Rapid changes in energy availability lead to the question of whether the sustainable availability of energy implies the sustainable availability of materials and vice versa. In particular, many researchers assume that materials can be produced from any resource type, irrespective of scarcity, by providing enough energy. We revisit this issue here for two reasons: (1) To avoid significant disruptions in daily life, no more than a few percent of total energy production and materials usage can be diverted to support a transition to new energy sources. (2) Such a transition could also be problematic if it requires large quantities of materials that are byproducts of other large-scale production cycles, as any increase in the production of a byproduct typically requires an almost proportional increase in the production of the primary product. In turn, increased production of the primary product could require materials and energy expenditures that are too large to be practical. Both limitations have to be taken into account in future energy planning.

Everyone has heard the slogan “Reduce, Reuse, Recycle”—but does observing this hierarchy really minimize negative impacts? With respect to reduction, it seems clear that using less of something decreases the impact. Similarly, reuse of a material or product should decrease the impact of each use, as long as the resources needed to restore the item to usable condition each time are not too large. For recycling, the picture varies by material and often involves tradeoffs among impacts. Life-cycle analysis aims to comprehensively compare all of the impacts of various disposition options. This article summarizes the pros and cons of recycling materials used in paper, drink containers, and the complex batteries for electric vehicles from the perspective of life-cycle analysis.

Materials play a major role in defining the sustainability performance of automobiles throughout their materials-production, manufacturing, use, and end-of-life stages. Materials production and manufacturing raise many sustainability issues, including resource scarcity and materials sourcing, energy and carbon intensity, and materials efficiency in parts fabrication. In the use stage, materials properties such as density and strength directly affect materials-mass requirements, which influence two dominant sustainability parameters for vehicles: fuel economy and service life. For conventional vehicles, the operation segment of the use stage accounts for about 85% of the total life-cycle energy consumption and greenhouse-gas emissions. Consequently, powertrain technologies and efficiencies as well as fuel-cycle processes control these impacts. Future trends in vehicle electrification will shift the magnitude and distribution of life-cycle impacts and the effectiveness of materials strategies for improving sustainability, such as lightweighting. In many cases, the materials-production stage could become a greater determinant in life-cycle impacts. With current vehicle end-of-life management infrastructure, 85% of materials are recyclable, but recovery of plastics and segregation of metal alloys represent opportunities for improvement. Life-cycle assessment and cost analysis provide the most comprehensive methods for evaluating the sustainability of materials strategies. Using a life-cycle framework, this article highlights the current and future materials challenges and opportunities driving vehicle sustainability performance.

Turbine engine performance, as measured by specific fuel consumption (defined as fuel consumed relative to the thrust produced by the engine), is a key criterion in engine selection. To achieve the specific fuel consumption required of modern engines, engineers combine advanced designs and materials to achieve higher operating temperatures and, therefore, higher engine efficiency. One of the difficulties of using advanced materials is that they exploit scarce, hard-to-replace elements to allow higher operating temperatures. In this article, we describe steps being taken by General Electric Co. and the turbine engine industry to continue to improve engines in a material space constrained by material availability. As a specific example, we focus on the transition metal rhenium.

Materials scientists today employ essentially the entire periodic table in creating modern technology. In an age of sharply increasing usage, it is reasonable to wonder about the supplies of these elemental building blocks. In this article, we review current and prospective supply and demand for a variety of metals. Although data are often sparse, available information suggests that current practices are likely to lead to scarcity for some metals in the not-too-distant future. We conclude by discussing policies that, if adopted, might defuse some of these concerns.

Over the past 12 years, photovoltaics enjoyed an average growth of ∼45% per year that was affected only marginally by the recent global financial crisis. Industrial roadmaps and analysts’ forecasts share visions of solar power becoming a major contributor to national and global electricity grids, with several terawatts of cumulative deployment by 2050 or earlier. For photovoltaics technology to become a major sustainable player in a competitive power-generation market, it must provide abundant, affordable electricity, with environmental impacts dramatically lower than those from conventional power generation. This article summarizes the prospects in each of three basic aspects of sustainability, namely, system costs, environmental impacts, and resource availability, all of which are examined in the context of prospective life-cycle assessment. Indeed, these three aspects are closely related: Increasing the efficiency of material recovery by recycling spent modules will become increasingly important in resolving cost, resource, and environmental constraints on large-scale sustainable growth.

Ensuring the continued availability of materials for manufactured products requires comprehensive systems to recapture resources from end-of-life and wastewater products. To design such systems, it is critical to account for the complexities of extracting desired materials from multicomponent products and waste streams. Toward that end, we have constructed dynamic simulation–optimization models that accurately describe the recovery of materials and energy from products, residues, and wastewater sludges. These models incorporate fundamental principles such as the second law of thermodynamics, as well as detailed, empirically based descriptions of the mechanical separation of materials at the particulate level. They also account for the evolution of the recycling system over time. Including these real-world details and constraints enables realistic comparisons of recycling rates for different products and technological options and accurate assessments of options for improvement. We have applied this methodology to the recycling of complex, multimaterial products, specifically cars and electronic wastes, as well as wastewater and surface-water systems. This analysis clarifies how product design, recycling technology, and process metallurgy affect recycling rates and water quality. By linking these principles to technology-based design-for-recycling systems, we aim to provide a rigorous basis to reveal the opportunities and limits of recycling to ensure the supply of critical elements. These tools will also provide information to help policymakers reach appropriate decisions on how to design and run these systems and allow the general public to make informed choices when selecting products and services.

Physical infrastructure, including buildings, roads, pipelines, bridges, power lines, communications networks, canals, and waterways, make up a substantial fraction of worldwide material usage and flows. Consequently, the overall mass of materials and the associated environmental impacts must be addressed to achieve sustainable development of infrastructure. This article surveys the magnitude of material use for infrastructure, including trends in the use per person, environmental impacts of the production and use of infrastructure materials, variations in the longevity of physical infrastructure, and changes in the recycling of infrastructure materials.