A Comparison of Closed-Loop Models


In nature, there is zero waste because every being serves a purpose to help the ecosystem evolve. Waste from one specie becomes food for another [1]. Our human industrial economy, however, produces tremendous amounts of toxic pollutants such as plastic polymers, chemical solvents, metals, as well as radioactive waste and greenhouse gases [2]. This waste has taken the form of extreme global pollution that has caused serious environmental and health consequences. The growing levels of waste will seriously constrain economic growth. For this reason, scholars, organizations, and some of the largest corporations in the world have been increasingly studying how to create industrial models that emulate nature’s waste-free ecosystem.

In essence, Circular Economy theory shares the goal of creating industrial closed loop systems for waste, energy, and materials, as those involved in the study of Industrial Ecology, Biomimicry, and Cradle-to-Cradle. A comparison of the different models provides a clearer path toward Zero Waste goals.

Industrial Ecology:

Around the world, several industrial parks have increased energy and material efficiency via industrial symbiosis. The collaborative partnerships that took place across diverse industrial sectors provided great economic benefits to the region, and the success of this model led to the study of Industrial Ecology.

The primary example of Industrial Ecology is the Danish city of Kalundborg, where gas for the Gyproc plant is piped from the Statoil refinery, which is cheaper for Gyproc than using oil [2]. Another local company, Novo Nordisk, gives its industrial sludge for free to fish farmers, who use it as fertilizer instead of discharging it to the sea because it is more cost effective [3]. The Asnaes power station sells fly ash to cement factories instead of sending it to a landfill, while reducing costs for the cement producers [4]. Waste cooling water from the refinery is supplied to Asnaes, which avoids thermal pollution and saves costs [5]. Furthermore, when excess gas from the oil refinery is treated to remove sulfur, the clean gas becomes an energy source, while the sulfur is sold as raw material for the manufacturing of sulfuric [6]. The Asnaes power station also removes sulfur from its flue gases, which allows the company to produce calcium sulfate, the main raw material in the manufacture of plasterboard at Gyproc [7].

A good example close to home is the Bruce Energy Centre in Tiverton, where residues generated by Bruce Agra Foods are used either for animal feed or as an input for ethanol by Commercial Alcohols, while Bruce Tropical Produce uses carbon dioxide from the fermentation plant in their agricultural process [8]. The Brownsville Eco-Industrial Park in Texas, USA, also demonstrates how Industrial Ecology can be realized; the refinery sells its residual oil to the asphalt company, the automobile parts manufacturer purchases a ringer system for absorbent socks and rags, the seafood processor uses brown water for non-critical cleaning processes, the ballast manufacturer sells scrap asphalt to the asphalt company, and the wallboard company receives waste gypsum from the power plant [9]. Another attempt to Industrial Ecology is the Kawasaki Eco-City initiative, which provides eight recycling facilities for turning waste form diverse industries into valuable raw materials [10].

From an Economic Development perspective, facilitating Industrial Ecology is a challenging task because companies belong to different industrial sectors. This means that developing industrial parks with Industrial Ecology in mind may not result in attracting businesses if relative cluster ecosystems are not in place. The revenue from the waste companies generate represents a small portion of their income [11]. Cluster Theory suggests that as companies benefit from being in close proximity to their supply chain [12], so attracting businesses on such savings may not prove enough.

Instead, the symbiotic relationships usually take place naturally within existing regions due to regulatory or economic needs, rather than from a top-down approach [13]. Despite the challenges, it is important for the Economic Development field to understand the regional waste streams, as this may lead to great economic benefits. For those regions with mature businesses, these savings may prove vital for local resiliency and job retention.


The Biomimicry concept is to mimic natural processes using better designs in order to improve efficiency in our economy. Although Biomimicry is not exclusively a closed-loop system, it deserves attention because the founder of the Biomimicry institute, Janine Benyus, expressed in an interview that cities could eventually apply advanced technologies and architecture that allow cities to build fertile soil, filter air, clean water, sequester carbon, cool the surrounding temperature, provide biodiversity, and produce food. Alexandra Ramsen, the program director of sustainability at the consulting firm Rushing Consulting suggests in an article that our buildings could mimic canopy trees if rooftops evaporated and collected rainwater, and advanced materials were implemented to clean the air and sequester carbon.

Some living examples of Biomicry are the Zimbabwean East Gate Centre, which mimics the structure of African termites nests, which maintain a constant temperature by opening and closing vents. This application of Biomimicry in the construction sector consumes less than 10% of the energy used in similar conventional buildings. In the green-tech sector, WhalePower looked at the bumps on the flippers of whales to improve the design the blades of its wind turbines and achieve a 20% increase in energy efficiency. In textiles, Speedo designed Fastskin FSII for Michael Phelps when he won 8 medals in the Beijing Olympics. The swimsuit mimics the shape and texture of shark skin to reduce up to 7.5% in drag. In transportation, the Kingsfisher’s beak inspired the nose of a bullet train. In the waste sector,  Waste Management is looking at Biomimicry to understand how waste turns to alcohols, organic acids, biogas, diesel, soil, ethanol, ethyl acetate, methanol, Fischer-Tropsch diesel, lube oil, and various chemicals.

From an Economic Development perspective, it is challenging to play a primary role in product design. Design is a private sector task. As it will be shown in another article, Zero Waste policies usually try to affect design in a long term fashion by raising the costs of waste. For example, Extended User Responsibility laws that internalize the cost of production cost can have a long-term impact on product design. However, regional adaptation institutions and tools, such as university research, grant programs, and procurement can lead to successful enterprises in highly paid science and green-tech sectors.


The Cradle-to-Cradle concept looks at the Life-Cycle of a product to design business and technological solutions that reduce material requirements.

