Consequential Life Cycle Assessment of Swine Manure Management within a Thermal Gasification Scenario

Mahmoud Sharara, Daesoo Kim, Sammy Sadaka and Greg Thoma
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Mahmoud Sharara: Biological & Agricultural Engineering Department, North Carolina State University, Raleigh, NC 27695, USA
Daesoo Kim: Department of Chemical Engineering, University of Arkansas, Fayetteville, AR 72701, USA
Sammy Sadaka: Department of Biological & Agricultural Engineering, University of Arkansas, Little Rock, AR 72204, USA
Greg Thoma: Department of Chemical Engineering, University of Arkansas, Fayetteville, AR 72701, USA

Energies, 2019, vol. 12, issue 21, 1-15

Abstract: Sustainable swine manure management is critical to reducing adverse environmental impacts on surrounding ecosystems, particularly in regions of intensive production. Conventional swine manure management practices contribute to agricultural greenhouse gas (GHG) emissions and aquatic eutrophication. There is a lack of full-scale research of the thermochemical conversion of solid-separated swine manure. This study utilizes a consequential life cycle assessment (CLCA) to investigate the environmental impacts of the thermal gasification of swine manure solids as a manure management strategy. CLCA is a modeling tool for a comprehensive estimation of the environmental impacts attributable to a production system. The present study evaluates merely the gasification scenario as it includes manure drying, syngas production, and biochar field application. The assessment revealed that liquid storage of manure had the highest contribution of 57.5% to GHG emissions for the entire proposed manure management scenario. Solid-liquid separation decreased GHG emissions from the manure liquid fraction. Swine manure solids separation, drying, and gasification resulted in a net energy expenditure of 12.3 MJ for each functional unit (treatment of 1 metric ton of manure slurry). Land application of manure slurry mixed with biochar residue could potentially be credited with 5.9 kg CO 2 -eq in avoided GHG emissions, and 135 MJ of avoided fossil fuel energy. Manure drying had the highest share of fossil fuel energy use. Increasing thermochemical conversion efficiency was shown to decrease overall energy use significantly. Improvements in drying technology efficiency, or the use of solar or waste-heat streams as energy sources, can significantly improve the potential environmental impacts of manure solids gasification.

Keywords: life cycle assessment; environmental impact; greenhouse gas; gasification; swine manure management (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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