Techno-Economic and Life Cycle Analyses of Thermochemical Upcycling Technologies of Low-Density Polyethylene Waste

Abstract

In this study we compare techno-economics and life cycle assessment of thermochemical depolymerization technologies, including pyrolysis, gasification, hydrocracking, hydrothermal liquefaction, and hydrogenolysis, to generate various products from low-density polyethylene (LDPE) waste. We elucidate the effects of production scale, collection cost, and concentration of LDPE in plastic waste. Pyrolysis of LDPE to olefins followed by their conversion to lubricant oils is the most profitable technology. Hydrogenolysis, producing a small fraction of lubricant oils, becomes profitable at plant sizes above 25 kt/y and produces the lowest CO 2 emissions. Hydrocracking is the second most environmentally friendly technology but becomes economically competitive at sufficiently large scales, and the supply chain for collecting plastics is optimized. Gasification of LDPE to H 2 produces high emissions, and the price of H 2 of ∼3 $/kg is higher than current markets and recently announced goals. Similarly, hydrothermal liquefaction also gives high emissions, making carbon capture systems imperative for both technologies. Our results demonstrate that lowering the cost of sorting LDPE from plastic waste, collecting waste near big cities, building sufficiently large plants, and achieving high selectivity to value-added products are critical to successful plastic waste management.

Method to Develop Potential Business Cases of Plastic Recycling from Urban Areas: A Case Study on Nonhousehold End-Use Plastic Film Waste in Belgium

“…Next, the annual costs of different selective collection schemes from urban areas (weekly, fortnightly, or monthly collection frequencies) are estimated using OptiFlow Route Optimization software . The annual costs of mechanical recycling of nonhousehold end-use plastic film are estimated by combined material flow analysis (MFA) in the recycling plant and economic assessment, as suggested by Larrain et al, Hernández et al, and Bashirgonbadi et al The required inputs for the MFA model are waste quantity and composition, recycling plant configuration, and separation efficiency of equipment used in the recycling plant. Later, the MFA results and data on capital investment and utility consumption are used as the basis for the economic assessment.…”

“…The economic assessment of nonhousehold end-use plastic film waste management demonstrates the difference between the costs incurred by waste collection (i.e., the results of the logistic simulation) and mechanical process and the revenue from regranulate sales, i.e., rPE basic/advanced . ,,, The estimation of capital investment for the mechanical recycling plant follows the approach described by Sinnott and Towler, which is also applied in previous studies. − The estimated total investment includes the price of individual recycling equipment (in Figure ) and additional procuring, transport, installation, and running test of the equipment, engineering and project management, and site infrastructure (i.e., building the recycling plant itself). The total investment per piece of equipment is provided in Table SI5, and the economic modeling parameters are provided in Table SI6.…”

“…The logistic simulations are done in OptiFlow software based on the input from waste operators. The material flows and economic modeling is developed by following the material flow analysis (MFA) and techno-economic assessment (TEA) modeling approach. − Finally, the GHG emission (in kg CO 2 -equiv) is quantified by following the life cycle assessment (LCA) modeling approach. − …”

Comparative Techno-economic Analysis and Life Cycle Assessment of Producing High-Value Chemicals and Fuels from Waste Plastic via Conventional Pyrolysis and Thermal Oxo-degradation

“…The mass and energy balance from the BioSTEAM process models were used for capital and operating cost estimates. The study employs the discounted cash flow rate of return (DCFROR) commonly used in similar studies ,, to estimate the net present value (NPV) of each scenario. The NPV was selected as the economic indicator to compare the scenarios because it allows for straightforward economic feasibility estimates and multiple technology comparison for multi-product facilities.…”

“…To the best of our knowledge, no study has investigated the economic feasibility and life cycle assessment of thermal oxo-degradation or compared the technology to conventional pyrolysis of waste plastics. Some studies have compared the economics and environmental impacts of various chemical recycling technologies for converting waste plastics into value-added products. , Hernández et al have compared the techno-economic analysis (TEA) and life cycle assessment (LCA) of pyrolysis, hydrogenolysis, gasification, hydrocracking, and hydrothermal liquefaction of low-density polyethylene waste (LDPE) to produce different products. The study found the pyrolysis of LDPE to olefins, followed by the conversion to lubricant oil, to be the most profitable thermochemical upcycling technology for LDPE, with a return on investment (ROI) between 13 and 17% .…”