A global survey of energy and material flows from 27 so-called “megacities” has been published in the Proceedings of the National Academy of Sciences journal.
The study, led by engineers at U of T with an international interdisciplinary team of researchers, identifies a “megacity” as a metropolitan region with over 10 million inhabitants. As of 2010, these 27 megacities collectively housed 460 million people, which is equivalent to 6.7 per cent of the global population. Most of the megacities included on the survey can be found in fast-growing developing countries, such as China, Indonesia, and Brazil.
Mega-cities consume large amounts of energy, mainly in the form of electricity. These colossal population hubs process essential services such as water treatment as well. The important question is whether these megacities can develop sustainably by reducing the toll they take on their environment. Iain Stewart, a post-doctoral fellow and geographer at the Global Cities Institute, highlights that although activities are much more concentrated in cities, “megacities are not particularly efficient in their use of energy and water.”
While this global survey does not examine the levels of pollution in these cities, it does examine the levels of material and energy consumed, by means of a longitudinal data collection process organized between 2001-2010. The survey also examines what is responsible for this consumption — whether it is heating-degree days, urban form, economic activity, or population growth. Ultimately, this study concludes that the larger the urbanized area per capita, the higher the level of electricity use.
Not all megacities are created equal. Some megacities that are located farther away from the equator, such as New York, Moscow, Seoul, and Tokyo, have a greater need for energy as result of a greater reliance on heating.
Some megacities have developed important policies and infrastructure that have enabled them to use energy more efficiently. For example, Tokyo has been able to reduce its water leakage to only three per cent. Moscow, as well, has maintained relatively high efficiency in the use of heating through a large district-centralized heating system, as opposed to having smaller, but more separate heating systems serving the city.
The study reminds us of the disparity between megacities in the developed world and those in the less developed world, given that a substantial number of citizens in less developed countries still do not have access to clean water, electricity, sewage, and formal waste disposal. Poorer megacities have to tackle these more mundane problems in addition to challenges posed by sustainability and efficient energy usage.
Stewart explains that in a study of such scale, errors in data are inevitable; however through much processing and analysis of data, “outliers are identified.” Stewart explains that this global survey is at the second phase of the overall research project. “In the latter days of the study,” Stewart says, “[we] will examine the role of utility companies in regulating the use of energy and water in the megacities.”
Correction: An earlier version of this article misidentified Iain Stewart as Christopher Kennedy.
