Biogas is becoming an important part of the renewable energy mix, but much about the process needs refining. Photo:

Too much hydrogen is problem for biogas

Producing biogas can be a chemistry nightmare. NTNU researchers are helping improve the process.

Biogas may sound like an exotic kind of energy alternative to fossil fuels, but the primary mechanism that produces it — bacterial digestion of biological material — is similar to what takes place inside a cow’s gut when it eats grass. The important difference, of course, is that biogas can be made at an industrial scale, using a chamber called a digester.

A biogas digester excludes oxygen, creating an atmosphere that allows a group of different bacteria to consume biological materials and generate biogas. Most commonly, biogas digesters use waste products from agriculture and the aquaculture industry.

However, the chemistry inside the digester has to be monitored very carefully because the different groups of bacteria at work digesting the biological material in the chamber can be quite sensitive to even the smallest of changes. The trick is designing sensors that can detect these small changes quickly enough to do something to keep the bacterial balance in the digester — and thus biogas production — at optimal levels.

Jacob Lamb, a postdoctoral researcher at NTNU’s ENERSENSE strategic research area, is working on developing a hypersensitive optical fiber sensor that can detect one critical substance, hydrogen, in the liquids in a biogas digester.

Read more about his research at NTNU’s TechZone blog.