Abstract The use of biogenic and waste feedstocks is a promising strategy to improve the chemical sector’s supply chain resiliency and carbon intensity. To help inform research efforts that transform these feedstocks into industrial chemicals, we used a systematic analysis framework to consistently evaluate the economics and environmental impacts of >200 alternative production pathways for 51 organic commodity chemicals in the United States under an optimistic future scenario that reflects the potential upper bounds of process scalability, energy availability, and carbon uptake. Lower-impact and lower-cost alternative pathways were identified for all but three chemicals, with 75% using thermochemical routes and half leveraging existing manufacturing infrastructure. Scenario analysis shows that the ranking of these pathways for half of the assessed chemicals is particularly sensitive to carbon uptake assumptions and criteria prioritization (i.e., cost only, environmental impact only, or both), with changes in electricity grid mix, hydrogen source, and underlying mass and energy flow data proving less influential. Implementing alternative pathways for just 11 chemicals could support a transition to net-zero greenhouse gas emissions from chemical production by 2050, with 11% lower cost than business as usual, similar water requirements, quadrupled electricity demand, and the use of most available woody biomass. These findings provide an exploratory guide toward a future chemical industry that harnesses alternative feedstocks.

Chemical manufacturing is a large and diverse sector of the U.S. economy, with products, fuels, and a wide assortment of materials used daily by both the public and businesses. Currently, several of the largest volume chemicals produced in the United States rely on fossil fuels as a feedstock, energy source, or both. The list of chemicals includes steam cracking products such as ethylene, propylene, benzene, and xylenes as well as products such as ammonia and methanol. The focus for this work is on platform chemicals that are both produced in the largest volume and have a high potential for subsequent processing into more specialized products. In this study, we explore several new pathways that reduce the overall energy consumption and greenhouse gas (GHG) emissions for each product. These pathways include energy efficiency measures applied to existing production methods, the use of bio‐based fuels and/or feedstocks as new production methods, and electrification of high‐energy‐input stages within current production methods. Scenarios for energy demand and GHG reduction were conducted with the National Renewable Energy Laboratory's Materials Flows through Industry tool. Projections of the energy demand and GHG emissions in 2030 and 2050 are included, using grid composition projections from the NREL ReEDS model. The alternative scenarios selected showcase the effect of realistic changes the industry could make, focusing on technologies with a high level of technical readiness.

Although established technologies are technically sound and have good commercialization records, they are not always sustainable. With companies aiming to develop and deploy more sustainable technologies to the market, there are often overlooked or unidentified social, economic, and environmental risks associated with the adoption of these new technologies. This paper evaluates a new method for assessing potential barriers to market adoption for developing technologies. As a case study, an example technology was selected in the enzymatic recycling of polyethylene terephthalate to produce recycled ethylene glycol and terephthalic acid. This technology was assessed for emissions to air, water, and waste streams; techno-economic viability; local economic impacts; life cycle; potential supply chain risks; and technology adoption rates using Bass diffusion curves. The framework can be used for evaluating the sustainability potential for the fast deployment of all technologies. It can also help decision makers such as investors, regulators, and manufacturers address the barriers associated with technology adoption and deployment to make informed decisions, as well as aid in technology transitions.

BACKGROUND:Achieving a net zero greenhouse gas United States (US) economy is likely to require both deep sectoral mitigation and additional carbon dioxide removals to offset hard-to-abate emissions. Enhancing the terrestrial carbon sink, through practices such as the adoption of no-till and cover cropping agricultural management, could provide a portion of these required offsets. Changing domestic agricultural practices to optimize carbon content, however, might reduce or shift US agricultural commodity outputs and exports, with potential implications on respective global markets and land use patterns. Here, we use an integrated energy-economy-land-climate model to comprehensively assess the global land, trade, and emissions impacts of an adoption of domestic no-till farming and cover cropping practices based on carbon pricing.RESULTS:We find that the adoption of these practices varies depending on which aspects of terrestrial carbon are valued. Valuation of all terrestrial carbon resulted in afforestation at the expense of domestic agricultural production. In contrast, a policy valuing soil carbon in agricultural systems specifically indicates strong adoption of no-till and cover cropping for key crops.CONCLUSIONS:We conclude that under targeted terrestrial carbon incentives, adoption of no-till and cover cropping practices in the US could increase the terrestrial carbon sink with limited effects on crop availability for food and fodder markets. Future work should consider integrated assessment modeling of non-CO2 greenhouse gas impacts, above ground carbon storage changes, and capital and operating cost considerations.

