* Materials, Technology and Growth: Quantifying the Costs of Circularity (with Z. Mahone)
Many governments have introduced policies intended to reduce material extraction and boost recycling - i.e., to improve circularity. We develop a growth model of directed technical change with material use and recycling to quantify what these policies can achieve. In the US, we find that material dynamics are moving toward greater circularity, but slowly. We find (i) there are significant welfare gains from shifting the economy away from virgin to recycled material use, (ii) current policy is ineffective at doing this and (iii) revenue-neutral policies pairing recycling subsidies with virgin material taxes can deliver welfare gains of up to 1.5%.
Conditionally Accepted, American Economic Journal: Macroeconomics
[Working Paper] (this draft: May 2026)
Some results from this paper are included in the National Academies Report (MSW Recycling in the United States, 2025).
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* Optimal Taxation of Heterogeneous Recyclable Materials (with Z. Mahone and E. Mattos)
Materials policy in the United States and elsewhere treats recyclable materials as a largely undifferentiated category: no material-specific virgin taxes or recycling subsidies and consumption taxes on recyclables are nearly absent. Yet materials are highly heterogeneous in the share of extracted material that is ever usable, in how readily recycled inputs substitute for virgin ones, and in the landfill damage each imposes at disposal. This paper asks whether efficient materials policy requires instruments that vary as much across materials as the materials themselves do. We develop a dynamic general equilibrium model of the material cycle in which a final good is produced from capital, labor, and a menu of materials, each combining virgin extraction and recycling in an endogenously chosen mix, and characterize the material-specific recycling subsidies and virgin material taxes, together with a uniform consumption tax, that implement the efficient allocation as a competitive equilibrium. We calibrate the model separately for five material categories -- ferrous metals, non-ferrous metals, glass, paper, and plastics -- accounting for the majority of U.S. virgin material extraction and municipal solid waste. The resulting heterogeneity is large: the optimal recycling subsidy ranges from 0.89 percent (Non-Ferrous) to 33.66 percent (Ferrous), while the optimal virgin material tax ranges from 4.07 percent (Paper) to 329.78 percent (Plastic); the optimal consumption tax, by contrast, is small and uniform at 0.59 percent. These findings indicate that a single, material-blind instrument cannot approximate the efficient policy for any of the three margins we study, underscoring the need for materials policy to be designed at the level of the material rather than the waste stream as a whole.
* Materials Use, Energy Consumption and Climate Change
To assess the role of economic policy in addressing material use and climate change, this research project develops a global economy-climate model using stochastic dynamic general equilibrium (DSGE) methods. The model treats the world as a uniform region inhabited by a representative consumer dynasty and incorporates global externalities from carbon dioxide emissions, a by-product of fossil fuel use in production, as well as from virgin material extraction and landfill waste. It captures the interaction between energy consumption and material use, both of which contribute to greenhouse gas emissions and climate change. The model also incorporates material recycling, which can reduce the need for virgin material extraction and lower associated environmental costs. By analyzing these dynamics, the goal is to quantify both the short- and long-term macroeconomic costs and benefits of policies aimed at reducing material extraction, improving recycling, and mitigating climate change.
* Informal Work as a Fallback: Vision Impairment, Employment, and Policy in Brazil (with M. Benegas, M. Correa)
Informal work may allow workers with functional limitations to remain employed when formal jobs become too costly to hold, rather than reflecting exclusion from good jobs. In Brazil’s 2019 Pesquisa Nacional de Saude, severe but partial vision impairment is associated with a formal employment rate 20.9 percentage points lower than among individuals with no difficulty, but with no difference in informal employment. The asymmetry survives adjustment for observables and other functional limitations, and it is not shared by mobility, upper-limb, or mental limitations. These patterns alone cannot reveal where affected workers would go if informal work were unavailable, or how policy would reallocate them. To answer these questions, we build a general-equilibrium incomplete-markets model in which individuals choose among formal work, informal work, and non-employment. Informal work is less productive, while formal work carries a rigidity cost that rises with functional limitation. We calibrate the model to occupational shares across four vision states. In the model, eliminating informal work lowers employment by 17.6 percentage points among individuals with a vision limitation. In illustrative counterfactuals, policies that reduce informality send workers to different destinations: stricter enforcement into non-employment, workplace accommodation into formal jobs, and broader disability-benefit eligibility into supported non-employment. Changes in informality are therefore an unreliable guide to the effects of disability and formalization policy.
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2026 Tri-Success Grant Program, University of Windsor ($5000)