Title:
Harvest of Cereal Straw and Catch Crops in Mixture for Biogas Production: Effect of Ensiling on Methane Yield
Author(s):
Larsen, S.U., Hjort-Gregersen, K., Hinge, J.
Document(s):
Paper
Slide presentation
Abstract:
Straw from cereal production and catch crops constitute large resources of residual biomass from agriculture with a large potential for biogas production. A major challenge for the use of straw for biogas is the need for pretreatment to increase the methane yield and reduce hydrophobicity, and ensiling may serve as a biological pretreatment of straw. Catch crops often have a low dry matter (DM) content with a risk of effluent run-off during ensiling which can be absorbed by straw. Co-harvest and co-ensiling of straw and catch crop biomass may, hence, provide higher yield per hectare, a pretreatment of the straw fraction and reduce the risk of effluent run-off from catch crops. Two field trials were performed with spring barley and with Italian ryegrass or red clover as catch crops. Barley was strip harvested in August, and the remaining, standing straw was harvested together with catch crop biomass in October. The biomass mixtures were ensiled for up to 10 months. The total DM yield of straw and catch crop ranged between 3.8 and 5.7 ton per hectare, with catch crops contributing with 24.7-50.4% of the DM in the mixtures. The potential methane yield per hectare ranged between 800 and 1,245 Nm3 methane per hectare for fresh unensiled biomass mixtures. The specific methane potential increased linearly with ensiling duration, with an increase of 9-12% over 10 months of ensiling. In conclusion, harvest of straw and catch crops in mixture may offer a rational way of harvesting two residual biomasses for biogas production, and the co-ensiling process may serve as a low-cost, biological pretreatment effect for straw.
Keywords:
biogas, fermentation, storage, straw, pretreatment, residues
Topic:
Sustainable Resources for Decarbonising the Economy
Subtopic:
Agroforestry Residues and By-Products
Event:
29th European Biomass Conference and Exhibition
Session:
1BO.1.1
Pages:
57 - 61
ISBN:
978-88-89407-21-9
Paper DOI:
10.5071/29thEUBCE2021-1BO.1.1
Price:
FREE
