Page 269 - Materials Chemistry, Second Edition

L1644_C06.fm Page 242 Monday, October 20, 2003 12:06 PM

have been estimated in different impact scores, they must be summed up. The
damage profile might contain potential damages in case accidents have been sim-
ulated. In principle, depending on the selected intermediate aggregation scheme,
the damage profile can be broken up into damages to the human health (morbidity,
cancer, mortality), manmade environment and natural environment AoPs, as well
as the so-called global damage indicators, which could be related to the life support
functions and resources sub-AoPs if resource depletion is considered an environ-
mental problem.
If the damage profile consists of different damage endpoints, their number can
be further reduced by applying the selected aggregation scheme. In this way a
reduced damage profile or an estimation of the total environmental cost of the process
chain under study is finally obtained.

6.5.8 ECO-EFFICIENCY
A further optional element is the calculation of the eco-efficiency of the industrial
process chain for which environmental damages have been estimated. The concept
of eco-efficiency has been proposed as an expression of sustainability for economic
activities (see Chapter 1). Eco-efficiency has been defined as the delivery of com-
petitively priced goods and services while progressively reducing environmental
impacts.
Thus, measuring eco-efficiency, hh hh , by the coefficient of the difference between
eco
production costs, C prod , and external environmental costs, C , to the production
env
costs, C prod , has been suggested. Although production costs are easy to obtain, the
environmental costs are not so visible. Nevertheless, they can be estimated by the
presented methodology of environmental damage estimations for industrial process
chains.
The expression of Figure 6.17 is applicable to the final result of the environ-
mental damage estimations for industrial process chains if this is expressed in a
monetary unit. This figure illustrates the procedure to calculate eco-efficiency
according to this expression. Instead of production costs (operation and investment
costs), the expected utility or net value could be used for determining eco-efficiency.

Environmental Cost

Production Cost
(operation and Eco-efficiency
investment costs)
OR η eco = (C prod -C env )/C prod
Expected Utility
(net value)
ηη η η
eco
FIGURE 6.17 Eco-efficiency of an industrial process chain.

© 2004 CRC Press LLC