Factors Leading to Increased Carbon Dioxide Emissions of Taiwan: The LMDI Decomposition Analysis

本研究使用LMDI (logarithmic mean divisia index)的乘法分解法，將資料依我國減少核電使用的改變過程，每8年分成一段來分解我國自1971-2014年二氧化碳(CO_2)排放變化的情形，透過分解法將人均CO_2排放分解成經濟活動效果(G)、人口成長效果(P)、能源強度效果(I)、能源組合的結構效果(S)及燃料的係數效果(CE)等五項效果後發現：經濟活動效果及人口效果一直以來均為造成CO_2排放變化增加的兩個最主要的因素，而能源強度、結構效果及係數效果雖然在多數期間扮演著減緩CO_2的排放，但在有些期間卻也是造成排放增加的因素；在2000年以前我國快速的經濟成長及人口的正常成長為該期間CO_2排放增加的最主要因素，但在1977-1985年期間由於我國開始引進核能來發電，結果在這段期間內由於能源效率的提升與碳排放係數的降低，大幅緩和了因經濟及人口成長所造成的排放增加；2000年以後我國的經濟成長趨緩，再加上少子化的關係，使得經濟及人口成長對CO_2排放增加的貢獻減少，但由於這段期間因核電使用的比例減少，導致增加對化石燃料的使用特別是使用燃煤發電的比例越來越高，結果在這段期間內碳排放的係數效果仍增加，形成在這段期間內我國的人均二氧化碳排放並未能有效的減少。This research applies the LMDI multiplicative decomposition to carbon dioxide emissions of Taiwan between 1971 and 2014. As Taiwan once use up to 51.71% of nuclear power in generating their electricity in 1985. One aim of this research is to understand the effect of possible reducing carbon dioxide emissions through using of nuclear power. Based on the period of intensive using of nuclear power, this research segments the 44-year of data into 6-period for most period contain 8-year time span. We summarized the results of this research as follows: Before 2000, the major effects that cause the increasing in carbon dioxide emissions are population increase and economic growth as during this period Taiwan economy experience rapid growth both in economic and population. To meet the demand of rapid economic growth, Taiwan starts to increase the share of nuclear power in generating their electricity during 1977~1985. Based on the decomposition results, we witness the slowdown of carbon dioxide emissions perhaps due to the improvement of intensity effect (ΔI) and coefficient effect (ΔCE) in the period of 1977~1985. After 2000, the slowdown of economic growth alone with the lowest birth rate in the world of Taiwanese seems not benefit the reduction of Taiwan carbon dioxide emissions a lot. Part of the reason for continuing increase in carbon dioxide emissions after 2000 might be because so called ＂nuclear-free homeland＂ becomes popular in Taiwan. Thus, the share of using nuclear in generating electricity has sharply decline to 16.03% in 2014. Without enough renewable energy back up, the fuel mix of generating electricity power has shift toward using fossil fuel especially coal again. As a result, the coefficient effect starts to deteriorate which offset the improving in intensity and structure (ΔS) effect