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Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy ARTICLE IN PRESS Energy Policy 38 (2010) 4828–4837 Contents lists available at ScienceDirect Energy Policy journal homepage: www.elsevier.com/locate/enpol Methodology for inventorying greenhouse gas emissions from global cities Christopher Kennedy a,Ã, Julia Steinberger b,1, Barrie Gasson c,2, Yvonne Hansen d,3, Timothy Hillman e,4, Miroslav Havranek f,5, Diane Pataki g,6, Aumnad Phdungsilp h,7, Anu Ramaswami e,8, Gara Villalba Mendez i,9 a Department of Civil Engineering, University of Toronto, 35 St. George Street, Toronto, Canada M5S 1A4 b Vienna Institute of Social Ecology, IFF, University of Klagenfurt, Schottenfeldgasse 29, 1070 Vienna, Austria c School of Architecture and Planning, University of Cape Town, 7701 Rondebosch, Cape Town, South Africa d African Centre for Cities, University of Cape Town, 7701 Rondebosch, Cape Town, South Africa e Department of Civil Engineering, University of Colorado Denver, Campus Box 113, P.O. Box 173364, Denver, CO 80217-3364, USA f Charles University Environment Center, U Krize 8, 15000 Prague, Czech Republic g Department of Earth System Science and Dept. of Ecology & Evol. Biology, University of California, Irvine, Irvine, CA 92697-3100, USA h Department of Energy Management, Dhurakij Pundit University, 110/1-4 Prachachuen Rd., Laksi, Bangkok 10210, Thailand i Institut de Ciencia i Tecnologia Ambientals, Autonomous University of Barcelona, Edifici Cn 08193, Bellaterra article info abstract Article history: This paper describes the methodology and data used to determine greenhouse gas (GHG) emissions Received 21 January 2009 attributable to ten cities or city-regions: Los Angeles County, Denver City and County, Greater Toronto, Accepted 21 August 2009 New York City, Greater London, Geneva Canton, Greater Prague, Barcelona, Cape Town and Bangkok. Available online 12 September 2009 Equations for determining emissions are developed for contributions from: electricity; heating and Keywords: industrial fuels; ground transportation fuels; air and marine fuels; industrial processes; and waste. Urban metabolism Gasoline consumption is estimated using three approaches: from local fuel sales; by scaling from Life-cycle analysis regional fuel sales; and from counts of vehicle kilometres travelled. A simplified version of an Climate change intergovernmental panel on climate change (IPCC) method for estimating the GHG emissions from landfill waste is applied. Three measures of overall emissions are suggested: (i) actual emissions within the boundary of the city; (ii) single process emissions (from a life-cycle perspective) associated with the city’s metabolism; and (iii) life-cycle emissions associated with the city’s metabolism. The results and analysis of the study will be published in a second paper. & 2009 Elsevier Ltd. All rights reserved. 1. Introduction as centers of wealth and creativity, with high population densities and economies of scale, cities must play a significant role in With the global urban population now exceeding 50 percent, tackling global climate change. This is particularly clear in a the inhabitants of cities are recognized as a major driver of global political context where goals and actions of groups such as the greenhouse gas (GHG) emissions (Satterthwaite, 2008). Moreover, C40 mayors exceed those of many national governments. As a first step to addressing climate change many cities have established inventories of GHG emissions, often using the simple pragmatic à Corresponding author. Tel.: +1416 978 5978. approach of the International Council for Local Environmental E-mail addresses: Initiatives (ICLEI, 2008). Such inventories of urban GHG emissions [email protected] (C. Kennedy), [email protected] (J. Steinber ger), [email protected] (B. Gasson), [email protected] (Y. Hansen), provide a basis for action on climate change. In particular, [email protected] (T. Hillman), [email protected] (M. Havranek), identifying cities with better per capita performance than others [email protected] (D. Pataki), [email protected] (A. Phdungsilp), Anu.Ramaswa may help to guide climate change policies for urban settings, but [email protected] (A. Ramaswami), [email protected] (G.V. Mendez). before this can be done we need comparable accounting systems. 1 Tel.: ++4315224000 411. 