Methodology and applications of city level CO2 emission accounts in China

Defining and advancing a systems approach for sustainable cities

The global response to warming of 1.5oC comprises transitions in land and ecosystem, energy, urban and infrastructure, and industrial systems. The feasibility of mitigation and adaptation options, and the enabling conditions for strengthening and implementing the systemic changes, are assessed in this chapter.

Strengthening and Implementing the Global Response

As national efforts to reduce CO2 emissions intensify, policy-makers need increasingly specific, subnational information about the sources of CO2 and the potential reductions and economic implications of different possible policies. This is particularly true in China, a large and economically diverse country that has rapidly industrialized and urbanized and that has pledged under the Paris Agreement that its emissions will peak by 2030. We present new, city-level estimates of CO2 emissions for 182 Chinese cities, decomposed into 17 different fossil fuels, 46 socioeconomic sectors, and 7 industrial processes. We find that more affluent cities have systematically lower emissions per unit of gross domestic product (GDP), supported by imports from less affluent, industrial cities located nearby. In turn, clusters of industrial cities are supported by nearby centers of coal or oil extraction. Whereas policies directly targeting manufacturing and electric power infrastructure would drastically undermine the GDP of industrial cities, consumption-based policies might allow emission reductions to be subsidized by those with greater ability to pay. In particular, sector-based analysis of each city suggests that technological improvements could be a practical and effective means of reducing emissions while maintaining growth and the current economic structure and energy system. We explore city-level emission reductions under three scenarios of technological progress to show that substantial reductions (up to 31%) are possible by updating a disproportionately small fraction of existing infrastructure.

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City-level climate change mitigation in China

While it is understood that cities generate the majority of carbon emissions, for most cities, towns, and rural areas around the world no carbon footprint (CF) has been estimated. The Gridded Global Model of City Footprints (GGMCF) presented here downscales national CFs into a 250 m gridded model using data on population, purchasing power, and existing subnational CF studies from the US, China, EU, and Japan. Studies have shown that CFs are highly concentrated by income, with the top decile of earners driving 30%-45% of emissions. Even allowing for significant modeling uncertainties, we find that emissions are similarly concentrated in a small number of cities. The highest emitting 100 urban areas (defined as contiguous population clusters) account for 18% of the global carbon footprint. While many of the cities with the highest footprints are in countries with high carbon footprints, nearly one quarter of the top cities (41 of the top 200) are in countries with relatively low emissions. In these cities population and affluence combine to drive footprints at a scale similar to those of cities in high-income countries. We conclude that concerted action by a limited number of local governments can have a disproportionate impact on global emissions. (Less)

https://iopscience.iop.org/article/10.1088/1748-9326/aac72a/pdf

Carbon footprints of 13,000 cities

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.

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Energy and material flows of megacities

In the municipality of Penjamo, Guanajuato, Mexico, the agroindustry is the most important productive sector, especially the swine industry. However, wastes form this industry still lack a proper management. There are residues such as hair, hooves and eyelids of pigs that could provide additional value and opportunities. This work proposes alternatives for the valorization of swine production residues, applying industrial ecology, which seeks to establish alternatives for the closing of the cycle of matter and energy utilization in industrial systems, thus building synergies between existing companies (or between an existing company and new ones) and encouraging residual flows being produced by one and reutilized as raw material by another. In this case, the environment of an agro-industrial cluster in Penjamo was analyzed and new synergies were proposed: the development of amino acids using pig hair, the manufacture of gelatine from hooves and eyelids, the transformation of slurry from porcine farms into biogas and/or electric energy and the production of slabs and boards using the agave bagasse. It was also proposed to promote the formation of other companies, for example by taking the organic residues of greenhouses, seed and plants, to create a composting plant. With the proposed synergies, the waste generated by the agro-industrial sector could be reduced, as well as waste generated by companies with different activities, thus generating environmental and economic benefits to the municipality and the agro-industrial sector.

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Gemma Cervantes

Papers

Energy and material flows of megacities

Valorización de residuos generados en la agroindustria en guanajuato aplicando principios de ecología industrial