Japanese utility Hokkaido Electric Power began shutting the country's last active nuclear reactor on Saturday, leaving the world's third-biggest user of atomic energy with no nuclear-derived electricity for the first time since 1970.

A crisis at Tokyo Electric Power's Fukushima Daiichi nuclear plant, where an earthquake and tsunami in March last year triggered radiation leaks, has hammered public faith in nuclear power and prevented the restart of reactors shut down for regular maintenance checks.

Hokkaido Electric said it started lowering output from the 912-megawatt No.3 unit at Tomari nuclear plant in northern Japan at 5 p.m. (2 a.m. New York time).

The maintenance on the unit is set to begin at around 11 p.m. (9 a.m. New York time) when power generation falls to zero, with the unit to be shut down completely by the early hours of Sunday.

The shutdown means all of Japan's 50 reactors have been taken off line, marking the country's first nuclear power-free day since May 1970.

Trade Minister Yukio Edano and three other ministers have been trying to win the support of communities to reactivate two idled reactors at Kansai Electric Power's Ohi nuclear plant to help ease expected power shortages of nearly 20 percent in coming hot-weather months.

The two Ohi reactors are the first to be considered for reactivation by the central government, but it faces an uphill battle of winning public support.

Kansai Electric's expected deficit for this summer was the highest among four Japanese nuclear plant operators that forecast shortfalls when demand peaks in the summer.

Costly Option

The last time Japan went without nuclear power was in May 1970, when the country's only two reactors operating at that time were shut for maintenance, the Federation of Electric Power Companies of Japan says. 

Nuclear power provided almost 30 percent of the electricity to keep the $5 trillion economy going before the March 11, 2011 disaster that killed almost 16,000 people and left more than 3,000 missing. 

A year on, the level of public concern about the safety of the industry is such that the government is still struggling to come up with a long-term energy policy, a delay having a profound impact on the economy and underlining just how costly it will be to contemplate a nuclear-power-free future. 

Having boomed in recent decades on the exports prowess of big brands like and Canon, the economy suffered its first trade deficit in more than three decades in 2011 as power producers spent billions of dollars on oil-and-gas imports to fuel extra generation capacity. 

At the time of the Fukushima crisis, then Prime Minister Naoto Kan called on Japan to wean itself off of nuclear power. Up to that point, Japan had been planning to lift the share of nuclear generation to over 50 percent by 2030 from about 30 percent.

The government of current Prime Minister Yoshihiko Noda has softened Kan's call. Noda says Japan can not afford to be nuclear free, although he still holds that as an ideal.

But the government has no clear timetable for getting nuclear power back up and running as it tries to navigate the public opposition—rare in Japan—and the demands of business that wants a stable supply of power.

Cabinet ministers last month rushed to try to win over the public to allow the restart of two nuclear power reactors at Kansai Electric Power's Ohi plant in western Japan, in what experts said was a recognition of the implications of a nuclear-free summer.

The public remained unconvinced. A poll by Kyodo news agency last weekend showed about 60 percent of the public opposed to restarting the two reactors.

Most mayors and governors whose communities host nuclear plants want safety assurances beyond government-imposed stress tests before agreeing to restarts, a Reuters poll showed in March.

To overcome the opposition, some politicians have been more forceful. Yoshito Sengoku, the acting president of the ruling Democratic Party of Japan, on April 16 called an abandonment of nuclear energy the equivalent of "mass suicide," Kyodo news reported. His comment was criticised by Chief Cabinet Secretary Osamu Fujimura, indicating internal divisions over how to handle the issue. 

Global Shift

Ultimately, some argue Japan's economy, already weakened by years of deflation, would suffer if reactors are not restarted. 

"It's not an option Japan should take. There will be less employment and the economy will be on a shrinking trend," said Takeo Kikkawa, a professor at Hitotsubashi University.

Japan's liquefied natural gas imports climbed 18 percent in volume and 52 percent in value to 5.4 trillion yen ($67 billion) in the year through March. 

Renewable energy, although given emphasis in energy policies being formulated, is not expected to be much of an immediate salve. Energy from renewable sources account for about 10 percent of Japan's power generation, most of that from hydroelectric dams. Wind and solar together contribute about 1 percent.

Worldwide, there has been a shift with Germany, Italy and Switzerland moving away from atomic energy, prompting the International Atomic Energy Agency to revise down its forecast for growth in the industry.

The United States, China and India are still planning to increase the number of reactors.

In Japan, a delay in setting up a new, more independent Nuclear Regulatory Agency due to deadlock in a divided parliament is further clouding the outlook.

Some analysts say the government is not going to turn public opinion unless it admits that nuclear power is never going to be absolutely safe. 

"The debate needs to be recast," said Bob Geller, a professor of geophysics at Tokyo University. "They have to come clean, and say, in effect - look we know they're not perfectly safe but we've made a careful evaluation of the risks, which we'll make public."