Voith Hydro, based in Heidenheim, Germany, was contracted to manufacture all six of the 306 MW turbines destined for the Xiaolangdi dam in Henan province, with the first batch put into operation in 2000.

Numerous cracks have developed on the blades of four of the turbines, according to a March 20 report in the Big River News (Dahe Bao), a Henan-based newspaper serving the Yellow River basin. The cracks have occurred in the same location on every damaged blade, the newspaper said. In the most serious case, cracks have appeared on 13 blades of one turbine.

The builders of the Xiaolangdi dam investigated the problem for more than a year, the newspaper reported. They concluded that the cracks were the result of violent shuddering that occurs when the turbines are started, stopped or operated at full capacity.

Working with the provincial import-export inspection agency, the dam builders began difficult compensation negotiations with Voith, Big River News reported. After several rounds of talks, the company agreed to pay US$2.15 million in compensation, plus $800,000 toward repairs, the newspaper said.

The Xiaolangdi dam, located 40 kilometres north of the ancient city of Luoyang, was built in the 1990s with assistance from the World Bank and the Canadian International Development Agency. The Yellow River Water and Hydroelectric Power Development Corp. oversaw the $5-billion project, which forced the relocation of 180,000 people.

After Xiaolangdi began generating electricity in 2000, the South China Morning Post reported that it was having trouble selling its power. “The economic viability of the dam, which has presented difficult engineering challenges and the import of costly equipment and know-how, is threatened by an electricity glut,” Jasper Becker wrote.

The Xiaolangdi project also has to contend with challenges posed by the world’s muddiest river. Patrick McCully of the International Rivers Network writes in Silenced Rivers that “the efficiency of a turbine is largely dependent upon the hydraulic properties of its blades, just as an aeroplane depends on the aerodynamic properties of its wings. The erosion and cracking of the tips of the turbine blades by water-borne sand and silt considerably reduce their generating efficiency and can require expensive repairs.”

Power Technology [PDF] (“the Web site for the power industry”) says that much of the Voith equipment for Xiaolangdi was manufactured at the company’s U.S. plant in York, Pennsylvania. Voith also subcontracted part of the work to others, including the Harbin Electric Machinery Company of Heilongjiang province, which supplied the six 333MVA generators, and Dongfang Electrical Machinery, based in Chengdu, Sichuan province, which supplied electrical equipment, Power Technology reports.

Voith Hydro merged its hydropower division in 1999 with another German company, Siemens. That joint venture, Voith Siemens Hydro Power Generation, is a member of a consortium including GE Canada and Sade Vigesa of Brazil that is supplying six of the 14 turbines that will operate in the left-bank power station at the Three Gorges dam. Subcontractors used for this order also include Dongfang Electrical Machinery. (See Probe International’s Who’s Behind the Dam.)

The eight other 700MW turbines that will be installed in the Three Gorges’ left-bank powerhouse are being built by Alstom Power of France and Switzerland’s ABB, working with subcontractors Harbin Electric Machinery Co.

Liang Weiyan, a member of the Chinese Academy of Engineering and a turbine expert with the Harbin Electric Machinery Co., says that production of the equipment that will generate the hydropower at the Three Gorges dam has generally gone well. However, in comments published March 15 in China Three Gorges Construction, a journal of the Three Gorges Corp., he also expressed concern about the difficulty of maintaining high quality-control standards when production of parts and components for the turbines has been widely subcontracted.

“It’s true that all of the main contractors that won the bidding to manufacture the [first] 14 turbines for the Three Gorges dam are among the world’s top companies. However, more than 100 factories from 17 countries have been subcontracted to provide parts, components and equipment for the turbines. So it’s hard to say for certain that the quality of the turbines can be guaranteed.”

He said “one of the greatest challenges” is dealing with cracks on turbine blades, which he described as a common problem afflicting such equipment, whether manufactured in China or abroad.

“Everything will be tested after the reservoir is filled, and we won’t know the truth about the quality of the turbines until they are actually put into operation,” Mr. Liang said.

Concern about the Three Gorges turbines has been expressed before, and at the highest political level. Even Li Peng, a former premier of China and long-time champion of the Yangtze dam, was openly worried about the project’s 26 giant turbines, which will be larger and more complicated than any ever attempted before.

During an inspection tour in late 2001 to the dam site near Yichang, Hubei province, Mr. Li, citing “many unknown factors,” said that uncertainty surrounds the manufacture and installation of the turbines. He said lessons must be learned from a serious technical accident that occurred during installation of the turbines at the Gezhouba dam, located 40 km downstream of the Three Gorges site and completed in 1988. Mr. Li’s remarks were carried in the Three Gorges Project Daily (Sanxia gongcheng bao), which provided no further information about the accident.

Then, a year ago, the senior official in charge of monitoring Three Gorges project quality control said she was “really concerned” about the design of the Three Gorges turbines.

Qian Zhengying, a former minister of water resources and electric power who heads the dam’s quality-control inspection group, said the turbines were not ideally suited to the conditions in which they will be operated, but it is too late to do anything about it. “The die is cast, since we have signed the contracts with the suppliers,” she said. Her remarks were published in the Three Gorges Project Daily (Sanxia gongcheng bao) on April 11 last year.

Ms. Qian said the reservoir water level will be kept lower than was anticipated when the equipment was ordered years ago, and that it remains to be seen how the turbines will operate “under these changed circumstances.” She gave no further details about the apparent change in operating regime.

She also warned that cracks could appear in the turbines, particularly the ones made in China, because of possible “flaws and weaknesses” in their manufacturing or installation.