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Sunday, Feb. 12, 2012

NATURAL SELECTIONS

A future free from nuclear energy? Yakushima may be ready


I once took a ferry from Kagoshima on the southernmost tip of Kyushu to Amami Oshima, halfway to Okinawa. Just 60 km out from the massive Sakurajima volcano that dominates Kagoshima City, our ship passed a huge granite hunk of rock some 50,000 hectares, covered in forest.

News photo
News photo
Natural beauty: Yakushima, an island with a population of 15,000, is famed for its yakusugi trees, a prime inspiration for anime director Hayao Miyazaki. A study has shown that the island could replace all of its petroleum-derived electricity with hydroelectric power. EDAN CORKILL

I didn't know it then, but that green island was Yakushima: inspiration for anime legend Hayao Miyazaki, home to one of the oldest trees in the world, and now an experiment in hydrogen power and a future sustainable society.

At Kagoshima University's Department of Applied Chemistry and Chemical Engineering, Yoshimitsu Uemura has made it his life's work to explore sustainable sources of power. The problem is that in practice sustainable power only delivers enough for relatively small-scale energy needs.

A population as big as Japan requires much more — and currently only nuclear and conventional fossil-fuel power stations can supply that. Both have their problems. Fossil fuels have to be phased out if we are to reduce the amount of greenhouse gases going into the atmosphere, and nuclear power stations are expensive to build and produce nasty waste. Besides which, they aren't enjoying huge amounts of popularity in Japan at the moment.

In a small survey by online research company Macromill Inc., 524 people were asked to indicate their opinions on energy and nuclear power. Questioned from Jan. 12 to 14, 2012, one-third of respondents said that nuclear power should be completely abolished "immediately." Two-thirds said by 2050. Renewable sources of energy are needed more than ever.

But how to do it? At the moment, solar and wind power are too inefficient. But writing in a paper in the journal Renewable Energy, Uemura and colleagues showed that Yakushima, which has a population of only 15,000, could replace all of its petroleum-derived electricity with hydroelectric power (journal reference DOI: 10.1016/S0960-1481(03)00166-6).

If you go to the island — and most people who do go to see the wonders of the yakusugi trees, of which more later — you might see a hydrogen-powered car winding its way along the coastal road. Honda's prototype FCX car — FCX stands for Fuel Cell eXperimental — uses hydrogen as fuel, reacting the gas with oxygen to produce energy that runs an electric motor, with only water as a byproduct.

Water is about the best waste product you could hope for, though Yakushima is not short of it. The high mountains catch a lot of moisture, and more rain falls here than in any other part of Japan. The island receives 4,000-10,000 mm a year, making it one of the rainiest places in the world.

At present, hydroelectric power is used to generate power for the hydrogen fuel cells, but Uemura calculated that the hydroelectric power on the island is sufficient to cover all its energy demands. "We found that fossil-fuel energy in Yakushima could be substituted with hydroelectric energy without causing an impact on the environment," his team concluded.

There have been many false dawns for the hydrogen economy. Former President George W. Bush declared in 2003 that the U.S. would become the world's No. 1 country for hydrogen-power automobiles. It never happened, of course, because hydrogen fuel-cell technology was not good enough. Barack Obama cut the funding for the hydrogen fuel cell program in 2009.

Could modest Yakushima show the way for a sustainable economy? A World Heritage Site, there's hardly a more appropriate place to make environmentally pristine.

The island is famous for the Japanese cedar that grows all over its mountains. The usual word for cedar is sugi (Cryptomeria japonica), but on Yakushima the trees grow very slowly, hampered by the nutrient-poor granite base to the island. This means many of them attain great age, and once they are over 1,000 years old they are known as yakusugi.

It was visiting these ancient trees that finally helped director Miyazaki finish 1997's "Mononoke-hime (Princess Mononoke)," a fantasy epic that calls for an ecological balance to be struck between human activities and the needs of the forest's ecosystem. Miyazaki had taken 16 years to develop the film and it seems that the sight of the yakusugi galvanized him.

On the north face of the highest peak on the island is a tree known as Jomon Sugi, the name referring to the Jomon Period of prehistory (14,000-300 BC). The tree is estimated to be between 2,170 and 7,200 years old, though the lower end is more likely. (The age estimate for Jomon Sugi has such a large range because the inner core is rotten, making the aging by core sample difficult. Estimating the age by the diameter of the trunk is a less reliable method.)

But though the location is particularly appropriate and the hydrogen experiment admirable, the plan for sustainable energy on Yakushima can't be scaled up to work on the Japanese mainland. And if you're wondering why a small island south of Kyushu is home to such futuristic experiments, you only need to look to its neighbor, Tanegashima.

This island is the home to the Tanegashima Space Center, Japan's largest space base. Satellites are launched from there, and rockets are tested. The facility uses a lot of hydrogen. For the rest of us, if we are to make the transition to a sustainable, hydrogen economy the key will be developing an infrastructure to supply it and fuel cells that can burn it cheaply.

Rowan Hooper (@rowhoop on Twitter) is the news editor of New Scientist magazine. The second volume of Natural Selections columns translated into Japanese is published by Shinchosha at ¥1,500. The title is "Hito wa Ima mo Shinka Shiteru (The Evolving Human)."


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