台灣部門別CO2排放拆解及政策工具效果之分析

半世紀以來各產業蓬勃發展，能源需求不斷升高，隨之而來的溫室氣體排放造成全球暖化，已被認為是人類生存的重大威脅之一。各國為達成減排目標，在減碳策略方面，冀能在維持經濟規模下，同時兼顧改善產業結構、提升能源效率及改善碳排放係數等目的。據此，本研究以拉氏指數拆解法(Laspeyres method)針對台灣1990-2016年工業、運輸業、農業、服務業四個部門進行探討，分析經濟規模、能源密集度、部門結構、碳密集度及人口五項因素對上述四部門CO2排放之貢獻度。研究結果發現，人口對所有部門CO2排放增量皆產生貢獻；經濟規模為工業、運輸業、服務業部門CO2排放增加的主要因素；能源密集度對所有部門皆是CO2排放減量因素，且是工業及運輸業部門的主要減量因素；部門結構為運輸業、農業、服務業CO2排放減量因素；碳密集度對四部門CO2排放皆是減量因素，且是服務業部門的主要減量因素。上述CO2排放組成因素又受不同政策工具之影響，故本文根據上述拆解實證結果，採用似不相關迴歸模型(Seemingly Unrelated Regression，SUR)評估政策工具對工業及服務業部門各組成因素之影響。結果發現，環境稅實質稅額對服務業之能源密集度及碳密集度有負向顯著效果，而對工業之碳密集度產生正向顯著，說明環境法規訂定需考慮周全，避免產業使用汙染程度更高的替代能源；時間趨勢之實證結果顯示，技術進步可降低能源密集度對產業CO2排放之貢獻；發展乾淨能源技術，改善能源結構則有助於碳密集度對產業CO2排放之貢獻。故提升對技術改善之投入，可推動產業朝低碳產業、綠色經濟發展；進口關稅平均稅率調整須考量產業競爭力，對優勢產業而言不宜提高關稅，對弱勢產業而言關稅則有助產業發展。

關鍵字

二氧化碳排放；拉氏指數拆解法；政策工具

並列摘要

Over the past half century, booming industries and rising energy demand, and the resulting global warming caused by greenhouse gas emissions, have been regarded as one of the major threats to human survival. In order to achieve emission reduction goals, countries should adopt a carbon reduction strategy that aims to improve industrial structure, energy efficiency and carbon emission coefficient while maintaining economic scale. Based on this, the Laspeyres method was used to analyze the contribution of five factors, including economic scale, energy intensity, sector structure, carbon intensity and population, to the CO2 emissions of the four sectors in Taiwan from 1990 to 2016. The results show that population contributes to CO2 emission increment in all sectors. Economic scale is the main factor for the increase of CO2 emissions in the industry, transportation and service sectors. The energy intensity is the CO2 emission reduction factor for all sectors, and is also the main reduction factors of the industry and transportation sector. The sector structure is the CO2 emission reduction factor for transportation, agriculture, and service industries; the carbon intensity is the reduction factor for the four sectors of CO2 emissions, and is the main reduction factor for the service sector. The results show that population contributes to CO2 emission increment in all sectors. Economic scale is the main factor for the increase of CO2 emissions in the industry, transportation and service sectors. The energy intensity is the CO2 emission reduction factor for all sectors, and is also the main reduction factors of the industry and transportation sector. The sector structure is the CO2 emission reduction factor for transportation, agriculture, and service industries; the carbon intensity is the reduction factor for the four sectors of CO2 emissions, and is the main reduction factor for the service sector. The results show that the substantial amount of environmental tax has a negative significant effect on the energy intensity and carbon intensity of the service industry, while a positive significant effect on the carbon intensity of the industry, indicating that the environmental regulations need to be carefully formulated to avoid the use of alternative energy sources with higher pollution levels. The empirical results of time trends show that technological progress can reduce the contribution of energy intensity to CO2 emissions of industry sector. Development of clean energy technologies and improvement of energy mix contribute to the contribution of carbon intensity to industrial CO2 emissions. Therefore, increasing investment in technology improvement can promote the development of low-carbon industry and green economy. The adjustment of the average tariff rate of import tariffs must consider the competitiveness of the industry, and it is not appropriate to raise tariffs for advantageous industries. For the disadvantaged industries, tariffs can help the development of the industry.