Models for Decarbonization in the Chemical Industry.

Various technologies and strategies have been proposed to decarbonize the chemical industry. Assessing the decarbonization, environmental, and economic implications of these technologies and strategies is critical to identifying pathways to a more sustainable industrial future. This study reviews recent advancements and integration of systems analysis models, including process analysis, material flow analysis, life cycle assessment, techno-economic analysis, and machine learning. These models are categorized based on analytical methods and application scales (i.e., micro-, meso-, and macroscale) for promising decarbonization technologies (e.g., carbon capture, storage, and utilization, biomass feedstock, and electrification) and circular economy strategies. Incorporating forward-looking, data-driven approaches into existing models allows for optimizing complex industrial systems and assessing future impacts. Although advances in industrial ecology-, economic-, and planetary boundary-based modeling support a more holistic systems-level assessment, more effects are needed to consider impacts on ecosystems. Effective applications of these advanced, integrated models require cross-disciplinary collaborations across chemical engineering, industrial ecology, and economics. Expected final online publication date for the Annual Review of Chemical and Biomolecular Engineering , Volume 15 is June 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Uncertain Future of American Lithium: A Perspective until 2050.

During the 20th century, the United States went from being the largest producer and user of lithium to being heavily reliant on imports from Asia, particularly lithium-ion batteries. To explore different futures for U.S. lithium, we here generate four scenarios─including COVID-19 implications─that model lithium use for its main applications: electric and hybrid vehicles, stationary energy storage systems, and small electronics. We find that the "Sustainable Future" scenario requires the highest amount of lithium (cumulatively 1281 Gg in the period 2020-2050, peak inflow in 2040 at 53 Gg); in contrast, "Fossil Fuel Everything" requires only 500 Gg and peaks in 2050 at 26 Gg. COVID-19 implications appear to be negligible in the long run. The future electrification of the U.S. vehicle fleet and energy storage systems will depend upon a reliable and resilient international supply chain of lithium chemicals and/or batteries as well as vigorous recycling efforts.

Material Flow Analysis from Origin to Evolution.

Material flow analysis (MFA), a central methodology of industrial ecology, quantifies the ways in which the materials that enable modern society are used, reused, and lost. Sankey diagrams, termed the "visible language of industrial ecology", are often employed to present MFA results. This Perspective assesses the history and current status of MFA, reviews the development of the methodology, presents current examples of metal, polymer, and fiber MFAs, and demonstrates that MFAs have been responsible for creating related industrial ecology specialties and stimulating connections between industrial ecology and a variety of engineering and social science fields. MFA approaches are now being linked with environmental input-output assessment, scenario development, and life cycle assessment, and these increasingly comprehensive assessments promise to be central tools for sustainable development and circular economy studies in the future. Current shortcomings and promising innovations are also presented, as are the implications of MFA results for corporate and national policy.

Assessing the Reliability of Material Flow Analysis Results: The Cases of Rhenium, Gallium, and Germanium in the United States Economy.

Decision-makers traditionally expect "hard facts" from scientific inquiry, an expectation that the results of material flow analyses (MFAs) can hardly meet. MFA limitations are attributable to incompleteness of flowcharts, limited data quality, and model assumptions. Moreover, MFA results are, for the most part, based less on empirical observation but rather on social knowledge construction processes. Developing, applying, and improving the means of evaluating and communicating the reliability of MFA results is imperative. We apply two recently proposed approaches for making quantitative statements on MFA reliability to national minor metals systems: rhenium, gallium, and germanium in the United States in 2012. We discuss the reliability of results in policy and management contexts. The first approach consists of assessing data quality based on systematic characterization of MFA data and the associated meta-information and quantifying the "information content" of MFAs. The second is a quantification of data inconsistencies indicated by the "degree of data reconciliation" between the data and the model. A high information content and a low degree of reconciliation indicate reliable or certain MFA results. This article contributes to reliability and uncertainty discourses in MFA, exemplifying the usefulness of the approaches in policy and management, and to raw material supply discussions by providing country-level information on three important minor metals often considered critical.

Deriving the Metal and Alloy Networks of Modern Technology.

Metals have strongly contributed to the development of the human society. Today, large amounts of and various metals are utilized in a wide variety of products. Metals are rarely used individually but mostly together with other metals in the form of alloys and/or other combinational uses. This study reveals the intersectoral flows of metals by means of input-output (IO) based material flow analysis (MFA). Using the 2007 United States IO table, we calculate the flows of eight metals (i.e., manganese, chromium, nickel, molybdenum, niobium, vanadium, tungsten, and cobalt) and simultaneously visualize them as a network. We quantify the interrelationship of metals by means of flow path sharing. Furthermore, by looking at the flows of alloys into metal networks, the networks of the major metals iron, aluminum, and copper together with those of the eight alloying metals can be categorized into alloyed-, nonalloyed-(i.e., individual), and both mixed. The result shows that most metals are used primarily in alloy form and that functional recycling thereby requires identification, separation, and alloy-specific reprocessing if the physical properties of the alloys are to be retained for subsequent use. The quantified interrelation of metals helps us consider better metal uses and develop a sustainable cycle of metals.

Criticality of non-fuel minerals: a review of major approaches and analyses.

The criticality of nonfuel minerals is an emerging research subject that captures both the supply risks and the vulnerability of a system to a potential supply disruption. The significance of material criticality for the mass deployment of sustainable and other key technologies is currently obscured by diverse, often immature, and still evolving methodologies. This review explores why principal studies agree or disagree in designating the criticality of certain nonfuel minerals. We survey the literature and analyze several well documented studies in depth, demonstrating that the platinum group metals (e.g., essential for catalytic reduction of air pollutants), and the rare earth elements (e.g., essential for efficient electricity generation in wind turbines) are frequently singled out as critical, albeit by differing criteria. We also discuss the impacts of methodological choices on the designation of raw materials as critical. The treatment of substitutability, time horizons, and the aggregation level of criticality indicators are shown to be significant in this regard. We determine several important issues that have thus far been largely disregarded, especially the justification of methodological components, and policy responses to criticality designation.

EPA at 40: bringing environmental protection into the 21st century.

Sustainability science suggests that effective environmental protection requires an integrated systems approach.

Getting serious about sustainability.

Sustainability and sustainable development are catchwords that dominate today's environmental science and policy discourse. It is easy to demonstrate that most of the activities of today's industrial society are unsustainable. Unfortunately, much of the talk about sustainability lacks a basic understanding of what truly sustainable activity would be. To set sustainability as a target or goal for our industrial society, we must be able to quantify that target or goal. We propose four basic steps to begin this process for one aspect of sustainability, the rate of use of resources: (i) establish the available supply of the chosen resource; (ii) allocate the annual permissible supply according to a reasonable formula or market process; (iii) establish the "recaptureable" resource base; and (iv) derive the sustainable limiting rate of use and compare to the current rate of use. We apply these sustainability measurement methods to three common materials in industrial society: zinc, germanium, and greenhouse gases. These examples demonstrate that with some basic (although potentially controversial) assumptions, quantitative sustainable use goals can be set and current performance relative to those goals can be evaluated. The assumptions and approximates we have used are meant to stimulate thought and debate, beginning a long conversation on the measurement of sustainability.