BEIJING, China -- China has unveiled plans to make offshore wind farms a key part of its renewable energy program within two or three decades.

The wind turbines, which would be built 50 kilometers (30 miles) out to sea, would be ideally situated to supply clean power to the populous and booming east coast area.

"Offshore wind sites are close to the main electricity load centers in eastern China, so offer great potential for future energy supply," Shi Pengfei, vice-chairman of the Chinese Wind Energy Association, told a conference this month.

"I am confident that in 20 to 30 years a very significant proportion of the wind power in China will be off-shore."

China's top state planner, Ma Kai, said in April the country was looking for more varied energy supplies to reduce its reliance on coal such as nuclear, wind and hydro power.

Coal accounted for about 67 percent of energy consumption and 76 percent of energy production in the world's fastest-growing major economy, he said.

Sea winds could be harnessed to generate an estimated 750 gigawatts, although few projects were under way now, Shi said.

This would be around 70 percent higher than the country's total installed generating capacity at the end of 2004 and maybe three times the potential of onshore sites.

China aimed to have 20 gigawatts of wind-generating capacity installed by 2020, equivalent to around 1.0 percent of annual electricity consumption at that time, Shi said.

At present the industry is limited by its high costs, with the price of power generated by a 100 megawatt wind project over two times higher than the equivalent from a coal generator.

The majority of equipment -- around four-fifths -- is imported and few Chinese firms make larger turbines.

However the government has set up wind power concessions to lure investment and know-how, guaranteeing a fixed price for power, as well as help with infrastructure like access roads.

Shi said he expected the cost of wind-generated power to move closer to that from coal-burning plants when there is around 3000 MW of market demand, and the country has set a generating target of 4000 MW by 2010.

Unlike European wind power leaders like Germany and Spain, China is not obliged under the Kyoto treaty to cut its emissions of greenhouse gases like carbon dioxide.

But the government is concerned by the effects of air pollution, much of it from coal-burning power plants, on health and is keen to boost clean energy.

A senior government adviser said recently that acid rain affected around one third of the country.