土地利用之生命週期衝擊評估工具開發

Development of Life Cycle Impact Assessment Tools for Land Use

謝佑昀(Yu-Yun Hsieh)

指導教授 ： 闕蓓德

國立臺灣大學/工學院/環境工程學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.03048

摘要

現行生命週期衝擊評估方法大多以生態相關指標來表示土地利用產生的衝擊，但有文獻指出土地利用亦會產生其他面向的影響，例如生質燃料在其生命週期中會直接及間接佔用土地並改變地表型態，從而導致所佔用土地之固定碳素總量或是溫室氣體排放量改變，進一步產生額外的溫室氣體排放；或是例如土地佔用使得地表植被覆蓋率及生長之植物種類產生變化，減少了土地的生物質，導致耗用額外的可用天然資源量。由於目前生命週期衝擊評估方法對於土地利用造成環境衝擊層面考慮的不足，本研究以近年應用生命週期評估經常被選用的衝擊評估方法IMPACT 2002+衝擊評估方法為基礎，加入土地利用產生的相關衝擊，新增三個中間點衝擊類別包含直接土地利用變遷排放、間接土地利用變遷排放以及土地覆蓋變遷，建立加入土地利用衝擊之評估方法，並分別以產製酒精汽油及生質炭為案例進行生命週期評估，透過使用IMPACT 2002+以及本研究修正的土地利用衝擊評估方法分別進行案例的衝擊評估，以瞭解增加土地利用衝擊對於生質燃料產生的環境衝擊以及溫室氣體減量效果之影響程度。
產製酒精汽油案例分析結果顯示，當以溫室氣體減量為評估目的，並且不考慮土地利用可能產生的氣候變遷影響，生質酒精確實比起車用汽油產生的溫室氣體排放來得略少，酒精汽油則介於兩者之間；但在增加土地利用產生的氣候變遷影響後，環境衝擊順序出現反轉，變成以車用汽油的溫室氣體排放量為最少，酒精汽油次之，生質酒精的排放量甚至較原衝擊增加約73倍。產製生質炭案例分析結果則顯示同樣以溫室氣體減量為評估目的時，當不考慮土地利用可能產生的氣候變遷影響，生質炭的溫室氣體排放量已較燃煤要高出4倍；而在增加土地利用產生的氣候變遷影響後，生質炭和燃煤的環境衝擊順序依然不變。以上結果均顯示出土地資源對於生質燃料為關鍵影響因素，雖可以提供更多的能源並減少資源損害，但同時也可能造成更多溫室氣體排放量，因此資源損害與氣候變遷損害分別為天平的兩端，如何平衡及取捨必須經由決策者和利害關係人充分討論。

關鍵字

土地利用 ； 生命週期衝擊評估 ； 生質燃料 ； 土地利用變遷排放

並列摘要

Land use is a human activity and widely exists in the life cycle of many products. Previous studies have indicated that land use has caused considerable environmental problems such as biodiversity loss, change in carbon stock, and the reduction of net primary production. Existing life cycle impact assessment (LCIA) methods can be used to quantify the environmental impact of land use. However, the characterization models for land-use in most existing methods reflect only loss of biodiversity and exclude the effect of land use on other essential environmental considerations such as climate change and net primary production. Thus, in this study, we adopted IMPACT 2002+ as a foundational methodology, accompanied by other relevant environmental aspects of land use. In addition, we used the life cycle assessment (LCA) software SimaPro 7 for modeling. The LCIA method we revised is called IMPACT 2002+ wLU, increasing three midpoint impact categories, i.e. direct land-use change, indirect land-use change and land cover change. Furthermore, we used IMPACT 2002+ and IMPACT 2002+ wLU to compare the impact difference between two methods in case studies on biofuel and fossil reference systems. These case studies have established that bioethanol produced using sugarcane and biocoal produced using rice straw represent first- and second-generation biofuels, respectively, and that the fossil reference systems correspond to the production of gasoline and the import of hard coal.
These case studies have also indicated that land-use change is a key factor in the use of bioethanol. In assessing the endpoint damage of climate change, the IMPACT 2002+ results revealed that greenhouse gases (GHGs) emissions from gasoline were slightly higher than those of gasohol and bioethanol, whereas the emissions which assessed by IMPACT 2002+ wLU were in reverse order, with bioethanol emissions exhibiting the highest effect, namely 73 times more than the original emissions. The effects of land-use change on climate change and resource depletion are limited for biocoal, and biocoal emissions are higher than those of hard coal, regardless of land-use change. In addition, production of first-generation biofuels has occupied large amounts of land to supply energy, while causing increasingly more GHG emissions. Therefore, based on our results, land-use change is a key factor in the use of bioethanol indeed.

並列關鍵字

Land use ； Life cycle impact assessment ； Biofuel ； Land use change

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