RENEWABLE ENERGY IN JAPAN (SOLAR THERMAL, PHOTOVOLTAIC, AND WIND POWER)

As introduced in the last month's issue of the JFS Newsletter, the Japanese government expresses its expectation, in the "Guidelines for Measures to Prevent Global Warming," that "new energy" will play a bigger role in Japan's energy supply in the long run, although this energy now accounts for only 1 percent of the primary energy supply in Japan. New energy is expected to revitalize the economy and create jobs by encouraging innovation and opening new markets.

"New energy" has somewhat a unique definition in Japan, meaning natural energy sources such as solar and wind power, "recycled" energy including refuse-derived fuel (RDF), and new ways to utilize conventional energy, such as fuel cells and co-generation using natural gas.

In terms of policy, "new energy" is defined here as "forms of energy needed to replace oil, that are reaching the commercialization phase from a technological standpoint, but have not yet become widely used due to economic factors." This definition excludes hydro power, which is already in commercial operation, and wave power generation, which is still in the research and development phase, although both are natural or renewable energy sources.

In 1994, the Japanese government formulated the Basic Guideline for New Energy Introduction as a cabinet decision. This guideline, revised in 2001, provides concrete measures to promote these forms of energy and numerical targets for their introduction by 2010. The table below shows these targets.

Professor Izumi Ushiyama of the Ashikaga Institute of Technology explains the current situation of renewable energy in Japan below.

The Japanese government set up the "Sunshine Project" in 1974, following the first oil crisis in 1973, and conducted long-term, comprehensive and systematic research and development until 2000 regarding the supply of clean energy.

(1) Solar Thermal Utilization

In starting out the Sunshine Project, the Ministry of International Trade and Industry (now the Ministry of Economy, Trade and Industry) turned its attention to solar thermal power generation, in which sunlight is focused and used to generate steam to drive a turbine generator. In 1981, the Ministry completed a 1000 kW pilot plant with a central power tower system and a parabolic trough system in the town of Nio, Kagawa Prefecture.

The plant successfully achieved its rated output for the first time in the world, during three years of continuous operation. The R&D of solar thermal power generation turned out to be technologically successful, but not economically viable in Japan.

Instead of such large-scale power plants, simpler rooftop solar water heaters are widespread for residential use in Japan. Japan is leading the world in their diffusion, with about 5 million units used nationwide.

More complex solar thermal systems are also set up to provide space heating and cooling as well as hot water. At present 0.7 million systems are in service. Because solar heat is a decentralized energy source by nature, it is more suitable for such small-scale, grassroots uses than for large-scale applications.

While the above-mentioned are collectively called "active" solar systems, there are also "passive" solar houses. Among them are houses that have double walls. Air is circulated between the walls, and the heated air from the south side of a house is blown to warm rooms on the north side.

(2) Photovoltaic Power Generation

Since the beginning of the Sunshine Project, the R&D of photovoltaic power generation made good progress, aiming at high efficiency and low cost. The cost of solar cell modules, initially a few million yen (about several tens of thousands of U.S. dollars) per kilowatt at maximum output, has been reduced to 0.6 million yen (about U.S.$5,000) per kilowatt. The cost can be reduced further to 0.5 million yen (about U.S.$4,200) if modules are mass-produced at a volume of about 10,000 kW per year.

The cost depends heavily on the efficiency of energy conversion, which is highest when monocrystalline silicon is used in the solar cells, reaching about 21 percent in laboratory tests and 14 to 16 percent for marketed products. The efficiency for multicrystalline silicon is about 16 percent in laboratories and that for amorphous silicon is currently about 11 percent.

In addition to photovoltaic modules, the whole system includes a DC-AC inverter, a charge controller grid to connect with a utility powerline, and a set of frames to hold the modules on rooftops, etc., costing 1.2 million yen (about U.S.$10,000) per kilowatt. This means that a 3 kW system, the size usually installed for one household, costs 3.6 million yen (about U.S.$30,000), which is rather expensive. To spread the use of household photovoltaic systems, the costs for the whole system would have to come down further, and subsidies would also be needed.

The Japanese government introduced a subsidy for the installation of home power generation systems in FY1994. The subsidy covers about a half of the equipment cost. The number of subsidy approvals was 557 in FY1994, 600 in the first half of FY1995, and 423 in the second half of FY 1995. The average installed capacity per household was 3.5 kW to 3.9 kW.

