It is the latter type of cascade - material cascading - which will be used in this report to study the potentials of using organic household waste. Circular Economy: Circular economy is most often understood as the recycling of residual products or waste from the last station in a given production chain (see for instance the MacArthur butterfly model). It is a very incomplete understanding of circular economy. It appears for instance of the previous figure (figure 1) that the greatest losses of material loss are not in the households, but throughout the whole life cycle, and especially in the first parts of the total life cycle. The figure below should illustrate types of the residues and side flows: Figure 2. Material flow in the circular economy, exemplified by wet biomasses in a biogas plant. Circular economy in the biosphere.
The circular economy is - as a concept - an incentive to recycle the materials in a given production life cycle. The figure illustrates that the various waste and side streams can be used for energy production, while at the same time nutrients and carbon are recycled to the agriculture. The important thing about the recycling process is, of course, that one obtains a substitution of other products, for instance fertilizers, based on fossil sources. The circular economy must - to be preferential - reduce the primary resource pull. A biogas plant is one of many forms of circular technologies, ie technologies that enable the recyle resources and a substitution of primary resources that would otherwise be used without this technology. The cascade shown in the figure is not the only and final cascade. Residual products and side-streams from the biogas plant can form the basis for new cascades, for example in
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