The nation's demand for energy is forecast to fall based on a declining population and slow economic growth after peaking at the equivalent of 436 million kiloliters of crude oil in fiscal 2022.
The latest estimate by the Ministry of Economy, Trade and Industry put the average annual pace of growth in energy demand at 0.2 percent for fiscal 2000-2030, down sharply from 1.9 percent on average for fiscal 1970-2000.
The pace of growth is projected to start contracting in fiscal 2023, according to officials.
The ministry also forecast that the average pace of growth in electric power demand will slide to 0.8 percent for fiscal 2000-2030 from 3.8 percent for fiscal 1970-2000.
Officials cited a decline in the population, slow economic growth and the widespread use of energy-saving equipment as the main factors.
If the projections prove accurate, electric utilities could be facing the prospect of excess capacity as a result of years of investment on expectations of higher power demand.
The ministry made the projections on the assumption that Japan's gross domestic product will grow at an average pace of 1.5 percent in fiscal 2000-2030 and the nation's population in fiscal 2030 will fall to a level seen around fiscal 1980 due to the aging society, according to the officials.
If the pace of economic growth is above the assumed level, energy demand will likely peak at fiscal 2028, they said.