Publications

Summary

The adoption of renewable energy technologies hinges on the availability of many critical minerals. To meet the large demand for critical minerals, it is vital to scale up mineral supply in an environmentally and socially responsible way while maintaining low materials costs for key technologies. To guide policy and technology innovation that meets this objective, we need robust approaches for evaluating the availability and costs of materials. However, traditional approaches for assessing material availability or ‘criticality’ do not incorporate price feedback or a structural understanding of how material supply evolves. In this thesis, I build a model that simulates metal demand, mine opening and operation decisions, and mineral reserve development while incorporating price feedback. This model is used to evaluate how factors such as the rate of demand growth, materials substitutability and recycling rates impact materials prices and availability in the long term. The model is then applied to data on real mining projects for two key battery materials: nickel and lithium. Model simulations analyze supply pathways till 2040 to identify strategies that reduce the risk of materials supply constraints impacting clean energy technology deployment. Results demonstrate that a combination of high mining productivity, development of material substitutes and large recycling rates reduce the prevalence of availability risks from ~90% to just under 2% for materials experiencing high demand. In the nickel case, results show that environmental regulation can reduce impacts such as supply-chain emissions by 50% but lead to a 2x increase in nickel prices with only 70% of baseline nickel demand being satisfied. However, if regulations are combined with innovation that lowers processing costs and market coordination that reduces project development timelines and risks, over 90% of the demand is met without price increases. Similarly in the lithium case, reducing mine development timelines from 8 years to 6 years can increase the percentage of demand satisfied from 82% to 92% by moderating supply shortages and lithium prices.

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Summary

Modern automobiles are composed of more than 2000 different compounds comprising 76 different elements. Identifying supply risks across this palette of materials is important to ensure a smooth transition to more sustainable transportation technologies. This paper provides insight into how electrification is changing vehicle composition and how that change drives supply risk vulnerability by providing the first comprehensive, high-resolution (elemental and compound level) snapshot of material use in both conventional and hybrid electric vehicles (HEVs) using a consistent methodology. To make these contributions, we analyze part-level data of material use for seven current year models, ranging from internal combustion engine vehicles (ICEV) to plug-in hybrid vehicles (PHEVs). With this data set, we apply a novel machine learning algorithm to estimate missing or unreported composition data. We propose and apply a metric of vulnerability, referred to as exposure, which captures economic importance and susceptibility to price changes. We find that exposure increases from $874 per vehicle for ICEV passenger vehicles to $2344 per vehicle for SUV PHEVs. The shift to a PHEV fleet would double automaker exposure adding approximately $1 billion per year of supply risk to a hypothetical fleet of a million vehicles. The increase in exposure is largely not only due to the increased use of battery elements like cobalt, graphite, and nickel but also some more commonly used materials, most notably copper.

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Summary

This memo provides an overview of nickel demand and the current nickel supply chain, focusing on recent market developments. It reviews relevant chemical processing routes, techno-economic considerations, and key geographies. The US battery industry risks losing competitiveness due to the growing concentration of the nickel supply chain in Indonesia and China. The memo identi es policies and strategies that can help reduce nickel supply chain risks to ensure an e ective energy transition.

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Summary

Mining sector investments in Africa should be structured in such a way so the continent can benefit from the carbon pricing policies in developed countries. Current supply chains rely on specialized networks where different parts of the production process are spread out globally. This system of global value chains (GVCs) leads to greenhouse gas emissions from transportation and waste generation. Carbon border taxes, coupled with a trend towards environment, social, and governance (ESG) investments, could incentivize multinational companies to avoid excess emissions and waste by moving intermediate stages of production closer to the source of mineral extraction. This, in turn, would provide a boost to foreign investment across Africa.

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Summary

In the United States, polyethylene terephthalate (PET) bottle collection rates have not increased in a decade. Recycling rates remain abysmal while industry commitments and policy targets escalate the demand for recycled plastics. We investigate the PET bottle recycling system, where collection is a critical bottleneck and recycled PET supply is not meeting the expected demand. We characterize demand for recycled PET (R-PET), analyze scenarios of expanding deposit return systems (DRS), and quantify cost barriers to improving PET bottle recycling. We find that a nation-wide DRS can increase PET bottle recycling rates from 24% to 82%, supplying approximately 2700 kt of recycled PET annually. With stability in demand, we estimate that this PET bottle recycling system can achieve 65% bottle-to-bottle circularity, at a net cost of 360 USD/tonne of PET recycled. We also discuss environmental impacts, stakeholder implications, producer responsibility, and complimentary policies toward an efficient and effective recycling system.

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Summary

This white paper was commissioned by the National Academy of Sciences as part of their report "Recycled plastics in infrastructure: Current practices, understanding, and opportunities," which was delivered to Congress, DoT and EPA. It analyses data for plastics generation (commercial and residential) by type, as well as collection rates, collection costs, and sorting costs. The paper also highlights changes in demand for recycled plastics by end-use sector and analyzes recycled plastics markets. Finaly, the brief discusses policy solutions for improving plastics recycling and circularity.

