| 摘要: | 本研究基於對產品生命週期評估生命週期末端的環境衝擊需要及廢棄物管理策略之生命週期評估探討，以生命週期評估方法、擾動分析及蒙地卡羅不確定分析方法探討廢棄物焚化處理之溫室效應、酸雨效應、優養化、重金屬及固體廢棄物方面之衝擊評估，並以一度電及一公噸廢棄物為功能單位，進一步探討紙類、廚餘及塑膠類回收率擾動及廢棄物含水率擾動對於溫室氣體排放之影響及不確定分析，以提高生命週期評估結果在決策上不確定分析風險結果。研究結果包括三個方向，廢棄物處理生命週期評估結果與釋意，廢棄物回收情境模擬結果探討及擾動分析與不確定分析，相關結果期能提供未來廢棄物管理策略的參考與建立生命週期評估基礎資料庫。相關細部結果包括：
1. 以台北市廢棄物為個案分析結果，紙類、塑膠及廚餘廢棄物於產品生命週期終了階段之碳足跡，分別為0.96 kg CO2-eq./kg paper、1.79 kg CO2-eq./kg plastic及0.67 kg CO2-eq./kg food waste。
2. 針對廢棄物回收率擾動方面，以紙類回收率增加對於溫室氣體減量最具效益，當各類廢棄物回收率增加30%時，總溫室氣體排放量均隨回收率上升而減少。
3. 紙類及塑膠類回收率擾動之溫室氣體排放，當回收率增加30%時，以每度電為功能單位之溫室氣體排放分別由基本情境2.39kg CO2-eq./KWh上升至2.44kg CO2-eq./KWh、2.69kg CO2-eq./KWh，而廚餘回收率增加30%時，每度電之溫室氣體排放則下降至2.31kg CO2-eq./KWh。
4. 以焚化處理每公噸廢棄物為功能單位，紙類、廚餘及塑膠類回收率對功能單位之溫室氣體排放僅微幅變化，即回收率擾動對溫室氣體減量效益較不明顯。
5. 回收擾動分析從生態效益結果顯示，紙類回收之生態效益4.17$NT/kgCO2-eq.最好、塑膠2.40$NT/kgCO2-eq.次之，廚餘類0.70$NT/kgCO2-eq.最不具回收之生態效益。
6. 針對廢棄物含水率擾動之溫室氣體排放分析，總溫室氣體排放隨含水率降低而減少，而各功能單位之溫室氣體排放亦由基本情境2.39 kg CO2-eq./KWh及1.00ton CO2-eq./ton waste下降至1.80kg CO2-eq./KWh及0.98ton CO2-eq./ton waste，顯示廢棄物含水率減少對溫室氣體排放減量具有明顯效益。
7. 廢棄物回收率對於溫室氣體排放減量之不確定性分析，以1KWh為功能單位時，以塑膠回收之溫室氣體減量不確定為最大；以1公噸廢棄物為功能單位時，則以廚餘回收之溫室氣體減量不確定最大。
8. 廢棄物含水率擾動之各功能單位溫室氣體排放不確定分析，當含水率下降12%時，各功能單位之溫室氣體排放不確定分析分別為0.17~2.87 kg CO2-eq./KWh及0.25~0.44 ton CO2-eq./ton waste。
9. 廢棄物回收率擾動相較於廢棄物含水率擾動，紙類、廚餘及塑膠類回收率擾動除了對廢棄物熱值、焚化發電量及廢棄物清運車輛影響外，對於廢棄物物理組成亦造成擾動，因此廢棄物回收率擾動對於不同功能單位之溫室氣體排放不確定影響較廢棄物含水率擾動為大。
This study is based on the need of the product life cycle assessment (LCA) and waste management strategy for Taiwan. The methodology are applied for the waste incineration case study of Taipei by life cycle assessment, perturbation analysis and uncertainty analysis. LCA studies focused on greenhouse, acidification, eutrophication, heavy metals and solid waste by LCA functional unit of waste (ton) and electrical power(KWh). Furthermore, greenhouses gases emission estimated using perturbation and uncertainty analysis for waste recycling scenarios on paper, plastic, food waste and water content. The results are including three parts, LCA and interpretation of incineration, perturbation analysis of recycling scenarios, and uncertainty analysis.
The relevant findings would provide information for future reference on LCA databases and the decision-making of waste management. The further results as follows,
The case of Taipei, the end-of-life carbon footprint of paper, plastic, and food waste were 0.96 kg CO2-eq./kg, 1.79 kg CO2-eq./kg and 0.67 kg CO2-eq./kg, respectively.
For the perturbation analysis results, the paper was the most benefit on the GHGs reduction for recycling ratio by 30%. The value will reduce by the recycling ratio increasing.
For the perturbation analysis results of recycling ratio by 30%, the GHG emissions were from 2.39 kgCO2-eq./KWh to 2.44 kgCO2-eq./KWh and 2.69 kgCO2-eq./KWh for paper and plastic recycling, respectively. The food waste recycling was from 2.39 kgCO2-eq./KWh to 2.31 kgCO2-eq./KWh.
For the perturbation analysis results of recycling ratio by 30%, the eco-efficiency was the best with 4.17 $NT/kgCO2-eq. for paper recycling. The next was 2.40 $NT/kgCO2-eq. for plastic recycling.
For the perturbation analysis results of water content with 12% decreasing ratio, the greenhouse gas emissions will reduce with the water content reducing. The LCA functional unit was from 2.39 kgCO2-eq. / KWh to 1.80kg CO2-eq./KWh. Reducing waste water content showed a better benefit on greenhouse gas emissions reduction. |
