Circular Economy and GHG Emissions, Current Situation

Abstract

Greenhouse gas (GHG) emissions are directly related to economic growth. Throughout the years, men’s search for human progress has disregarded the idea of planetary boundaries, and, as a result, our societal organization is now built around a linear economic model in which overconsumption is stimulated, pushing resources’ exploitation to aggressive levels, and normalizing the generation of waste and pollution. GHG emissions are among the greatest impacts of human activity, because, as levels of CO₂ in the atmosphere rise, the world’s average temperature increases, causing a series of disturbances into the climate that are already threatening life on Earth. Experts suggest that over half of the world’s GDP is moderately or highly dependent on nature, and, therefore, is also subjected to the risks of nature loss. In this scenario, the concept of sustainability can be understood as the choice of practices that do not compromise the life of future generations and their access to critical resources, a system of values that often clashes with business as usual. Promoting this change is a complex problem that requires a great amount of innovation and adaptation from industry leaders, consumers, and policy-makers so that growth can be decoupled from GHG emissions and other environmental impacts. The idea of a circular economy dates back to the 80s, but only now it has gained the spotlight as it encompasses a new framework for business which could potentially help to cap GHG emissions significantly while guaranteeing economic profits and reducing risks of feedstock scarcity. This chapter recapitulates the path of modern society towards a linear economy and describes how it impacts GHG emissions and ultimately the climate. It provides a brief history of how scientists first developed ideas around sustainability and minding of resources and systems’ limitations, and presents the impacts of waste generation and waste management, to finally introduce the circular economy model. The principles of Circular Economy are presented and their benefits to the society are highlighted, as well as the challenges around its implementation in the current system. Circularity on natural resources and energy is exemplified and some key processes and industries are identified as potential areas of change with great leverage to solve the climate crisis.

1 Nature and Human Progress

Throughout the history of humanity, the concept of progress has been associated with the improvement of the standards of living, which can be translated as easier access to food, better health, safer shelters, and the simplification of all types of tasks through inventions and machines that can replace manpower in the most creative ways. It is quite common to refer to economic growth and productivity indexes as an attempt to measure progress. However, over the last centuries, not one decade has passed without communities having to experience some crisis: social, environmental, and financial problems have always haunted countries regardless of their location and development stage; quite often, these crises emerged unexpectedly, at periods where economic indicators would suggest great prosperity (Stiglitz et al. 2018). This repeated sequence of events shows patterns that put into question the concept of progress and growth that many nations and companies seek nowadays. Suppose these institutions (and consequently, society’s well-being) were more vulnerable to crises than what indicators such as gross domestic product (GDP) or productive rates can gauge; then, what elements would be missing in this analysis? Only what is monitored and measured can be acted upon; as a result, a society that focuses on the economy and not on other indicators such as the environment and inequality will systematically neglect the environment and the most vulnerable populations on most of the decisions and action plans (Stiglitz et al. 2018). Moreover, the World Economic Forum estimates that over half of the world’s GDP is moderately or highly dependent on nature, and, therefore, is also subjected to the risks of nature loss (Paleari 2024; World Economic Forum 2020). Experts have criticized how productivity has been measured over decades, disembodied from the physical inputs of production, and disregarding the fact that nature is an essential condition of production. On top of it all, economies have put too much focus on the output products and growth rates, while failing to reflect on the actual purpose of productivity, which should be seen as an enabler for a more harmonized life between men and the planet (Burkett 2006; Morseletto 2023).

The supposedly obvious perception that the inhabitable world we live in is part of nature and therefore subjected to its systemic rules and boundaries is something that has been forgotten year after year, particularly after the Industrial Revolution. Since 1650, the modern methods developed by men to grow and distribute food and improve human health have caused profound effects on population growth, as the mortality rate decreased (Meadows et al. 1972) thus creating a sense of progress based on technological solutions that can somehow overrule nature’s limits. Nevertheless, most techniques established and sustained until today rely heavily on resource extraction from the Earth and generate large amounts of waste that are not often adequately treated. This exploitation approach oversees the idea that the environment is critical for the survival of mankind and treats nature as a separate and objectified element.

