Construction on China's Three Gorges Dam is set to finish next week. Environmentalists say the lessons about the environmental consequences of the world's largest hydropower project have yet to be learned.

Water of the Yangtze River rush out from the Three Gorges Dam in this October 2005 file picture. The dam, the world's largest hydroelectric power project, will be completed in May this year, nine months ahead of schedule, state media reported.[AFP]

With the last of the concrete being poured nearly a decade after China stemmed the flow of the Yangtze River to begin work, environmentalists say it should provide a cautionary tale to an energy-hungry government pushing similar hydropower dam projects.

China says the Three Gorges will tame flooding on the mighty Yangtze, whose waters have claimed 300,000 lives in the 20th century, fuel industrial growth in the area and improve shipping -- as well as having a generating capacity of 18 gigawatts when it is complete in 2009.

"If we look at the four purposes, only the first has been realized -- it can produce power," said Dai Qing, China's most outspoken opponent of the Three Gorges.

"But compared to other methods of generating power that electricity is much more expensive," she told Reuters.

The dam started generating power in mid-2003 and will have 26 turbines when it reaches full capacity in 2009.

The dam's price tag, estimated at $10.8 billion in 1993, is expected to reach $25 billion when completed.

How the costs of the power it generates are calculated is no academic question.

It cuts to the heart of the compromises facing China, which relies on sulphur-belching coal for about 70 percent of its energy, as it seeks less polluting but affordable sources of power to fuel an economic growth of more than 10 percent a year.

ENVIRONMENTAL COSTS

On construction costs alone, analysts say Three Gorges power is competitively priced.

But its critics argue that with the need to resettle about 1.3 million people flooded out of their homes, and environmental impacts of erosion, sediment build-up and the tons of sewage flowing into the dam's reservoir each year, the true costs are much higher.

And with China's total generating capacity about 508 GW by the end of 2005 and another 75 GW to be added this year, the dam's 18 GW will not have the same impact it would have when the project was approved in 1992.

"When it was approved, nobody in their right mind would have thought that China would be adding the equivalent of the capacity of the whole of the UK in one year," said Joseph Jacobelli, an analyst at Merrill Lynch in Hong Kong.

"Any additional capacity helps, but in the global scheme of things the Three Gorges is quite small."

With the end of the project that has been debated in China for decades in sight, critics say opposition is still relevant because of the effect on future dam-building.

More than a dozen hydropower projects for the upper reaches of the Yangtze have been proposed, including one to dam the Tiger Leaping Gorge, a tourist mecca in the Tibetan foothills of China's southwestern province of Yunnan.

Debate is also raging over plans to harness Yunnan's Nu River with a chain of up to 13 hydropower stations, a project that would take a decade to build and generate more power than the Three Gorges.

Since the Three Gorges was approved there is now environmental impact legislation in China, but critics such as Dai Qing say the problem is that there is a lack of public participation and open debate about such massive projects.

Environmental impact studies of the Nu River proposal have been done, but not publicly released.

"I think the government can really only proceed with more dams if they can maintain a fiction that Three Gorges makes sense," said Patricia Adams, executive-director of Probe International, a Canadian environmental think-tank.

"There are better methods of electricity production being locked out in order to protect a bigger project like the Three Gorges," she said.