Development of life cycle greenhouse gas emission factors for organic waste biogasification processes

초록

This study aimed to develop life cycle greenhouse gas (GHG) emission factors for biogasification processes targeting food waste, sewage sludge, and livestock manure in South Korea. The system boundary encompassed pretreatment, anaerobic digestion, biogas utilization, and digestate treatment. Within this boundary, four scenarios were evaluated using life cycle assessment (LCA): a conventional biogas process (Scenario I), biogas utilization for power generation (Scenario II), application of the ANAMMOX process in wastewater treatment (Scenario III), and a combination of both strategies (Scenario IV). To ensure comprehensive comparisons, two functional units were considered: 1 ton of substrate input and 1 Nm3 of biogas produced. The results showed that GHG emissions per ton of substrate were substantially reduced for food waste and sewage sludge in Scenario II, by 99.1% and 70.2%, respectively. In Scenario III, sewage sludge and livestock manure achieved moderate reductions of 12.9% and 13.9% through the application of the ANAMMOX process. When evaluated based on energy output, biogasification exhibited higher GHG emissions than LNG, but significantly lower emissions compared to grid electricity. Overall, these findings suggest that electricity generation from biogas, rather than biogas production alone, offers a more promising pathway for achieving low-carbon goals in organic waste management.

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