More than three centuries after the Industrial Revolution, governmental organizations and business representatives started to realize that this linear mode of living has imposed increasing pressure on the world’s resources and climate and, most importantly, acknowledging the dramatic effects that an overexploited planet can have on men (European Union 2020; World Commission on Environment and Development 1987). Seeking feasible solutions to sustain modern and globalized life without burdening the environment has become the main topic on most agenda worldwide: the Kyoto protocol adopted in 1997 committed industrialized countries and economies in transition to limit and reduce greenhouse gases (GHG) emissions according to individually agreed targets (United Nations Climate Change); by 2015, 196 countries adopted the Paris Agreement, a legally binding international treaty on climate change whose goal is to hold the increase in the global average temperature to well below 2 °C above pre-industrial levels (United Nations Climate Change); in the same year, the United Nations adopted the Sustainable Development Goals (SDGs) as a universal call to action to end poverty, protect the planet, and ensure peace and prosperity by 2030 (United Nations Development Programme); in 2019, by means of the European Green Deal (EGD), a strategy to achieve climate neutrality by 2050 and decouple economic growth from resource use was concerted by EU members (European Union 2020). Experts expect the EGD to work as the never-before-seen linkage between topics of climate change, biodiversity, and circular economy, which often call for conflicting action plans and thus must be addressed in a holistic framework (Paleari 2024). While these movements respond to the urgency of the various crises that society has been facing, they also raise debates about the current ways of living and producing and pose enormous challenges and threats to state leaders and entrepreneurs (Sanford 2011; World Economic Forum 2020). As a result, not surprisingly, despite continued revision of policies and implementation strategies, a consolidated positioning of society remains lacking (Hartley et al. 2024). Honouring these commitments requires a deep understanding of the current economy and its relationship with the planet’s resources, plus the strength, resilience, and political activity to promote major changes in the current system.

2 Resource Scarcity, Limits to Growth, and Sustainability

To sustain economic growth, it is undeniable that a series of physical necessities are required to support physiological and industrial activity (food, raw materials, fossil and nuclear fuels, and the ecological systems of the planet that are capable of absorbing waste and recycling important chemicals) (Meadows et al. 1972). The availability of these necessities is associated with the concept of resources, or stocks, which are tangible and must be managed wisely. Another category of factors necessary for economic growth is that of the social necessities, which involves peace, social stability, education, employment, and technological progress (Meadows et al. 1972), all of which are mutable and subjected to events and cultural pacts developed throughout history and are capable of capping growth even if the physical conditions for growth are met.

The ensemble of natural resources used in the production of goods and services can be regarded as natural capital, and this concept is one of the foundations of sustainability (García-Navarro et al. 2013). As such, the natural capital can be finite, as is the case of minerals, crude oil, and gas, or renewable, such as the case of wood, fishery, and pasture, meaning that the latter can regenerate (ideally, in a faster rate than the rate of its consumption). This understanding leads to the principle of sustainable development, an idea that was openly discussed in the Brundtland report in 1987, and which calls for humans’ responsibility to ensure that the needs of the present are met without compromising the ability of future generations to meet their own needs (World Commission on Environment and Development 1987). Contrary to previous statements issued by the Club of Rome in 1972, which forecasted the depletion of resources impacted by exponential population growth without accounting for disruptive technological progress (Meadows et al. 1972), the sustainable development concept promoted in 1987 and sustained to these days does not necessarily impose limits for growth but rather takes into account limitations of the current technologies and organization plus the ability of the biosphere to absorb and compensate the effects of human activities. In short, the idea is to achieve a decoupling of growth and environmental impacts. This, of course, opens various opportunities for improving manufacturing technologies and population organization and leaves the promise of a feasible, clean, and more equal era of economic growth. On the other hand, the implementation of sustainable development challenges our status quo and imposes the adoption of new paradigms for the way that materials are sourced, processed, and disposed of.

3 Human Activity and Climate Change

Since the industrial revolution period that dates back to the seventeenth and eighteenth centuries, society has adopted practices of land exploitation, fossil fuel use, and consumption habits that have severely interfered with the planet’s fauna, flora, and atmosphere, which have been the cause of significant changes in the climate, especially a never-before-seen increase in the world’s average surface temperature when compared to the long-term average from 1951 to 1980. Analyses from several climate research groups indicated that 2016 and 2020 have been the hottest year on record ever since recordkeeping began in 1880 (Earth Science’s Communication Team at NASA’s Jet Propulsion Laboratory 2023; Osborn, 2023). Technical reports issued by the Intergovernmental Panel on Climate Change have strengthened the evidence that human-related emissions of greenhouse gases ultimately influenced recent climate change, including regional scale effects and extreme weather events (Arias et al. 2021). Other human activities influencing climate include the emission of aerosols and other short-lived climate forcers, as well as social-economic phenomena such as urbanization, which promote land-use change by replacing virgin areas with cities. All these anthropogenic activities lead to or contribute to a climate response because greenhouse gas emissions originating from fossil carbon cannot be incorporated into the natural systems (for example, fixed by forests) at the same rate that they are generated. The accumulation of GHG in the atmosphere alters its radiative properties concerning sunlight, resulting in the warming of the atmosphere, ocean, and land components of the climate system (Arias et al. 2021). The slightest variations in the temperature of a region or ocean can trigger serious crises in animal species that rely on specific conditions of biomes to feed, shelter, reproduce, and migrate.

