Life Cycle Aspects of Nanoproducts, Nanostructured Materials, and Nanomanufacturing: Problem Definitions, Data Gaps, and Research Needs
Chicago, Illinois: November 5-6, 2009
Critical issues in Nanotechnology
Roland Clift
Emeritus Professor, University of Surrey
President of the International Society of Industrial Ecology
1. Introduction
At least until now, the most revolutionary (or “disruptive”) applications of nanotechnology have been in medicine, which I assume to be outside the scope of this workshop. Such industrial applications as have emerged have been in developments, usually incremental, to existing technologies. This raises the question of the purpose of applying LCA to nanostructured materials, specifically whether the analysis should be attributional or consequential. The confusion of messages over biofuels has highlighted the importance of making this distinction and clarifying the purpose (i.e. “goal and scope”) of the analysis from the outset.
2. Life Cycle Stages
2.1 Mining and Resource Availability?
In general, LCA does not deal well or transparently with the environmental and social impacts of resource extraction. This is an issue for all abiotic resources, not just those used in the production of nanomaterials. As an illustrative example, an analysis of the fuel cycle for nuclear fuel revealed that extraction can be the most significant stage in the life cycle, dependent on ore grade and mining practice. This is likely to be the case even more strongly for, as an extreme example, “artisanal” mining in the Western Congo. In addition to the recognised (but usually ignored) impacts of land use change and risks such as leachate from waste and tailings dams, there are the issues of:
-Workplace health and safety; this is usually omitted in LCA although SETAC-Europe produced a report, more than ten years ago, on how it might be included;
- Social Impacts; there is a question of whether the UNEP/SETAC approach is fit for this purpose.
The attributional vs consequential distinction affects the significance of the results. As an obvious example, it is very likely that scarcity of platinum group metals will constrain the large –scale deployment of fuel cells. Therefore, if nanotechnology can reduce the quantities of material needed for specified functionality, it could enable more widespread use of fuel cells. This requires analysis and modelling which go beyond the usual scope of LCA. The analysis gets even more “difficult” for materials like Te. If developments in nanotechnology reduce the quantity of materials needed to achieve a specific functionality, will this reduce or increase total demand?
2.2 Manufacturing and Use
This stage in the lifecycle of nanoengineered products probably requires the least re-examination of LCA methodology. The problem lies in the lack of data. In the absence of any body of data on the actual performance of manufacturing processes, the studies published so far are necessarily based on hypothetical scale-up of laboratory or pilot scale production. The uncertainties in this scale-up are obvious. Furthermore, if and when production of nanomaterials becomes widespread, it is likely to take the form of distributed production rather than the centralised model which characterises conventional processing: to avoid hazards and possible loss of functionality in transport and storage, production is likely to be flexible and relatively small scale, making nanostuff for immediate incorporation into the manufactured product.
Trading off impacts from manufacturing against performance and service life of nanoengineered products require careful definition of the functional unit, but should not require any new methodology, although the distinction between attributional and consequential analysis remains central. It is too early in the development of nanotechnology to identify applications which show a clear benefit from the technology.
2.3 End - of - life
The behaviour of nanoengineered materials in waste management operations is another area of current ignorance, arguing for a precautionary approach to material containment (see below). Where nanomaterials are key functional elements in specific components, it may be feasible to recover and reprocess these components. Larger volume uses are likely to be in composite structural components. Given that re-use and recycling of composites are only feasible in a very few cases, even where conventional materials are used, it seems very unlikely that they will be generally feasible for composites incorporating nanomaterials for the foreseeable future. The emphasis will therefore be on safe contained disposal or, at best, recovery of energy and/or bulk materials. There is a research need for composites and processes which enable reshaping of used components, but this lies outside the scope of LCA unless there is a question of comparing the impacts of waste disposal and replacement resource use with possibly resource-intensive re-engineering. This would require data to become available but it is not evident that it is a new methodological problem.
3. Regulatory Issues
The biggest problem in regulation (and LCIA) of nanoengineered products is the almost complete absence of data on the human and ecological toxicity of nanomaterials. This will continue to be a problem for the foreseeable future. Given that the properties of nanomaterials depend strongly on their surface condition, can be the conventional approach to toxicological testing deal with the range of possible variables? Given that the objective of regulation is to prevent harm to human health and the environment, the hope is that epidemiological information will never be available, unless data can be found from established industries which produce nanomaterials; fumed silica and carbon blank are possibilities.
In the absence of firm toxicological information but with evidence suggesting that nanomaterials could pose significant risks, regulation has no alternative to taking a precautionary approach. Nanomaterials incorporated in manufactured products can be contained by enforcing strict end-of-life management. Should there not be a precautionary presumption against uses which inevitably lead to unconfined release, of which nanosilver is an egregious example?