlorine production first, 240 million tons of chlorine would be produced per year - which is three to four times what the world needs in chlorine. Therefore, there is likely no point in replacing hydrogen made by fossil fuels with hydrogen production that could be damaging our environment in a different way.
In the new method developed by the Materials for Clean Energy and Environment research group at RMIT University, a special type of catalyst has been developed to work specifically with seawater in the process of creating green hydrogen, which requires very little energy to run and can be used at room temperature. This represents a significant breakthrough as the complexity of other catalysts previously developed to produce green hydrogen from seawater were likely much harder to scale to produce the amount of green hydrogen the world will likely require.
The approach used by MC2E focuses on changing the internal chemistry of the catalysts through a simple method, which makes them relatively easy to produce at large-scale so they can be readily synthesized at industrial scales; giving the technology promise to significantly bring down the cost of electrolysers— likely enough to meet the Australian Government's goal for green hydrogen production of $2 (AUD)/kilogram, and make it competitive with fossil fuel-sourced hydrogen.
MC2E has stated that the next stage in their research is the development of a prototype electrolyser that combines a series of catalysts to produce large quantities of hydrogen, potentially providing another significant step forward in providing affordable green hydrogen to the masses.
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