清潔發展機制專案計畫之成本及效率分析─ ─以技術水準觀點評估投資國的表現

有鑑於全球溫度逐年上升，氣候變遷所帶來之影響危及人類生活及生態系統，《京都議定書》提出清潔發展機制（clean development mechanism，CDM）幫助工業化國家成為投資國，得以專案形式至開發中國家投資減量；在此機制下，身為主辦國的開發中國家得以減少國內溫室氣體。然而投資國可能為了搜尋合適主辦國、監督主辦國減量而花費過高的交易成本，導致徒增減量成本的無效率情形，本研究主要分析投資國至各主辦國減量的減量成本、成本效率（cost efficiency，CE）及技術缺口比率（technology gap ratio，TGR）以得知各主辦國的成本節省空間，藉此進行成本差異分析，即分析主辦國的國外直接投資（foreign direct investment，FDI）、教育程度、貿易政策、電力使用情形、累積排放量等政經條件如何影響無效率，以找出主辦國的改善方向；另外，探討投資國至不同主辦國從事各專案類型的減量成本，以分析投資國在《京都議定書》第二承諾期合適的投資專案組合。為分析無效率，本研究須以隨機邊界法（stochastic frontier approach，SFA）估計不同技術競爭力的主辦國從事CDM的隨機減量成本邊界（stochastic abatement cost frontier）函數，藉此可擷取出效率值；而在SFA建構出的共同邊界分析法之架構下得以分析最具成本有效性（cost effectiveness）的減量成本，可藉由校正的普通最小平方法（corrected ordinary least squares，COLS）估計而得，此為共同減量成本邊界（meta abatement cost frontier）。研究資料為2005年5月至2014年12月已註冊之專案資料。本文按照技術準備度指標（technological readiness）及創新指標（innovation）將主辦國分為不同技術競爭力的國家群組，以減排量、專案期間、專案類型、主辦國所得水準、專案執行是否在承諾期間、電力產出、是否使用整合性方法學等資訊估計各群組國家的減量成本函數。估計結果顯示，以目前的成本來看，平均而言減量成本隨著技術競爭力愈高而愈低；高技術競爭力、中高技術競爭力、中低技術競爭力及低技術競爭力國家每噸減量平均分別可節省159美元、529美元、311美元及852美元。成本差異因素分析結果隱含，主辦國須注意貿易開放的產業是否具高汙染、應善用FDI授予之減量技術於CDM上、提高電力普及率的同時須注意是否有能源浪費的情形、提高高等教育就學率的同時須兼顧環保意識的提升、二氧化碳累積排放當量愈低則能降低成本差異，一旦主辦國降低成本差異，應能吸引更多CDM以提升國內競爭力並改善國內自然環境。由減量成本的估算可知，不同承諾應減量下有各自合適的投資選擇，包含主辦國與專案類型之選擇；而投資國可將承諾應減量分配至數個專案，惟須注意的是，減量規模愈小可能衍生額外的行政管理費用導致無效率，但單筆投資專案的規模太大則可能增加投資風險，投資國應當心投資組合的配置。

關鍵字

清潔發展機制；減量成本；隨機邊界法；共同邊界分析法；成本效率；技術缺口比率

並列摘要

With the climate change generated by global warming and its potential impact on human life and ecology system, United Nations signed the Kyoto Protocol and proposed clean development mechanism (CDM): industrialized countries become the credit countries that invest reduction technologies in developing countries that are host countries. It is expected that the emission of greenhouse gas (GHG) will decline in developing countries under CDM. However, credit countries may spend too much transaction costs on searching suitable host countries, and monitoring host countries to abate GHG, etc. The abatement costs will then increase, that is the inefficiency. This research mainly analyzes the abatement costs, cost efficiency (CE), and technology gap ratio (TGR) in order to find out the specific cost saving. According to the above estimation, it is essential to analyze how the political and economic conditions, including foreign direct investment (FDI), education, trade policy, electricity usage, and accumulated GHG emission, etc. of host countries affect cost inefficiency, that is the cost difference analysis. In addition, it intends to compute the abatement costs of different CDM project type in different host countries in order to find out the suitable project portfolio for Kyoto second commitment. For the sake of cost efficiency analysis, this research estimates stochastic abatement cost frontier for host countries with different technological competitiveness by stochastic frontier approach (SFA). In such a manner, it can use corrected ordinary least squares (COLS) to explore the meta abatement cost frontier with cost effectiveness. CDM project data for the research are from May 2005 to December 2014. It categorized host countries into four groups with different technology levels including technological readiness and innovation indexes. This research also applies the information of GHG emission reductions, project duration, project type, income level of host countries, project registered date, electricity productions, and the methodologies of the project to estimate abatement cost function for each group. The result of estimation implies that the abatement costs decline with the improvement of technology. On average, high technological-completeness countries, upper-middle technological-completeness countries, lower-middle technological- completeness countries and lower technological-completeness countries should save 159, 529, 311, and 852 U.S. dollars per ton, respectively. The cost difference analysis suggests that the host countries should be aware of the following consideration: the pollution in specific sector once trade openness increases, making good use of technology derived from FDI, avoiding waste of energy while enhancing the popularity of electricity usage, enhancing the environmental awareness while increasing the enrollment rates of tertiary education, and reducing the accumulated emission of carbon dioxide equivalents. Host countries may attract more CDM projects to enhance national competitiveness and improve environment once they reduce the cost differences. According to the measurement of abatement costs, there are different ideal investment portfolios for different emission reduction quantities. Credit countries can distribute their own reduction commitment into several CDM projects. However, less reduction quantities may come along with higher transaction costs; on the contrary, too much reduction quantities may come along with higher investment risk. The above facts make the credit countries ought to pay attention to the allocation of the project portfolio.