For years, wind farm operators in Hokkaido have hoped that submarine cables spanning the Tsugaru Strait to Honshu would help them feed Tokyo's insatiable appetite for electricity with renewable energy.

Yet the three cables of Hokkaido-Honshu High Voltage Direct Current (HVDC) Link, which bridge two utility companies' grids, remain underused since their completion in 1979, according to the operator of the cables.

With a maximum capacity of 600 megawatts of electricity, which is enough to supply an average 200,000 households, the cables have been averaging about a little more than 10 percent that capacity.

And that is a pity, wind power operators say.

Encouraged by the relatively low cost of generating large amounts of power, other countries are turning to wind power as their top alternative energy choice.

But in Japan, a lack of coordination between power companies and differences in opinion over its efficacy have slowed its spread here.

The wind power networks operate independently of Japan's nine electric power companies, which also run each of their grids.

Interconnection lines between the grids, such as the one running under the Tsugaru Strait, are held in reserve primarily for delivering power in natural disasters or other emergencies. Few moves have been made to feed in alternative power sources, such as wind power, to the main power grids on a regular basis.

Worldwide, total wind power generation capacity was 121 gigawatts at the end of 2008. That figure is equivalent to the generation capacity of 120 nuclear power plants and represents a twelvefold increase from over a decade ago.

It is also about nine times greater than the equivalent figure for solar power generation worldwide.

Yet in Japan, solar power has been singled out as the prime alternative energy source. The government has plans that will raise solar power capacity to 53 gigawatts, 40 times its current level, by 2030. Modest targets set

And although the cost of wind power is between one-fourth and one-fifth that of solar power, the government nevertheless set a final target for wind power capacity of a modest 6.6 gigawatts.

Construction of wind farms has stalled.

In Tomamae in Hokkaido, where 42 wind turbines jointly operated by the town government and private companies harness the strong winds from the Sea of Japan to produce electricity, officials have put expansion plans on hold.

"We have all the wind we need, but electric power companies will not let us hook up to their grids. It's a pity," said Toshio Mori, the mayor of Tomamae, who also heads a nationwide council of municipalities for promoting wind-power generation.

Tomamae promotes wind power as a source of revenue and tourism. With one of the largest turbine farms in the nation, the town has drawn officials from other communities interested in harnessing the wind.

However, several years ago, a utility company that owns the grids started limiting acceptance of wind electricity from the wind farm.

Council officials were told that the large influxes of wind-generated power in the grids had caused "fluctuations in output and frequency," and "lowered the quality of the electricity supply."

In supplying electricity nationwide, the major utility companies meticulously balance output with demand to stabilize the voltage and frequency supplied by their networks.

Wind-power supplies, however, tend to fluctuate with wind strength. That means that a power network's delicate balance can be disrupted if large amounts of wind electricity flood the grid, they said.

Mori has argued that existing rules on operating grids have hindered further development of wind power. He is urging changes in the rules and a review of plans for building wind farms.

All 59 communities on the council face similar problems. According to one official, "There are virtually no communities currently planning to build new wind turbines."

With little prospect for growth, wind turbines have fallen into disrepair in various parts of Japan, and some generators have been standing immobile for months.

To overcome the problem of wind power's volatility, a new wind farm with 34 wind turbines opened in Rokkasho, Aomori Prefecture, in April 2008. Operated by Tokyo-based Japan Wind Development Co., the Futamata power plant also has storage batteries to hold and stabilize the generated electricity before feeding it into grids. Dubbed a "new generation" wind power plant, it is the first in the world to combine the two features.

Simply erecting wind turbines would have cost 12 billion yen. Adding the batteries ran the bill up to a hefty 22 billion yen. Central government subsidies paid for one-third.

"If we were able to send out all the electricity generated, as is the case in other countries, we wouldn't need batteries," Kenji Yamamoto, director of the plant, said.

Although the batteries stabilize the Futamata plant's electricity, it is only allowed to send 40 megawatts, or half its maximum output, into Tohoku Electric Power Co.'s grids.

Tohoku Electric officials defended their decision to curtail output as necessary "to maintain the quality of electricity." High cost of wind batteries

Meanwhile, the fact that the nation's nine power companies each operate separate grids is also to blame for the difficulty in absorbing volatile electricity flows.

Tohoku Electric offered a bid for wind-power businesses to supply 70 megawatts, on condition that the businesses install batteries. While two businesses successfully drew winning lots, both passed on the opportunity, citing high construction costs.

Aside from the problems of providing a stable flow of power, other drawbacks posed by wind turbines include possible damage to the landscape, bird strikes and a negative impact on health from low-frequency sound waves emitted by rotating turbine blades.

Officials are also wary of constructing wind turbines offshore out of fear of compensation demands from fisheries.

"We are close to reaching the limit for introducing wind power," said Kyoji Yoshino, director of the electricity infrastructure division at the Agency of Natural Resources and Energy, under the Ministry of Economy, Trade and Industry.

Meanwhile, proponents of wind power continue to hope. A 2005 report issued by the New Energy and Industrial Technology Development Organization (NEDO), affiliated with the trade ministry, said that Japan could have a capacity of 20 gigawatts of wind power by 2030.

The Tokyo-based Japanese Wind Power Association estimates that 81 gigawatts could be generated by setting up turbines on "half on the land and 10 percent of offshore areas" that are deemed suitable for wind farms.

Tetsuo Saito, director of the association's planning office, says that simply opening up interconnection lines between the utilities' grids to receive wind-generated electricity supplies could easily provide 10 gigawatts.

The association also said other hindrances to the spread of wind power are low purchase prices for electricity supplies set by the nation's electric power companies and strict building standards for wind generators.

A further problem is that the nation's demand for electricity has leveled off, delaying the need for new facilities. Still, political action could sweep away such obstacles, experts said.