Comparative Analyses for City Greenhouse Gas Inventories
|關鍵字:||城市;部門;溫室氣體盤查;指標;生態效益;永續環境系統分析;city;sector;greenhouse gas inventory;benchmark;eco-efficiency;sustainable environmental systems analysis|
Greenhouse gas (GHG) reduction has become an essential task for cities. Domestic and foreign cities are thus reporting their GHG inventories. However, these inventory reports are difficult to compare directly because of different guidelines, calculation methods, and selections of activity data. Therefore, this study was initiated to develop a method to compare the inventories and analyze their differences for discovering the benchmarks and exemplars in major sectors. GHG Inventory reports from domestic and foreign cities were collected. Inventory information and data were grouped by sector. Various differences were observed for every sectors. Adjusted and common emissions were determined by excluding the emissions from the items that were not commonly reported or had small quantities. Both adjusted and common emissions were used as bases for following benchmark analyses. First, the characteristics of cities and various GHG-related factors, including population density, employed population, average income, and electricity emission factors, were compared and analyzed. The amount of degree days, for analyzing climate effects on energy usages, were calculated, and regressive equations for domestic cites were established and applied to revise the benchmarks for those cities. Then, comparative analyses for each sector for their characteristics and GHG-related factors were implemented. For the industrial sector, its energy usage, employed population, gross production and water usage were analyzed. For the residential and commercial sector, its energy usage, employed population, gross production, water usage, number of households and the ratio for high-rise buildings were compared. For the transportation sector, its road area or length density, number of vehicles, vehicle kilometers traveled were analyzed. According to the results obtained from these comparative analyses and a preliminary aggregative analysis, the commercial employed population, population, number of households were selected as outputs, and the common emission was used as input, to establish indicators for evaluating the performance of major sectors in studied cities. Equations were established for determining the average and benchmark emissions of each city, the former is the typical target should be achieved and the latter is the goal to be pursued. Paradigm cities and sectors were identified based on the average and benchmark emissions. With the average and benchmark emissions and the paragons, how far their gaps to the emissions and paragons of each city were determined and discussed. Sectors with poor performance were also identified and possible policies or actions for reducing GHG emissions were suggested. The results are expected to facilitate the GHG reduction planning for cities in Taiwan.