As the world faces escalating challenges from climate change and resource depletion, the need for sustainable production systems has never been more urgent. In response, the concept of a circular economy—where resources are reused and recycled rather than disposed of—has gained significant traction. However, effectively measuring and evaluating the circularity of such systems has remained a challenge. Researchers at the University of Illinois Urbana-Champaign have now made a breakthrough in this area by developing a Circularity Index (CI), a comprehensive metric designed to quantify circularity within bioeconomic systems.
The Circularity Index: A New Tool for Sustainability
The Circularity Index is a novel tool that offers a systematic way to measure how circular or linear a bioeconomic system is. It does so by assigning a value between 0 and 1, where 0 represents a completely linear system (one that follows the traditional “take-make-dispose” model) and 1 signifies a fully circular system, where waste is minimized, and resources are continually reused.
This innovative index covers eight critical categories: take, make, distribute, use, dispose, recover, remake, and reuse. Each category represents a stage in the lifecycle of a product or resource, from initial extraction to final disposal or recovery. The CI is computed by entering data relevant to each category, providing a clear and concise measure of the system’s overall circularity.
Case Studies: Practical Applications of the CI
To demonstrate the practicality of the Circularity Index, the researchers applied it to two distinct case studies: a corn-soybean farming operation in the Midwestern United States and the broader U.S. food and agriculture system.
1. Corn-Soybean Farming Operation
In the first case study, the researchers examined the nitrogen cycle within a typical corn-soybean farm over an eight-year period. They specifically compared two different fertilizer treatments: urea and manure. By inputting production and output data into the Circularity Index, they were able to calculate a CI of 0.687 for urea and 0.86 for manure. This result indicates that using manure as fertilizer supports a more circular economy, as it more effectively recycles nutrients back into the farming system.
2. U.S. Food and Agriculture System
The second case study took a broader view, analyzing the entire U.S. food and agriculture system with a focus on energy use. The researchers used national data from agencies like the USDA, EPA, and DOE to compare the current system to one based on the Environment-Enhancing Food Energy and Water System (EE-FEWS) framework. This alternative approach emphasizes the recovery, remake, and reuse of organic waste. The findings were striking: the current system had a CI of just 0.179, while the EE-FEWS framework could achieve a CI of 0.84. This significant improvement demonstrates the potential of circular practices to transform the U.S. bioeconomy into a more sustainable model.
Implications for Policy and Industry
The development of the Circularity Index has far-reaching implications, both for policymakers and industry leaders. As nations and organizations worldwide strive to meet sustainability targets—such as the United Nations’ Sustainable Development Goals—the CI offers a powerful tool to measure progress and identify areas for improvement.
For example, food companies could use the CI to assess and demonstrate the circularity of their production processes to consumers, potentially gaining a competitive edge in a market increasingly driven by environmental considerations. Moreover, the CI could guide governmental policy by identifying the most effective strategies for reducing fossil fuel use, increasing renewable resources, and minimizing water consumption.
A Versatile and Scalable Metric
One of the most significant advantages of the Circularity Index is its versatility. It can be applied to various resource types, including minerals like carbon and nitrogen, or non-mineral resources such as water and energy. Additionally, the CI can be used to evaluate different scales of systems, ranging from individual processes or farms to entire industry sectors, national economies, or even global markets.
“Our current production system heavily relies on fossil fuels, with minimal recovery of biowaste,” said Yuanhui Zhang, lead author and professor in the Department of Agricultural and Biological Engineering. “If we can recover food waste and manure, turning it into energy and fertilizer, we can recycle these resources back into the agricultural systems they originate from. The CI provides a straightforward yet powerful metric to guide these efforts, helping us transition toward a more sustainable bioeconomy.”
Conclusion: A New Era for Circular Bioeconomy
As the global community continues to grapple with the twin challenges of climate change and resource scarcity, the Circularity Index represents a significant step forward in the quest for sustainable production systems. By providing a clear, quantitative measure of circularity, the CI enables more informed decision-making and supports the development of policies and practices that can help secure a sustainable future for generations to come.