The traditional economic system is linear—we produce, distribute, use, and dispose of products. To increase sustainability, we need to develop a circular economy. Rather than just using natural resources, we must recover, reuse, and recycle waste materials, said Yuanhui Zhang.
Zhang, a professor in the Department of Agricultural and Biological Engineering at the University of Illinois Urbana-Champaign, is the lead author of a new paper published in the journal Resources, Conservation and Recycling. In it, Zhang and his colleagues outline a method for quantifying circularity in bioeconomic systems.
As the world faces the challenges of mitigating climate change and providing resources for a growing population, there is increasing focus on developing circular economies for sustainable production. But to evaluate strategies and impacts, it is necessary to have reliable metrics.
“Circular bioeconomy has become a hot topic in research, but most studies are merely descriptive and there’s no way to measure impacts.” said Zhang. “To move the technology forward, we need measurements to quantify effects, establish benchmarks, compare approaches, and identify weak spots.”
In the paper, the researchers provide a step-by-step outline of the Circularity Index (CI), which measures circularity on a scale from 0 to 1. Zero means the system is completely linear, and 1 means it is completely circular. The index includes eight categories: take, make, distribute, use, dispose, recover, remake, and reuse. The CI is computed by entering available data into each of these categories.
The CI is a scalable method that can be used on different resource types and systems, depending on the focus of interest. Resources can be minerals, such as carbon or nitrogen, or non-mineral, such as water or energy. Systems can range from a process or a farm to an industry sector, a national economy, or even the global economy.
The CI can serve as an indicator to support policy initiatives such as the United Nations’ Sustainable Development Goals. It also has potential commercial value; for example, food companies can demonstrate their production circularity to consumers.
“We know it’s important to reduce fossil fuel use, increase renewable resources, and minimize our water consumption. But to do so effectively, we need to know how much, and what the weak links and tradeoffs are,” said Zhang. “The CI provides a single number that allows you to establish a baseline, compare systems, and determine best strategies for action.”
Read the study here.