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Circular Economy

How do materials circulate in a circular economy?

In a circular economy, materials circulate in two separate cycles: the bio-cycle and the techno-cycle. The distinction between these cycles helps to understand how materials can be used in a long-lasting and high quality way. A general rule of thumb is that the less process steps a material has to go through for reuse, the higher the quality of the material it can contain.

Technical and organic materials

Organic materials follow a different reuse process than technical materials. Technical materials are also called synthetic materials. Because of this difference in the reuse process, it is important that after use, organic and technical materials can be properly separated from each other after use (see figure 1).

Technical materials such as fossil fuels, plastics and metals have limited availability and cannot easily be recreated. In the techno-cycle it is important that stocks of such finite materials are properly managed. In a circular economy, these materials are only used instead of being consumed. After use, materials are recovered from residual flows at their original value.

Organic materials such as wood, food and water can be incorporated into the ecosystem and re-generated through biological processes. In the bio-cycle it is important to let the ecosystem do its work as well as possible. Consumption may take place during this cycle (fertilization, food, water) as long as the streams are not contaminated with toxic substances and ecosystems are not overloaded. Renewable organic raw materials can then be regenerated (Ellen MacArthur Foundation, 2015a).

Figure 1: The Butterfly Diagram (Ellen Mac Arthur Foundation, 2015a)

The inner circle

Within the techno-cycle there are different levels of reuse (see the right side of Figure 1). The rule of thumb is that the smallest or inner circle is preferable to larger cycles, because these require less processing, labour, energy and new material to be of original value again (Ellen MacArthur Foundation, 2015a).

The different reuses within the techno-cycle are (see figure 1):

  • Maintanance (& repair): Repair and maintenance during use to extend the lifespan.
  • Reuse/redistribution: Direct re-use by re-marketing a product.
  • Refurbish/Remanufacture: The thorough refurbishment and repair of a product by the manufacturer.
  • Recycle: Retrieving parts or materials from the product for reuse.

Re-use in cascades

Within the bio-cycle, reuse takes place in cascades. Cascading means ‘using (part of) a product for another application’. When a product is no longer able to perform its initial function, it is passed on for reuse. During cascading, the quality of the material is reduced and energy is consumed (Ellen Macarthur Foundation, 2013a).

Cascading differs from ordinary re-use and recycling in that it changes function and the extent to which the product is processed. A cotton T-shirt can serve as an example. When reused, a worn T-shirt is sold in a second-hand shop. When recycled, the T-shirt is shredded into cotton fibres, which are then spun into new yarn. Cascading is the use of old T-shirts as cushion filling .

Long-term cycles

For both the bio-cycle and the techno-cycle, the lifespan of a product must be made as long as possible. The lifespan of products can be extended by:

  • Ensuring that a product is used longer, thereby ‘slowing down’ the process, for example by focusing on emotional attachment to a product, lasting fulfilment of a need and adaptability of the product, so that it can keep up with the times.
  • To ensure that multiple consecutive cycles of direct reuse are followed, by facilitating the interchangeability of products and by properly maintaining products so that they can be used for a long time without repair (Ellen MacArthur Foundation, 2015a; Bocken, Bakker & De Pauw, 2015).

Pure flows

For both the bio-cycle and the techno-cycle, residual flows that are not contaminated with other materials are the easiest to collect and re-use. By ensuring that materials are easily separated from each other after use and that residual flows are collected in such a way that they are not contaminated with toxic substances, residual flows are the most useful (Ellen MacArthur Foundation, 2015a).

Within the bio-cycle, orange peels can serve as a good example. The company PeelPioneers collects orange peels from catering establishments and extracts essential oils from them. If there is food residue in the peelings, the essential oils are polluted and can no longer be used for cosmetics, so the value decreases. Within the techno-cycle, plastic toys can serve as a good example. If the toy is completely made of polyethylene, it can be completely melted down and reused. If the toy also has polyester components, these must first be separated before the toy can be recycled at high quality (Peelpioneers, 2019).