Combustion properties and quality of the perennial wild plants common tansy (Tanacetum vulgare L.), common knapweed (Centaurea nigra L.) and mugwort (Artemisia vulgaris L.)

Background: Perennial wild plants (PWPs) common tansy, common knapweed and mugwort not only provide biomass for biogas production, but also food supply for pollinators and versatile habitats for open land animals. These ecosystem services could be improved shifting the harvest date from late summer to late winter and using the PWPs for thermochemical conversion instead of anaerobic digestion. Results & Discussion Energy yield of PWPs twice as high through combustion compared with anaerobic digestion Tansy and mugwort showed better ash melting behavior and similar higher heating value (16-17 MJ kg-1) compared with Miscanthus (A, B) and switchgrass Combustion properties of all PWPs somewhat comparable to Sida (Sida hermaphrodita L. Rusby), but lower dry matter yields lead to lower energy yield per hectare (130.2–221.6 GJ ha-1) --> 446.8 GJ ha-1 were reported by Jablonowski et al., 2017 (https://doi.org/10.1111/gcbb.12346) Conclusions PWPs have a low methane yield potential, thus farmers hesitate in growing PWPs, although the other ecosystem services are convincing. Switching to thermochemical conversion could help increase energy yield per hectare of PWPs, thus convince more farmers of PWP as a complementary bioenergy cropping system and thereby further contribute to a more ecologically sustainable transition to a bioeconomy.