Iain Stewart

Energy and material flows of megacities

Significance Our quantification of energy and material flows for the world’s 27 megacities is a major undertaking, not previously achieved. The sheer magnitude of these flows (e.g., 9% of global electricity, 10% of gasoline; 13% of solid waste) shows the importance of megacities in addressing global environmental challenges. In aggregate the resource flows through megacities are consistent with scaling laws for cities. Statistical relations are established for electricity use, heating/industrial fuels, ground transportation, water consumption, waste generation, and steel production in terms of heating-degree days, urban form, economic activity, and population growth. Analysis at the microscale shows that electricity use is strongly correlated with building floor area, explaining the macroscale correlation between per capita electricity use and urbanized area per capita. Understanding the drivers of energy and material flows of cities is important for addressing global environmental challenges. Accessing, sharing, and managing energy and material resources is particularly critical for megacities, which face enormous social stresses because of their sheer size and complexity. Here we quantify the energy and material flows through the world’s 27 megacities with populations greater than 10 million people as of 2010. Collectively the resource flows through megacities are largely consistent with scaling laws established in the emerging science of cities. Correlations are established for electricity consumption, heating and industrial fuel use, ground transportation energy use, water consumption, waste generation, and steel production in terms of heating-degree-days, urban form, economic activity, and population growth. The results help identify megacities exhibiting high and low levels of consumption and those making efficient use of resources. The correlation between per capita electricity use and urbanized area per capita is shown to be a consequence of gross building floor area per capita, which is found to increase for lower-density cities. Many of the megacities are growing rapidly in population but are growing even faster in terms of gross domestic product (GDP) and energy use. In the decade from 2001–2011, electricity use and ground transportation fuel use in megacities grew at approximately half the rate of GDP growth.

Developing a community-based worldwide urban morphology and materials database (WUDAPT) using remote sensing and crowdsourcing for improved urban climate modelling

This paper outlines the WUDAPT (World Urban Database and Access Portal Tools) concept and highlights progress to date in developing this database for cities around the world. The next steps in the WUDAPT project are outlined, both in the immediate and longer term. Ultimately the goal is to provide an open access resource on urban morphology, materials and metabolism for all major cities that can be used for many different applications, in particular for climate and weather modelling, and urban climate change studies.

World Urban Database and Access Portal Tools (WUDAPT), an urban weather, climate and environmental modeling infrastructure for the Anthropocene

Capsule Summary:WUDAPT, an International community generated urban canopy information and modeling infrastructure (Portal) to facilitate urban focused climate, weather, air quality, and energy use modeling application studies.

The Electric City as a Solution to Sustainable Urban Development

ABSTRACT Comprehensive frameworks for sustainable urban development have been advanced by many scholars and global institutions in recent years. These frameworks are broad and overlapping in nature, but each has its own structure and emphasis. We review a cross-section of these frameworks, examining their foundations and general predictions for an urban future. From this review, we cultivate an argument that continued progress toward sustainable urban development hinges on low-carbon electrification. Our position for electric cities is supported by the sustainability literature and by empirical evidence gathered from the worlds largest cities, which shows that economy, physical environment, and basic service delivery improve with per capita electricity consumption. We close with an overview of the challenges associated with urban electrification.