Figure 1 shows the long-term evolution of carbon dioxide concentration in parts per million (ppm) in the atmosphere over the past 800,000 years. Over time CO₂ concentration has experienced fluctuations but never exceeded 300 parts per million (ppm) until the Industrial Revolution and the rise of human emissions of CO₂ from burning fossil fuels. Over the past few centuries and more noticeably over the last decades, global CO₂ concentrations increased dramatically, surpassing the mark of 400 ppm (Ritchie et al. 2020).

Fig. 1

Global atmospheric CO₂ concentration (National Oceanic and Atmospheric Administration (NOAA) 2023)

The problem of climate change reveals a complex issue around the erosion of natural capital. If the problem was first triggered during the first industrial revolution, over the last decades it is visible that it has been accelerated by poorly managed urbanization: food, energy, and water supply often develop somehow chaotically as communities grow and needs arise, without proper planning from authorities nor coordination among stakeholders on the best technologies for a specific region (Owen and Garniati 2016). Globally, around 70% of anthropogenic GHG emissions emanate from urban environments. While cities in lower income countries barely contribute to global emissions, cities in high-income and upper middle-income countries emit 18 and 21 times more CO₂ per capita than low-income countries’ cities, respectively (Mukim and Roberts 2022). This suggests that the activities associated with technological progress and the well-being of an urban lifestyle are the drivers of the GHG emissions’ increase.

Consequences of climate change include dangerously poor air quality in many cities, competition for water between urban and rural areas, unnecessary loss of fertile agricultural land, deforestation, and loss of biodiversity. For instance, studies estimate that 1 million species of animals and plants are already at risk of extinction (Ellen MacArthur Foundation and Material Economics 2021). Also, when examining the potential climate change-related hazards (floods, heat stress, tropical cyclones, sea-level rise, water stress, and wildfires), there is evidence that low- and lower middle-income countries will be the most affected by these extreme events. These trends overlap with rising levels of inequality in many cities globally, are obstacles to the eradication of worldwide poverty, and end up reinforcing climate change (Mukim and Roberts 2022).

A key challenge of actual society is to have high- and upper middle-income countries developing technological, business, and social solutions to cap their emissions without compromising their current standards of living, while the low-income countries need to path their economic development without following the CO₂ emission trajectories of the former. Still, to seek solutions to the climate change crisis, it is important to breakdown GHG emissions by categories, as depicted in Fig. 2: besides analysing emissions per region or country, it is critical to understand how each segment of society operates and why they emit GHG so that pain points can be spotted and tackled.

Fig. 2

Global greenhouse gas emissions by sector (Ritchie et al. 2020)

In 2016, the energy sector alone was responsible for 73.2% of global emissions, followed by activities of agriculture, forestry, and land use, which accounted for 18.4%. While the data clearly shows that energy use in industries, buildings, and transportation are the major polluters, followed by livestock and agricultural soil associated with the food sector, it also provides valuable insight on what to prioritize when fighting climate change: understanding how the energy matrix of countries and industries is established is key to promote alternatives to fossil fuel combustion; on the other hand, understanding that some sectors’ emissions are related to the waste that these sectors produce is an opportunity of applying the principles of circular economy to solve these issues. For example, the wastewater and landfills represent 3.2% of global emissions, because when organic matter decomposes it produces methane and nitrous oxides (Ritchie et al. 2020). If the problem of waste is tackled with a circularity approach, both methane and other by-products could be recycled and supplied to industries as fuel and feedstock.

Another example of how the linear approach is deleterious for many systems, including men, is that of the agricultural sector: while large-scale agricultural practices have proven to be extremely irresponsible in terms of water used for irrigation, hazardous for soil systems due to excessive use of fertilizers and energy inefficiency (Fusco et al. 2023), it is estimated that 20% of food produced in the EU is lost or wasted (European Union 2020). On one side, the planet’s resources are consumed at faster rates than they can regenerate, while the distribution system for food is so flawed that a fifth of the produce is lost to the environment. Moreover, increased food waste contributes to GHG emissions and landfill environmental problems (Olawade et al. 2024), and the effects of climate change put at risk the very conditions that make agricultural activities possible (Fusco et al. 2023). Incidentally, it is interesting to see how adverse events such as the COVID-19 pandemic introduced a paradoxical situation regarding food waste: while some countries experienced a 12% increase in food disposal associated with virus transmission concerns and food distribution challenges, others saw food waste decline as house cooking habits improved during lockdown measures and as the economic and access uncertainty made people more mindful of their consumption behaviour (Olawade et al. 2024).

As previously stated, all anthropogenic activity interferes with Earth’s systems and as a part of these systems will also be ultimately affected by them. By understanding the systems which provide physical support for population and economic growth and the relationships between these and Nature (i.e. extraction, emissions, waste), effective changes can be proposed (Meadows et al. 1972).

