"The pressing global issue of climate change has driven the development of clean energy technologies. The clean energy technologies addressed in this dissertation include those used to produce energy and provide mobility with reduced emissions, as well as technologies outside the energy and transportation sectors which utilize energy in a more efficient way. Many of these technologies rely on materials that are considered critical due to their importance to the technology’s functionality and their potential vulnerability to supply disruption. Supply disruptions can stem from a variety of factors such as geographical supply concentration, production in unstable areas, low ore grades, or a large portion of the production occurring as a byproduct of another material. First, critical material intensity data from academic articles, government reports, and industry publications are aggregated and presented in functional units. These functional units vary based on the functionality of each technology and incorporate aspects of lifecycle assessment in order to allow for comparison of material intensities. The clean energy technologies analyzed include natural gas turbines, direct drive wind turbines, three types of solar photovoltaics (silicon, CdTe, and CIGS), the proton exchange membrane (PEM) fuel cells, permanent-magnet-containing motors, nickel metal hydride and Li-ion batteries from electric vehicles, and finally energy-efficient lighting devices (CFL, LFL, and LED bulbs). To further explore the role of critical materials in addressing climate change, emissions savings units are provided to illustrate the potential for greenhouse gas emission reductions per mass of critical material in each of the clean energy production technologies. The impact of drastic and unexpected price increases of critical materials caused by supply disruptions on the cost of clean energy technologies are also explored. For this economic analysis three case study clean energy technologies are analyzed. These case studies are PEM fuel cells, NdFeB permanent magnets in direct drive wind turbines, and Li-ion batteries for electric vehicles. Using the calculated critical material intensities in these technologies, as well as material price information, we analyze technology-level costs under potential material price change scenarios. By benchmarking against target costs at which each technology is expected to become economically competitive relative to incumbent energy systems, the impact of unexpected price increases on marketplace competitiveness are evaluated. For the three case studies, technology level costs (of the fuel cell, generator, and battery) could increase by between 13% and 41% if recent historical price events were to recur at current material intensities. By analyzing the economic impact of material price changes on technology-level costs, the need for stakeholders to push for various supply risk reduction measures is stressed, and the potential options for doing so are summarized. One potential solution to the issues caused by critical materials is to substitute out those materials for less critical materials. A survey of national laboratory, academic, and industry stakeholders allows for a better understanding of how groups are making substitution decisions, and then that information is applied to the development of a novel, dynamic framework for quantifying substitutability that integrates technological, economic, criticality, and environmental tradeoffs. An in-depth literature review shows that current substitution analyses are done qualitatively or semi-quantitatively. The problem with addressing substitution through qualitative metrics is that they often necessitate expert analysis and are usually done for specific applications at a snapshot in time, which is time consuming and variable. The development of fully quantitative metrics allows for reassessment to be done much more frequently by updating the numeric values as they change. Through the development of the decision framework, a methodology that can be implemented to enable more informed decisions while respecting the realities of industry priorities and efforts is provided. This methodology is applied to a case study of elemental level substitution of nickel for cobalt and manganese in Li-ion batteries. These results capture the technical, economic, criticality, and environmental tradeoffs that would be realized by selecting any of the three demonstrated cathode chemistry combinations of the three materials (NMC111, NMC622, or NMC811)."--Abstract.