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.

1.6.1. 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 organic and technical materials are 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).

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 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 period of 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).

1.7. How does circularity relate to sustainability?

Circularity contributes to a more sustainable world, but not all sustainability initiatives contribute to circularity. Circularity focuses on resource cycles, while sustainability is more broadly related to people, the planet and the economy. Circularity and sustainability stand in a long tradition of related visions, models and theories. Below are some examples. In addition, we briefly explain how circularity fits in with the Sustainable Development Goals (SDGs) of the United Nations.

Regenerative design

The idea behind regenerative (restorative) design, developed by American professor John T. Lyle in the 1970s, is that processes within all systems can reuse their own energy and materials. Demand from society is also met within the limits of nature.

Performance Economy

Walter Stahel developed the vision of a closed-circle economy, including the principles of life extension, product repair and waste prevention. Selling services instead of products is an important part of his thinking: everyone pays for the performance of a product. This leads to the concept of the performance economy.


In the cradle-to-cradle model, developed by Michael Braungart, materials in industrial and commercial processes are considered as raw materials for technological and biological reuse. Design is literally from cradle to cradle – in the design process the entire life cycle of the product and the raw materials used are considered. Technical raw materials do not contain any components that are harmful to the environment; biological raw materials are completely biodegradable.

Industrial Ecology

Industrial ecology is the science of material and energy flows, where waste within industrial cycles serves as a raw material for a subsequent process. Production processes are designed in such a way that they resemble ecological processes.


Biomimicry is an approach, developed by Janine Benyus, in which inspiration comes from nature. Biomimicry imitates designs from nature and applies these to solutions in human society.

Green Economy

The Green Economy, defined by the United Nations Environmental Platform (UNEP), is an economy that results in increased well-being and increased social equality, while at the same time greatly reducing environmental risks and ecological scarcity.

Blue Economy

The Blue Economy, developed by Günter Pauli, is an economic philosophy that derives its knowledge from the way in which natural systems form, produce and consume. This knowledge is applied to the challenges we face, and is converted into solutions for local environments with specific physical and ecological properties.

Bio-based Economy

A bio-based economy is an economy that does not run on fossil fuels, but an economy that runs on biomass as a raw material. In a biobased economy it is about the use of biomass for non-food applications.

The donut economy

The donut economy, developed by Oxford economist Kate Raworth, is a model for measuring the earth’s prosperity, based on the Sustainable Development Goals and the planetary boundaries. Many of the planetary boundaries relate directly to ‘unlocked’ cycles, such as those of greenhouse gases, toxic substances, eutrophication, fresh water, aerosols and oxygen radicals.

The circular economy and the Sustainable Development Goals

Circular economy is also a way of implementing the Sustainable Development Goals (SDGs). In particular, there is a strong relationship with SDG 6 (clean water), SDG 7 (affordable and clean energy), SDG 8 (work and economic growth), SDG 12 (responsible consumption and production), SDG 14 (life below water) and SDG 15 (life on land). Aspects of the circular economy, such as recycling of household waste, e-waste and waste water, provide a ‘toolbox’ to comply with the SDGs (Schroeder, Anggraeni, and Weber, 2018).