Robert De Kleine

We conduct a life cycle greenhouse gas (GHG) assessment of class 3–8 internal combustion engine vehicles (ICEVs), hybrid electric vehicles (HEVs), fuel cell electric vehicles (FCEVs), and battery electric vehicles (BEVs) in the United States. Compared to conventional diesel fueled alternatives, HEVs reduce emissions by 1-26% across vehicle types, FCEVs using hydrogen produced from steam methane reforming reduce emissions by 1-45%, and BEVs powered by the grid result in a 55-75% reduction. FCEVs using hydrogen produced from electrolysis powered by renewable electricity reduce emissions by 81-87% across vehicle types, while BEVs powered by renewable electricity result in an 89-94% reduction. These ordering of these powertrains holds across cargo weights, drive cycles, regional electricity grids, and grid projections. We also assess renewable electricity consumption and hydrogen leakage, two factors not included in most comparative life cycle assessments, which must be considered when evaluating the suitability of different powertrains for decarbonization.

Graphite is a key material in electric vehicle batteries. Currently, China dominates global graphite production, and US sourcing of graphite could mitigate geopolitical supply‐chain risk. We explore the feasibility of domestic natural graphite sourcing in North America by characterizing current deposits and modeling the expected demand from 2025 to 2040. The United States has 19 Mt of measured and inferred graphite resources in four deposits, and additional unevaluated resources in several other areas. We estimate that this graphite resource could produce enough natural battery‐grade graphite (7.3 Mt) to meet the demand from 2025 to 2040 (1.9 Mt). Issues of concern for domestic sourcing include the fact that the US deposits have a lower average graphite content (2.4%–5.1%) than profitable graphite mines globally, and the timeline for mine development, production, and commercialization might not align with the growth of demand. Additionally, battery‐grade synthetic graphite supply, derived from needle coke, might be constrained unless refineries increase production of needle coke or alternate feedstocks are commercialized. Compared to China, US natural graphite production would likely decrease greenhouse gas emissions through lower electricity grid emissions during refining, despite lower ore grades.

The research evaluates mitigation potential of electrofuels at the fleet level under various direct electrification scenarios.

The ongoing transition toward electric vehicles (EVs) is changing materials used for vehicle production, of which the consequences for the environmental performance of EVs are not well understood and managed. We demonstrate that electrification coupled with lightweighting of automobiles will lead to significant changes in the industry's demand not only for battery materials but also for other materials used throughout the entire vehicle. Given the automotive industry's substantial consumption of raw materials, changes in its material demands are expected to trigger volatilities in material prices, consequently impacting the material composition and attractiveness of EVs. In addition, the materials recovered during end-of-life recycling of EVs as the vehicle fleet turns over will impact recycled material supplies both positively and negatively, impacting material availabilities and the economic incentive to engage in recycling. These supply chain impacts will influence material usage and the associated environmental performance of not only the automotive sector but also other metal-heavy industries such as construction. In light of these challenges, we propose the need for new research to understand the dynamic materials impacts of the EV transition that encompasses its implications on EV adoption and fleet life cycle environmental performance. Effectively coordinating the coevolution of material supply chains is crucial for making the sustainable transition to EVs a reality.

Quantification of environmental impacts through life cycle assessment is essential when evaluating bioenergy systems as potential replacements for fossil-based energy systems. Bioenergy systems employing localized fast pyrolysis combined with electrocatalytic hydrogenation followed by centralized hydroprocessing (Py-ECH) can have higher carbon and energy efficiencies than traditional cellulosic biorefineries. A cradle-to-grave life cycle assessment was performed to compare the performance of Py-ECH versus cellulosic fermentation in three environmental impact categories: climate change, water scarcity, and eutrophication. Liquid hydrocarbon production using Py-ECH was found to have much lower eutrophication potential and water scarcity footprint than cellulosic ethanol production. Greater amounts of renewable electricity led to lower greenhouse gas emissions for the Py-ECH processing. When the renewable fraction of grid electricity is higher than 87%, liquid hydrocarbon production using Py-ECH has lower greenhouse gas emissions than cellulosic ethanol production. A sensitivity analysis illustrates the major role of annual soil carbon sequestration in determining system-wide net greenhouse gas emissions.