Life Cycle Aspects of Nanoproducts, Nanostructured Materials, and Nanomanufacturing: Problem Definitions, Data Gaps, and Research Needs
Chicago, Illinois: November 5-6, 2009
Bhavik Bakshi, Ph.D.
Professor, Department of Chemical and Biomolecular Engineering
Ohio State University, Columbus
Availability of sufficient quantities of materials for use in nanostructured devices:
At least for the time being there should be sufficient quantities of low availability materials for making nanostructure devices and products on a large scale. However, this could change quickly. The question should not about the availability of these materials but, as for energy resources (Bullard and Herendeen, 1975), about the return on the resources invested for obtaining these materials. With increasing demand, this return on investment will decrease, and require more exploration and energy use, thus increasing the overall waste burden. Socio-political factors will certainly matter due to the occurrence of many minerals in “less friendly” or disturbed areas. Furthermore, the availability of valuable resources may be more of a curse for less developed countries, as has often been the case in less developed but oil rich nations. This raises important challenges from a global sustainability point of view.
Potential for the development and application of green technologies and design for the environment principles for the manufacture of nanostructured materials:
The potential for applying green technologies and design for environment principles certainly exists, and they may lead to a more eco-efficient and environmentally benign manufacturing approach. However, there is not enough reason to believe that applying these principles will ensure the sustainability of nanomanufacturing because most such approaches, including life cycle assessment and design for the environment do not account for ecosystem goods and services that are essential for supporting all human activities, and the state of those services or carrying capacities of services that are needed to support nanomanufacturing. In addition, simply enhancing manufacturing efficiency does not consider the scale of the nanoproducts' use, which could ultimately determine its environmental impact. Economic aspects such as a rebound effect should also be considered.
Encouraging some nanotechnological products as replacements for current systems:
Based on our evaluation of polymer nanocomposites for automotive use, the energy saving over a typical automobile's life cycle is about 1.5-10% as shown in the figure (Khanna and Bakshi, 2009). This translates to about 65 GJ/car. Unfortunately, this lower life cycle energy use is not enough to encourage the use of polymer nanocomposites for automotive use since significant challenges exist in recycling these materials at their end of life. If these challenges are met and the energy efficiency of making carbon nanofibres is improved, this nanoproduct maybe attractive for large scale use, but it is not there yet.
Adequacy of current LCI and LCA methodologies for application to the LCA of nanomaterials:
Current LCI and LCA methodologies are adequate only if the relevant data are available. These data are not easy to find due to the emerging nature of the research and because environmental and life cycle studies lag quite far behind nanotechnology research. This highly data intensive nature of LCA is a major limitation. Research is needed in predictive LCA methods that can estimate life cycle impact based on variables for which data are easier to find. Examples of such work include finding relationships between the properties of nanoparticles such as their surface area or exergy and their toxicity. Similarly, relationships between life cycle resource consumption and impact would also be helpful. Developing such models requires the use of statistical methods and enough data to obtain statistically relevant predictive models.
References
C. W. Bullard and R. A. Herendeen. The energy cost of goods and services. Energy Policy, 3:268–278, 1975.
Khanna, V., Bakshi, B. R., Carbon Nanofiber Polymer Composites: Evaluation of Life Cycle Energy Use, Environmental Science and Technology, 43, 6, 2078–2084, 2009.