以物質流分析結合系統動態探討台灣鋼鐵業二氧化碳排放

Abstract

全球暖化為廿一世紀人類需要解決的最大難題，其中CO2又是全球暖化的主要元兇。鋼鐵業屬高耗能產業，作業過程中排放大量CO2，因此是工業國家制定節能減碳措施的首要對象。目前國際間重點關注鋼鐵廠整體排放，較少探討製程間物質的流動及個別製程之排放，因此本研究將利用物質流分析探討鋼鐵業各製程中的CO2排放及能源消耗。 本研究使用物質流分析，架構出台灣鋼鐵業碳及能源的流佈，並結合系統動態，考慮不同情境下未來鋼鐵業CO2排放量，並與鋼鐵業業界定下之目標比較。 研究結果顯示，2006年台灣鋼鐵業總排放量為3668萬噸，當中直接排放佔74.4%，間接排放佔25.6%；以行業別計算，一貫作業煉鋼廠排放量佔總排放的74.9%，當中直接排放佔一貫作業煉鋼廠排放量的87.1%，間接排放佔12.9%；電弧爐煉鋼廠排放量佔總量的25.1%，當中直接排放佔電弧爐煉鋼廠排放量的36.6%，間接排放佔73.4%。 一貫作業煉鋼廠中，CO2主要排放源依次為汽電共生廠、高爐製程及燒結製程；能源消耗最多的依次為高爐製程、燒結製程及汽電共生廠。電弧爐煉鋼廠主要CO2排放來外購電力的使用，佔63%；能源消耗方面，電力亦為主要消耗能源，佔57%。 透過系統動態模型，模擬三種不同情境下台灣鋼鐵業未來CO2排放量，顯示單獨以替代能源或投資減量設備均不足以讓鋼鐵業排放量達到預定目標，故必須要兩者配合，另外亦顯示業界所訂下之減量目標在現今技術水平下難以達到。

Global warming is the greatest tribulations in the world and human have to solve the issue of CO2 because it contributes the most in global warming. Iron and Steel Industry is a high energy-consuming industry, which releases huge CO2 emissions during the plant is manufacturing. Therefore, this industry is the first instance target by the government to reduce carbon dioxide emissions and energy-saving. In this study, Material Flow Analysis has been used to construct the carbon flow and energy flow in Iron and Steel Industry. The combination of Systems Dynamic can be forecasting the CO2 emissions with different scenarios in future and comparing the goals of CO2 emissions, which set by industry. The results showed that Taiwan’s total CO2 emissions of Iron and Steel Industry is 36.68 million tons in year 2006, which accounted 74.4% for direct emissions and 25.6% for indirect emissions. The integrated steelmaking plant (ISP) accounted for 74.9% of total emissions, which showed 87.1% for direct emissions and 12.9% for indirect emissions. On the other hand, electric arc furnace (EAF) steelmaking plant emissions accounted for 25.1% of total, which conducted 36.6% for direct emissions and 73.4% for indirect emissions. The contributions of the sources in ISP of CO2 emissions are cogeneration, blast furnace process and sintering process. However, blast furnace process consumes the highest energy, followed by sintering process and cogeneration. CO2 emissions from EAF mainly to the use of purchased electricity, which accounting for 63%. As for the energy consumption, electricity it the main energy source which accounting for 57%. Through the Systems Dynamic model, we can forecast the CO2 emissions of Taiwan steel industry with three different scenarios in the future. Nevertheless, the results showed that separately “using alternative sources of energy” or “install reduction equipment” is not meeting the reduction targets for the Iron and Steel Industry; because it must be applied with both scenarios to achieve the reductions target and it is difficult to achieve under present level.