A serpent biting its tail symbolises infinity, while round mandalas represent our universe's size and shape. Both are imposing and long-lasting metaphors that humanity has employed throughout its history. Here in environmental sciences, we also get our own impressive symbol: the mighty doughnut - circular like our intended economy. This also means we get to call its inner workings "the doughnut economics"1.
The Definition of Circular Economy
A circular economy refers to the sustainable use and reuse of waste and the integration of other sustainability principles in an established economic system.
Any economy needs to be sustainable. To maintain a sustainable lifestyle, there can only be infinite exploitation of materials by reusing and recycling. It is important to remember that the sustainability of all economic models depends on several variables, such as resource accessibility and population size.
An activity that is sustainable for a small population may not be for a large population.
Our current economy is somewhat "linear" and does not efficiently plan to dispose of and use the generated anthropogenic waste. Most of the rubbish simply gets incinerated, and more materials used in industries are virgin (meaning newly extracted) than recycled. This may happen due to recycling being more expensive in the short term.
91% of all plastic made globally isn't recycled.2
In a circular economy, waste is minimised, and materials are reused or recycled to remain in use for as long as possible.
The economist Kenneth Boulding first proposed the concept of a circular economy in 1966. It has gained traction in recent years as businesses and governments have begun to seek more sustainable ways of doing business.
The Concept of a Circular Economy
A circular economy is an example of a closed-loop system. It intends to eliminate the concept of waste and use all by-products of our activities and industries.
In a closed-loop system, materials that can be recycled and reused are preferred over single-use, unrecyclable items.
Items that can be reused or recycled several times and then composted include wood and plant fibre. Many minerals, rocks and metals, like nickel, aluminium (from which cans are made), and glass, can be recycled indefinitely.
Plastic combined with paper, such as our regular mail, or alloys composed of two or more metals, such as nichrome (nickel, chromium and iron), need to be separated into their constituent elements first and then recycled.
Single-use items can usually only be used once and must be recycled, incinerated, or disposed of in some way. This includes paper towels, needles or plastic water bottles.
Some of the most environmentally harmful single-use materials are plastics, and the most widely used material for them is Polyethylene terephthalate (PET). They become harmful because they may leak toxic substances, or the sun and other abiotic elements may only manage to break this plastic down into smaller particles called microplastics.
Microplastics are then ingested by animals and by ourselves, affecting our health.
The process of analysing the "journey" of a product is often called a cradle-to-grave analysis or a lifecycle assessment (LCA).
A cradle-to-grave assessment follows, for instance, the life cycle of a banana, from the tree it was picked from and the fertiliser used on the soil to the transportation, selling and recycling stage.
The circular economy intends to change the "grave" part and turn the concept into "cradle-to-cradle" instead. This means that a product is not meant to end up in a landfill immediately after it has been produced and used. This is also called improving system effectiveness. The circular economy isn't perfect either and constantly benefits from input and innovation.
Examples of Circular Economy
One typical example of a circular economy is recycling materials such as glass, metal, and paper. These materials can be reprocessed and used again rather than sent to landfills. It is a process that mimics the biogeochemical cycles.
Biogeochemical cycles refer to 'any of the natural pathways by which essential elements of living matter are circulated.'3
Other examples include water reuse in irrigation systems and the capture of methane gas from landfill sites to generate electricity. Land bioremediation after a mine closes or water remediation after being used for industrial processes is further considered essential.
From the design stage, materials and objects must enable reuse and recycling. This includes domestic machinery and everyday objects, from dryers to personal cars.
The Importance of a Circular Economy
Identifying the transition to a more circular economy means establishing a few basic principles, application styles in real life, and maintenance requirements.
Initiatives to support the circular economy include:
Appropriate legislation through biodiversity conservation laws.
Green infrastructure and removal of invasive species.
Proper waste management for both industries and residential areas.
Water, food and energy need improved efficiency and quality (nutrient density or energy density) per unit or item. Finally, the design stage should not intentionally plan for obsolescence and recyclable or replaceable materials.
The Basic Principles of a Circular Economy
A few basic principles characterise the sustainable processes on Earth. Firstly, all sustainable processes handle biological materials (such as manure or hair) that are processed into new forms/products, such as compost. Secondly, energy is generated from renewable sources or is allowed to occur slowly if generated from non-renewable processes (e.g. the radioactive decay inside the Earth's mantle and crust).
By also choosing to cycle resources within the ecosystem, the circular economy reduces the need for virgin materials and minimises pollution.
Material cycling: rare finite materials can be kept within the closed-loop system (e.g. uranium) while biodegradable materials (e.g. manure or human waste, made of water & dry solids of carbohydrates, bacterial mass, etc.) can be reintegrated into the Earth's natural cycles (the biogeochemical cycles).
"3.6 million tonnes of sewage sludge is reprocessed and spread onto agricultural land across the UK" every year, but "the rules around the use of human sewage waste as crop fertiliser are more than 30 years out of date" according to the BBC.4
Natural ecosystems: Earth's biological lifeforms are critical mediators in the biogeochemical cycles, helping regulate essential processes for our survival, such as cloud formation and carbon cycling. If any form of energy use can promote natural ecosystem species diversity and resilience, this further works to advance our species.
Overproduction in nature (of seeds, eggs, fruits, etc.) tends to promote the growth of more individuals from different species and thus enrich ecosystems.
