Fatih Birol, newly installed executive director of the Paris-based International Energy Agency, has said the nation's energy policy following the Fukushima meltdowns provides a "realistic and balanced outlook," underscoring the importance of continued use of nuclear power in the country.

In its future energy mix, decided in July, the government plans to have nuclear energy account for 20 percent to 22 percent of the country's total electricity supply in 2030. This compares with 28.6 percent in the fiscal year that ended in March 2011, the year of the disaster.

"I believe Japan without nuclear energy will face major challenges," such as higher energy prices, greater energy security problems and greenhouse gas emissions, Birol, who took office Tuesday, told Kyodo News by phone last week.