2006 Volume 2 Issue 4 Pages 326-340
It is necessary to select material cycle system with less environmental burdens for establishment of sound material-cycle society. Regional material cycle is often desirable in term of transport and price of recycled products. However, Supply and demand of recycled product in certain region are not always balanced, so the surplus must be disposed as usual. It has not been considered sufficiently in the existing studies applying Life Cycle Assessment (LCA) to material cycle system. Influence of supply-demand balance of recycled products on comparative results of environmental burdens with material cycle systems was considered and formulated in this study. As a result, it was found that only the technological factors dominate the comparative results of the environmental burdens with the systems when both the possible supplies of recycled products are less than their demands. The demands become the factor when both of the supplies are more than them. The waste generation also becomes the factor when only the one side of the supply is more than the demand. As a case study, regional material cycle systems including garbage composting or biogasification in City A were assumed. Greenhouse gas emission with them was compared by application of LCA, and impacts of waste generation and product demand on the results were considered. As a result, compost demand influenced on difference of GHG emission among the systems stronger than liquid fertilizer demand. As a conclusion, supply-demand balance must be considered to exactly compare the environmental burdens with regional material cycle systems.
