Journal article
Utilization of semi-natural grassland through integrated generation of solid fuel and biogas from biomass. III. Effects of hydrothermal conditioning and mechanical dehydration on solid fuel properties and on energy and greenhouse gas balances



Publication Details
Authors:
Richter, F.; Fricke, T.; Wachendorf, M.
Publication year:
2010
Journal:
Grass and Forage Science
Pages range:
185-199
Volume number:
65
Start page:
185
End page:
199
ISSN:
0142-5242

Abstract
The integrated generation of solid fuel and biogas from biomass (IFBB) procedure separates biomass into a readily digestible press fluid, from which biogas is produced, and a fibrous press cake that is used as solid fuel. The effects of mechanical dehydration and prior hydrothermal conditioning (5, 60 and 80 degrees C) on biomass from five species-rich, semi-natural grasslands, typical of mountain areas of Germany were investigated. Proportional reduction of ash constituents in the press cake compared with the parent material was up to 0 center dot 80, 0 center dot 61 and 0 center dot 81 for potassium, magnesium and chloride, respectively, at 60 degrees C, resulting in potassium, magnesium and chloride concentrations in the press cake of 2 center dot 43, 1 center dot 22 and 0 center dot 93 g kg-1 dry matter (DM). Emission-relevant constituents were reduced by up to 0 center dot 19 (nitrogen) and 0 center dot 39 (sulphur), yielding nitrogen and sulphur concentrations of 11 center dot 13 and 0 center dot 97 g kg-1 DM respectively. Ash softening temperatures were significantly increased up to 1250 degrees C, falling within the range of wood fuels. Thus, quality of IFBB fuels is superior compared with conventional hay and is comparable to hay of delayed harvest in winter or the next spring. Calculated energy conversion efficiency for IFBB was up to 0 center dot 51, compared with a maximum of 0 center dot 22 for anaerobic whole crop digestion (WCD) and 0 center dot 74 for combustion of hay (CH). High energy demands in IFBB resulted in a greenhouse gas mitigation potential of up to -4 center dot 40 t CO(2)eq ha-1 which is lower than for CH (up to -6 center dot 17 t CO(2)eq ha-1), but higher than for WCD, which mitigated up to -2 center dot 24 t CO(2)eq ha-1.

Last updated on 2019-01-11 at 16:05