The energy agency envisions a need to build about 10 nuclear reactors by fiscal 2030, according to a draft long-term outlook on energy supply and demand.
The Natural Resources and Energy Agency presented the draft Monday to the Advisory Committee for Natural Resources and Energy, an advisory panel to the minister of economy, trade and industry.
The panel is expected to finalize the report in June.
Compared with the outlook report revised in 2001, the latest draft lowered the projection of the number of reactors that would start operations by fiscal 2010 to four, less than a half its initial target.
The energy agency foresees difficulty in gaining consent from local residents for the construction of nuclear reactors and expects energy demand to taper off after peaking in fiscal 2021.
The draft says the volume of greenhouse gas emissions in Japan in fiscal 2010 is expected to exceed the government target.
The agency proposes the creation of a new system providing consumers with information about energy-saving methods before the stalled Kyoto Protocol on global warming takes effect.
Breaking down projected primary energy supply in Japan in fiscal 2030, the draft says petroleum will account for 42 percent, natural gas 18 percent and nuclear energy 15 percent.
It says the ratio may vary depending on the progress of energy-saving efforts or a possible slowdown in the country's economic growth.