Exploitation of Mowed Grass from Green Areas by Means of Anaerobic Digestion: Effects of Grass Conservation Methods (Drying and Ensiling) on Biogas and Biomethane Yield

Alessandro Chiumenti, Andrea Pezzuolo, Davide Boscaro and Francesco da Borso
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Alessandro Chiumenti: Department of Agricultural, Food, Animal and Environmental Sciences (DI4A), University of Udine, 33100 Udine, Italy
Andrea Pezzuolo: Department of Agroforesty and Landscape, University of Padua, 35020 Legnaro, Italy
Davide Boscaro: Department of Agroforesty and Landscape, University of Padua, 35020 Legnaro, Italy
Francesco da Borso: Department of Agricultural, Food, Animal and Environmental Sciences (DI4A), University of Udine, 33100 Udine, Italy

Energies, 2019, vol. 12, issue 17, 1-11

Abstract: Grass from landscape management or from agricultural practices is currently destined mainly for composting, with the production of a valuable product; however, this process demands energy. Anaerobic digestion, instead, represents an energy-positive process that results in the production of fuel, biogas, and a fertilizer, namely digestate. Previous tests for the evaluation of biogas yield from freshly harvested grass gave promising results. However, for a practical exploitation of this resource, appropriate conservation is necessary in order to enable the daily load of digesters while reducing the loss of organic matter. The present work is focused on the evaluation of biogas and methane yield from dried and ensiled grass (without conditioning) in order to assess eventual biogas potential losses in comparison to digested fresh grass. Tests were performed with grass collected from riverbanks (Veneto, Northern Italy) in batch, lab scale digesters. Dry and ensiled grass showed a good potential for exploitation in the anaerobic digestion process, reaching biogas yields of 565.9 and 573.4 NL?kgVS −1 , respectively. Compared to the biogas yield of 639.7 NL?kgVS −1 of the fresh grass, the conservation treatment determined yield reductions of 11.5% and 10.4% for dried and ensiled grass, respectively. However, considering the methane yields, conservation treatments showed lower reductions, amounting to 4.8% for dry grass and 0.5% for ensiled grass; presumably the higher concentration of organic acids in ensiled grass determined a higher methane content in biogas and the consequently lower reduction of methane yield.

Keywords: energy source; anaerobic digestion; biogas potential; BMP; grass (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (9)

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