Post-Fukushima Japan may be approaching an energy death spiral, says Nobuo Tanaka, past executive director of the International Energy Agency.

He argues that if Japan does not find a way to “turn on” its now shuttered nuclear energy reactors, not only will Japan’s already sluggish economic condition be crushed with much larger oil and gas imports from Russia, Southeast Asia and the Middle East — but because of the costs and risk uncertainty — Japan’s powerful manufacturing base may begin pulling out of the world’s third largest economy.

Tanaka explained that at current levels, Japan consumes about 5 million barrels of oil a day. Without domestically produced nuclear energy,  Japan falls about 10% or half a million barrels of oil short of what it must have.

Japan has 54 nuclear energy reactors — only two of which are running at the moment and both of which are scheduled for regular check ups and will be shut down by early May 2012. As regular maintenance has required shutting down plant after plant, none of Japan’s governors has allowed the nuclear energy plants to be returned to operation.

On top of the post-Fukushima nuclear plant disaster, global tensions with Iran are threatening Japan’s dependence on Iranian oil exports, which Japan’s share amounts to about 300,000 barrels a day.

This makes Japan’s current potential daily energy deficit about 800,000 barrels per day.

Tanaka said that if Japan has a very hot summer — which some are projecting — Japan will run another 10% short of supplies on top of the shortages it already projects.