Life Cycle Aspects of Nanoproducts, Nanostructured Materials, and Nanomanufacturing: Problem Definitions, Data Gaps, and Research Needs
Chicago, Illinois: November 5-6, 2009
Delcie R. Durham
Professor of Mechanical Engineering
University of South Florida
Dr. Durham initiated the global study in Environmentally Benign Design and Manufacturing, followed by several cross-cutting programs supporting interdisciplinary research including nanomanufacturing while at NSF. She funded numerous research projects addressing the issues of environmental impact during nanomanufacturing, with a focus on life cycle concerns for products rather than particles.
One area of particular interest is the design and manufacture of functionally graded materials that take advantage of unique properties associated with their nanostructures. An example is the use of very thin films with embedded nanotubes that improve the desired properties of biomedical implants, photovoltaics, wear resistant surfaces, environmental sensors, and MEMS/NEMS devices.
In terms of the need to conduct both an inventory of materials flows and a life cycle assessment for these products, the argument has been that very limited amounts of scarce materials are used in these devices and products. However, the key issues are very similar to macroscale considerations of materials such as copper or silver – tailings from mining, energy, water and catalysts necessary to refine, wastes during the production of product (in the case of thin film deposition, this includes the material deposited on all surfaces within the deposition chamber), and the effect of dispersion of minute amounts of these materials as product or devices (societal concerns), the potential for degradation and wear during use (societal concerns), and finally the end-of-life disposition. These are all total life cycle management issues for nanostructured materials.
In the past decade, the focus has been on the creation of novel particles and devices that take advantage of nanoscale phenomena, and the producibiity of particles, nanotubes, etc in larger amounts. Although there have been several workshops addressing nano-bio-enviro, no specific solicitation has been directed to the evaluation of environmental issues or pollution prevention. One reason given was that characterization at the nanoscale at that time was impossible. The questions above need to be answered in order to assure human health and safety.
In terms of product use, there is little documentation to date on the wear debris associated with products that incorporate nanoscale structures. The longterm effects are unknown. The actual particle sizes of wear debris are dependent upon the mechanisms of wear or degradation.
Are current LCI and LCA methodologies adequate for application to the life cycle impacts of nanotechnology/nanomaterials? In terms of nanomanufacturing processes, the current methodologies may not deal effectively with the scale of the effect with respect to the scale of the material. The current LCA does not integrate well with performance metrics for design of product at any scale. For example, if nanocrystalline diamond extends tool life by 300%, how does the LCA for that machine tool insert inform decision-makers regarding the trade-offs between the production and the use of such materials?
Similarly, if particles are carried in a matrix (nanocomposites), how will the LCI / LCA consider the total life cycle that includes disposal aspects of non-separable materials? Since total life cycle management includes cradle to grave (or cradle) considerations, how can we effectively promote the performance while still understanding the implications on both the environmental and economic aspects of sustainability?