Trace elements by energy crops – mass flux and recommendations for an optimized process biology in biogas plants

If only maize silage input is used (minimum cobalt content) in biogas plants, the trace elements are not sufficient for optimal methane formation. Currently, more than 3,000 biogas plants in Germany feed industrial additives to counter this shortage. Although this helps, it involves environmental risks and costs. Other possible energy crops accumulate considerably more essential trace elements than maize. By adding other energy crops, it should be possible to ensure a sufficient supply of trace elements for fermentation, which would make artificial trace element additives unnecessary. This is verified in quasi-continuous laboratory fermenters. Correlations of element concentrations, process data as well as the composition and activity of microbial communities in the biogas reactor should show fundamental correlations. Ecological, social and economic aspects are included in the assessment of the cultivation worthiness of the investigated energy crops. With a more diverse cultivation of energy crops, the sustainability requirements of biogas production are much better met.