Grantee Research Project Results
Final Report: A Life Cycle Analysis Approach for Evaluating Future Nanotechnology Applications
EPA Grant Number: R830905Title: A Life Cycle Analysis Approach for Evaluating Future Nanotechnology Applications
Investigators: Lave, Lester , Lloyd, Shannon
Institution: Carnegie Mellon University
EPA Project Officer: Aja, Hayley
Project Period: May 1, 2003 through April 30, 2005
Project Amount: $100,000
RFA: Environmental Futures Research in Nanoscale Science Engineering and Technology (2002) RFA Text | Recipients Lists
Research Category: Nanotechnology , Safer Chemicals
Objective:
The objective of this research project was to develop a framework employing quantitative analysis to evaluate projected nanotechnology-based products. We used technology scenarios and prospective hybrid life-cycle assessment to estimate the economic and environmental life-cycle implications of two projected nanotechnology-based products. In the case of using nanocomposites in light-duty vehicle body panels, the ability to disperse nanoscale particles in polymers would reduce vehicle weight, thereby improving fuel economy. In the case of nanofabricated catalysts, the ability to position and stabilize platinum-group metal (PGM) particles in automotive catalysts would reduce the amount of PGM required to meet emissions standards, thereby reducing mining and refining activities. For each application, we compare a conventional product to its nanotechnology-based substitute to assess whether the nanotechnology substitute can be cost-effective and improve environmental quality.
By reducing the energy and materials required to provide goods and services, nanotechnology has the potential to provide more appealing products while improving environmental performance and sustainability. Although nanotechnology offers great potential, it is unlikely to be the first entirely benign technology. My hypothesis is that a technological push toward greater investment in nanotechnology without a commensurate consideration of the net environmental benefits will lead inevitably to cases where the nanotechnology substitute is inferior to the product or process replaced. Whether and how soon the promise of improved environmental quality could be realized depends on phrasing life-cycle questions during research and development and pursuing commercialization intelligently.
Efforts have been initiated to develop a fundamental understanding of the behavior of nanotechnology-based materials in natural systems and their influence on biological systems. This understanding will improve the ability to project the direct environmental and health effects of these materials. To obtain a complete picture, it also is necessary to consider life-cycle and sustainability implications on nanotechnology-based products.
Life-cycle assessment typically is used to estimate the resource and environmental implications associated with existing products. Changing a product to reduce its environmental impact after the product has been developed can cost orders of magnitude more than making the change during research and development. As shown by the work conducted under this grant, policymakers and industry can identify technology scenarios and employ prospective life-cycle assessment during early research and development to evaluate future nanotechnology-based products and emerging nanotechnologies. The ability to evaluate life-cycle implications of alternative courses of action during research and development improves the ability to evaluate tradeoffs, optimize products for all aspects of life-cycle performance, and make more strategic research and development choices. A more informed understanding of the commercial, societal, and technological possibilities and its consequences will enable better decisions in regards to the selection, development, and commercialization of nanotechnology.
Summary/Accomplishments (Outputs/Outcomes):
We developed a framework, illustrated in Figure 1, to employ quantitative analysis to evaluate the life-cycle implications of projected nanotechnology-based products. In particular, we used technology scenarios and prospective hybrid life-cycle assessment to evaluate two projected nanotechnology-based products: (1) substituting montmorillonite clay-polypropylene nanocomposites for steel in motor vehicle body panels; and (2) using nanofabrication techniques to reduce PGM in automotive pollution control catalysts. In each study, we developed technology scenarios, modeled product performance, and estimated expected economic and environmental implications. We assumed the nanotechnology-based product to be a direct substitute for the current product. This allowed for a direct quantitative evaluation of whether the nanotechnology substitute can be cost-effective and improve environmental quality.