The cost of solar power systems has fallen steadily, from 6 million yen (about U.S.$50,000) for a 3 kW system in FY1994, to a little less than 4 million yen (about U.S.$33,600) in FY1996, and 2 million yen (about U.S.$16,800) for the same size of system in FY2000. The subsidy in Japan has been reduced to only one-third of the equipment cost. (By comparison, the German government provides a 70-percent subsidy to promote solar power generation.)

Since January 1992, Japanese power companies have been purchasing surplus electricity at competitive rates from renewable sources such as solar and wind power, giving great momentum to promote solar power systems. Remarkably, this momentum has been gained in the absence of regulations regarding price-setting or obligatory purchasing.

According to Professor Emeritus Yoshihiro Hamakawa of Osaka University, photovoltaic power generation in Japan has the potential to generate 307.7 billion kWh per year, or 40 percent of Japan's current total electrical power generation. This could be realized if 80 percent of Japan's 25 million households were equipped with solar panels generating 3 kW and 50 percent of Japan's 450,000 collective housing complexes were equipped with rooftop panels generating 20 kW per building.

The implications are impressive. Just think! As much as 40 percent of Japan's total electricity needs could be met by photovoltaic systems installed on existing houses and buildings.

(3) Wind Power Generation

Since the 1990s, when the global warming issue started to attract attention, the production of wind power worldwide has rapidly increased. It has grown by some 30 percent per year over the past five years.

In recent years, wind power generation has made significant progress in Japan, thanks to the government's policies and measures, including the enactment of the Law concerning Promotion of the Use of New Energy. As of January 2003, installed capacity was about 400 MW, but this accounts for only 1.2 percent of global output.

It has been considered that Japan, despite being hit by numerous typhoons every year, did not have the kind of wind suitable for power generation. As part of the New Sunshine Project, the New Energy and Industrial Technology Development Organization (NEDO) observed wind conditions throughout the country for eight years and compiled a wind map. It revealed the country did actually have more than enough wind resources.

In fact, one-seventh of the Japanese land boasts wind with the annual average velocity of six meters per second, the lower limit for economically viable power generation. If wind turbines of 40 meters in diameter (the largest size now in practical operation) were installed in Japan at all suitable sites on land, considering the various obstacles, total power generation would amount to 25 million kW. This amounts to 20 percent of the country's annual power output today.

Three scenarios for potential energy demand have been considered: optimistic, moderate, and pessimistic. Even in the moderate estimate, 3.5 percent of power demand is likely to be met by constructing wind turbines that collectively generate 6.87 million kW.

Japan is a marine nation with one of the longest coastlines in the world. And yet no feasibility study of the potential of offshore wind farms has ever been released to date. Some experts unofficially estimate, however, that the potential for offshore wind power is over 14 times greater than on land, even under the most pessimistic scenario.

Today, wind power generation has reached a practical stage that is also profitable. Generally speaking, volume efficiency and economies of scale lead to lower prices. Thanks to the progress in these factors, the construction cost of a wind turbine has fallen remarkably since the beginning of the 1990s.

Currently, wind turbines with power output of over 1000 kW benefit from the advantages of scale, their construction costs have not dropped as they are not yet being mass-produced. In a few years, however, one-megawatt turbines are expected to increase in number, and multiplier effects of economies of scale and volume efficiencies will lower the construction cost of large 1000 kW turbines.

Since the power output is proportional to the cube of wind velocity, the site of a wind turbine greatly affects power generation costs. Selecting sites favorable to wind power generation and reducing the construction cost of a wind turbine will help lower the overall power generation cost.

The following are some of the articles in the field of renewable energy from the JFS Information Center.

Harnessing Offshore Wind Power

Promoting Wind Power Generation at Ports and Harbors

First Wind Turbine Completed on Tokyo Bay Waterfront

Tomamae Is "Japan's Denmark" And A Mecca for Wind Farms

Wind Turbines of the People, by the People and for the People in Aomori

Sharp Introduces World's Most Efficient Photovoltaic Module

Sanyo Electric Unveils Giant Photovoltaic Monument, the "Solar Ark"

Honda Engineering Develops Next-Generation Thin Film Solar Cell

Photovoltaic Power Generation by Clay Roofing Tile

NEDO Develops New Solar Cell with Reduced Power Generation Cost

Yokohama City to Install 100 Solar-LED Lightposts

Hokkaido Housing Community Has World's Top Solar Power Ouput

In our next newsletter, we will introduce other means of power generation, including medium and small-sized hydraulic power, wave power, ocean thermal energy conversion, biomass, and geothermal power.

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