The Little Book of Circular Economy in Cities

We are currently living in an era of constant change and urban growth. We recently reached the point at which more than half of the world’s population is concentrated in cities and urban areas. This many people living in cities is a consequence of several factors; but perhaps the most important is the migration of people from rural to urban areas. Over time, cities have expanded so much that they have absorbed the small towns near them, or conversely several cities have merged into a single metropolitan zone. Furthermore, cities have developed a high dependency on their surroundings, specifically for the supply of resources and the disposal of waste. Besides urban population growth, the increase in average income in both developed and developing countries has resulted in a growing middle-class, which is demanding more products and services.2 To meet this growing demand, an increasing volume of raw materials is being extracted globally (flowing into the city), producing large amounts of waste (flowing out of the city) in the process.3 These flows require careful consideration for current and future city generations. Research to address this has been referred to as Urban Metabolism (UM); it is an important concept in this respect where cities are conceptualised as a living and breathing organism. The term was originally used by Abel Wolman in 1965,4 and has been developed and adopted by different disciplines to study different aspects of a city’s operation and performance. UM offers a technique to identify, describe and measure city flows that can provide city planners and politicians, as well as citizens, with information to aid decision-making that make cities (more) liveable. T here are varied diverse arrays and quantities of flows (and accompanying interactions) that occur in, around and outside of a city. These flows include, but are not limited to: 1. FLOWS IN – resources (metals, plastics, timber, fuels, food, water, etc.); 2. FLOWS OUT – manufactured products, but also wastes (i.e. solid, liquid and gas), these include, for example, municipal solid wwaste water, atmospheric (carbon dioxide emissions) in addition to other types of pollution. 1. FLOWS IN – resources (metals, plastics, timber, fuels, food, water, etc.); 2. FLOWS OUT – manufactured products, but also solid, liquid and gas wastes. These include, for example, municipal solid waste, waste water, and atmospheric pollution (from carbon dioxide emissions). As resources flow through a city, they are treated / processed in order to provide clean water, food, heat and power for inhabitants to survive and thrive, for example through the creation of roads, buildings and other city infrastructures that are so essential to 21st Century civilised life. UM refers to these physical structures as stocks, analogous to the bones and flesh of a set of biological defined organisms.

source :

https://blog.soton.ac.uk/serg/files/2017/12/littlebookofcirculareconomyincities.pdf