(73a) Chemical Engineering Outside the Pipe: Industrial Ecology and Sustainability

The 2010 Danckwerts lecture will be concerned with explaining the emerging field of Industrial Ecology (IE) and why it represents a new and important area for application of the skills of the chemical engineer. That guide to popular understanding, Wikipedia, defines Industrial Ecology (IE) as [1] ?a ?systems-based, multidisciplinary discourse that seeks to understand emergent behaviour of complex integrated human/natural systems' [2]. The field approaches issues of sustainability by examining problems from multiple perspectives, usually involving aspects of sociology, the environment, economy and technology. The name comes from the idea we should use the analogy of natural systems as an aid in understanding how to design sustainable industrial systems?. Wikipedia also says that [1] ?Chemical engineering is the branch of engineering that deals with the application of physical sciences?. and life sciences?. with mathematics to the process of converting raw materials or chemicals into more useful or valuable forms?. While surprisingly sound, these definitions do not bring out the close relationship between industrial ecology and chemical engineering. Put simply, chemical engineering principles can be applied to managing material and energy flows and transformations in an economy or an industrial sector or a company - i.e. to industrial ecology - as much as to flows and transformations in pipes and vessels [3]. The common ground is shown by two of the analytical tools which are central to IE: Life Cycle Assessment (LCA) and Material Flow Analysis (MFA). LCA is used to identify and, where possible, quantify the full resource uses and environmental impacts associated with supplying a product or service; ?a product is followed from its ?cradle' where raw materials are extracted from natural resources through production and use to its ?grave', disposal? [4]. The all-important Inventory phase of a LCA is essentially a material and energy balance over the whole supply chain. LCA is the tool used to measure the greenhouse gas emissions (sometimes called the ?carbon footprint?) of a product or company or plant. MFA is another application of material balances: ?a method of analyzing the flows of material in a well-defined system? [1], which may be a national or regional economy or an industrial sector or a defined area such as a city. While the concepts behind these basic IE tools are not new to chemical engineers, the purpose may be. The Wikipedia definition highlights that IE aspires to address ?whole systems? which may be complex and chaotic. This idea is illustrated by Figure 1, a very broad-brush view of human activities which illustrates some of the ideas in industrial ecology including that of a ?circular economy?, one of the ideals of IE, in which materials are re-used many times on their passage through the economy. Material is only lost from the economy when it is dispersed; therefore undispersed ?waste? is seen as a resource which can be reused. Realising such an economic system goes beyond re-use and recycling; it involves designing and planning for multiple uses and finding ?industrial symbioses? in which a waste or low-value product from one industry can be a valuable input to another - which is the heart of the ?ecology? metaphor. The result can be an industrial network which looks much like the kind of process system familiar in chemical engineering. One of the differences from a process system is that the viability and success of such a network depend not just on the characteristics of the flows but on the relationships between the different actors in the system. This is one of the reasons why IE examines ?problems from multiple perspectives, usually involving aspects of sociology, the environment, economy? as well as technology. Multiple perspectives imply multiple objectives so that single-objective optimisation is rarely appropriate: decision structuring and deliberative processes are also central to the IE agenda [5,6]. Figure 1. The Human Economy [5]: E ? emissions. The Wikipedia definition also emphasises that IE is concerned with ?issues of sustainability?. Among the myriads of definitions of sustainability, one of the most succinct is due to Jackson [7]: ?Sustainability is the art of living well, within the ecological limits of a finite planet?. ?Ecological limits? are at the heart of the problem of sustainability: indefinite growth in consumption is as impossible as ?business as usual? in the global economy. Furthermore, ?living well? is to be interpreted in an ethical sense, not merely equated with material consumption or physical comfort. Since the first attempts to articulate the meaning of sustainable development [8], the importance of equity has been recognised: one person's quality of life must not be at the expense of the well-being of someone else, living now or at some future date. Therefore a further discipline must be added to the mix: ethics (which is a branch of philosophy, not religious studies). This is one of the reasons behind the increasing interests in ethics shown by many national engineering institutions. Applying ethical principles to globalised supply chains raises some ?interesting? questions? References 1. en.wikipedia.org (accessed July 19, 2010) 2. Allenby, B. (2006) ?The ontologies of industrial ecology?. Progress in Industrial Ecology 3 (1/2): 28-40 3. Clift, R. (2007) ?Time to leave the process sandpit?. The Chemical Engineer July: 21-2. 4. Baumann, H. & Tillman, A.-M. (2004) The Hitch-hiker's Guide to LCA. Lund: Studentlitteratur. 5. Mitchell, C.A., Carew, A.L. & Clift, R. (2004) ?The role of the professional engineer and scientist in sustainable development?, Chapter 2 in Sustainable Development in Practice (ed. A.Azapagic, S.Perdan & R.Clift). Chichester: John Wiley & Sons. 6. Elghali, L. , Clift, R. , Begg, K. G. & McLaren, S. (2008). ?Decision support methodology for complex contexts?. Engineering Sustainability, 161(1), 7-22. 7. Jackson, T. (2010) ?Keeping out the giraffes?, p. 20 in Long Horizons (ed. A.Tickell). London: British Council. 8. World Commission on Environment and Development (1987) Our Common Future. Oxford: Oxford University Press. Figure 1. The Human Economy [5]: E ? emissions.