2015 年 81 巻 827 号 p. 15-00164
The purpose of this paper is to estimate the feasibility of a low-carbon society in Japan through developing an energy flow, carbon flow and cash flow. In addition to total primary energy supply (TPES) and final energy demand, the energy flow contains estimated renewable energy potential, energy services and energy losses. TPES in 2012 is estimated as 18.9 EJ, of which 17.9 EJ (= 17.9 ×1018 J)was supplied by fossil fuels. Total renewable energy potential is estimated as 21.2 EJ which is enough to meet Japan’s TPES. Wind energy has large potential of 18.3 EJ. As for demand sectors, the transportation sector has the largest energy losses, 2.62 EJ, due to low energy efficiency. Total CO2 emission in 2012 was 1,223 Mt-CO2, of which 956 Mt-CO2 was emitted from both coal and petroleum. Coal is mainly supplied to electricity generation sector, and petroleum is supplied to transportation sector. Total payment for energy supply in final demand sector is estimated to be 41.9 trillion JPY. Total CIF price of 20.6 trillion JPY is paid to foreign countries due to imported fossil fuels. This study indicates that introduction of renewable energy and energy supply system transition, in particular of the transportation sector and electricity generation sector, leads to CO2 reduction and revitalizes local economies. Wind energy, which has a great potential, is important to design a low-carbon society.