森林生物質發電與生質酒精共構廠之供應鏈最佳化

Abstract

溫室氣體排放與能源供給結構息息相關。當全球能源需求不斷成長，若不改變目前以化石燃料為主的能源供給結構，溫室效應與氣候變遷將更加嚴重。近年來使用森林生物質取代化石燃料越來越受到重視。森林生物質為可再生資源，具有儲存時間長且用途廣泛等好處。然而，森林生質能源發展至今，遇到不少阻礙如轉換率太低、原物料供給不穩、運送成本高、處理成本高、原物料品質參差不齊等，造成森林生質能源系統的效率及資源的利用率都未能達到和其他能源匹敵的標準。要解決上述問題，需要一個系統性的、有效率的森林生質能源供應鏈管理。過去森林生質能源供應鏈管理研究大多考慮單一產出的供應鏈系統，缺乏探討兩種以上的產出，且對於發電而燃燒森林生物質產生的碳排放亦未加以考慮。其次，近來興起二代生質酒精與熱電共生設備結合的新技術，綜合上述，本研究提出有兩種產出的森林生物質發電與二代生質酒精共構廠之戰略層級供應鏈最佳化問題，在追求最大利潤下，以及考慮環境成本、燃燒森林生物質的碳排放下，利用混整數線性規劃模型決定最佳生產計劃決策。能源發電與生質酒精廠結合除了可共用設備與設施，減少投資成本外，還能分散原料風險進而產生綜效。由於沒有實際的個案研究，本研究採實證模擬分析以驗證所提之共構廠模型擁有存在的優勢。並進一步運用情境分析與敏感度分析探討各種可能的情境對供應鏈策略決策之影響，以及是否比獨立運作更能降低風險。實驗結果顯示，共構廠模型相較火力發電廠獨立運作模型所得的利潤更高。在面臨電力需求降低的情境時，共構廠會提升生質酒精的產量並減少利潤損失；面臨原物料量不足時與火力發電廠獨立運作模型較無差異；面臨碳排放成本升高情境時，共構廠會失去存在的優勢。敏感度分析結果顯示，電力售價是影響模型利潤最重要的參數，其次是原物料高熱值，第三是單位碳排放成本。

The development of forest bioenergy has been met with several obstacles. Therefore, the efficiency and resource usage rate of the forest bioenergy system have not met a comparable standard to that of other types of energy. To solve this problem, a systematic and efficient forest bioenergy supply chain management system must be established. Most previous related studies focused on only single-output supply chains, did not investigate a system that involves generating two or more types of energy simultaneously, and did not consider the carbon emissions caused by electricity power generation of forest biomass combustion. In addition, a new technology that combines bioethanol and biomass electricity generation equipment has recently emerged. Con-sequently, this study addressed the problems regarding the tactical supply chain opti-mization of a forest biomass electricity and second-generation bioethanol coproduc-tion system. A mixed-integer linear programming model was employed to determine the optimal production strategies to maximize the profit and to minimize the carbon emissions cost. Empirical simulation results indicated that the coproduction model yielded more profit than the independently operated model. When electricity demand is reduced, the coproduction model mitigates its profit losses through an increase in its bioethanol production. However, when faced with an increase in carbon emission costs, the coproduction model loses its advantages. According to the sensitivity analy-sis, electricity prices are the most vital parameter to the profit of the model, followed sequentially by the higher heating value of raw materials and carbon emission costs.