The American Wind Energy Association is expected to release a survey next month that says the US has become the world's leading wind producer, and that the industry expects rapid growth to continue in places like Texas, the Great Plains and California.

The survey calculates that the US wind industry now tops Germany in terms of how much energy is being produced from wind.

Germany still has more installed capacity - 22,000 megawatts compared with 17,000 in the US at the end of 2007. But the average wind speed is stronger in America, which means more energy is being generated, the group said.

And this year, Germany will add only about 1,600 megawatts of wind energy, while the US will add more than 6,000 megawatts, said Randy Swisher, executive director of the association.

"The numbers themselves are not what matters," said Swisher.

"What matters is that the wind industry around the world recognises that the US is the largest market."

That's important because many of the world's leading wind companies are not US companies, and they will need to move manufacturing jobs to the US as the wind industry grows, Swisher said. His group says 4,000 wind-related manufacturing jobs have been added in the US since 2007.

Currently, wind provides about 1% of US electricity.

In California, Pacific Gas & Electric has been using wind power for decades, and has been aggressive in adding new contracts for wind energy in the last four years as it strives to meet the state's renewable energy goal of 20% by 2010.

PG&E has 1,164 megawatts of wind energy in operation or under contract, said spokeswoman Jennifer Zerwer.

The cost of wind power is almost comparable to fossil fuels such as coal, at between 4.5 and 7.5 cents per kilowatt hour, according to FPL Energy, builder of the country's largest wind farm in Horse Hollow, Texas.

But building a wind farm costs more than a fossil-fuel plant - between $1.5m and $2m per megawatt of capacity compared with $800,000 for a natural-gas plant.

Once constructed, though, wind plants have no fuel costs compared with coal and natural gas plants.

The industry says that 250 to 300 average US homes are served by one megawatt of wind energy.