Renewable energy poses challenge for Tokyo

America leads in wind power

The world’s largest wind turbine looms over the port of Onahama, dwarfing the derricks of a bulk carrier as it unloads coal at a nearby pier. Each blade on this 7 megawatt (MW) monster is longer than the wingspan of an A380 superjumbo.

What is more, this wind turbine floats. About 100 metres out in the harbour are two bright yellow spars, all part of the underwater superstructure needed to stabilise and buoy this colossal machine. “To assemble this 7MW turbine we had to bring a crane all the way from Holland,” says Takeshi Ishihara, a professor at the University of Tokyo, who inspired the consortium behind the machine. “There wasn’t one big enough in all of Japan.”

Lacking fossil fuels of its own, Japan has always wrestled with energy policy, but the public’s desire to abandon nuclear power in the wake of the 2011 Fukushima disaster has made the challenge even more severe. The government wants to increase renewables from 10 % of its energy mix to 24 % by 2030, further reducing its reliance on gas, coal and nuclear.

But in crowded, mountainous Japan, finding places to install renewables is tricky so Tokyo is searching for new technologies — from Mr Ishihara’s floating windmills to more far-fetched ideas such as beaming power from space — that open up fresh locations for renewable power.

At climate talks this year, Japan is likely to propose a 26 % emissions cut over 2013 levels by 2030, a “practical and reasonable” goal, says Yoshiaki Shibata, senior economist at the Institute of Energy Economics in Tokyo. But the challenge remains where to put new generation technology.


The hot springs resort of Tsuchiyu, in Fukushima prefecture, has long had dams to control erosion on its steep-falling East Crow River. This June it plugged in a 140-kilowatt hydroelectric power station at the bottom of the dam.

Water is one natural resource with which Japan is well supplied: about 9 % of its generation is hydroelectric. But most of the country’s 2,700 irrigation and flood control dams do not generate any electricity, says Hikaru Kobayashi, principal economist at the Japan Center for Economic Research.

Simply adding generators to these existing dams could cover 4 % of Japan’s electricity needs with clean, reliable, low-cost power, he says.

But gaining “rights to use water are fixed — for power, irrigation or flood control — and changing them is incredibly difficult”, says Mr Kobayashi. New hydro proposals always lead to a row about who profits and Mr Kobayashi thinks the law will have to change.

Chart: Proposed changes to Japan’s electricity mix


Japan suffers from frequent volcanic eruptions, but volatile tectonics also mean geothermal power. Geothermal is almost carbon free and when the steam is easy to find it produces cheap electricity.

After a 20-year lull, new geothermal plants are under construction. Idemitsu Kosan is adding 5MW of geothermal capacity at an existing plant in Kyushu, while a consortium headed by J-Power is building a new 42MW geothermal facility in the northern province of Akita.

But geothermal produces a tiny fraction of Japan’s electricity and analysts are not optimistic that it will ever be much more. “We have 30GW of potential but most of the resources are located in national parks,” says Mr Shibata. What is more any hint of using them produces a fierce backlash from hot spring resorts who think power stations will steal their hot water.

Officials at the industry ministry are promoting research into deep geothermal power, found kilometres underground, but it will take costly exploration and drilling.


Onerous environmental rules have slowed the growth of onshore wind turbines in Japan. Nor are there a lot of shallow seas in which to build windmills offshore. But Japan does have plenty of deeper water — out of sight and out of mind — which is where floating turbines come in.

Mr Ishihara’s personal estimate is that floating turbines could generate as much as 10 % of Japan’s electricity needs. With a 7MW turbine complete, his next target is 10MW and upwards, because out at sea the bigger the turbine the better. “We’ve solved the technological problems but not the cost problems,” says Mr Ishihara. With floating turbines, for example, power cables need enough slack not to snap. At present, that requires costly manual work.


In Okayama prefecture, investors are turning a former salt field into Japan’s largest solar facility, with 231MW of capacity. In Hyogo, solar-panel maker Kyocera has put floating solar cells on a reservoir. In Kyoto, it plans to build 23MW of solar on one of Japan’s many abandoned golf courses.

Spurred by a generous feed-in tariff, solar power has been Japan’s most successful renewable and Mr Shibata, at the Institute of Energy Economics, says there are already enough projects in the pipeline to meet the 2030 renewables target. There is a physical limit on the number of unused golf courses, however, creating doubt about the scalability of solar power in Japan. –

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