Working Papers
Permanent URI for this collection
Browse
Recent Submissions
Publication Team-Based Staffing, Teacher Authority, and Teacher Turnover(Center for Reinventing Public Education, Arizona State University, 2025) Ingersoll, RichardThis study evaluates an innovative, team-based model of organizing teaching staff in elementary and secondary schools called the Next Education Workforce™ (NEW) initiative. The objective of the NEW initiative is to offer a viable and practical alternative to the long-criticized conventional classroom model of individual teachers each with their own classroom. In contrast to this traditional one-teacher, one-classroom approach, the NEW model integrates teams of teaching staff who share a roster of students, share multiple learning spaces, and collectively plan their teaching program with the aim of providing student-centered instruction. The model was designed at Arizona State University and first implemented in 2018 in partnership with two local school districts. The data for this study are from our statistical analyses of a survey of teachers in one of those districts, combined with district administrative records. In this study we examine whether NEW Team members have implemented key elements and practices associated with the NEW model and to what extent this varies across different types of teachers and schools. In addition, we focus on a key component of the NEW model— that teams are provided with professional-like decision-making authority in regard to the design and implementation of the NEW model—and we investigate the level of authority NEW Team teachers hold. Finally, we assess whether NEW Team membership and teacher authority are related to teacher turnover—the departure of teachers from their schools or from teaching altogether. Our analyses show that the overwhelming majority of teachers on NEW Teams, across different types of teachers and schools, reported that they and their Team have implemented key elements of the NEW model. The data also show that NEW teachers are more likely to report they have authority than non-NEW teachers. In addition, we found that, after controlling for other factors, NEW Team members are less likely to depart from their schools or districts. Similarly, teachers with more authority are less likely to depart than teachers with less authority. Finally, our analyses found a strong interaction and synergy between NEW Team membership and teacher authority. The relationship between turnover and NEW Team membership strengthens as the latter’s level of authority increases. Our findings, based on a limited, non-random sample of descriptive, non-causal data, suggest that the NEW model of team-based staffing is related to increased retention of teachers and that an essential component of the NEW model is the degree to which teachers are able to wield professional-like authority in regard to educational decisions.Publication Helium Liquefaction by Reverse Brayton-Cycle Cryogenic Refrigeration(2025-04-15) Bargallo Gonzalez Lugo, Paulina; Han, Alan; Dong, LiangHelium liquefaction is an energy-intensive process that often serves as a limiting step for the recovery of limited Helium resources from natural gas feeds. Starting from a feed of 10 MMSCFD of natural gas, we account for the entire process of sweetening, hydrocarbon fractionation, nitrogen rejection, LNG production, and Helium purification and liquefaction. We propose a novel multi-expander liquefaction design complete with liquid nitrogen pre-cooling, with energy savings of 36.1 % compared to the existing models of liquefaction typically used for Helium liquefaction. Additionally, the energy savings allow us break even on capital expenditures despite the increased equipment count, thus giving us the advantage in both energy savings and purchase costs. Thus, our project accomplishes the following: 1) Estimate and account for every major process unit in the typical treatment of natural gas to co-produce NGL and LNG, 2) Model a novel liquefaction design using the Reverse-Brayton refrigeration cycle and 3) Optimize the specific power to 0.701 kW-hr/L for liquefaction, surpassing existing liquefaction designs to save on energy usage. Assuming a cost of capital of 15%, a plant lifetime of 15 years, liquid Helium sales price of $30/L, and a natural gas feed consisting of 4.53% Helium, a plant built according to our design has an ROI of 127.85%, and IRR of 45.37%, and an NPV of $247,395,300.Publication Hydrometallurgic Recycling of Lithium-Ion Batteries(2025-04-15) Dedhia, Sara; Pfahnl, Stefanie; Takenaka, Sara; Zhao, NicoleThe global lithium supply is projected to stagnate amid rapidly growing demand, driven primarily by electric vehicle (EV) adoption and global net-zero emissions goals. By 2040, planned mining operations are expected to fall short of projected demand, exacerbated by geopolitical tensions and trade barriers. To mitigate supply chain risks and support the clean energy transition, the development of sustainable refining and recycling infrastructure for critical battery materials (e.g. lithium, cobalt) is imperative. Current U.S. battery recycling facilities process approximately 10,000 tonnes/year of material per facility, with aspirations to reach 100,000 tonnes/year, yet many rely on energy-intensive pyrometallurgical methods. This design project serves to evaluate the technical and economic feasibility of a hydrometallurgical black mass recycling process at the 100,000-tonne/year scale, where ”black mass” is a fine powder derived from shredded EV batteries. Our process offers three key advantages: (1) lower emissions and higher selective recovery of individual metals than pyrometallurgy, (2) scalable capacity surpassing existing recycling infrastructure, and (3) reduced environmental and ethical concerns compared to traditional mining. Economic analysis reveals various challenges. Under the base case assumptions (25-year plant lifetime, NMC carbonate mixture at $9,341/tonne, lithium carbonate at $9, 758/tonne), the process produces a negative NPV at -$683 MM. Profitability (NPV $125MM) is achievable only at the highest prices of NMC -$19,650/tonne. Despite marginal economics, the process achieves 95% separation efficiency, competitive with pyrometallurgical benchmarks. This work establishes a critical baseline for large-scale recycling and highlights its potential necessity if global supply shortages occur.Publication BTEX Produced from CO2 via Direct Aromatization and Combined Hydrogenation with Zeolite Catalysis(2025-04-15) Kaproth, Kenji; Maurer, Madeline; Joseph, SoniaIn the coming decades, sustainable BTEX (benzene, toluene, ethylbenzene, xylene) production will become increasingly viable as demand for petrochemical derivatives continues to rise. Global industrialization and urbanization are driving growth in plastics, polymers, insulating materials, coatings, sealants, and adhesives, positioning BTEX as a key feedstock across multiple sectors. Market forecasts project a CAGR of 3.8–5.2%, suggesting favorable long-term pricing for BTEX producers. This paper explores the feasibility of a novel BTEX production pathway using CO2 and H2 via direct aromatization and combined hydrogenation with zeolite catalysis. Achieving commercial viability will require an improvement in catalyst selectivity, and therefore, separation efficiency. The process offers a potential return on investment of 24.81% by the third year of operation and 3 to 4 times fewer CO2 emissions compared to fossil fuel-derived BTEX. However, market challenges persist due to competition from both current petro-based production methods and emerging chemical recycling technologies. Overall, the proposed plant’s design presents a compelling case for the future of BTEX production, balancing environmental objectives with operational profitability. Key considerations include hydrogen procurement aligned with DOE’s Hydrogen Shot targets and sourcing captured CO2 as a feedstock.Publication Extending Healthspans in an Aging World(2025-08-11) Stephen P. Utkus; Olivia S. MitchellExtensions in human longevity are prompting a growing interest in maximizing healthspan, or the number of years of life unencumbered by the chronic diseases of old age. This chapter reviews recent research on healthy life extension, including several measures and determinants of longer healthspans. We also provide an overview of recent efforts by medical and business enterprises to enhance longevity and healthspan, followed by a discussion of policy and workplace options to foster healthier lives. Such efforts hold the promise of improving quality of life, expanding labor supply, and lowering the cost of health care costs associated with population aging.