We developed the scheme of profitability analysis of a microgrid. The scheme consists of 5 processes. The first process is to calculate the optimal sizing of energy supply system in a microgrid by solving Mixed Integer Non-Linear Programming by using The General Algebraic Modeling System (GAMS). The second one is to determine the distribution of system equipment by taking space in each area into account. The third one is optimal operation planning of energy system by taking thermal transfer among areas into account. The forth one is to design electric equipment. The fifth one is evaluation of pay-back time, reduction rate of primary energy consumption and that of carbon dioxide emission. By using this scheme we also evaluate pay-back time about construction of a microgrid consisting of 3 existing District Heating and Cooling areas in Tokyo. We found that construction of a microgrid consisting of 3 DHC areas needs 8 years for recovery of investment, can reduce 26% of primary energy consumed in existing DHC areas, and can reduce about 40% of carbon dioxide emitted from existing DHC areas.