4 Consumption and the Problem of Waste

The modern lifestyle is based on a continuous, and often accelerated, desire to grow: population, land use, production, and consumption increase are usually regarded as positive symptoms of progress. This belief assumes that Earth will allow such expansion, that external factors will counterbalance the negative effects of human activity or that science will create alternative technologies that prevent future problems (Meadows et al. 1972). The problem with current consumption habits is that most products and services quite often are not sourced responsibly and involve some degree of waste disposal, while the impacts of such practices on the environment — the so-called “negative externalities” — are not accounted for by industries when pricing their products. Both sourcing and disposal represent the edges of a linear economy, which depletes resources from the planet to create goods that will eventually become waste and interfere with ecosystems.

The urge for differentiation and competitive advantages to gain customers and increase profits has led companies to flush the market with a great variety of products and intentionally decrease the durability of some of them, to create a welcoming environment for the next collection or model. Moreover, the lack of manufacturing requirements has allowed for the appearance of products with very short life and whose reparability and maintenance are impossible by design. In parallel, marketing strategies and permissive regulations have supported consumerism and the promotion of disposable products through the narrative of a superior lifestyle associated with non-negotiable hygiene, convenience and time-saving needs. As a result, consumers have been adopting a materialistic “make-use-dispose” mentality and promoting the renouncement and disposal of a product once used, or, in some cases, once it is no longer considered fashionable. Besides the cases in which the actual product that reaches the end of life is declared waste and eventually disposed of in landfills, a relevant fraction of waste is that composed of several parts of the product that lie broken and forgotten—material value that may or may not be seized depending on the cultural behaviour of consumers and the context of resources availability: times of abundance tend to increase waste generation while times of necessity tend to diminish it (Morseletto 2023). Thus, the problem of waste is a critical piece of the challenge towards a more sustainable economy (Sileryte et al. 2022):

Waste generation and its treatment is often the starting point for monitoring the transition towards a circular economy… as it represents the final stage of the undesired linear economy.

—Rusne Sileryte (2022)

According to the EU Directive 2008/98/EC, waste has been defined as any substance or object which the holder discards or intends or is required to discard (European Parliament and Council of the European Union 2008). Subcategories can then be created: hazardous waste is waste that presents any of a series of properties that pose a risk to human health and the natural environment; bio-waste means biodegradable garden and park waste, food and kitchen waste from households, restaurants, and similar activities and comparable waste from food processing plants; and waste oil category encompasses any lubricating or industrial oils that may have become unfit for the use they were intended. Also, waste resulting from prospecting, extraction, treatment, and storage of mineral resources and the working of quarries is usually treated as a separate category (European Parliament and Council of the European Union 2008) and is often omitted in most statistics about waste.

The fact that waste definition relies primarily on the subjective view of the waste holder to determine what is useful and what is not for their process opens the possibility of great losses of material and energy, besides the impacts that waste disposal techniques cause to the environment. Also, gathering accurate statistics about waste generation and disposal can be extremely challenging since there is no global harmonized policy or definition for waste management. The reliability of solid waste data is commonly influenced by undefined words or phrases, incomplete or inconsistent definitions, lack of methodology, inconsistency in units or dates, and estimates (Kaza et al. 2018). The question of which economic activities effectively produce which type of waste remains, and solving this issue is critical to evaluate if these sectors can be held responsible for waste production. Authors are starting to propose experiments using geospatial proximity to link companies’ primary activities to waste reports (Sileryte et al. 2022) and discuss frameworks that improve environmental and economic impact transparency and dissolve inconsistencies among waste generation reports provided by countries (Albizzati et al. 2024).

The best estimate on waste generation is that in 2016 around 2.01 billion tonnes of municipal solid waste were disposed of worldwide (Kaza et al. 2018). A more recent dataset published by European Union statistics, in 2020, points out that 775 million tonnes of waste were generated in Europe (excluding major mineral waste), which represents a waste generation of 1.7 tonnes per capita per year (Eurostat 2023). As a comparison, the World Bank estimated in 2018 that on a global scale, the average citizen generates 0.74 kg of waste per day, i.e. 270 kg per capita per year, while national rates fluctuate from 0.11 to 4.54 kg per capita per day (Kaza et al. 2018). This disparity is caused by the strong correlation between waste generation volumes, income levels, and urbanization rates. Additionally, authors have analysed the effect of the COVID-19 pandemic on waste production and reported a downward trend of up to 4% depending on the country, mostly associated with the reduction in the economic and industrial activities imposed by the crisis. On the other hand, when municipal solid waste was analysed and isolated, an upward trend of plastic and healthcare waste generation was observed, caused by the increased use of disposable items for personal protective equipment to prevent virus transmission coupled with the absence of robust waste sanitation measures (Olawade et al. 2024).

In Fig. 3, data about the waste of EU countries is shown for each key economic activity: construction and demolition sectors were responsible for more than a third of the waste mass generated in 2020, followed by mining activities. Other sectors related to urban lifestyle such as households, wastewater, and manufacturing, each represent around 10% of the share. An exam of the dataset also reveals a great variability from country to country, showing that the organization of cities, industries, and agriculture of society will directly influence the pattern of the waste streams that they produce.