Figure 1. Framework Using Technology Scenarios and Life-Cycle Assessment to Evaluate Expected Nanotechnology-Based Products
In the first study, we examined the material processing and fuel economy implications associated with using a montmorillonite clay-polypropylene nanocomposite instead of steel or aluminum in light-duty vehicle body panels. The exfoliation of montmorillonite clay into individual platelets with dimensions on the nanoscale and dispersion of these platelets into a polymer matrix leads to improved composite mechanical properties. The critical property for substituting a material in automotive body panels is its stiffness, as measured by Young’s modulus. Current levels of uncertainty concerning the performance of the nanocomposite lead to constructing lower and upper performance bounds of Young’s modulus based on micromechanical principles. We estimated vehicle weight, lifetime fuel consumption, and emissions of CO2 during vehicle use for vehicles with body panels made from steel, aluminum, and the lower and upper performing nanocomposite. We used Carnegie Mellon University’s economic input-output life-cycle analysis model to evaluate the economic and environmental effects across the supply chain from material substitution and reduced petroleum consumption. A life-cycle analysis shows the potential benefits of reducing energy use and environmental discharges through reducing vehicle weight, thereby improving fuel economy by substituting either the nanocomposite or aluminum for steel in motor vehicle body panels. For example, Figure 2 summarizes the relative change in each supply chain environmental impact from producing materials for body panels and reducing fuel requirements for a 1-year fleet of vehicles. Figure 3 summarizes the CO2 equivalents generated across the supply chain during material and lifetime petroleum production and the CO2 emissions generated during vehicle use for the lifetime of a 1-year fleet of vehicles (16.9 million vehicles).
Figure 2. Relative Change in Supply Chain Life-Cycle Environmental Impact From Substituting a Clay-Polypropylene Nanocomposite or Aluminum for Steel in Body Panels for a 1-Year Fleet of Light-Duty Vehicles in the United States (16.9 Million Vehicles)
Figure 3. Life-Cycle Production of CO2 Equivalents for a 1-Year Fleet of Vehicles in the United States (16.9 Million Vehicles)
Aluminum costs less than the nanocomposite and offers better performance than the lower bound level for the nanocomposite. The production costs for steel are much lower than alternative materials, and steel is an ideal material for mass production of vehicles. The inability of aluminum to penetrate this market indicates that efforts to develop and commercialize lighter materials for automotive body application will not succeed unless a lightweight material offers much larger savings or additional advantages, such as satisfying a high Corporate Average Fuel Economy standard.
In a second study, we considered the environmental implications from using nanotechnology to stabilize PGM particles in automotive emission control catalysts. In automotive catalysts, CO, HC, and NOx emissions are abated by oxidation and reduction reactions occurring on the surface of PGM particles. To increase the amount of PGM surface area exposed to vehicle exhaust, PGM particles are dispersed on high surface area particles such as aluminum oxide. This washcoat then is applied to a high surface area ceramic or metallic support. The resulting ratio of PGM surface atoms to total PGM atoms is termed metal dispersion. A General Motors’ test on a commercial automotive catalyst found metal dispersion to be approximately 50 percent in the new catalyst, below 10 percent in 10,000 miles, and below 5 percent in 25,000 miles. This indicates that only 50 percent of PGM atoms in a new catalyst are exposed to a vehicle’s exhaust with current technology; metal dispersion deteriorates rapidly during vehicle use, primarily caused by particle sintering and agglomeration from exposure to high temperatures and vehicle vibration; and current emission standards are met with 5 percent of PGM participating in catalytic reactions during 80 percent of a vehicle’s life. Assuming PGM dispersion is correlated with required loading levels, manufactures could meet emissions standards with 5 percent of current PGM loading levels by overcoming current design, manufacturing, and system inefficiencies.
Whereas conventional catalyst design relies on rational planning and lengthy trial-and-error testing, advances in nanotechnology are expected to offer increased understanding of and control over catalyst design and performance. The ability to control the size, shape, and placement of PGM particles would improve metal dispersion in new catalysts. Furthermore, the ability to anchor particles securely to the substrate would aid in maintaining high metal dispersion during vehicle use. As indicated above, such technological advances could reduce loading levels by as much as 95 percent. We estimated the amount of PGM required to meet U.S. vehicle emissions standards through 2030 based on current catalyst technology. Rather than attempt to predict the structure and composition of future exhaust catalysts, we provide a first approximation of maximum possible reductions in PGM loading levels. We suggest, as an upper bound, that loading levels from current technology could be reduced by 95 percent, as discussed in the introduction. This assumes an optimal atomic structure and arrangement resulting in complete dispersion and eliminating all sintering, agglomeration, and other deactivation during vehicle use. Figure 4 shows estimated annual PGM requirements for each loading level scenario.
