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Because of increasing concern about global climate change,there has been a growing research interest in carbon footprint analysis recent years.Carbon footprint analysis on urban energy use takes both direct carbon emissions and indirect emissions into account,so it has great significance for the in-depth analysis on nature process of carbon emissions and scientific formulation on carbon reduction plan.Taking Xiamen as a study area,the hybrid analysis method of carbon footprint was used to access the carbon footprint on the energy use of Xiamen city in 2009.Besides the direct carbon emissions from the urban energy end-use in traditional research,the indirect carbon emissions from the cross-boundary traffic and the embodied energy of key urban materials were also included.The direct emissions include emissions from direct energy use in industrial sector,commercial sector,household sector,transport sector and so on,which often called scope 1 by WRI/WBCSD.The direct emissions also include emissions due to electricity and steam purchases for the sector in the city,often called scope 2 emissions.And indirect carbon emissions,which called scope 3,incorporate the surface,sailing and airline travel′s emissions across cities and the embodied energy of key urban materials: food,water,fuel,and concrete.Research result showed that:(1) Direct carbon emissions from the energy use on the sectors inside the city boundary including industry,transport,commerce and so on,namely scope 1 and scope 2,only take up 64% of the total city carbon footprint.However,the indirect emissions from the cross-boundary traffic and embodied energy of key urban materials account for 36%,which has usually been ignored as scope 3.(2) In the direct emissions,the carbon emissions of industry contributed the largest share,which counts for 55%.And the emissions from the chemical industry account for 25% of the whole industry sector.(3) In the indirect emissions,the shares of emissions from cross-boundary traffic and embodied energy of key urban materials were 27% and 73% respectively.The carbon emissions of long-distance road transport take the largest proportion of cross-boundary traffic,which accounted for 38%.And the embodied energy emissions from the fuel were the most important part of embodied energy emissions,accounting for 51% of embodied emissions.(4) From the perspective of per capital carbon footprint,the per capital direct carbon emissions of Xiamen and Denver were 5.74 t CO2e/cap and 18.9 t CO2e/cap respectively.And the per capital carbon footprint of Xiamen and Denver,including direct and indirect emissions caused by the energy use,were 9.01 t CO2e/cap and 25.3 t CO2e/cap.In the total carbon footprint by Xiamen and Denver,the emissions from the cross-boundary transport all took up 10%,and the emissions caused by embodied energy of key urban materials were 26% and 15% respectively.The embodied emissions by Xiamen were relatively higher than Denver because the urbanization and industrialization consumed more materials in Xiamen.Comparing the per capital carbon emission excluding embodied emissions with typical cities in the worldwide,Denver took the first place with 21.5 t CO2e/cap,and Los Angeles,New York City,London,Bangkok,Cape Town and big city like Shanghai,Tianjin and Beijing in China were more than 10 t CO2e/cap averagely.That of Xiamen was 6.63 t CO2e/cap,which was far less than most cities. |
