Sewage seen as hydro source
Researchers have produced hydrogen from wastewater.
New technology developed at RMIT University uses a special material derived from biosolids to spark chemical reactions for producing hydrogen from biogas.
The approach means all the materials needed for hydrogen production could be sourced on-site at a wastewater treatment plant, without the need for expensive catalysts.
The method also traps the carbon found in biosolids and biogas, which could in future enable a near zero-emission wastewater sector.
It could be a big step forward, given that existing commercial methods for producing hydrogen are emission and capital-intensive, and rely heavily on natural gas.
“Our alternative technology offers a sustainable, cost-effective, renewable and efficient approach to hydrogen production,” says lead researcher Associate Professor Kalpit Shah.
“To enable the transition to a circular economy, we need technology that enables us to squeeze the full value from resources that would ordinarily go to waste.
“Our new technology for making hydrogen relies on waste materials that are essentially in unlimited supply.
“By harnessing the power of biosolids to produce a fully clean fuel from biogas - while simultaneously preventing greenhouse gas emissions - we can deliver a true environmental and economic win.”
Biosolids are commonly used as fertiliser and soil amendment in agriculture, but around 30 per cent of the world’s biosolids resource is stockpiled or sent to landfill, creating an environmental challenge.
In the new method, biosolids are first converted to biochar – a carbon-rich form of charcoal used to improve soil health.
The biosolids-derived biochar contains some heavy metals, which makes it an ideal catalyst for producing hydrogen out of biogas.
Researchers have shown that the biochar made from biosolids is highly effective for decomposing the gas into its component elements – hydrogen and carbon.
The decomposition process can also be conducted in a specially designed and hyper-efficient reactor developed and patented by RMIT, which can produce both hydrogen and a high-value biochar that is coated with carbon nanomaterials.
By converting the carbon found in biogas and biosolids into advanced carbon nanomaterials, their method can also capture and sequester the greenhouse gas to prevent its release into the atmosphere.
The carbon nanomaterial-coated biochar produced through the novel technique has a range of potential applications including environmental remediation, boosting agricultural soils and energy storage.
“We’ve radically optimised heat and mass transfer in our reactor, while shrinking the technology to make it highly mobile,” Associate Professor Shah said.
“There are no reactors available that can achieve such phenomenal heat and mass integration, in such a small and cost-effective package.
“And while it’s already energy efficient, with further integration, this reactor could turn biosolids and biogas conversion into a process that actually produces energy instead of consuming it.”
As well as being used in wastewater treatment, the novel reactor has potential applications in the biomass, plastics and coating industries.
The research was supported by South East Water, which will be trialling the biosolids and biogas conversion technology in a pilot plant currently under fabrication.
More information is available in this scientific paper.