Industrial Ecology - Some basic definitions

The demand for natural resources has been increasing steadily over the last decades, resulting from both the growing consumption in established industrialized countries and the economic rise of emerging countries in Asia and South America. Due to this development an increasing ecological damage can be observed. Against this background, the scientific field of Industrial Ecology was created at the end of the 1980s: Its new idea was an integral view on material flows used in industrial processes. Influenced by the principles of the natural ecosystem, the goal is to use waste streams of one industrial process as input material for other processes, minimizing the losses of substances to the environment (Frosch, Gallopoulos 1989). In the best case, this leads to an industrial system with a full recycling and reuse of materials and minimal waste flows which both reduces needs of primary materials and emissions to the environment. The main component of research in industrial ecology is the identification and quantification of material and energy flows through industrial systems. Therefore, Industrial Ecology is also referenced as 'the industrial metabolism' (Ayres 1994).

An important tool of industrial ecology is the Substance Flow Analysis (SFA): SFA can be seen as a specific instance of the more broadly defined Material Flow Analysis (MFA). A MFA has a defined system in focus, e.g. a geographical region or an industrial process, and tries to track and quantify the material flows both within the system and between the system and the environment.
SFAs on the other hand are focusing on a specific substance and its way through an industrial process, respectively a value chain. According to the principle that input equals output a closed mass balance is attained in the end. Moreover, not only flows are of interest. Identifying material accumulations and their quantification is of significant importance, especially in the case of toxic substances (van der Voet 2002).

Besides the environmental aspect, another - more recent - development has been paying attention to the SFA methodology: The increased demand of humanity for resources has led to a stronger competition on global raw material markets. In the case of energy resources this has already been observed for some time whereas for other raw materials, particularly metals, this development is new. Here the SFA approach offers a contribution to an improved material utilization by making the metal flows and anthropogenic stocks more transparent, which is essential for minimizing the losses and the development of tailor-made recycling methods.

Moreover, a model-based SFA is able not only to provide information but also to evaluate the effects of political instruments on material cycles through scenario simulations and analyses, e.g. the impact of a mandatory recycling quota on primary material demand. A further potential field of application for SFA models is the risk management of raw material-dependant companies such as car manufacturers

Industrial Metabolism - Ayres (1989) :

"We may think of both the biosphere and the industrial economy as systems for the transformation of materials. The biosphere as it now exists is very nearly a perfect sys-tem for recycling materials. This was not the case when life on earth began. The indus-trial system of today resembles the earliest stage of biological evolution, when the most primitive living organisms obtained their energy from a stock of organic molecules ac-cumulated during prebiotic times. It is increasingly urgent for us to learn from the bios-phere and modify our industrial metabolism, the energy- and value-yielding process essential to economic development. Modifications are needed both to increase reliance on regenerative (or sustainable) processes and to increase efficiency both in production and in the use of by-products." More...

Strategies for Manufacturing - Frosch, Gallopoulos (1989) :

"[...] that the traditional model of industrial activity-in which individual manufacturing processes take in raw materials and generate products to be sold plus waste to be disposed of-should be transformed into a more integrated model: an industrial ecosystem. In such a system the consumption of energy and materials is optimized, waste generation is mmimized and the effluents of one process- whether they are spent catalysts from petroleum refining, fly and bottom ash from electric-power generation or discarded plastic containers from consumer products-serve as the raw material for another process. The industrial ecosystem would function as an analogue of biological ecosystems. (Plants synthesize nutrients that feed herbivores, which in turn feed a chain of carnivores whose wastes and bodies eventually feed further generations of plants.)" More...

Substance flow analysis methodology - van der Voet (2001) :

"SFA aims to provide relevant information for an overall management strategy with regard to one specific substance or a limited group of substances. In order to do this, a quantified relationship between the economy and the environment of a geographically demarcated system is established by quantifying the pathways of a substance or group of substances in, out and through that system." More...