Biogas as a Renewable Energy Source: The Effect of Gas Composition and Process Temperature on Energy Efficiency in a Landfill Gas Power Plant — A Case Study

Abstract

Biogas and landfill-gas power plants, part of the renewable energy portfolio, generate electricity by combusting gas collected from waste sites in engine-generator units. This study statistically examines 121 daily operating records (gas extraction rate, energy output, CH₄/CO₂/O₂ content, and gas temperature) from a biogas power plant in Türkiye, covering 1 February–31 May 2024. Descriptive statistics, Pearson and Spearman correlation coefficients, and multiple linear regression models were applied. Daily energy output was most strongly determined by gas extraction rate (r = 0.81, p < 0.001). Methane and CO₂ content were both positively associated with a specific energy-yield indicator (r = 0.19, p = 0.042 and r = 0.21, p = 0.022, respectively), while oxygen content was significantly negatively associated with it (r = -0.24, p = 0.009), consistent with the literature's treatment of O₂ as an indicator of air intrusion into the collection system. Gas temperature rose steadily over the period (43.9°C → 49.4°C) and was significantly negatively associated with specific efficiency (r = -0.33, p < 0.001), pointing to a possible effect of seasonal warming on engine/process efficiency. A regression model combining gas flow, composition variables, and gas temperature explained roughly 70% of the variance in daily output (R² = 0.70); the robustness of these findings was confirmed through four complementary sensitivity analyses (sub-period exclusion, leave-one-month-out, winsorizing, and split-half comparison). As a single-plant case study, the findings indicate that flow stability, gas-quality monitoring, and temperature management need to be considered jointly in biogas plant operation, supporting continuous efficiency gains at existing landfill-gas facilities as part of the renewable energy portfolio.