バイオマス素材の活用に伴うGHG排出と水消費の比較—シャンプー製品を事例として

抄録

Objective. Using the biomass materials to suppress the GHG emissions is now spreading all over the industries. On the other hand, it would increase other environmental burden, for example fresh water consumption, to cultivate the crops. In this study, we carried out GHG and water analysis of our product —SUPER-MiLD Shampoo, which bottle is made by sugarcane-derived polyethylene (PE)—and some bio-plastics in order to figure out the trade-off effect and the contribution to reduction.
Results and Discussion. The shampoo emits 15.3 kg-CO₂e of GHG, and consumes 1.85 m³ of fresh water through its life cycle. Especially the largest contribution of use-stage has come out. Sugarcane-derived PE can decrease 0.129 kg-CO₂e of GHG emissions in spite of increasing 0.133 m³ of water consumption compared to the fossil derived PE bottle. When we use the biomass materials in order to reduce GHG emissions, the water consumption would increase as a trade-off. So we defined “Water Efficiency” as following, Water Efficiency = Decrement of GHG emissions [kg-CO₂e] / (Increment of water consumption [m³] * Water availability factor), and tried to estimate the index of some bio-plastics, PET (Brazil, Sugarcane, Plant ratio: 20%), PE (Brazil, Sugarcane, Plant ratio: 100%) and PLA (U.S., Maize, Plant ratio: 100%). The Water Efficiency index, that takes into account the water scarcity of growing area, showed the fact that there is a big difference between bio-plastics. These results indicate the utility of the index on product design from the viewpoint of sustainable water use.
Conclusions. In economic activities, it is necessary to consider also the increase in other environmental impacts as well as climate change issue. In addition, we should aim balanced and optimized environmental performance of products.