Scotland contributes one million to the one billion litres of wastewater produced by the distilling industry annually. Now, researchers from Heriot-Watt University claim they have developed a method to harness this wastewater to facilitate green hydrogen production. 

Distillation is one of the most polluting industries, since ethanol fermentation results in large quantities of liquid waste with organic matter, nitrogen compounds, low pH, high temperature and salinity.  

The researchers believe that this new approach could not only lower the waste produced by distillation, but also reduce the freshwater footprint associated with green hydrogen production. 

“To help protect the planet, we need to reduce our use of freshwater and other natural resources. So our research focused on how to use this distillery wastewater for green hydrogen production with a simple process that removes waste materials present in the water,” said Dr Sudhagar Pitchaimuthu, associate professor at Heriot-Watt’s Institute of Mechanical, Process & Energy Engineering, and associate director at the university’s Research Centre for Carbon Solutions.

To do this, the researchers developed a nanoscale material, which is one in 10,000th the diameter of a human hair, that allows the wastewater to replace freshwater in the hydrogen production process.

The Heriot-Watt nanoparticle addresses a significant challenge faced by electrolysers, which typically fail when using wastewater due to its substance composition

According to Dr Pitchaimuthu, 20.5 billion litres of freshwater is consumed every year to develop hydrogen. 

This in turn generates a source of renewable energy which does not emit carbon when burned, and can be used to power vehicles or heat our homes. 

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“It takes 9 kg of water to produce every 1 kg of green hydrogen. Meanwhile, every 1 litre of malt whisky production creates about 10 litres of residue,” he said. 

“The potential of this process is huge,” he continued. “Using industry wastewater means we can reduce the extensive freshwater footprint associated with green hydrogen production.”

In addition to the environmental benefits, the researchers will explore whether other valuable materials can be extracted from distillery wastewater alongside hydrogen and oxygen.