Present production systems are linear.

Cleaner production systems are cyclical. They try to imitate nature’s processes. Wastes are used as secondary materials so that fewer new materials and less energy and water are required.

In their path-breaking textbook, Industrial Ecology, Graedel and Allenby provide the following short definition of Industrial Ecology, the way all production systems need to head:

Industrial ecology is the means by which humanity can deliberately and rationally approach and maintain a desirable carrying capacity, given continued economic, cultural, and technological evolution. The concept requires that an industrial system be viewed not in isolation from its surrounding systems, but in concert with them. It is a systems view in which one seeks to optimise the total materials cycle from virgin material, to finished material, to component, to product, to obsolete product, and to ultimate disposal. Factors to be optimised include resources, energy, and capital.

The concept of industrial ecology builds on the biological concept of ecology, which is "the branch of biology dealing with the relations of organisms to one another and to their physical surroundings." Rather than examining an individual organism, ecology looks at the systems within which organisms live and of which they are a part. Individual organisms consume resources and leave wastes behind. Within natural ecosystems resources are not depleted and wastes do not accumulate because there are cyclical processes in place that make use of all "wastes" as resource inputs (food) for other organisms.

In the history of Earth, large-scale natural systems have not lasted forever but they have often survived for tens of thousands or even millions of years. This kind of stability is possible only where the recycling of resources is essentially complete (with the exception of the constant input of solar energy.)