The US Commerce Department on Friday announced plans to charge duties of up to 73 percent on wind-turbine towers imported from China and up to 60 percent from Vietnamese imports, adding to trade tensions over renewable-energy equipment.

The Wind Tower Trade Coalition, a group of US manufacturers of tower, filed a complaint with the department in late 2011 claiming dumping by Chinese competitors.

Under the preliminary tariffs — a final decision on their imposition is expected by December — some Chinese wind-tower makers are specified by name. Chengxi Shipyard Co and Titan Wind Energy (Suzhou) Co face tariffs of 30.93 percent and 20.85 percent, respectively. All other Chinese manufactures could be hit with duties of between 26.25 percent and 72.69 percent.

The Commerce Department, acting on the dumping allegations in the compliant, investigated the manufacturing and pricing of so-called utility-scale wind towers, which support the blades used in wind turbines that generate electricity of 100 kilowatts or more.

The department said that in 2011, imports of such towers from China and Vietnam were valued at $222 million and $79 million, respectively.

Friday's announcement was the fourth time this year that the United States has accused Chinese makers of renewable-energy products, including solar panels and wind towers, of selling their products in the US market at below market value.

In May, the Commerce Department set preliminary anti-dumping tariffs of 31 percent to 250 percent on Chinese solar-panel makers to protect US producers. The same month, it set preliminary countervailing duties of 14 percent to 26 percent on Chinese-made towers, blaming local governments' subsidies to the industry.

Imports of solar cells from China in 2011 were estimated at $3.1 billion, according to the Commerce Department.

Experts say the series of tariffs will constrain trade between China and the US in the burgeoning renewable-energy sector, and likely lead China to sell less in the US market.

Chinese solar-panel companies, for example, would do well to invest in partnerships to get their products marketed in the US with reduced exposure to tariffs, said Philip Grothe, of Simon-Kucher & Partners, a global consulting firm in Bonn, Germany.

"In the US, Chinese companies can no longer sell solely through price. They have to improve their understanding of value to customer," he said.

"Mostly, price is not the most important criterion. If you understand what your customers value and are able to improve the value you sell, you will be able to raise prices."

Contact the writer at yuweizhang@chinadailyusa.com