Make your own gas from your apple peelings soon

Fruit and vegetable waste: keep it in a container in your garden for a week, where it fermits a bit, which you can clearly smell. But what if we turn that problem into a solution? Put the waste in an oxygen-tight - and therefore odour-tight - container and optimise fermentation? Then you can make your own gas and soil enrichment. That is the idea behind the consumer biodigester.

Biodigesters are already widely used in agriculture. But no small bio-digester exists yet. Researcher Petra Meeuwse: "It's more complicated to make those because what you throw in has more impact. What if on Saturday mornings you always make freshly squeezed orange juice, after which you have a pile of orange peels. These contain substances that are harmful to bacteria: if you throw too much of it into the digester, the bacteria can die. Therefore, we need to make a digester that understands what you throw in and can respond accordingly, for example by storing the orange peels for a while in the storage vessel and adding them to the digester in smaller portions."

Because the bacteria mix is matched to the waste, the small digester extracts much more gas from a kilo of waste than the large digesters. "We saw that already in the first trials. And we are going to improve this much further," said Spencer Schols, CEO of CIRC, a young company developing sustainable solutions. "Ultimately, I want to achieve that (with a device so small that it fits in a kitchen cupboard) you can provide 80% of your home heating."

"I don't have a background in chemistry myself," Spencer said. "Whereas Petra holds a PhD in bioprocess engineering and has an extensive background as a researcher." Petra researches how the biodigester can ferment bioplastic, teaches students research skills and supervises them in their research. By working together, students learn to think innovatively, new knowledge is developed about digestion processes and the biodigester comes closer to consumers.

"One of our larger digesters is on the grounds of a sports hotel. Here, they heat the rooms and shower water almost entirely with self-produced biogas," says Spencer. "We would like to be independent of fossil fuels. If we turn our waste into an optimised energy source and combine it with other renewable energy solutions - that becomes possible for households."

• CIRC Energy 
• Chemical Engineering Programme (NL)
• Research group Innovative Testing in Life Sciences & Chemistry