Fig. 3

Waste generation by economic activities and households, 2020 (Eurostat 2023)

The problem of waste starts when it has to be managed or disposed of, as each final destination will provoke a degree of impact on society. Income and urbanization levels play an important role in the extent of waste collection: while high- and upper middle-income countries tend to provide universal waste collection, low-income countries reach about 48% of waste collection in cities and only 26% in rural areas. Rural waste collection improves in the case of middle-income countries reaching 33–45% recovery in those areas (Kaza et al. 2018).

In 2020, 1971 millions of tonnes of waste were treated in the EU, including waste imported and excluding waste that was exported. More than half of the waste was treated in recovery operations, which include recycling, backfilling or energy recovery, which is way above the global average: worldwide, it is estimated that material recovery through recycling or composting represents only 19% of waste treatment methods (Kaza et al. 2018). In the EU, the remaining residues where landfilled or incinerated with energy recovery or disposed of otherwise. Figure 4 shows the share of treatment type by European country.

Fig. 4

Waste treatment type of recovery and disposal, 2020 (Eurostat 2023)

In general, from 2004 to 2020, most of the EU countries have improved waste management and significantly increased their rates of recycling of all types of waste. However, as shown in Fig. 4, some countries such as Italy, Belgium, Slovakia, and Latvia have recycling more advanced, while Sweden, Finland, Romania, and Bulgaria recur mostly to landfilling and the difference in recycling rates is large.

Specifically regarding municipal solid waste recycling rates, the difference was even more noticeable. While Germany’s municipal waste recycling rate was 70%, Malta achieved only 11%, and Kosovo registered no recycling. Germany, Austria, Slovenia, the Netherlands, Switzerland, Luxembourg, Belgium, and Italy achieved recycling rates of 50% or higher, while another seven countries recycled less than 20% of their municipal solid waste. Besides municipal solid waste, challenges around packaging and waste electrical and electronic equipment must be addressed to achieve some of the targets established by the EU concerning recycling rates (European Environmental Agency 2023).

Scientists have analysed how different waste management technologies perform environmentally by applying life cycle analysis methodologies to specific case studies and comparing the impacts of treating residues, bio-waste, cardboard, plastics, metals, and glass and the evolution of management techniques. Due to increasing pressure on landfill bans, residues have been directed to energy recovery instead of landfills, which allows for the recovery and use of methane emissions as fuel. Thanks to investments in material sorting and the use of secondary raw materials, the recycling industry has been developing to hopefully replace fossil fuels and virgin materials. As the separate collection of waste increases, so does the scale of this industry; therefore, advances can be proposed such as the use of biofuels obtained from waste to replace fossil fuels and ease the burden on other renewable energies, and the deployment of carbon capture in the energy recovery plants (Hupponen et al. 2023).

It is estimated that by 2050 global population will reach 10 billion (Ellen MacArthur Foundation and Material Economics 2021), and if current waste generation per capita rates apply, this will mean a prohibitive amount of material to be managed and disposed of. As a response, according to the revised EU Waste Directive 2018/851, 55% of municipal waste must be recycled by 2025 and 60% by 2030 (Hupponen et al. 2023). Consequently, recycling targets for packaging waste will also increase, and the rules governing how the recycled rate of municipal solid waste is calculated will become stricter.

5 From Industrial Symbiosis to a Circular Economy

While the “take-make-waste” approach of the current economy is proving to be the trigger of many of the problems faced nowadays, the concept of a circular economy proposes to manage the economic activity of our society in the same way that the global environment circulatory systems operate. This implies that there is a balance between demand and material production, with no surplus nor deficit, and that everything can be reused and recycled, thus aiming for a zero-waste system. Also, industrial sectors and value chains are interconnected and benefit from each other’s streams, just like ecosystems do.

Water, energy, and food give the example of how interdependent resources are and why it is important to tackle them systemically: to grow, process, and distribute food, a vital element of human existence, water and energy are required. In its turn, water cannot be treated nor transported without energy. Future and sustainable solutions in the field of energy must tackle the problem of consumption, in the sense that they may propose measures for energy use reduction and efficiency. At the same time, energy must be sourced from sustainable sources. Finally, a sustainable energy system must guarantee equal and secure access to energy resources (Owen and Garniati 2016).

