Trip to the biogas plant in Wolnzach

Thursday the 25th of february the C​lean Tech and Green Energy c​ooperation paid the biogasplant in Oberlauterbach just outside Wolnzachen a visit. Even though we were met by an interesting odor we pulled through it and got a tour around the biogas plant built in 2012.

One of the two managing partners of the plant was kind enough to guide the tour. We started the tour with an introduction to the plant and why it was special ­ it uses hops and corn as the biomass instead of only using corn. Shortly thereafter our guide took us to the corn and hops storages with space for around 80.000 tonnes of bio matter. While the hops smelled surprisingly bad, we managed to get some really interesting information about the plant, apparently it used worse so they added biofilters to one of the buildings in which the hop were treated. The plant itself costed 25 million euros, but since it runs on biomass, it will continue producing renewable energy until it breaks down.

Traditionally, biogas plants solely utilizes corn, which creates an ethical dilemma; is it okay to use food in such a way? By using hops, this plant mitigates said problem, as the cones (which are used for beer) are harvested beforehand. The use of hops is especially smart since the region has the biggest production of hops in the world. However, the use of hops has created some new and unexpected problems. One of them is the smell, but also the structure of the hops plant is challenging. Because hops is more like trees than corn, that is the fibers are more durable, the methane­producing bacteria can’t break down the hops as efficiently as the corn. To overcome this, the hops has to be preprocessed, before being fed

into the rest of the system. This preprocessing is mostly about crushing the fibers, giving the bacteria more surface to work with.

Another rather serious problem is the fact that the hops are delivered on the wire that they grow on. These wires can potentially destroy the plant, if they get into the tanks. Therefore an additional step has been added to the preprocessing of the hops, that should remove the wires from the material. This in turn solves another problem, as the hops­farmers used to throw out the hops with wires and all. These wires ended up on the streets, greatly annoying Bavarian car drivers who suddenly had a wire­damaged car and tire.

The product of the plant is 5 MW of electricity and the farmers get the remaining biomass which is around 50% of the original content, still containing important nutrients like phosphor.

In conclusion it was a very interesting experience and we see the idea behind using these crops to make biogas as a good and an environmentally friendly alternative to coal etc.

Article by

Andreas Poulsen, Nicolai Lindegaard, Adrianna Bankowska (H.C. Örstedt-gymnasiet, Kopenhagen-Ballerup), Nicola Scherb, Kathrin Vela