3.3.1           Weighting category Claiming of resources

Frequently, the synthesis of a chemical substance is possible in varying ways, wherefore different substrates are reverted to. The merely comparison of the syntheses leading to the target product, without consideration of material and production expenses for the production of the maybe qualitatively very different substrates does not present the whole truth. To show that the claiming of resources is worth to be regarded as environmentally relevant, the history of the materials used in view of material and production expenses including safety and environmental engineering demands should be illustrated. Mostly, detailed information about these, like number of synthesis steps or toxicological aspects of the chemicals used thereby are not available, not existing at all, or, normally, only investigable with efforts. It is more workable to esteem the price of the dimension of the environmental impact in the production of the substances involved. Therefore, the substance price was selected as measurement for the claiming of resources.

Because of the large range in the substance prices possible in comparison to the weighting factors Q 1 to 10 to be seized, with a logarithmic function a classification was made. The weighting factor Q of substance prices will be determined by the following equation:

‘ represents the integer function of Gauß, i. e., e. g.,

This equation results from the conversion of the equation  to Q, which clearly results from the pairs of value determined for this weighting category (Q = 2 / price = 0.1 Euro/g) and (Q = 10 / price = 100 Euro/g) with the basis given (here e = 2.718...). With this function (Figure 23), after changing ordinates and abscissas and application of the integer function of Gauß , which converts the resulting logarithmic function (Q = f(price)) in a step function, price ranges of Table 1 are obtained.

 

Table 1    Assignment of substance prices to the weighting factor QClaiming of resources

  

 [Euro/g] 

 

1

for free

to

0.10

2

0.10

to

0.24

3

0.24

to

0.56

4

0.56

to

1.34

5

1.34

to

3.17

6

3.17

to

7.51

7

7.51

to

17.80

8

17.80

to

42.22

9

42.22

to

100.13

10

100.13

to

infinite

Figure 23          Exponential functions for the determination of QClaiming of resources

By multiplication with the substance specific weighting factor Qclaiming of resources, the mass index S-1 is weighted under formation of the environmental index El_in, to which, besides, the category ‘risk’ described as follows can contribute.

 

Back to Main Menu Next Chapter