Evaluation of greenhouse gas emissions from a biogas plant in Korea

Biogas is a renewable energy source generated through anaerobic digestion, yet Korea lacks specific emission factors (EFs) to quantify its emissions. This study measured methane (CH₄) and nitrous oxide (N₂O) emissions from a co-digestion biogas plant treating 70 tonnes of swine manure from approximately 20,000 heads of swine and 30 tonnes of food waste per day, including potential leakage, and evaluate its performance and environmental impacts. Emissions were monitored from July 7, 2022, to September 27, 2023, using an open dynamic chamber approach, treating interconnected feedstock and aeration storage buildings as a single measurement system. Greenhouse gas (GHG) emissions from the 2019 Refinement Intergovernmental Panel on Climate Change (IPCC) Guideline were also calculated and compared with field-measured GHG emission rates. Results showed that the IPCC-calculated CH₄ and N₂O emissions were 72.5 % lower than estimates from the 2019 IPCC Guidelines. The CH₄ leakage rate was 0.38 %, aligning with European facility standards. However, N₂O emissions increased due to improper aeration, emphasizing the sensitivity of N₂O production to operational conditions. These findings highlight the necessity of accurate field-based EFs, suggesting that well-managed biogas plants can achieve low emissions, while low aeration may cause substantial increases, especially in N₂O. This study supports improved emission inventories and performance benchmarks for Korea's biogas sector.