Figure 4. Estimated Annual PGM Requirement for Vehicles Sold in the United States (Excluding California).
Data points represent expected PGM demand for meeting current emission standards using baseline loading levels, meeting new emission standards with current technology, and meeting new emissions standard with a fully effective deployment of nanotechnology. Whereas the baseline and new emission standards scenarios provided expected PGM usage for specified emission standards and technology, the nanotechnology scenario provides the maximum possible performance improvement. Because catalyst technology will improve over time, the new standards scenarios is viewed as a lower performance bound. As a result, a fully effective deployment of nanotechnology is unlikely to be realized. The nanotechnology scenario is viewed as an upper performance bound. Hence, the new standards and nanotechnology scenarios show an inclusive range of possible performance for any given year.
We used economic input-output and process-based life-cycle assessment models to estimate the direct life-cycle benefits from reducing PGM mining and refining. Figure 5 illustrates the range of change in life-cycle effects from changes in PGM usage for 2005 and 2030. Black columns show the difference in effects between the new standards and baseline scenarios, representing the maximum possible increase in effects from producing more PGM to meet new standards with current technology. Gray columns show the difference in effects between the nanotechnology and baseline scenarios, representing the maximum possible reduction in effects from using less PGM to meet new standards with a fully effective deployment of nanotechnology.
Figure 5. Change in Life-Cycle Effects From Changes in PGM Production. Black columns show the maximum expected increase from producing more PGM to meet new standards with current technology and gray columns show the maximum expected reduction from producing less PGM while still meeting new standards with a fully effective deployment of nanotechnology.
Pollutants discharged during PGM extraction are substantial. The application of nanotechnology to improve PGM dispersion in emission control catalysts should result in environmental improvements and cost savings from reducing PGM requirements and improving catalyst performance. A more detailed analysis is required to evaluate the life cycle implications of fabricating catalysts using nanofabrication.
Toxicity studies of nanomaterials are not available.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
Other project views: | All 11 publications | 4 publications in selected types | All 2 journal articles |
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Type | Citation | ||
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Lloyd SM, Lave LB. Life cycle economic and environmental implications of using nanocomposites in automobiles. Environmental Science & Technology 2003;37(15):3458-3466. |
R830905 (Final) |
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Lloyd SM, Lave LB, Matthews HS. Life cycle benefits of using nanotechnology to stabilize platinum-group metal particles in automotive catalysts. Environmental Science & Technology 2005;39(5):1384-1392. |
R830905 (Final) |
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Supplemental Keywords:
nanotechnology, life cycle analysis, EIO-LCA, sustainable industry/business, chemistry and materials science, economics & decision making, engineering, environmental chemistry, environmental engineering, new/innovative technologies, sustainable environment, technology for sustainable environment, decision-making, cost-effective ecosysem protection, economic benefits, economic incentives, economic input output, environmentally applicable nanoparticles, innovative technologies, life cycle assessment, nanoparticles, sustainability,, RFA, Scientific Discipline, Economic, Social, & Behavioral Science Research Program, Sustainable Industry/Business, Sustainable Environment, Environmental Chemistry, Technology for Sustainable Environment, New/Innovative technologies, Chemistry and Materials Science, decision-making, Environmental Engineering, Economics & Decision Making, life cycle analysis, waste reduction, detoxification, membranes, economic benefits, nanotechnology, environmental sustainability, economic incentives, environmentally applicable nanoparticles, economic input output, sustainability, life cycle assessment, hazardous organics, nanoparticles, cost-effective ecosysem protection, innovative technologiesRelevant Websites:
Carnegie Mellon University Civil and Environmental Engineering Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.