One area's or country's sewage sludge can be turned into fertiliser by another. The space to build and operate a sludge treatment facility may only be present in one of the two "communicating" economies.
Another example would be shops or special dispensers that accept buyers' used bottles and other cleaned materials.
Laptop, phone and camera batteries currently operate within optimal parameters for about three years, after which their performance declines.
Quality over quantity: the quality of energy, waste and materials produced ensures that the overproduction stage generates only a little waste. Intensive agriculture tends to focus on the size and number of crops rather than their nutritional density, preferring quantity over quality.
Genetically modified (GM) crops can help produce more vitamins and minerals from the same resources and thus be more nutritious. "Golden rice" (Oryza sativa variety) was engineered to help people get their dietary intake of vitamin A in areas of the world where they suffer from such deficiencies.
The Application of Circular Economies
Sustainable lifestyles may have different characteristics depending on the geography and climate of a region. Land use and other resource management must be handled carefully and promote native biodiversity.
Land use that supports healthy natural ecosystems means promoting:
hedgerows in agriculture,
the growth of wild plant & fungi strips,
connectedness with forested patches,
the use of non-hazardous pesticides,
and not killing wild species (although some animal deterrents may be necessary).
Furthermore, the issue of agricultural fields is coupled with urban sprawling and development, which means that housing tends to spread out and occupy more land without councils' careful space-use planning. This converts strips of fertile land into roadwork and locks them under construction materials such as concrete and asphalt aggregates, slowly chipping away the soil's quality over time.
Forestry and fishery management means considering threatened species alongside their habitats and preventing regular or irreversible damage done to them.
An example of such avoidable damage to an environment is the bottom trawling of fish nets (across the sea floor).
It requires that human societies be prudent in their extraction of wildlife resources or breed the species they need to be used as food or medical supplies.
Globally, regulations need to be stronger to incentivise large businesses and corporations to be sustainable in their harvesting practices.
Forest or fishing communities historically tended to be sustainable when the activities carried out were local and regional. Some exceptions mean that seasonal abundance allows for national-scale harvests.
Agriculture in the UK for the current most economically profitable crops tends to be more difficult because of the temperate-oceanic climate and low solar irradiation input (warmer and dryer climates, on the other hand, promote arable agriculture).
In June 2021, the Utilised Agricultural Area (UAA) was 17.2 million hectares, covering 71% of the total UK land area. UAA is made up of arable and horticultural crops, uncropped arable land, common rough grazing, temporary and permanent grassland and land used for outdoor pigs.5
Pollution control can be achieved by using biologically derived pesticides engineered to only affect a target species (for example, a pest), with no side effects on other species or subspecies. Pollution control also involves stopping waste from reaching open seas directly from the areas that pollute the most by using trapping nets or "bubble barriers". We can also trap greenhouse gases, reduce the number of pharmaceutical compounds in our water supply, etc.
Greenhouse gases can be trapped by using carbon capture and storage technologies. Rock mineralisation technology filters CO2 molecules out of the air and injects them into rocks to create minerals (and more rocks!).
Pharmaceuticals can be removed from the water supply through selective nanofiltration, which would be materials that specifically filter certain compounds in water.
Energy supply management refers to water or minerals that help our society function. Aquifers can be polluted or depleted, and the rivers can be overexploited through unsustainable water catchment techniques. Low-temperature extraction and renewable energy production processes are necessary to ensure less energy consumption and reduced chemical reactivity. The removal of planned obsolescence from economic systems is further required.
Storage and transportation methods of these resources can also be improved.
The Issues with a Circular Economy
A circular economy merely intends to incorporate sustainability concepts at all levels. There are several benefits to a circular economy, including reduced environmental pollution, but there are also downsides. It can often be difficult to:
Close the loop on materials: prevent downcycling (lowering the quality of the recycled material) and landfilling.
Build the recycling infrastructure: some countries or regions still need to build closed-loop recycling systems.
Obtain scientific awareness: the circular economy needs to base its principles on ecological and environmental science rather than economic philosophies. It's not enough to hear or see the words "science", "environmental", or "sustainability" but also to understand how they work.
Cooperation between businesses and consumers is essential for making the circular economy work. The circular economy offers a sustainable alternative to the linear model of take-make-waste, and it has the potential to create new jobs and stimulate economic growth. With continued effort, the circular economy will one day become a reality.
Circular Economy - Key takeaways
The circular economy is meant to include sustainability principles, such as water and soil quality remediation, biodiversity enhancement, renewable energy promotion, and reuse and recycling at all levels.
The circular economy accentuates the end-of-life stage in which products are often incinerated and landfilled in the "linear" economy, with negative impacts on health and the environment.
Downsides of a circular economy include the technological difficulties in recycling or reusing, building the necessary infrastructure and acquiring the proper scientific knowledge.
Applying a sustainable economy includes land use schemes that support the health of natural and wild ecosystems, responsible forest and aquatic resource management, pollution and waste control, and energy use.
To keep functioning, circular systems must operate with healthy ecosystems, connected economies and renewable energy sources.
References
- Doughnut Economics, About Doughnut Economics, 2022.
- Natgeo, A Whopping 91 Percent of Plastic Isn’t Recycled, 2018.
- Britannica, Biogeochemical cycle, 2022.
- Ben Robinson and Claire Bolderson, Rules around human waste in farming are 'out of date', 2020.
- DEFRA, Agriculture in the United Kingdom, 2021.
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