Multiple-criteria decision analysis techniques for anaerobic digester technology assessment.

Area of Science:

• Agricultural Engineering
• Environmental Science
• Decision Science

Background:

• Effective decision-making in technology selection necessitates evaluating multiple criteria.
• Small-scale anaerobic digester technology is crucial for low to middle-income countries.
• Previous methods often fail to adequately address the complexity of multi-criteria decision problems in technology adoption.

Purpose of the Study:

• To develop and apply a multi-criteria selection method for assessing small-scale anaerobic digester technologies.
• To identify the most suitable digester technology for South African smallholder farmers under different farming contexts.
• To provide a robust decision support tool for technology selection in similar settings.

Main Methods:

• Combined the Simple Multi-Attribute Rating Technique (SMART) and Analytical Hierarchy Process (AHP) for multi-criteria decision analysis.
• Evaluated eleven potential small-scale digester technologies.
• Applied the developed method to two distinct scenarios: subsistence and commercially oriented smallholder farming in South Africa.

Main Results:

• The DIY Biobag digester was highly preferred (82.1%) in the subsistence farming scenario.
• The Puxin digester was preferred (73.7%) in the commercially oriented farming scenario, contingent on funding and construction feasibility.
• The AGAMA BiogasPro digester ranked second in both scenarios, indicating its strong performance.

Conclusions:

• The developed model provides a knowledge-based framework for selecting appropriate small-scale anaerobic digester technologies.
• The Biobag and Puxin digesters emerge as leading options, with suitability dependent on specific farmer contexts and economic conditions.
• Sensitivity analysis confirmed the stability and robustness of the selected alternatives, supporting the model's reliability.