2 Tel.: +27 21650 2366. Closer inspection shows that there are several technical issues 3 Tel.: +27 21650 5903. with GHG inventories for cities: lack of full life-cycle perspective; 4 Tel.: +1303 556 4734. problems with defining spatial and temporal context; and issues 5 Tel.: +420251080351. of assigning emissions by political jurisdiction (Ramaswami et al., 6 Tel.: +1949 824 9411. 2008; Kennedy and Mohareb, 2009). It is also questionable 7 Tel.: +662 9547300x587. 8 Tel.: +1303 556 4734. whether existing inventory schemes are being used consistently 9 Tel.: +93 58124 88. between cities. This is particularly the case for transportation 0301-4215/$ - see front matter & 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.enpol.2009.08.050 Author's personal copy ARTICLE IN PRESS C. Kennedy et al. / Energy Policy 38 (2010) 4828–4837 4829 Table 1 Definition of cities or city-regions used in the study, with their populations and year of GHG inventory. City or city-region Definition Total land area (km2) Population Year Bangkok City 1569 5,658,953 2005 Barcelona City 100 1,605,602 2006 Cape Town City 2454 3,497,097 2005 Denver City and County 397 579,744 2005 Geneva Canton 282 432,058 2005 London Greater London Area (GLA) 1579 7,364,100 2003 Los Angeles County (88 cities) 10,518 9,519,338 2000 New York City City 789 8,170,000 2005 Prague Greater Prague Area (GPA) 496 1,181,610 2005 Toronto Greater Toronto Area (GTA) 7195 5,555,912 2005 emissions, where the ideal approach is based on quantification of WRI / Spatial Life-cycle Components Measure fuel consumed in a regional urban area, i.e., a commutershed. WBCSD boundary perspective definition Many estimates of transportation emissions from cities are based on computer simulated measures of vehicle kilometres travelled Embodied emissions from (VKT) within politically defined city boundaries. How well do food and materials consumed in cities these approaches compare? To develop and test a more robust and transparent inventory Out of Production Emissions upstream of boundary chain electric powerplants procedure, this research has undertaken a comparative study of energy use emissions (iii) GHG emissions, including life-cycle impacts, from a small group of Scope 3 (and further global cities. These include Los Angeles (County), Denver (City & out of Upstream emissions from boundary fossil fuel use County), Greater Toronto, New York City, Greater London, Geneva emissions, (ii) (Canton), Barcelona, Greater Prague, Cape Town and Bangkok not included in Scope 2) Combustion of aviation and (Table 1). These cities were chosen because they have been the marine fuels subject of urban metabolism studies (Gasson, 2002; Sahely et al., ICLEI 2003; Emmenegger et al., 2003; Ngo and Pataki, 2008; CUEC, Out of boundary waste 2008), urban energy or GHG studies (Baldasano et al., 1999; (landfill) emissions Phdungsilp, 2006; Ramaswami et al., 2008), or are prominent Out of boundary district global cities with detailed publicly accessible GHG inventories Single heating emissions (Mayor of London, 2006; New York City, 2007). process Note that these existing studies were useful as background emissions Scope 2 In boundary Out of boundary electricity material, but not all could be used directly for this work; indeed, electricity emissions at powerplant most of the data which are presented in this study is compiled use from original sources and has never been published before. (i) Results for the determination of GHG emissions will be published In boundary fossil fuel elsewhere (Kennedy et al., 2009). This paper describes the combustion methodology that was used in the study, and presents a In boundary waste (landfill) substantial new data set for the energy and waste components Scope 1 In boundary emissions of these cities urban metabolism. emissions In boundary industrial The global warming potential of GHGs attributable to cities, processes and product use including carbon dioxide, methane, nitrous oxide and several In boundary agriculture, other gases, is expressed in terms of carbon dioxide equivalents, forestry and other land use eCO2. From a practical perspective, emissions of CO2 itself dominate the urban inventory, with methane of significance for Fig. 1. Comparison of measures for attributing greenhouse gas emission to cities landfilled waste, and other gases mainly of significance for considering spatial boundaries and life-cycle perspective. industrial emissions where they occur. The methodology and data used to quantify the emissions