第二代生質酒精水足跡之研究 －以稻稈與蔗渣為例

A study of water footprint of second-generation bioethanol : Case study of rice straw and bagasse

邱從甲(Chung-Chia Chiu)

指導教授 ： 林久翔 ； 項衛中

中原大學/電機資訊學院/工業與系統工程研究所/博士(2015年)

https://doi.org/10.6840/CYCU.2015.00172

摘要

本文的目的在藉由計算台灣第二代生質酒精水足跡，進而提出當生質燃料利用農產品製造時之水足跡估算公式，並提出台灣第二代生質酒精示範廠降低製程用水之改善建議。為因應全球暖化、氣候變遷及國際油價劇烈波動的情況，各國均積極投入替代能源的研發計畫，並推動增加綠色再生能源之開發與提高能源使用效率以降低對石油的依賴。生質酒精是生物能源中做為運輸最重要的替代燃料，然而，在運輸生物燃料應用增加的趨勢下，勢必大幅增加生質作物在生長過程中淡水資源的競爭，水資源問題將可能繼能源問題之後成為另一值得探討的議題。
本研究以台灣第二代生質酒精示範廠為案例，計算當第二代生質酒精以稻稈與蔗渣為原料時之水足跡，計算結果，以蔗渣為原料時是268.8 L H2O / L EtOH，以稻稈為原料時為4674.85 L H2O / L EtOH，這個結果比第一代生質酒精的水足跡都低，最主要的原因是第二代生質酒精的原料是使用被利用後的作物殘渣，作物水足跡帳目已完全或大部份轉移至第一次使用之上。本研究也依據生質酒精示範廠的製程用水資料提出改善建議，估計至少可以再省20%的操作用水。最後，本研究提出一個以農產品為原料的產品水足跡的計算通式，設計工程師在設計規劃之時就可以依此公式預估產品的水足跡，進而對原料及製程規劃做最佳的選擇。

關鍵字

生質酒精 ； 生質作物 ； 生物能源 ； 水足跡

並列摘要

This study is to propose the formula for estimating the water footprint of biofuels made from agricultural products and make suggestions to lower process water usage in the second-generation bioethanol pilot plant through the water footprint calculations for the second-generation bioethanol in Taiwan. Due to global warming, climate change, and severe oil price fluctuations, many countries have conducted researches on alternative energies, and have also promoted the development of renewable energies and the increase of energy efficiency, so as to reduce the dependence on petroleum. Bioethanol is the most important alternative fuel for transportation among bio-energies. However, the trend of increasing biofuels uses will result in significant competition for fresh water for growing biomass crops. Water resource is likely to be the next issue worth discussion after the energy issue.
This study takes the bioethanol pilot plant in Taiwan as an example to calculate the water footprint of second-generation bioethanol while using rice straw and sugarcane bagasse as raw materials. The calculated water footprint is 268.8 L H2O / L EtOH if the feedstock is bagasse, or 4674.85 L H2O / L EtOH if the feedstock is rice straw. Both results are less than the water footprint of first-generation bioethanol. The main reason is that the raw materials of second-generation bioethanol are crops’ residues, and the water footprints of these crops had already been counted to their primary usages completely or mostly. This study also proposes suggestions for saving water based on the water consumption information of the pilot plant’s process. It is estimated that at least 20% of the operational water could be saved. At last, this study proposes a general formula for calculating water footprint of the products made from agricultural materials. Design engineer can use this formula to predict water footprints of the products even at planning stage, so that the optimal raw materials and process design could be determined.

並列關鍵字

bioethanol ； water footprint ； biomass ； biofuels

參考文獻

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