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3. Ecological Rucksacks and MIPS |
3.1 Ecological Rucksacks
Schmidt-Bleek thinks that, in each product
or service that we use, we are carrying "in a rucksack" the materials
that were moved from their locations in nature to make the goods or
services. These are called ecological rucksacks (Figure 1). The ecological
rucksacks indicate the amounts of materials that were moved in nature
to make the goods, and so the ecological rucksacks represent the degree
of stress exerted by the goods on the environment.
The ecological rucksacks of goods are
easily calculated. All materials used in the production of goods are
listed by weight and multiplied by rucksack factors, and then summed
to include all materials.
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Here,
MI is the ecological rucksack or material intensity, and Mi is the
weight of the material in terms of kilograms, and Ri is the rucksack
factor. Figure 2 shows the process for calculating ecological rucksack
of an automobile.
The rucksack factor (or MI factor) is
the amount (in kilograms) of materials moved to obtain 1 kilogram
of the resource. For example, Steel: 21 (One kilogram of steel carries
an ecological rucksack of 21 kilograms.), Aluminum: 85, Recycled Aluminum:
3.5, Gold: 540,000, Diamond: 53,000,000, Rubber: 5.
The rucksack factors for the main essential
materials necessary for economic activities have been studied at the
Wuppertal Institute.
3.2 MIPS
MIPS is the material intensity per unit service or per unit function with respect to the entire product life.
Energy consumed during the entire product life is also taken into account. MIPS are thereby defined for service-yielding, final goods. The material transportation and energy requirements for the entire product life are also taken into account.
It is now possible to show how material requirements are divided over the various process steps of the life of a service-yielding final good, including the process of manufacturing, using (operating, maintaining, cleaning), repairing, re-using (perhaps using only component parts), collecting, sorting and disposing the good. Additionally, transportation enters the calculation as an almost ubiquitous link between various steps. This is then related to the total number of deliverable (or, in hindsight, delivered) use, function or service units.
In the case of non-reusable packaging material and throwaway products (which actually vanish in landfills and are not used for other purposes), the "S"(Service) of MIPS is equal to one. The MIPS value in this case is equal to the aggregate amount of material for all process increments.
The MIPS value decreases as the number of service units delivered by the product rises. Each successive service unit cuts in half the value of MIPS achieved with the previous use. The MIPS value thus shrinks with each successive use, and the environmental compatibility of the product improves in step.
A sundial is the simplest example. Here, neither material nor energy is required at any time during the use of the device, and it is never cleaned. The device never needs any extra material during its service life, and so its MIPS decreases continuously.
In the case of a washing machine, the MIPS curve falls more slowly because water, energy and detergent are used in each wash cycle. If the use of water and energy rises with the age of the machine, the curve might even reach a minimum, after which it would start to rise again. If a repair becomes necessary (figure 3, point X), we have a "MIPS stimulus," after which the curve begins to fall again. A repair that is very "expensive" in terms of material, energy or transportation (point Y) can lead to a situation in which the machine is operating at a higher MIPS value than when it was new. This would be an example of an ecologically absurd repair-if MI (the material intensity) for the distance Y-B were greater than for O-A. (In other words, if the MI value of the repaired machine is higher than the original MI value of the new machine.)
The MIPS value is calculated as follows: |
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MI is the ecological rucksack.
"S" is the service number, and represented as Sn. p.
"n" is 1 for consuming products, and n is the number of times of usage or the amount of usage , for example, hours or surface area for durable consumer goods .
In the case of a cup of orange juice, S=1. If a person uses a bicycle for n kilometers, S equals n.
If p persons use a train for n kilometers, then S equals nEp.
3.3 The relationship between MIPS and resource productivity
We are now concerned with the question of defining resource productivity as carefully as possible, so that it can increase its status as a criterion for economic and technical decision-making.
The resource productivity of each goods is the total sum of available service units, divided by the total consumption of material for the service-yielding good, as calculated from cradle to grave, including the material flows needed for the purpose of providing the requisite energy. In other words, the resource productivity of a good is the inverse of its MIPS, and is measured in "per kilogram" terms.
Resource productivity is also called eco-efficiency. The material wealth of a region could then be expressed in terms of the number of service units available there. If resource productivity rises while material consumption remains the same, material wealth increases. In other words, "dematerialized" technologies can yield more service units with constant of falling material effort. Were one to increase the global resource productivity fourfold, it would be possible, under this definition, to double the number of service units and have the material inputs cut in half. Dematerializing in economic terms does not mean moving back to lower consumption; it means progress, as such a development would not be possible without concomitant technical improvements. We can refer to this as a technical approach to a sustainable economy.
3.4 What MIPS can-and cannot-do
From a technical perspective, the use of the MIPS has the following advantages:
1) |
Material and energy expenditures
are measured in the same units. In so doing, contradictions
in ecological evaluation are avoided, and the evaluation becomes
directionally stable. |
2) |
The concept can be used to set
up Life Cycle Analysis at the level of screening procedures.
The effort involved in the analysis is hereby dramatically reduced,
and the results become directionally stable. Decisions about
successive analyses can follow in the form of a phased plan. |
3) |
The concept can serve as an instrument
with which to test the ecological significance of technical
procedures in light of their contribution toward a sustainable
economy, as well as for measuring attendant successes. |
4) |
The MIPS approach helps in the
design of industrial products, in the planning of environmentally
friendly processes, facilities and infrastructures, as well
as in the ecological assessment of service. |
5) |
The concept can serve as the basis
for a comprehensive ecological labeling strategy, and can be
an aid in purchasing decisions and consumer counseling. |
6) |
The MIPS approach is suitable
as a tool for distinguishing ecologically sensible recycling
loops and circulation systems from those that are ecologically
absurd. |
7) |
The approach can be used to establish
ecological tariffs, issue licenses, set insurance premiums,
assess taxes, and to make decisions about subsidies. |
8) |
The concept is suitable for examining
various codes and standards for their ecological coherence. |
9) |
The MIPS concept can help make
decisions about what kinds of research and development projects
deserve financial support. |
10) |
The MIPS approach should be well
suited to assessing technical projects which are part of development
aid to the Third World, and for the former socialist countries,
with respect to their environmental characteristics. |
11) |
The concept shows promise in
the context of future international harmonization because of
its simplicity. This would be important for the possibility
of making progress toward ecological structural change on the
level of major regions such as the European Union, or worldwide. |
The concept cannot cover the following problems.
1) |
The concept does not take into
account the specific "surface-use" for industrial
as well as for agricultural and forestry activities. This is
of considerable importance as the amount of the earth's surface
available for our purposes is limited. |
2) |
As already indicated, the MIPS
approach does not take into account the specific environmental
toxicity of material flows. The approach is not intended to
supplant the quantification of eco-toxicological dangers of
materials in environmental policy, but rather to supplement
it by stressing the material and energy intensity of economic
services. |
3) |
The MIPS concept makes no direct
reference to questions of biodiversity. It seems to speculate
that the chances for species survival are related to the intensity
of soil and resource use. Therefore, one cannot exclude the
notion that the material intensity of a society's economy has
something to do with its contribution to species extinction.
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For example, in 1996, Theo Colborn(7) warned that some synthetic materials destroy the hormone system of livings. Problems such as this cannot be addressed by MIPS. It is necessary to combat with toxic materials for human health.
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