以生命週期評估探討竹材利用之環境效益

Abstract

自工業革命以來，人類追求繁榮發展卻造成了環境汙染、生態破壞及氣候變遷等現象，其中又以溫室氣體所引起的全球暖化最為嚴重，為了削減與緩和此環境災害，世界各國以減少溫室氣體排放為目標努力。台灣有豐富的竹資源，竹類具有生長快速、輪伐期短等特性，而作為利用時竹材之拉力強度與鋼可相互媲美，又竹材具有碳貯存之功能，因此若能妥善經營利用竹資源，不但可確保自然生態環境的永續經營、填補資源之短缺，且作為替代資源可以帶來環境衝擊減量之效益。本研究是以竹材加工產品為對象，收集竹材於生產過程中資源的投入及產出，透過生命週期評估方法評估生產竹材利用時各階段的環境衝擊及竹材在碳貯存與二氧化碳減量上的貢獻，並且探討竹材在取代其他材料使用時的優勢及劣勢。研究結果顯示，竹材之生產主要以機械加工處理為主，因此機械的電力消耗及生產效率是影響生命週期潛在環境衝擊的關鍵因素。加工處理所造成的環境衝擊主要來自於熱壓積層、乾燥及藥劑使用等階段，對於可吸入性無機物質、全球暖化、非再生能源等項目造成較高的衝擊，而熱處理竹材積層板之整體環境衝擊較漂白竹材積層板高。將竹材積層板與其他材料相比可知，鋁材所造成的環境衝擊最高，混凝土除了在氣候變遷之損害項目較竹材積層板高以外，其所造成的環境衝擊皆較其他材料低，而竹材積層板則在氣候變遷的損害項目上具有衝擊減量的正面效益。竹材積層板之碳貯存效果可以抵消加工過程中所造成的碳排放，故使用竹材積層板對溫室氣體減排具有正面的環境效益。雖然竹材積層板在全球暖化及氣候變遷項目具有減量的效益，然而在其他衝擊項目也造成了相當的衝擊，故決策者應考量此部分所造成的環境影響，可更新選用較節能、生產效率高之設備，或檢視生產供應鏈之配置以提升效率，更進一步降低加工所造成的環境衝擊。

Phenomena of environmental pollution, ecological damage and climate change which has resulted from human activities, since the industrial revolution. The most significant issue is global warming caused by greenhouse gases. For the purpose of reducing and mitigating these environmental disasters, the whole world tries to reduce greenhouse gas emissions. Owing to a suitable climate and environment for the bamboo growth, it is rich in bamboo resource both in species and area in Taiwan. The growth patterns of bamboos are different from timber and unique characteristics include fast growth, high production and rapid maturation from shoot to culm. In trials of tensile strength, bamboo outperforms most other materials, reinforcement steel included. Bamboo is also an important part of carbon storage. If we can manage and utilize bamboo resource appropriately, it will ensure the sustainable management of ecosystem, fill the shortage of resource and produce available products which have less environmental impact. This study focuses on production chains which produce plybamboo for utilizing. The production chains are investigated using a Life Cycle Assessment(LCA) approach, which takes into account all the input and output flows occurring along the production chain. The results show that major processing of the plybamboo production is mechanical processing. Therefore, the energy consumption and productivity are the key factors of potential environmental impact. The other results show that plybamboo production chain had high impact in impact categories of respiratory inorganics, global warming and non-renewable energy. The impact of the processing mainly originates from the step of hot pressing, drying and chemicals using. The comparative results show that plybamboo had low environmental imapct, but it had more impact than concrete. Concerning carbon storage of the plybamboo, utilizing plybamboo has environmental benefit in impact categories of climate change and global warming. Although the plybamboo has low impact in impact categories of climate change and global warming, it has high impact in other impact categories. Therefore, policy makers should consider the highest impact of the above-mentioned processing step, and use energy-saving and high productivity equipments to reduce the environmental impact.