Back in 1940, geographers and economists developed the term “industrial symbiosis” to study the location of industries that would result in efficient utilization of resources and avoid waste (Ekins et al. 2019). In 1966, Boulding opened a discussion of closed and open systems and provided the first definition of linear flows as the “econosphere”, a system in which materials are extracted from the Earth only to end up in noneconomic reservoirs (i.e. the idea of waste as loss of value). Until the late 1970s, industry experts such as Spilhaus did recognize that waste problems existed and should be tackled, but unfortunately, that idea was not the priority of the economy back then. In 1982, award-winning architect and economist Stahel developed a paper that would be the foundation of the “closed-loop” approach to production processes: by fostering product-life extension, long-life goods, reconditioning and waste prevention, the focus of the economy would shift from “take-make-waste” to pursuit for a “Performance Economy”. By 1989, Frosch and Gallopoulos proposed the model of industrial ecosystems (Ekins et al. 2019), suggesting that waste from a process could be used as raw material by another process: it was the birth of “Industrial ecology” discipline, also known as the “science of sustainability”, given its interdisciplinary nature (Ellen MacArthur Foundation 2023).

To understand the foundations of a circular economy, it is important to be familiar with industrial ecology and its concept of industrial metabolisms. These could be regarded as the collection of physical processes that uses labour to convert flows of materials, energy, and labour into finished products and wastes (Washington and Ayres 1994). This school of thought compares the industrial metabolisms with the natural metabolism of the Earth and highlights the main difference between them: natural cycles are closed, meaning that they don’t need external sources or sinks and recycle all types of nutrients, while industrial cycles are open, usually relying on the extraction of high-quality materials from the Earth and returning a degraded version of them to nature (Washington and Ayres 1994), often in the form of pollution or negative impact. Over the last decades, several scientists of various disciplines worked to understand how to close industrial cycles and build the basis of what today is called the circular economy. As the Club of Rome first pointed out, planetary boundaries are a reality and must be considered when planning economic growth (Meadows et al. 1972). The motivations behind the circular economy school were well summarized by Nancy Bocken in 2016:

The recognition of the limits to planetary resource and energy use, and the importance of viewing the world as a ‘system’ where pollution and waste are seen as a defeat, lay at the foundations of the circular economy thinking.

—Bocken et al. (2016)

While the schools of thought around the concepts of circular economy have gained the spotlights over the past few decades, some authors argue that circular solutions have been historically applied to a multiplicity of products and the proportion of circular economy has expanded or contracted in the economy according to the contexts faced by society such as profit targets; business opportunities; or scarcity of time, skills, labour, or resources (Morseletto 2023).

6 Circular Economy Principles

According to the Ellen MacArthur Foundation, in a circular economy, men’s activities build and rebuild overall system health, meaning that they are restorative and regenerative by design (Ellen MacArthur Foundation 2023):

The circular economy is a framework for systems solutions and transformation that tackles global challenges like climate change, biodiversity loss, waste, and pollution.

—Ellen MacArthur Foundation (2021)

There are three principles of circular economy, all driven by design. The first is to eliminate waste and pollution, which seeks to prevent losses of valuable resources and avoid waste’s impacts on human health and natural systems. The second is the design of circulated products and materials, which favours activities that preserve energy, labour, and materials that were input to a product and employs reuse, remanufacturing, and recycling to keep the value circulating in the economy. The third principle is that of the regeneration of nature, which aims to return valuable nutrients to soil and support carbon sequestration (Ellen MacArthur Foundation and Material Economics 2021).

Studies have shown that industries, such as cement, aluminium, steel, and plastics, could benefit from circular economy strategies to eliminate over 9.3 billion tonnes of CO₂ equivalent by 2050. This could escalate to the reduction of 45% of global emissions, which would mean a major advance to the committed targets by EU countries (European Union 2020; Ellen MacArthur Foundation and Material Economics 2021).

Regarding financial and societal aspects, while, for many years, common belief has been that the wealth of a nation lies in the linear economy model and anything different would inevitably collapse GDP and prosperity, circular economy concepts challenge this idea. Waste reduction can reduce GDP as reducing production surely does, but the limited availability of goods to buy enables consumers to allocate their income to higher quality products and services. Ultimately, a circular economy can have positive effects on industry and society such as optimization, material and energy cost savings, efficiency gains, value retention, the promotion of innovation, economic growth, business and job opportunities, local community empowerment, social inclusion, and equity (Morseletto 2023).

The ensemble of all these potential benefits also suggests that the circular economy concept can be an effective crisis response but also boosted by this context: during crises, major innovations are pushed to materialize to quickly solve problems; scarcity stimulates the simplification and regionalization of supply chains to mitigate sourcing depletion, while governments gain power to regulate, tax, and guarantee a fair-play market and social well-being (Hartley et al. 2024).

7 Designing Out Waste

Experts estimate that more than 80% of a product’s impacts are determined at the design phase (DG Enterprise and Industry and DG Energy 2012). This means that, if the appropriate incentives are given, a company would be able to design solutions that pose less harm to the environment. The concept of eco-design takes sustainability principles to guide the development of goods that will break the linear cycle of production currently in place and avoid the generation of waste. The key requirements to be considered when eco-designing a product suggested by the Circular Economy EU Action Plan are (European Union 2020):

• Increase energy and resource efficiency of products.

• Improve product durability, reusability, upgradability, and reparability.

• Enable remanufacturing and high-quality material recycling.

