The environmental and economic impacts
of implementing a circular
economy in plastic waste supply chains are not well understood. The
proposed systems analysis framework assesses environmental, social,
and economic impacts of plastic waste supply chains in a circular
economy. The first objective of this article is to identify data sets,
models, and knowledge gaps associated with waste plastic supply chain
processes, mainly in the U.S. Our literature review indicated that
the best data sets exist for virgin plastic resin production, mechanical
recycling, landfilling, and incineration, with the materials recovery
facility being intermediate, and with chemical recycling the lowest.
The second objective of this perspective is to develop an illustrative
application of the framework by conducting a preliminary systems analysis
of PET bottles with closed-loop recycling. The preliminary systems
analysis of polyethylene terephthalate (PET) bottles utilized a linear
programming optimization method. Our optimization model indicated
that both chemical and mechanical recycling processes are needed to
achieve a true circular economy of PET bottles with the least greenhouse
gas emissions, specifically reductions of 24% when compared with the
linear economy. Good quality and standardized life cycle assessment
and techno-economic analysis studies are needed to better understand
the environmental, economic, and social impacts of advanced sorting
and chemical recycling technologies.
The U.S. Department of Energy (DOE) promotes the production of advanced liquid transportation fuels from lignocellulosic biomass by funding fundamental and applied research that advances the State of Technology (SOT). As part of its involvement with this mission, Idaho National Laboratory (INL) completes an annual SOT report for biomass feedstock logistics. This report summarizes supply system impacts of Bioenergy Technologies Office (BETO)-funded research and development efforts at INL and elsewhere (such as the High-Tonnage Feedstock Logistics projects (Webb et al. 2013a, Webb et al. 2013b, Webb et al. 2013c, Webb and Sokhansanj 2014, Sokhansanj et al. 2014)) that lead to improvements in feedstock supply systems. These include improvements to and observed performance of innovative harvest and collection methods, storage technologies, transportation and handling approaches, and advanced preprocessing technologies. Biomass quality and variability, and the interface between feedstock quality and conversion performance are key drivers in addition to delivered feedstock cost. In this report, we estimate the benefits of R&D improvements to individual supply system unit operations and present the status of feedstock logistics technology development for converting biomass into biofuels. These analyses are supported by experimental data where possible and help to align the SOT relative to the cost goals defined in the Multi-Year Program Plan. The 2019 Herbaceous SOT incorporates several technology changes in feedstock preprocessing and introduces opportunities from the integrated landscape management (ILM) strategy and increased grower participation to reduce biomass access costs, while maintaining or improving grower profitability. During FY18 uneven flow from the horizontal bale grinder was identified as a significant issue limiting preprocessing system throughput. Based on FSL-funded research at INL, the 2019 Herbaceous SOT replaces the horizontal bale grinder used in the first ton/acre. However, it is purported that MOG is lower in moisture and ash content
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