Influence of sward maturity and pre-conditioning temperature on the energy production from grass silage through the integrated generation of solid fuel and biogas from biomass (IFBB): 1. The fate of mineral compounds

The IFBB process, which separates biomass into a press fluid for biogas production and a press cake for combustion, is aimed at converting low-input high-diversity grasslands into energy, which is problematic with conventional conversion techniques. Herbage from a lowland hay meadow (Arrhenaterion) was sampled on eight dates between 24 April and 21 June 2007. Silage from each date was processed in six treatments without and with hydrothermal conditioning at different temperatures. The impact on mass flows of plant compounds and on elemental concentrations in the press cake was investigated. Elements detrimental for combustion were significantly reduced in the press cake compared to the silage. Mass flows and elemental concentrations in the press cake were strongly influenced by conditioning temperature as well as concentration of neutral detergent fiber and dry matter in the silage (R2 from 0.70 to 0.99). Press cakes of late sampling dates were considered best suitable for combustion.