Environmental Engineering Reference
In-Depth Information
global carbon, nitrogen, and hydrologic cycles, and the environmental
implications of all sectors involved in the process (e.g., agriculture or
forestry; agricultural chemical production, distribution and application;
biomass transportation and processing; energy production and transmis-
sion; and energy end use efficiency). Such industrial ecology approaches
form the science and technology base for the practice of Earth Systems
Engineering. 17
With current technologies and economic incentives, achieving a total
Type III system for many materials and technological systems will be
extremely difficult because of the dissipative uses of materials discussed
above. Tires, for example, wear under normal circumstances, and major
categories such as food and many personal care products (e.g., soaps and
shampoos) are inherently dissipative. In such instances, minimization of
dissipative uses, especially any dissipative uses of toxics or materials that may
be toxics, may be the best that can be hoped for.
In all such instances, the systemic principle underlying industrial ecology
highlights the point that there is no inherent requirement for the materials
management function in any of these recycling systems to include only one
firm or one sector, although in some cases such “tighter” loops may be
more environmentally efficient. In principle, rather, the goal should be a
self-contained global economy, as illustrated in figure 3, with materials effi-
ciency optimized over the larger system.Thus, for example, the concept of
geographically co-located industrial material cycling systems, such as eco-
parks, is interesting, but is only one possibility among many. To focus too
intently on any one potential subsystem runs the risk of overlooking the
need to improve system performance as a whole. Note also that these sys-
tems are energetically open, as are natural systems: the constraint here is that
energy use by the system as a whole must be sustainable over some period
of time.
This simple discussion illustrates several critical aspects of industrial ecol-
ogy. Most important, industrial ecology is profoundly systems-oriented.
This does not mean that every industrial ecology activity should include all
possible impacts on any relevant system; it does, however, require a sensi-
tivity to the systems aspect of industrial ecology research. Thus, for exam-
ple, where boundaries are drawn around particular activities or subsystems,
they should be justifiable and reasonable in the context of the relevant sys-
tem, and the interfaces between the subsystem and the external environ-
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