Is Anaerobic Digestion Energy Viable?

Research Article

Austin J Biotechnol Bioeng. 2025; 12(1): 1139.

Is Anaerobic Digestion Energy Viable?

Nait Hmad L1,4, Colin A2, Terekhova A2, Boissonnade M2, Diop S3, Boussaada I3,4 and Taidi B1*

1University of Paris Saclay, CentraleSupelec, Laboratoire de Génie de Procédés et Matériaux (LGPM), 3 rue Joliot Curie, 91190 Gif Sur Yvette, France

2University of Paris Saclay, CentraleSupelec, 3 rue Joliot Curie, 91190 Gif Sur Yvette, France

3University of Paris-Saclay, CentraleSupelec, CNRS, Inria, Laboratoires des Signaux et Systèmes (L2S), 5 rue Joliot Curie, 91190 Gif Sur Yvette, France

4IPSA, 63 Bd de Brandebourg Bis, 94200 Ivry-sur-Seine, France

*Corresponding author: Behnam TAIDI, University of Paris Saclay, CentraleSupelec, Laboratoire de Génie de Procédés et Matériaux (LGPM), 3 rue Joliot Curie, 91190 Gif Sur Yvette, France Email: behnam.taidi@centralesupelec.fr

Received: January 02, 2025; Accepted: January 22, 2025 Published: February 03, 2025

Abstract

Anaerobic digestion (AD) is a biological process carried out by microorganisms that convert organic matter into microbial biomass and biogas, primarily composed of methane and carbon dioxide. AD is increasingly being implemented on farms for renewable energy production. For AD to be energetically viable, the energy generated from the biologically produced methane must exceed the energy spent for its production. The energy spent for the production of methane is related to the transport of biomass to the anaerobic digester, together with stirring and heating the bioreactor. The latter are influenced by the size and volume of the reactor.

To facilitate the energetic assessment of various AD operations, publicly available data was utilized to develop an ExcelTM model. This model takes into account associated operations, such as biomass collection and transportation to the AD reactor. The model was used to determine the energetic break-even point for bio-methane generation. A feed mixture of 60% energy crops and 40% cow dung, with energy crops represented by sugarcane, was used for all simulations at different tonnages of feed per year.

Across eighteen simulations, the model demonstrated an average annual energy productivity of 2.42 × 106 Wh/ton of volatile solids (VS). Notably, for all digester volumes exceeding 75 m³, the AD process was energetically efficient, producing more energy than required for its operation. The overall economic viability of an AD operation is highly dependent on local and national financial incentives and was not modelled.

This tool enables the identification of optimal conditions concerning size and location for any AD operation, thereby enhancing its efficiency and profitability.

Keywords: Energetic balance; Anaerobic Digestion; Biogas; Energetic viability; Circular economy; Renewable energy; Sustainability

Graphical Abstract