Techno-economic analysis and life cycle assessment of microwave co-pyrolysis of food waste and low-density polyethylene

Abstract

This paper presents a techno-economic analysis (TEA) and life cycle assessment (LCA) of microwave (MW) co-pyrolysis of comingled food waste (FW). Lab scale (capacity- 1 kg/d) MW co-pyrolysis studies of FW and low-density polyethylene (LDPE) yielded 42 wt.% of bio-oil, 42 wt.% of biochar and 16 wt.% of pygas. The fixed and monthly operating cost of the lab scale MW co-pyrolysis reactor was 10,00,000 INR/kg and 8,248 INR/kg, respectively. The respective cost of a commercial MW co-pyrolysis plant (capacity-100 kg/d) was estimated as 53,12,585 INR/kg and 24,420 INR/kg. It was estimated that with 7 % of the internal rate of recovery (IRR), the breakeven point would be achieved within 4 years. The LCA of the commercial MW co-pyrolysis plant evaluated that the drying and pyrolysis unit consumed 91 % of total energy and contributed most to environmental impact. Thus, emission of 38.92 kg CO2 eq, 48.00*10-3 kg SO2 eq, 7.70*10-3 kg PO4-3 eq, 1100.10*10-3 kg dichlorobenzene (DCB) eq and 3.50*10-3 kg C2H6 was projected for MW co-pyrolysis of 100 kg FW and LDPE. Overall, TEA and LCA suggested that the commercial MAP plant would provide higher conversion efficiency, lower energy consumption (0.54 kWh/kg) and environmental risk with an attractive economic return by selling bio-oil + biochar at the rate of 40 INR/kg. � 2022