Methods:
Ecological Rucksacks

The indirect material flows (or "ecological rucksacks") results directly from the listing and accounting of all materials which stand behind a final product or a service, or any economic output in general. It is defined in general as the sum of all materials which are not physically included in the economic output under consideration, but have been necessary for production, use, recycling and disposal.

Thus, by definition, the "ecological rucksack" results from the life-cycle-wide material input (mi) minus the mass of the product itself. Ecological rucksacks are calculated integrating the five main categories of material flows.
We distinguish two types of indirect flows ("ecological rucksacks"):
§ Unused extraction: Unused extraction are materials translocated in the course of the extraction of primary materials, but which are not economically used. Examples are overburden from mining and unused biomass from harvest.
§ Indirect flows (ecological rucksacks) of products: These are the rucksacks in the strict sense, comprising all materials used in the life-cycle of a product. These rucksacks are of special importance for analyses of international trade relations.

On the level of national MFAs, unused extraction is both part of the domestic and the foreign extraction. Ecological rucksacks of production chains refer to the indirect material flows associated with the imported products.

Besides all the material activated in the life cycle of a product or service, all materials are counted which have been consumed indirectly for the production, packaging, operation or use (washing agents, water, fuels etc.), maintenance (paints, cleaners etc.) and repair (spare parts etc.) of the output under consideration. In addition, all materials are counted, as far as possible, which have been necessary for the production or operation and disposal of an output, in terms of materials consumed for energy generation and also the share of - normally already existing - infrastructures like transport-, extraction-, production-, and disposal-installations - including all inputs necessary for erection, operation, maintenance and destruction.

Recycling, in general, refers to processes from which materials are provided in such a way that they can replace raw materials or materials in other processes. If materials are materially recycled (secundary raw materials), only the material input necessary to run the recycling process is counted as their ecological rucksack. The mass of secundary raw material itself remains with the rucksack of the main product of the original process and will not be counted again for the recycled product.

By definition, by-products are all products which result from a process that has not as its principle aim to produce them (additional products) and which can substitute main products as inputs in further processes. By-products may become main products due to changing situations of markets, e.g. in the field of chemicals. The rucksacks of by-products are those input materials which have to be provided for further processing. In case that the original process consumed inputs which exclusively relate to the improvement of quality and, thereby, the better use of by-products, those inputs will be acccounted for the ecological rucksack of the by-product. The mass of the by-product itself is contained in the rucksack of the main product (for more details see the MAIA handbook).

...back

Contact

Stefan Giljum