Listen to this article
A group of researchers at the University of Melbourne have developed a way to generate hydrogen directly from the air, eliminating the dependency on freshwater resources and providing a new direction for a carbon-free future.
Green hydrogen is considered the ultimate clean energy because burning hydrogen does not release carbon dioxide or other greenhouse gases, unlike fossil fuels. Moreover, green hydrogen uses renewable energies — solar, wind, geothermal or tidal in its production. Hydrogen can also store the power produced by renewable sources and complements renewables by offering a continuous power supply.
The team of researchers successfully developed a working prototype of a device that produces hydrogen without consuming freshwater resources. The tech is called Direct Air Electrolyzer (DAE) and works by draining water directly from the air before going through the standard electrolysis process.
The idea came to the lead researcher, Kevin Gang Li while considering how water supply challenges hydrogen production.
Producing hydrogen via water electrolysis requires a very clean supply of water, which is scarce. While purification processes are available, they add complexity and cost to the overall production. According to an U.N.-Water report in 2021, around 2.3 billion people live in water-stressed countries. Moreover, industrial power plants, agriculture, and other industries consume a substantial amount of water.
“We see an area with no groundwater and think it is unsuitable for hydrogen production. But there is always abundant fresh water in the air,” said Gang Li. “Even Alice Springs (a town in Australia), which is part of the desert, has around 20% relative humidity. This is more than enough for us to produce hydrogen onsite using renewable energy,” he added.
What is Direct Air Electrolyzer?
In what appears to be the first report of pure hydrogen production directly from the air, the device produces hydrogen when exposed to air. Unlike electrolyzers that use liquid water, the air is used to feed the device.
Like any other electrolyzer, DAE is made of a panel of metal plates — the electrodes — which supply a current for the water splitting process. The innovation is the porous medium between the plates, soaked with a chemical – hygroscopic ionic solution that can absorb moisture from air spontaneously. The core of the invention is that this material can take water molecules from the air. Once taken from the air, it becomes liquid and is ready for electrolysis.
Possibilities with DAE
The innovation decouples hydrogen production from the limitations of the world’s freshwater resources. It provides economic and environmental benefits and opens vast potential applications wherein pure hydrogen could be generated anywhere on earth.
“Renewables could still be used during the day, but DAE could convert part of the solar to hydrogen, which can be stored, to allow for a continuous supply of power that would remove any reliance on fossil fuels,” Li says.
In the context of high-carbon industries, the DAE may offer complete decarbonization by combining the technology with solar and other renewables currently used to lower emissions. Another large scale-opportunity that the innovation provides is integrating the technology with existing systems to further lower emissions. For instance, if it is paired with gas grids or boosts green hydrogen production. Energy companies could embed it within their existing solar farms and produce sustainable hydrogen for global export.
However, DAE is not set to replace conventional modes of hydrogen production entirely, but instead, be a “perfect complementary.” The device is believed to be capable of easily being upscaled and coupled with renewables. It can generate high-purity hydrogen continuously at a relative humidity as low as 4% and is technically and structurally viable and low maintenance.
A research team from the Indian Institute of Science, Bengaluru, has found a way to extract green hydrogen from biomass, a renewable energy source. In the first step, biomass is converted into syngas – a hydrogen-rich fuel gas mixture – in a novel reactor using oxygen and steam. In the second step, pure hydrogen is generated from syngas using an indigenously developed low-pressure gas separation unit.
A recent report by government think tank NITI Aayog, in partnership with Rocky Mountain Institute (RMI), prescribed ten ways India could emerge as the global hub of green hydrogen.