淨零運輸策略成效評估之研究—以臺北市為例

Abstract

在極端氣候發生次數逐年增加下，全球開始意識到我們所居住的環境正逐漸改變，而這些改變與人為活動導致大氣中溫室氣體含量上升有著密切關係。為了維持當前適合人類居住的生態環境、避免極端氣候持續發生，國際上已有許多相對應的作為，如聯合國、國際能源組織、氣候組織等都有針對溫室氣體控管提出見解或約束。我國由於地緣政治上的因素，無法直接參與大多數的國際組織，但也積極推出淨零碳排的國家政策。細看我國2020年溫室氣體排放情形，以製造部門（51％）占比最多，其次依序為住商部門（20％）與運輸部門（13％）；若根據六個直轄市所公布的數據顯示，運輸部門占比以新北市（24％）最高、臺北市（20％）次之，且長年來看，運輸部門每年排放量雖非最高，但皆占一定比例，故面對國際上減排浪潮，我國從中央至地方針對運輸活動的去碳化是絕對必要的。 我國自2021年蔡英文總統於世界地球日（4月22日）宣示我國將朝向2050年達到淨零而努力起，中央及地方政府陸陸續續公布各自的減排路徑與相關條例，讓臺灣邁向2050淨零排放的道路更為明確。然而，尚未有相關研究探討政策藍圖是否能順利達成預期成效，且運輸部門長期以來依賴化石燃料作為車輛主要能源的狀況若無及時提出有效的策略，將難以降低運輸部門的溫室氣體排放量。因此，在政策推動前期進行政策評估，對於未來策略推動與修正，都具有實質助益。 本研究針對當前淨零進程步調較為快速的臺北市，應用ASIF模式，以情境分析法，針對淨零運輸政策之目標進行評估。研究中首先以「由下而上」的分析方法，估算臺北市2005年至2021年運輸部門溫室氣體排放情形，並將各年度分析結果與臺北市政府環境局以當前「由上而下」的分析結果進行比較，同時建構迴歸模型推估臺北市未來之客貨運輸需求，以當前運輸部門減排策略以及國際城市經驗，進行保守、政策與積極等不同作為之情境分析，應用ASIF模式進行運輸部門溫室氣體排放計算，據以評估臺北市2030年、2040年與2050年所提出之減排目標是否能如期如實達成。 研究結果指出，對於臺北市運輸部門的統計分析，在兩種統計方式之間存在15.73％～41.41％的差異，且差異有逐年減少的趨勢。運輸需求預測模型則是藉歷史資料與人口數、實質國內生產毛額等資料，針對臺北市的客運和貨運需求分別建立迴歸模型，以此作為未來目標年度運輸需求和溫室氣體排放分析的基礎。在預測模型的分析中，發現客運需求的模型相較於貨運需求有著較準確的預測表現。根據對目標年度溫室氣體排放的分析結果顯示，在現有政策情境下，臺北市的運輸部門可望於2030年時將排放量相較於2005年減少40％。然而，對於「2040年相較於2005年，減少65％排放量」的目標，則可能無法達成，存在著些微差距。 本研究於積極情境中，參考國際城市在移轉綠色運輸及限制燃油機動車輛之減排政策，並針對各車種的去碳化比例重新進行評估。分析結果顯示，除了達成2030年及2040年的目標外，積極情境相較於政策情境還有著顯著的改善。對於2050年達到淨零排放的最終目標，積極情境可減少約23％的所需碳匯量。本研究成果可作為國家及相關公私部門，在面對溫室氣體減排及2050淨零目標研議策略與路徑之參考。

