In the coming years, major urban areas of the planet will continue to expand, with an increasing population consuming more and more resources.
It is therefore necessary to identify the best practices for the future of megacities, especially in developing areas, so as to ensure a better balance of the ecosystem worldwide, a sustainable growth and management of resources, from energy to materials.
The topic was the focus of the study Energy and Material Flows of Megacities, developed by a team of 28 researchers from 19 universities – led by Professor Chris Kennedy from the University of Toronto, President of the International Society for Industrial Ecology and Senior Fellow of the Global Cities Institute – in collaboration with Enel Foundation.
The study, which was recently published in the prestigious American scientific journal PNAS (Proceedings of the National Academy of Science), is based on a comparative analysis of the so-called "urban metabolism" of 27 megacities worldwide, from New York to Tokyo, from Moscow to Mexico City and from Delhi and Los Angeles to Cairo.
The research analysed the differences between the cities' use of resources (energy, water, materials) compared to the waste (solid and liquid) each city produced. The unique method used, consists in the analysis of matter and energy flows that go beyond the administrative boundaries of the city, including metropolitan areas with a population of over ten million. The cities were then studied as a socio-economic and geographic continuum, rather than organisational entities. In fact, the urban metabolism method, of which Professor Kennedy is among the world's leading experts, considers the city as a living thing that grows and feeds from a series of input flows which allow for its development, once metabolised.
The collection and analysis of data, which involved more than a year of research, demonstrates that the strategic use of energy to increase the GDP, is rising faster than their actual population growth.
The 27 megacities that were examined account for 6.7 percent of the global population, but product 12.6 percent of global solid waste, and consume 9.9 percent of global gasoline and 9.3 percent of global electricity. They also contribute to the production of 14.6 percent of the global GDP. The study shows that the efficiency of these cities is often directly proportional to the population density. This is due to the fact that, among the many reasons, heating an apartment building that houses 100 people, requires less energy compared to heating single houses spread throughout a territory.
The research also confirms that the economy of megacities will continue to expand, as will their consumption levels and the actual number of megacities, which is expected to rise from 27 to 40 by 2020.
In this context, the various utilities will play a crucial role in the improvement of management performance and service supply (energy, waste management, transport), as well as in the development of more efficient solutions. The research highlights the need to define best practices aimed at achieving, through the collaboration of all of the major elements within the city (utilities, citizens, universities, research institutions and policy makers), a more sustainable urban dimension.