Using microbes, it is possible to extract hydrogen from process wastewater from industries such as the food industry as well as the pulp and paper industry. This is known as a bio-based method, and RISE has demonstrated, on a pilot scale, the possibility of producing biological hydrogen in this way.
One common way of producing hydrogen is electrolysis, where water is split into hydrogen and oxygen using electricity.
However, hydrogen can also be produced using specific microbes. Over the past three-four decades, scientists around the world have isolated and characterised microbes that are particularly suitable for use in hydrogen production. In collaboration with Lund University, researchers at RISE have further developed this technology.
“In order for the microbes to be able to be used for hydrogen production on an industrial scale, they must have specific properties, which we have listed and published,” explains Sudhanshu Pawar, researcher at RISE.
The microbes in question can convert bioavailable carbohydrates into hydrogen. Lactose from dairy water, sugar from water taken from sugar mills and hemicellulose from water from paper and pulp mills are examples of such carbohydrates.
One advantage of bio-based technology compared to electrolysis is that, whereas electrolysis requires clean water, the bio-based method can purify water to some extent. Another advantage is that the bio-based technology does not only produce hydrogen, but also acetic acid, which is a substrate for biogas.
“This makes it possible to extract more than 80 per cent of the energy from the bioavailable carbohydrates,” says Sudhanshu Pawar.
We have developed the technology in the laboratory and have also scaled it up to pilot scale
Slower than electrolysis
Drawbacks of the bio-based technology include the fact that it is slower than the electrolysis technology, and that it requires water at a temperature of 70°C and is consequently more energy-intensive.
“There are various solutions to the problem of energy consumption. You can either use heat exchangers to utilise the residual heat from industry, or you can concentrate the water. As a result, the concentration of carbohydrates is higher and the process can be performed more rapidly. Concentrating the water costs money, unfortunately, but this is something we are looking at in greater detail as part of the research,” says Sudhanshu Pawar.
He stresses that the technology is not yet fully developed and that many issues remain, including the cost aspect.
“We have developed the technology in the laboratory and have also scaled it up to pilot scale. At the moment we are somewhere between 4 and 5 as regards the technology readiness level, which goes from 0 to 9. The next step will be to conduct cost calculations and initiate real-life experiments in an actual industry.”
Part of the future image
Sudhanshu Pawar points out that the bio-based technology is only one part of the picture when it comes to future hydrogen production.
“It is important to view bio-based hydrogen technology as one aspect of biogas production. Anyone thinking about biogas technology should be aware that it is possible to use bio-based hydrogen technology as a pretreatment stage for both generating energy in the form of hydrogen as well as facilitating the biogas process,” says Sudhanshu Pawar.
RISE not only conducts research into hydrogen production. We also have experts at system level and within business development, for example, which makes it possible to offer complete solutions for those investing in this area.
“We also collaborate with universities, which means that we have access to experts and stakeholders outside of our own organisation as well,” says Sudhanshu Pawar.