Energy Potential and Economic Analysis of Biogas from a Domestic-Scale Lay-Down Biodigester: A Study of Specific Yield, Calorific Value, and Greenhouse Gas Emission Reduction

Abstract

This study investigates the energy potential and economic value of biogas produced from a 254-liter concrete lay-down biodigester integrated with a centrifugal pump, through three 22-day anaerobic fermentation cycles using cow manure. Parameters analyzed include specific yield (m³/kg feedstock), coefficient of variation of daily production (CV), volumetric production rate (VPR), estimated biogas energy content (kWh), LPG equivalent value, economic value per cycle, and net greenhouse gas (GHG) emission reduction. Results show that specific yield progressively increased from 0.01610 m³/kg in Trial 1 to 0.01779 m³/kg in Trial 3 (10.5% increase), with average VPR of 0.203 m³/m³·day. The highest biogas energy was obtained in Trial 3 at 5.777 kWh/cycle, equivalent to 0.451 kg LPG valued at IDR 9,027, representing a 39.7% increase compared to Trial 1. Net GHG reduction ranged from 0.149 to 0.209 kg CO₂eq/cycle. This study affirms that improving biogas quality (methane content) is the primary strategy to maximize energy value in domestic-scale biodigesters.