Biogas production from catch crops: Increased yield by combined harvest of catch crops and straw and preservation by ensiling. (August 2015)

• Record Type: Journal Article
• Authors: Molinuevo-Salces, Beatriz; Larsen, Søren U.; Ahring, Birgitte K.; Uellendahl, Hinrich
• Is Part Of: Biomass and bioenergy. Volume 79(2015:Aug.)
• Page Start: 3
• Page End: 11
• Publication Date: 2015-08
• Subjects: Catch crops -- Raphanus sativus var. oleiformis -- Lolium perenne -- Trifolium sp. -- Vicia sativa -- Silage; Biomass energy -- Periodicals; Biomass -- Periodicals; Energy-Generating Resources -- Periodicals; Bioénergie -- Périodiques; 333.9539
• DOI: 10.1016/j.biombioe.2015.04.040
• Languages: English
• ISSNs: 0961-9534

Abstract

Abstract: The combination of catch crop cultivation with its use for biogas production would increase renewable energy production in the form of methane, without interfering with the production of food and fodder crops. The low biomass yield of catch crops has been shown as the main limiting factor for using these crops as co-substrate in biogas plants, since the profit obtained from the sale of methane barely compensates the harvest costs. Therefore, a new agricultural strategy to harvest catch crops together with the residual straw of the main crop was investigated, in order to increase the biomass and the methane yield per hectare. Seven catch crops harvested together with stubble from the previous main crop were evaluated. The effects of stubble height, harvest time and ensiling as a storage method for the different catch crops/straw blends were studied. Biomass yields as TS ranged between 3.2 and 3.6 t ha −1 y −1 of which the catch crop constituted around 10% of the total biomass yield. Leaving the straw on the field until harvest of the catch crop in the autumn could benefit methane production from the straw both due to increased biomass yield and an increased organic matter bioavailability of the straw taking place on the field during the autumn months. Ensiling as a storage method could be feasible in terms of energy storage and guaranteeing the feedstock availability for the whole year. This new agricultural strategy may be a good alternative for economically feasible supply of catch crops and straw for biogas production. Highlights: An agricultural strategy to increase the biomass yield of catch crops was studied. Ensiling as a storage method for different catch crops was evaluated. The specific methane yield per hectare was 486–702 m 3 ha −1 y −1 being economically feasible. Late harvest results in organic matter degradation in the straw increasing CH4 yield. Dry matter content control before ensiling is crucial to ensure silage quality.