• Tackle issues of hazardous components in products.

• Increase recycled content in products, without jeopardizing performance or safety.

• Reduce carbon and environmental footprints.

In parallel, some measures are proposed at the policy-making level, to ensure that the business environment and infrastructure support and reward the implementation of circular solutions:

• Prolonged product use by restricting single use and countering premature obsolescence.

• Introducing a ban on the destruction of unsold durable goods.

• Incentivise product-as-a-service models where producers keep the ownership or the responsibility for the product’s performance throughout its lifecycle.

• Mobilize the potential of digitalization of product information to support material traceability, including solutions such as digital passports, tagging, and watermarks.

• Rewarding products based on their different sustainability performance, including by linking high-performance levels to incentives.

8 The 3 R’s Policy and Beyond: The 9 R’s

To reduce the amount of waste disposed in the environment when using a product, a series of actions should be taken which follow what is often known as “waste hierarchy”. The 3R policy is a popular sustainability motto because it encompasses three main ideas: reduce, reuse, and recycle. The idea of reducing waste pushes designers and consumers to seek other solutions to execute a certain product function, such as choosing multi-purpose tools and materials and avoiding disposable items. It also brings up deeper reflections on consumption habits and learning to distinct superfluous wishes from essential needs (Qamar and Al-Kindi 2020). The idea of reusing products extends their lifetime before disposal and has beneficial effects on the overall system because it slows down materials’ use flows and consequently the resource’s depletion rates to manufacture new items (Bocken et al. 2016).

The third R refers to recycling, meaning that an item will be transformed again into a raw material to produce the same or a different item (Qamar and Al-Kindi 2020). Material use and their potential recyclability could be classified into three clusters: (1) uses economically and technologically compatible with recycling under current prices and regulations such as structural metals and industrial catalysts; (2) materials that are technically recyclable, but whose uses that are not economically compatible with recycling under current prices and regulations, such as packaging materials, refrigerants, solvents, and other structural materials; and (3) use for which recycling is inherently not feasible, such as most coatings, pigments, pesticides, herbicides, germicides, preservatives, flocculants, explosives, fuels, lubricants, reagents, detergents, and fertilizers (Washington and Ayres 1994). When material recycling is impossible, a fourth R is recommended as a last and more sustainable alternative than landfilling: recovery. Several types of waste are used as fuel for energy recovery, with successful results.

To transform the economy into an ecosystem that applies the 3 R’s, current companies need to reframe product value chains and incorporate a series of practices that prevent materials from dissipating and ending up in landfills. Thus, a framework with 6 R’s are proposed: refuse, suggesting consumers commit to consciously avoid waste and fight consumerism and irresponsible manufacturing practices (Morseletto 2023); reduce, by buying only what is needed; reinvent/rethink, in which consumer habits are questioned and challenged and innovation is used to solve critical problems (Hartley et al. 2024); reuse and repair, to expand the usable lives of things by revisiting items for their functionality rather than fashion or trend, and by replacing defective components with new or as-good-as-new, thus preventing the disposal of fixable goods (Knäble et al. 2022); recycle, technically or biologically, as a pillar of sustainable waste treatment for waste to be reintroduced as a raw material (Kubiczek et al. 2023); and rebuy (or replace), fostering consumption of second-hand and recycled products (Qamar and Al-Kindi 2020; Ellen MacArthur Foundation 2019), which allows material resources to serve different individuals multiple times (Knäble et al. 2022).

To summarize all these concepts, the Ellen McArthur Circular Economy System diagram (Ellen MacArthur Foundation 2019), popularly known as the butterfly diagram, depicts the state-of-the-art design approach for circular products and businesses and incorporates most of the aforementioned R’s and key initiatives. The diagram shown in Fig. 5 highlights the main cycles that sustain a circular economy. On the left, the circularity of nutrients and carbon is described: the anaerobic digestion is highlighted as an aspect of the biological cycles since biogas combustion will result in biogenic (i.e. not fossil-based) CO₂ emissions and the by-products of the digestion will foster land regeneration and nutrient flows. On the right, technological cycles propose paths to minimize resource losses (repair, remanufacture), avoid product manufacturing (reuse, sharing, and other models), and adopt material recycling, thus contributing to a closed-loop ecosystem where waste and negative externalities are minimised.

Fig. 5

Circular economy systems diagram (Ellen MacArthur Foundation 2019)

9 Energy, Industries, and the Circular Economy

While the framework of circular economy is somehow recent and various business models have been built with linearity in mind, it is important to recognize that circular economy solutions date as far back as humans themselves: in the ages of scarcity, reuse, repair, and recycling were common practices to deal with the limitations of raw materials, land, and food. As P. Morsoletto described human’s attitude towards materials in the Prehistoric and the Bronze Eras:

…materials and objects tended to be precious in the age that can be defined as the age of scarcity. When something required time, skills, labour, and resources, it was preserved.

