Last week the CLOSECYCLE consortium visited the showcase in Sweden. At the Sötasen school in Vastra Gotaland, the participants got a very close look into the green biorefinery plant and the biochar production.
Biorefinery plant
On the school, almost 200 students follow the practical lessons and education. The school aims to be the bridge between education and farming. Sustainability and circularity is paramount. And also part of the lessons. One of the very practical sites at the school is the biorefinery plant. Grass silage is the input for this machine. The grass is a valuable source for carbon and for proteins. The grass silage is added to the machine. Silage grass is pressed, resulting in a fibre rich dry matter fraction. This can be used for feeding the calves, but also has potential in textile industry or for making biochar or pellets. Besides the solid fraction the refinery produces also protein juice which will be centrifuged to have a more homogene end product. In a small amount, this juice can be used to feed the pigs. The juice, with a high sugar content, can also be the input for the biogas installation. There is also the possibility to dry this liquid to a protein powder.
The challenge of recycling the different organic waste streams is to use all the end and by products. So the biological cycle is closed in a sustainable way.
Biochar and biogas production
The school is also investigating the production of biochar and biogas.
Pig manure and potato waste material is the input for the biogas plant. The biogas is upgraded to biomethane. This is normally done with a membrane technology, but this is very expensive and not feasible on a small scale. In the Sötasen show case, production to biomethane is done with a cascade of three ash filters. This results in 99% pure methane for 2 cars and 1 tractor.
In the biochar installation, woodchips are the input for the production of biochar. At the moment experience is gained with the production of biochar.
Photos: Esther Hessel