A massive rise in single-use plastic consumption has resulted in uncontrollable terrestrial and marine plastic pollution. Waste management systems currently do not have sufficient capacity to safely dispose of waste plastic. Apart from the plethora of negative environmental impacts due to mismanaged plastic waste both inland and in the oceans, landfilled plastics represents a significant recoverable energy footprint disposed of after a single use or a very short lifetime. Recovering these materials could reduce their carbon footprint by displacing the production of virgin plastic. The goal of this research is to develop a plastics circular economy framework that includes critical technological, economic, and policy constraints to help decision makers compare end of life options and inform investment decisions. In addition to implementing metrics for measuring circularity, the framework employs life cycle assessment to compare the environmental impact of pathways for improving circularity in the plastics economy. A case study exploring the recycling of polyethylene terephthalate (PET) bottles from 2020 to 2049 reveals that chemical recycling using glycolysis along with improved collection systems through drop-off recycling centers will significantly improve the circularity of PET bottles as well as reduce carbon footprints by displacing virgin PET manufacture. While waste incineration rather than recycling shows improved landfill-diversion-based circularity potential, it results in a significant increase of greenhouse gas emissions due to the combustion process.

Glass manufacturing is a major part of the U.S. economy, and glass products in multiple sectors - flat glass, container glass, and fiberglass - are a part of everyday life. Despite glass manufacturing's long history, there are still many opportunities for glass production to improve in terms of both in overall energy consumption and greenhouse gas (GHG) emission reduction. Scenarios for the flat, container, and fiberglass sectors show the effect that each improvement has on primary energy demand and GHG emissions, starting from an industry baseline that reflects current manufacturing practices. Using the National Renewable Energy Laboratory's Material Flows through Industry tool, multiple scenarios are examined for each glass sector by applying a combination of energy reduction, increased electrification, hydrogen cofiring, a more renewable electric grid, and increased use of cullet. Additional decarbonization options are possible for glass but are left for later analysis due to cost, feasibility, or data issues. Primary energy demand can be reduced by 75%-83% compared to baseline inputs, depending on the sector, and GHG emissions are reduced by 82%-86%. Applying the maximum level of improvements listed here has the potential to save over 300 million GJ and 25 million metric tons of GHGs by 2050.

The production of commodity organic chemicals today is both primarily sourced from and powered by fossil carbon resources. Toward decarbonization of this key global economic sector, it is imperative to quantitatively understand the contributions to energy usage and greenhouse gas (GHG) emissions along the petrochemical manufacturing supply chain, which can inform judicious policy development and impactful technology options to improve or reimagine existing manufacturing practices. To that end, here we use the Materials Flows through Industry (MFI) tool to estimate the supply chain energy and GHG emissions for 51 organic petrochemicals and 6 intermediates that are globally produced at a capacity of at least 1 million metric tons (MMT) per year. This analysis focuses on supply chains in the United States, from which industrial data are readily sourced to obtain accurate energy and GHG emission estimates. Analysis for each chemical includes contributions from sourcing chemical feedstocks, electricity use, and fuel usage for transportation and manufacturing. This analysis predicts that process fuel, which is primarily used for heating, dominates GHG emissions in all cases except for chlorochemicals, where electricity is used extensively for the chloroalkali process and results in a large electricity GHG emission contribution ranging from 7 to 54% of total GHG emissions. Additionally, the contribution of electricity to GHG emissions ranges from 6 to 63%, representing the decarbonization potential in the transition toward renewable electricity with existing manufacturing processes. Taken together, these data serve as a critical baseline toward industrial decarbonization of the organic chemical sector, against which to compare changes to the electrical grid and industrial heat sources, improvements to existing technologies to manufacture the same chemicals, and new technologies to source alternative feedstocks to manufacture direct or functional replacement chemicals.

The term "zero waste" can be somewhat misleading, as it implies an idealization of a concept that may never be achieved in real-world practice. According to Waste360 , "many in the solid waste industry think zero waste is an impossible goal. (Zero-waste advocates) believe just the opposite that a zero-waste approach makes the most economical and environmental sense...Most everyone agrees, however, that actually reaching the point where absolutely no waste is created is unlikely" (Leroux 2001). "Zero waste is a goal. It's completely unachievable...It's not about perfection; it's about making better choices" (Kellogg 2018). The immediate value of moving towards a zero-waste society is not immediately clear, but since the world we live in is finite in its resources, at what point does that value become evident? How do we broaden our value analysis to better incorporate the longer-term view? What are strategies that we can easily incorporate now that will significantly increase that longer term value and mitigate the impacts for future generations? This report considers these questions through a series of case studies from different parts of the U.S. manufacturing sector.

Esterases have emerged as important biocatalysts for enzyme-based polyester recycling of poly(ethylene terephthalate) (PET) to terephthalic acid (TPA) and ethylene glycol (EG). Here, we present process modeling, techno-economic, life-cycle, and socioeconomic impact analyses for an enzymatic PET depolymerization-based recycling process, which we compare with virgin TPAmanufacturing. We predict that enzymatically recycled TPA (rTPA) can be cost-competitive and highlight key areas to achieve this. In addition to favorable long-term socioeconomic benefits, rTPA can reduce total supply chain energy use by 69%-83% and greenhouse gas emissions by 17%-43% per kg of TPA. An economy-wide assessment for the US estimates that the TPA recycling process can reduce environmental impacts by up to 95% while generating up to 45% more socioe-conomic benefits, also relative to virgin TPA production. Sensitivity analyses highlight impactful research opportunities to pursue toward realizing biological PET recycling and upcycling.