In the face of increasing occurrences of extreme weather events, many countries are becoming increasingly aware of the gradual environmental changes taking place in our world. These changes are closely linked to the rise in greenhouse gas levels in the atmosphere, primarily driven by human activities. To maintain an ecologically suitable environment for human habitation and mitigate the continued occurrence of extreme weather events, many countries and organizations have provided valuable insights and regulations regarding greenhouse gas management. Taiwan faces challenges in direct participation in international organizations on numerous occasions. However, this does not diminish our government's commitment to achieving net-zero carbon emissions. Particularly, according to statistics from international organizations, Taiwan's emissions are comparable to those of countries like France and Thailand. A closer examination of Taiwan's greenhouse gas emissions in 2020 reveals that the manufacturing sector accounted for the highest proportion at 51%, followed by the residential and commercial sector at 20%, and the transportation sector at 13%. Data published by the six municipalities in Taiwan shows that the transportation sector's contribution is highest in New Taipei City at 24%, followed by Taipei City at 20%. Despite not having the highest annual emission volume, the transportation sector consistently maintains a significant proportion. Given the global trend of emission reduction, it is imperative for Taiwan, from the central government to local authorities, to decarbonize transportation activities in response to international efforts to reduce carbon emissions. Since President Tsai declared on World Earth Day in 2021 that Taiwan would strive towards achieving net-zero emissions by 2050, both central and local governments have progressively unveiled their respective emission reduction pathways and related regulations, making Taiwan's path towards net-zero emissions by 2050 clearer. However, the lack of relevant research assessing whether the policy blueprint can achieve its intended outcomes raises concerns. Furthermore, without promptly implementing effective strategies to address the transportation sector's persistent reliance on fossil fuels as the primary energy source for vehicles, reducing greenhouse gas emissions from this sector will remain challenging. Therefore, conducting policy evaluations in the early stages of implementation is essential to inform future strategy promotion and revisions, offering tangible benefits. This study focuses on Taipei City, where the net-zero progress is relatively rapid, and applies the ASIF model to assess the objectives of net-zero transportation policies through scenario analysis. Initially, employing a "bottom-up" approach, the analysis estimates greenhouse gas emissions from the transportation sector in Taipei City from 2005 to 2021. The results for each year are juxtaposed with the current "top-down" analysis results from the Taipei City Government Department of Environmental Protection. Additionally, a regression model is constructed to project future passenger and freight transportation demand in Taipei City. Scenario analyses, encompassing conservative, policy, and aggressive actions, are conducted based on current emission reduction strategies in the transportation sector and international urban experiences. Subsequently, the ASIF model calculates greenhouse gas emissions from the transportation sector, evaluating the feasibility of meeting the emission reduction targets proposed for Taipei City in 2030, 2040, and 2050. The research findings indicate a disparity of 15.73% to 41.41% in the statistical analysis of Taipei City's transportation sector between two methodologies, showing a diminishing gap over time. The transportation demand prediction model utilizes historical data alongside gross domestic product indicators to develop regression models for both passenger and freight transport demand in Taipei City, serving as the foundation for future analyses of transportation demand and greenhouse gas emissions. Analysis of the prediction model reveals a more accurate performance in predicting passenger demand compared to freight demand. Analysis of annual greenhouse gas emissions targets reveals that under the current policy framework, Taipei City's transportation sector is projected to reduce emissions by 40% by 2030 relative to 2005 levels. However, achieving the goal of a 65% reduction by 2040 compared to 2005 may prove challenging, with minor discrepancies remaining. In the aggressive scenario examined in this study, insights from international cities' initiatives in transitioning to sustainable transportation and limiting emissions from fossil fuel-powered vehicles were incorporated. Additionally, recalibration of decarbonization rates for vehicle categories was undertaken. The results indicate substantial improvements beyond meeting the 2030 and 2040 targets compared to the policy scenario. Furthermore, in pursuit of the ultimate aim of achieving net-zero emissions by 2050, the aggressive scenario could reduce the required carbon offsets by approximately 23%. These research findings can inform national and relevant public and private sector stakeholders in strategizing and navigating pathways towards greenhouse gas emissions reduction and the 2050 net-zero emissions goal.