Techno-Economic Assessment of Solid–Liquid Biogas Treatment Plants for the Agro-Industrial Sector

Abstract

The urgent need to meet climate goals provides unique opportunities to promote small-scale farm anaerobic digesters that valorize on-site wastes for producing renewable electricity and heat, thereby cushioning agribusinesses against energy perturbations. This study explored the economic viability of mono-digestion of cow manure (CWM) and piglet manure (PM) in small manured-based 99 kWel plants using three treatment schemes (TS): (1) typical agricultural biogas plant, (2) a single-stage expanded granular sludge bed (EGSB) reactor, and (3) a multistage EGSB with a continuous stirred tank reactor. The economic evaluation attempted to take advantage of the financial incentives provided by The Renewable Energy Sources Act in Germany. To evaluate these systems, batch tests on raw and solid substrate fractions were conducted. For the liquid fraction, data of continuous tests obtained in a laboratory was employed. The economical evaluation was based on the dynamic indicators of net present value and internal return rate (IRR). Sensitivity analyses of the electricity and heat selling prices and hydraulic retention time were also performed. Furthermore, an incremental analysis of IRR was conducted to determine the most profitable alternative. The most influential variable was electricity selling price, and the most profitable alternatives were TS1 (CWM) > TS1 (PM) > TS3 (CWM). However, further studies on co-digestion using TS3 are recommended because this scheme potentially provides the greatest technical flexibility and highest environmental sustainability.

Techno-Economic Assessment of Anaerobic Digestion Technology for Small- and Medium-Sized Animal Husbandry Enterprises

“…Organic waste management poses a significant challenge for the animal husbandry sector, which produces substantial quantities of residues and wastes, both liquid and solid, necessitating proper treatment and disposal [25]. Inadequate waste management can result in greenhouse gas emissions, environmental pollution, health hazards, and economic losses [24].…”

“…The techno-economic assessment of anaerobic digestion facilities, ranging from 50 to 400 kW installed CHP electric power, entailed both capital (CAPEX) and operational (OPEX) expenditures. CAPEX included the engineering, procurement and construction of various components, such as a buffer tank with a mixer and pumps, a digester tank with a mixer, heat exchanger and a membrane gas holder [24][25][26]. Additionally, biogas equipment comprising a scrubber, dryer, and combined heat and power (CHP) unit was accounted for, along with monitoring equipment including liquid and gas flow meters, temperature, pressure and level sensors.…”

The Role of Biogas and Biomethane as Renewable Gases in the Decarbonization Pathway to Zero Emissions

“…Herman and colleagues investigate how waste composition affects the quality of biogas and digestate fertilizer, characterizing the biogas and digestate quality of anaerobically digested food waste from four diets and estimating the difference in biogas produced from co-digested food waste and brewery waste [6]. Hernández and co-authors present a techno-economic assessment of biogas treatment plants for the agro-industrial sector, optimizing the design and operation of these plants to reduce greenhouse gas emissions and improve the circular use of nitrogen [7]. Häner and colleagues explore the use of fixed-bed and expanded granular sludge bed reactors for the anaerobic digestion of pig slurry, aiming to increase efficiency by using reactors with biomass retention [8].…”