Sustainable Marine City (SuMaC) is proposed as an experimental island of 800-900 ha with 39,000 residents for marine environmental education, research, and preservation of Osaka Bay. As a series of studies, energy utilization and water/material cycle systems for SuMaC were evaluated by the emission of greenhouse effect gas in this study. Use of recycling water inferred decrease in the water consumption by 25.9%. Considering the difference in time between supply and demand, electric self-sufficiency was estimated to be 90.6%. Moreover, it was suggested that self-sufficiency on hot water, cooling, and heating energy was 78.2%, 41.9%, and 45.2%, respectively. The emission of the green house effect gas from the systems proposed is inferred lower than that from a typical city by 2.30×10^5 t-C for 30 years.