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Summary

Material production drives an increasingly large fraction of CO2-equivalent emissions. Material efficiency strategies such as recycling serve to reduce these emissions. Current analyses of the effectiveness of such strategies do not include economically induced rebound effects, overestimating the associated environmental benefits. We present a dynamic supply chain simulation model for copper through 2040 incorporating inventory-driven price evolution, dynamic material flow analysis, and life cycle assessment alongside mine-level economic evaluation of opening, closing, and production decisions. We show that permanent increases in recycling displace ∼0.5 kilotonnes mine production per kilotonne increase in scrap supply on average, while short-lived recycling policies can lead to increased mine production. We find evidence for supply chain evolution pathways minimizing the rebound effect and maximizing displacement of primary material, where increasing refined copper and concentrate prices and decreasing demand serve to decrease mining. However, even in best-case scrap supply scenarios, CO2e emissions from the copper sector increase 25% by 2040 relative to 2018 due to demand growth, ore grade decline, and lower displacement among large scrap supply changes. With implementation of best available technologies across all supply chain components, we estimated 2040 CO2e emissions 10% below those of 2018 are possible, though still well short of 2°C emissions targets. We find increasing mine taxes and royalties, reclamation costs, and exploration costs further increase displacement, as does the inclusion of scrap prices on major futures exchanges. These results highlight the importance of considering the economics of the entire material supply chain when implementing material efficiency strategies.

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Summary

Climate change will increase the frequency and severity of supply chain disruptions and large-scale economic crises, also prompting environmentally protective local policies. Here we use econometric time series analysis, inventory-driven price formation, dynamic material flow analysis, and life cycle assessment to model each copper supply chain actor’s response to China’s solid waste import ban and the COVID-19 pandemic. We demonstrate that the economic changes associated with China’s solid waste import ban increase primary refining within China, offsetting the environmental benefits of decreased copper scrap refining and generating a cumulative increase in CO2-equivalent emissions of up to 13 Mt by 2040. Increasing China’s refined copper imports reverses this trend, decreasing CO2e emissions in China (up to 180 Mt by 2040) and globally (up to 20 Mt). We test sensitivity to supply chain disruptions using GDP, mining, and refining shocks associated with the COVID-19 pandemic, showing the results translate onto disruption effects.

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Summary

Predictions of metal consumption are vital for criticality assessments and sustainability analyses. Although demand for a material varies strongly by region and end-use sector, statistical models of demand typically predict demand using regression analyses at an aggregated global level (“fully pooled models”). “Un-pooled” regression models that predict demand at a disaggregated country or regional level face challenges due to limited data availability and large uncertainty. In this paper, we propose a Bayesian hierarchical model that can simultaneously identify heterogeneous demand parameters (like price and income elasticities) for individual regions and sectors, as well as global parameters. We demonstrate the model's value by estimating income and price elasticity of copper demand in five sectors (Transportation, Electrical, Construction, Manufacturing, and Other) and five regions (North America, Europe, Japan, China, and Rest of World). To validate the benefits of the Bayesian approach, we compare the model to both a “fully pooled” and an “un-pooled” model. The Bayesian model can predict global demand with similar uncertainty as a fully pooled regression model, while additionally capturing regional heterogeneity in income elasticity of demand. Compared to un-pooled models that predict demand for individual countries and sectors separately, our model reduces the uncertainty of parameter estimates by more than 50%. The hierarchical Bayesian modeling approach we propose can be used for various commodities, improving material demand projections used to study the impact of policies on mining sector emissions and informing investment in critical material production.

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Summary

Raw materials costs form an increasingly significant proportion of the total costs of renewable energy technologies that must be adopted at unprecedented rates to combat climate change. As the affordable deployment of these technologies grows vulnerable to materials price changes, effective strategies must be identified to mitigate the risk of higher input costs faced by manufacturers. To better understand potential threats to deployment, a market modeling approach was developed to quantify economic risk factors including material demand, substitutability, recycling, mining productivity, resource quality, and discovery. Results demonstrate that price changes are determined by interactions between demand growth, mining productivity, and resource quality. In the worst cases with high demand and low productivity, development of material substitutes and large recycling rates help reduce the prevalence of price risk from over 90% to under 10%. Investing in these strategies yields significant benefits for manufacturers and governments concerned about costs of materials critical to decarbonization and other advanced technologies.

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Summary

Meeting corporate sustainability goals requires policies and business models that incentivize sustainable product design. We create a simple modeling tool that examines the conditions in which it is profitable for companies to sell more sustainable versions of a product. Users can input variables that relate to consumer demand (e.g. proportion of consumers willing to pay the price premium for a sustainable product), policy (e.g. carbon tax) and costs of production including the added costs associated with incorporating sustainable materials and practices. To demonstrate the utility of our tool, we input values for sneaker production and identify the demand and policy conditions under which sustainable sneaker design leads to increased profit. Policymakers and companies can use this as a decision-support tool to promote sustainable design for various ranges of products.

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Summary

Material production drives an increasingly large fraction of CO2-equivalent emissions. Material efficiency strategies such as recycling serve to reduce these emissions. However, prior analyses of such strategies do not include economically induced rebound effects, overestimating the associated environmental benefits. We present a dynamic supply chain simulation model for copper through 2040 incorporating inventory-driven price evolution, dynamic material flow analysis, and life cycle assessment alongside mine-level economic evaluation of opening, closing, and capacity utilization decisions. We show that increases in recycling suppress raw material prices, driving increases in demand that limit primary production reduction and offset ~45% of the potential environmental benefits. Sufficiently small recycling increases and policy reversals were found capable of increasing mining and CO2-equivalent emissions. This model was expanded to accommodate regional variations and assess the impacts of China’s solid waste import ban and the COVID-19 pandemic, demonstrating the need for further investment in secondary market.

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