—Piero Morsoletto (2023)

Nowadays, however, scarcity is not always an issue, since there is a large concentration of resources on the stakeholders that are often the protagonists of pollution. As a result, scarcity cannot be the only driver for a circular economy. In an Era that could be called the age of opportunities, the possibility of profit increase, cost reduction, or simple convenience can be enough to push business models towards circular alternatives (Morseletto 2023). Finding novel commercial opportunities from waste is a booster of circularity and industry symbiosis.

Among the various challenges to building a circular economy and limiting the global average temperature rise to no more than 1.5 °C above pre-industrial levels, there are key enabling technologies that support waste reduction and/or decarbonization of relevant sectors of the economy. Recent reports have discussed strategies for the municipal solid waste, metal, petrochemical, cement, and transportation sectors (Cucina 2023; International Renewable Energy Agency 2020; IRENA 2017; Knäble et al. 2022; Kubiczek et al. 2023; Renewable Energy Agency 2020; Zhang et al. 2023).

Regarding circularity and the reintegration of materials into the economic system, a recent review of 34 case studies across the EU deduced that recycling is the solution adopted in 24% of the cases, while reduction of raw material use is the method chosen in almost 18% of the cases. The food and beverage sectors appear to be the best-performing industry in terms of circular practices, while capital equipment is the worst (De Pascale et al. 2023). Complimentary, studies suggest that, in most contexts, circular economy pillars (renewable energy use, reuse, repair, and recycle) have a strongly significant impact on GDP per capita, while supporting GHG emission reduction and fighting unemployment (Knäble et al. 2022).

As to energy sourcing, much expectation is put around renewable energy consumption, which has proven to have a significant impact on the reduction of GHG emissions, without compromising GDP per capita (Knäble et al. 2022). Nonetheless, the renewable energy industry has major challenges to overcome, such as balancing supply intermittency against supply security, sourcing critical raw materials for renewable energy, and infrastructure set up for electrification, to name a few (Renewable Energy Agency 2020). Renewable and low-carbon technologies used in photovoltaic materials currently use various combinations of silicon, gallium, arsenic, tellurium, cadmium, copper, indium, and selenium, among other elements that guarantee their advanced properties. Hybrid, electric vehicles and wind turbines rely on specific motors that require rare earth elements such as neodymium, praseodymium, dysprosium, samarium, cobalt, and copper. Finally, replacing fossil fuels with electrification imposes high-performance energy storage, which is currently intensive on lithium and graphite (Goddin 2020). All these are critical raw materials, if not for scarcity, due to their geographical concentration. In parallel, all this new technology comes associated with the problem of electrical and electronic equipment waste (WEE or e-waste), whose management is an urgent issue to be tackled both on social and technological levels (Jabbour et al. 2023): collection of e-waste and treatment methods to recover critical raw materials are still limited and represent a barrier to the implementation of a sustainable, zero emission value chain for the energy sector.

Therefore, tackling the climate change and sustainable development challenges requires a systemic energy transition, and the latter can only be accomplished sustainably if the circular economy principles are applied to guarantee that the material resources are exploited with the lowest possible impact.

This book explores the problems of various sectors of the society and how the application of circular economy principles is supporting them to find efficient and sustainable solutions. Sustainable energy can be defined as any energy source with economic viability that does not provoke negative social or environmental impacts, in particular not being a contributor to climate change (Owen and Garniati 2016). That reasoning can be applied to other industrial sectors when assessing sustainability. Chapters will be dedicated to discuss: how energy storage issues can be solved with the reuse of abandoned mines; circular approaches to transform the problem of agricultural waste into an opportunity for biofuel distribution; how secondary resource from waste dumps can supply energy and materials for a greener clinker production; how wastewater treatment with algae can provide valuable biomass; current possibilities of CO₂ storage in coal bed methane deposits; policy-making for circular economy strategies at city level and in the tourism sector; circular economy approaches and best practices for the fossil fuel industry; recovery of lithium batteries to support circularity of vehicle electrification; plasma gasification techniques for biomedical waste; recovery and use of coal waste; case study of biofuels for the cement industry based on hazardous and contaminant wastes; assessment of Colombian industrial situation and gaps towards a circular economy; and, finally, an overview of the limits and potentials of the circular economy design.

10 Concluding Remarks

Moving away from the “take-make-waste” linear business models and establishing a regenerative economy by design requires a systemic approach to change the status quo of most value chains. Once sustainability and circular economy principles are integrated into industrial activities, the value creation and progress concept must be shifted to focus on societal benefits. As a result, energy and materials are safe and obtained from renewable sources and the superior design of products prevents waste generation. These combined actions create cycles that preserve the embodied energy of materials and increase carbon sequestration (Ellen MacArthur Foundation and Material Economics 2021), thus ultimately capping GHG emissions and, at the same time, creating job and business opportunities for all.