Evaluation of Contribution to Greenhouse Gas Reduction and Economic Benefits of Livestock Manure based Solid Fuel

Abstract

Objectives : In the context where the greenhouse gas (GHG) emissions from livestock manure (LSM) account for more than half of the GHG emissions in the livestock sector, it is necessary to find alternatives to composting due to the decrease in agricultural land. This study aims to calculate the GHG reduction contribution and economic benefits when converting LSM into solid fuel as an alternative to traditional composting.Methods : The study compares the results of converting the entire LSM generated domestically into solid fuel replacing it with hard coal for fuel (HC-F), bituminous coal for raw materials (BC-R), bituminous coal for fuel (BC-F). The GHG reduction contribution is calculated following the domestic GHG inventory methodology, using the IPCC guidelines and the method for calculating carbon emission reduction effects. For the assessment of economic benefits, were evaluated by aggregating the impacts of reducing coal imports and GHG reduction benefits in line with EU-ETS standards. Economic benefits are assessed by combining the effects of avoiding coal imports and the GHG reduction benefits according to the EU-ETS.Results and Discussion : The GHG reduction effect was found to be highest when replacing with HC-F, and this is attributed to the lower heating value and higher GHG emission coefficient of HC-F compared to BC-R, and BC-F, indicating that the substitution with HC-F is most effective in terms of import avoidance. If 20% of the annual coal consumption in 2022 is replaced with solid fuel from LSM, the GHG reduction effects for coal substitution are 1.4% for HC-F, 2.1% for BC-R, and 1.9% for BC-F based on the LSM generation CO₂ emissions from biomass fuel are considered climate-neutral and are excluded from the national total emissions. Solid fuel from LSM serves as an alternative in addressing the GHG generated during the LSM treatment process, contributing to potential reduction. If all generated LSM is replaced with HC-F, BC-R, or BC-F, there are respective GHG reduction effects of 13,193,591 tGHG, 11,320,572 tGHG, and 11,226,331 tGHG.Conclusion In 2018, the livestock sector accounted for approximately 42% of the GHG emissions in the agricultural sector, totaling 9.4 million tCO₂ eq. Assuming the complete conversion of LSM into solid fuel for coal substitution, regardless of the type of coal replaced, it offsets the entire GHG emissions from the agricultural sector. Currently, there is limited demand for the conversion of LSM into solid fuel due to a lack of proof and awareness, but with some coal-fired power plants scheduled for partial shutdown and the government considering energy options for LSM, a promising stage is anticipated in the future for the substitution and expanded use of solid fuel from LSM in place of coal in the coal fuel. Although it may not be possible to entirely replace the coal used in power plants and steel mills with solid fuel from LSM, it can be utilized by increasing the proportion of coal blending. However, even if not reported in the national GHG inventory, the treatment of pollutants generated by solid fuel combustion remains an ongoing challenge. As solid fuel becomes more commonplace in the future, a comprehensive assessment of the entire process, including potential environmental impacts throughout the life cycle, will be necessary to establish a basis for GHG reduction measures.