Cradle-to-Cradle solutions can be applied by various industrial sectors. For example, the Interface carpet company in Atlanta has a rental model that provides an incentive to the company to design a more durable product that only requires replacement by parts, rather than as a whole. This combination of modular design and service model concept is cheaper for the company and the consumer. At the end of its life cycle, the carpet is biodegraded into compost and fertilizers for new revenue streams and cost savings activities. In the foods and beverages sector, the Alaskan Brewing company uses a boiler system to turn spent grain into energy. Worldwide, there are countless of companies in the clothing, textiles, home design, and furniture manufacturing sectors have designed premium materials out of waste. Others, such as the Portland based company gDiapers, have designed premium products that become resources such as compost or energy at the end of their life cycle . The Cradle-to-Cradle Product Innovation institute has a certification process to assess material health, material reutilization, renewable energy and carbon management, water stewardship, and social fairness.

Some Cradle-to-Cradle cases share the characteristics of Industrial Ecology, as is the case of The Plant, which closed-loop farming organization in Chicago that produces kombucha tea, tilapia fish, beer, and vegetables with virtually no waste. Other Cradle-to-Cradle cases apply the use of Biomimicry, as is the case of the Ford River Rouge Complex, which uses Sedum vegetation to retain and cleanse water, and moderate internal temperature. The partnership between Ford and William McDonough, founder of the Cradle-to-Cradle Product Innovation Institute, has led to the concept car Model U, which is a hydrogen powered vehicle that uses upholstery fabric capable of perpetual recycling, and a car top made of a corn-based biopolymer that can be composted after use. The Ford Motors company has also developed some models with car seats made of plastic bottles.

From an Economic Development perspective, Cradle-to-Cradle shares the same challenges and opportunities in the impact of product design,

Toward a Circular Economy:

Implementing a model that clearly shows the true impact of Zero Waste policy and Economic Development programs is important because green washing is a serious problem, as it oftentimes increases the growth of the linear economy.

From the cases presented above, The Plant in Chicago deserves attention for applying  Zero-Waste closed-loop systems to food production. The Interface carpet company in Atlanta, is also a product with a high rate of circularity because it integrates both modular product designs and processes that turn waste into materials. Model U would also be a business model with high circular rate, as it integrates both modular product design with closed-loop manufacturing. However, the car remains a concept model and there are also more circular options than the use of GMO foods or plastic bottle recycling.

Most other cases of Industrial Ecology, Biomimicry, or Cradle-to-Cradle provide energy and materials savings, but it remains unclear how most solutions alter the high rate of new product replacement of the global economy. For this reason,  the Circular Economy model developed by the Ellen MacArthur Foundation provides a more comprehensive closed-loop model. For example, those activities that turn waste to new energy or materials belong to only half of the model (The Biological Nutrients side).

From an Economic Development perspective, one of the biggest barriers to a Zero Waste region is that production of the products consumed locally largely takes place in other countries. For example, in the United States, every person consumes about 6 pounds of natural resources a week, while 2,000 pounds of waste are discarded to support that consumption (Hawken, 2000). Those cities that apply closed-loop systems for energy and carbon savings may have little impact on overall global circularity if consumer products are manufactured in very detrimental ways to the environment and workers, and sent quickly to a landfill without being reused, repaired, and remanufactured to the greatest possible extent. Economist Richard Heinberg argues that focusing on energy-based solutions without making any structural change to the linear global economy would result in higher rates of resource depletion because higher energy productivity would enable us to extract and discard resources at an even faster rate (Heinberg, 2007).

A Zero Waste region requires closed-loop systems that go beyond energy and materials. We need to produce less.  A report by the Smart Prosperity Institute shows that decoupling growth creates greater economic and environmental benefits than energy-based solutions. This is because consumer waste only represents 5% of the raw material involved in the production and transportation of the final product (Hawken, 2000). The concept of increasing economic growth while consuming less is difficult to comprehend in our consumer culture, but the scholarly literature on The Technical Side of the Circular Economy model offers a very comprehensive map for reaching Zero Waste goals. While most Economic Development programs are targeted for recycling and green-tech sector initiatives, the reuse, repair, and remanufacturing sectors will create the biggest economic benefits in terms of cost savings and job creation. Developing these sectors will allow regions like Ontario to both reverse the process of globalization that destroyed many good paying jobs in the manufacturing sector and affect product design and innovation.

[1] Salvador, Oscar Jimenez. Biomimicry and City Design. The Meiated City Conference. Architecture_MPS; Ravensbourne; Woodbury University London: 01—03 April, 2014

[2] Pompeu Fabra University (UPF).

[3-9] El-Haggar, Salah M. PE, PhD. Sustainable Industrial Design and Waste Management. Cradle-to-Cradle for Sustainable Development. Professor of Energy and Environment. Department of Mechanical Engineering. The American University of Cairo. 2013

[10] Global Environment Centre Foundation, 2011

[11] Deutz and Gibbs, 2008

[12] Porter, Michael E. Clusters and the New Economics of Competition. Harvard Business Review, Nov/Dec98, Vol. 76 Issue 6, p77. Unites States.

[13] El-Haggar, Salah M. PE, PhD. Sustainable Industrial Design and Waste Management. Cradle-to-Cradle for Sustainable Development. Professor of Energy and Environment. Department of Mechanical Engineering. The American University of Cairo. 2013

Hawken, Paul. Natural Capitalism: Creating the Next Industrial Revolution. US Green Building Council. USA October 12, 2000.

Heinberg, Richard. Peak Everything: Waking Up to Centuries of Decline. New Society Publishers. USA. October 12, 2007






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