Geothermal energy is Japan's buried treasure

[FOX80]

Kyushu Electric's Hatchobaru geothermal power station boasts the largest generation capacity in Japan.
MASANORI TOBITA

Staff writer

Japan may be a small nation, poor in most natural resources, but it is sitting on an abundance of energy in the form of geothermal heat. In fact, it has the world's third largest stores of geothermal energy. Efforts have now begun to unlock its potential.

Aboveground, Japan sees more of the downside of earthquakes and volcanic activity. But belowground, all that hot magma has created vast stores of thermal energy locked up in geological formations. Japan is an engineering powerhouse in this field, with Japanese companies boasting about a 70% share of the global market for geothermal power station equipment.

The promise of geothermal energy as a clean energy resource has also captured the attention of other countries. As interest heats up, this is a field with great growth potential.

Ready-made steam

Circled by mountains in a protected area, the Oita Prefecture town of Kokonoe boasts many picturesque hot springs. It is also home to the largest geothermal power operation in Japan.

The Hatchobaru geothermal power station, operated by Kyushu Electric Power Co., produces 110 megawatts of electricity from a pair of generators made by Mitsubishi Heavy Industries Ltd.

A geothermal power plant produces electricity by spinning turbines using steam extracted from underground, where water has been heated to high temperatures by magma deep in the earth.

The earth's core is extremely hot. The temperature can exceed 1,000 C even 30km underground, so in a sense, all nations are sitting on top of vast stores of heat energy. Unfortunately, existing technologies cannot reach down that far to exploit this resource.

In regions with volcanoes or hot springs, however, magma pools of around 1,000 C may be just several kilometers underground. Rainwater can seep down to that level and collect as heat pools inside geological formations. These are the energy stores that can be tapped for geothermal power generation.

Technical hurdles

Thermal power plants typically burn some type of fossil fuel such as liquefied natural gas (LNG), oil or coal to produce the heat to produce the steam that spins the turbines, a process that releases large amounts of carbon dioxide. In contrast, almost no release of CO2 is associated with geothermal power. The pressing need to reduce CO2 emissions and prevent further global warming explains why geothermal energy is now in the spotlight.

And whereas the power output of wind turbines and solar panels is dependent on the weather, geothermal power stations produce reliable, stable supplies of electricity. Despite these advantages, geothermal energy is not without its challenges.

The heated water extracted from underground is full of impurities that can damage turbines. "To maintain high output you need to eliminate those impurities," explained Shojiro Saito, chief engineer in the thermal power business division of Mitsubishi Heavy. His company's solution was to design drip holes in the nozzles that inject steam into the turbines. A constant drip of cold water coats the inner walls of the turbines and prevents impurities being deposited.

Other companies are developing their own technologies to prevent corrosion and scaling from damaging the turbines. Fuji Electric Co., for example, is working on a corrosion resistant coating. Toshiba Corp. has also developed a material with greater corrosion resistance and modified the design of its turbine nozzles to reduce scaling caused by natural steam. Toshiba’s equipment, installed at a geothermal power station in California in 2002, operated for 10 years without a single day of downtime.

Making it easier

Japan has an estimated 23,000Mw worth of geothermal resource capacity, equivalent to the output of more than 20 nuclear power plants and third only to the U.S. and Indonesia. The advanced technologies developed by Japanese companies have given them a roughly 70% share (in terms of output) in the global market for equipment to generate geothermal power. In addition to Mitsubishi Heavy and Toshiba, another major player is Fuji Electric, which is strong in Indonesia.

When it comes to the exploitation of geothermal resources in its home market, however, Japan lags behind other nations. Many of its geothermal reservoirs are located inside parks where the Natural Parks Law prohibits the construction of power plants. This and other regulations have stymied progress in the domestic industry.

But political momentum is building to ease such restrictions. Regulations in the Natural Parks Law were eased last year, and this September the Ministry of Economy, Trade and Industry announced support for the development of geothermal energy in 16 regions, spurring Kyushu Electric Power to begin a survey of Aso Kuju National Park. Also, as part of its strategy for national economic growth, the Abe administration has proposed that the environmental assessments required for geothermal power stations be performed more quickly.

Companies are also finding more ways to apply existing technologies. Last year, Toshiba developed a simplified geothermal power generator that can be transported on a trailer and installed in around three months. Measuring just 2.4 x 11m, these power stations can be installed on sites as small as 300 sq. meters. A 2Mw system produces enough electricity to supply 2,000 homes, and versions with output capacities of up to 9Mw are possible.

Thanks to the introduction of a feed-in tariff mechanism last year that guarantees the purchase price of all electricity generated from renewable sources, "the investment can be recovered in less than five years," explained Toru Shibagaki, head of Toshiba's renewable energy business. "And the revenues from selling power can help finance other activities in regions that have hot springs," he added.

Advances like these can stimulate domestic demand, but the biggest markets are overseas.

The Japanese government considers geothermal power systems a promising infrastructure export opportunity and intends to support the development of geothermal power in Kenya, Tanzania and other nations in the large geothermal belts of East Africa.

More large-scale projects in places like these will give Japanese firms more opportunities to win orders. But with other companies now working to catch up technologically, this is a field where the international competition is destined to heat up.

Keywords

Easing of Natural Parks Law

The Natural Parks Law strictly regulates development in protected areas to preserve their scenic beauty and natural environment. Many of Japan's geothermal resources are located in such areas, but the Natural Parks Law was revised last year to conditionally allow drilling for geothermal energy inside national parks and quasi-national parks.

There are worries, however, that the use of geothermal energy for power generation will deplete the nation's hot spring resources.

Environmental assessment

In order to prevent environmental damage, assessments are required to estimate the nature and extent of environmental impacts from regional development. Because impacts must be evaluated before development is allowed to proceed, construction plans for wind and geothermal power plants typically spend three to four years in the assessment stage.
The Abe administration seeks to expedite this process as part of its strategy for economic growth, and this has accelerated investments in new energy.

Renewable energy feed-in tariff mechanism

Producers of electricity from renewable energy sources such as geothermal, wind and solar power can sell all of their output to electric power companies for a certain period of time at prices determined by the government.
The current mechanism, put into effect in 2012, promotes the generation of electricity from what are sustainable but higher-cost sources. The cost is borne by all users (both businesses and individuals) in the form of higher rates for the electricity they consume.