一般廢棄物處理系統溫室氣體盤查-以新北市為例

Abstract

廢棄物處理系統所產生的碳排放與所在地的風土民情、地形及氣候條件有很大的關聯性，因應國際間即將實施的交易碳排放量制度，有必要對於本地現況進行盤查與分析。 本研究利用IPCC（Intergovernmental Panel on Climate Change）、USEPA及我國環保署所提供的溫室氣體盤查資訊，建構一般廢棄物處理系統之溫室氣體排放量評估模式，選出具本土代表性的城市-新北市，從生命週期盤查的概念進行廢棄物處理系統各項措施的溫室氣體排放量盤查與分析。 由盤查結果得知，新北市廢棄物清運過程中產生之碳排放量相當可觀，其中清運每公噸一般家戶垃圾之碳排放量（5.14×10-2 MTCE/tonne）較清運其他廢棄物高，應與清運一般家戶垃圾時，均先進行垃圾壓縮，並由引擎提供動力，需耗費部分油料有關。廚餘養豬雖然可使食物二次利用，但依據2011年之盤查結果顯示，廚餘養豬(0.090 MTCE/tonne)比堆肥(0.056 MTCE/tonne)產生更多的溫室氣體排放量，就溫室氣體減排的觀點而言，臺灣傳統的廚餘利用方式有重新檢討與改進的空間。此外，由2011年之盤查結果得知（計入收運所產生之碳排放），資源回收之淨碳排放當量（-0.579 MTCE/tonne）為各處理方案中最低的，這顯示有效的資源回收為當前廢棄物管理系統溫室氣體減排的重要方案。 此外，為探究盤查估算與實廠排放現況間之落差，本研究選用目前臺灣地區最主要的廢棄物處理方式-焚化，利用新北市焚化廠煙道排放數據，配合發電產生之碳抵減，得出焚化所產生之淨溫室氣體排放量，與盤查估算模式所得之結果進行比較，探究估算與實廠情形間的落差。運用估算方式盤查得出，新北市焚化廠單位淨溫室氣體排放量約在0.030至0.092 MTCE/tonne 之間；使用實廠數據計算得出，新北市焚化廠單位淨溫室氣體排放約在0.059至0.223 MTCE/tonne。比較兩者所得之結果，顯示美國環保署盤查方法提供之係數應用於臺灣地區時，有著一定程度的落差，應依據當地情形進行本土化校正。而由本研究所得出之各類廢棄物處理方案的溫室氣體排放係數可知，資源回收（-0.579 MTCE/tonne）為較佳的溫室氣體減排方案。對於可回收的廢棄物應優先使用回收的方式處理；對於無法回收再製的廢棄物，則以焚化處理為佳 最後，本研究也期望藉由盤查訊息的提供，使研究人員與決策者在資訊取得的對稱性上更加完備，在努力達成溫室氣體減排目標的同時，建構出更加完善的廢棄物處理策略，使民眾能生活於更高品質的環境中，構築真正的永續都市。

Level of waste carbon emissions generated from municipal waste treatments is influenced by different locality, topographic, and climatic conditions. In response to the imminent implementation of the international carbon emissions trading system, it is necessary to understand and analyze local inventory. This objective of this research is to investigate greenhouse gas emission in relation to different waste treatment systems currently available in New Taipei City from the concept of life-cycle inventory by reviewing available information from Intergovernmental Panel on Climate Change (IPCC), USPEA and Taiwan Environmental Protection Agency. Based on the available information, the waste transport activity is one of the major sources of carbon emission in New Taipei City, among which household waste transportation and disposal accounts for 5.14×10-2 MTCE/tone of carbon emission, which is more significant than any other waste. Therefore, household garbase should be compressed and compacted during transportation by vehicle engine. In addition, while recycling kitchen waste as feedstock for pigs is widely accepted, carbon emission from recycling kitchen waste was estimated to be 0.090 MTCE/tonne, much higher than composting of 0.056 MTCE/tonne. Therefore, there is room for improvement for the disposal and use of kitchen waste. According to 2011 analysis, net carbon emission from recycling waste was estimated to be -0.579 MTCE/tonne, which was the lowest of all waste treatment systems, making it an ideal approach to waste removal. While waste incineration is the most efficient method of waste removal, its carbon emission is also the largest of all methods. In order to compare the carbon emission, this research estimates the net carbon emission by deducting the electricity generated from waste incineration by the carbon emission generated in the incineration plant. The result is compared with available information to evaluate the accuracy. Based on the estimation, carbon emission from incineration ranges from 0.030 to 0.092 MTCE/tonne, which is very different from the actual values of 0.059 to 0.223 MTCE/tonne. This shows that the estimation of actual carbon emission by U.S. Environmental Protection Agency (EPA) methodology is significantly underestimated, indicating the estimation value should be corrected according to different locality, topographic, and climatic conditions. Moreover, the greenhouse gas emission coefficients obtained by this study shows that recycling (-0.579 MTCE/tone) is the most effective green house gas reduction approach of all types of waste disposal program. Therefore, it is recommended to collect all recyclable material and only incinerate waste that cannot be recycled. Lastly, based on the summarization of carbon emission in New Taipei City, the city will be able to achieve higher level and more efficient methods of reducing carbon emission and create a sustainable city.