The company, which is also developing smaller wind-power projects in Canada, plans to raise about half the capital needed through tax-equity financing, under which banks bankroll renewable energy projects and win tax breaks.
Investors get a generous tax credit for money they invest. Another quarter of the money needed would come from loans and the company itself will finance the rest.
"Our business model is to sell projects once they're built and operational," Patrick Maguire, chief operating officer of the U.S.
unit, said in a telephone interview.
"We take the high risk, which is taking the sites from greenfield through construction. Once they're built, the risk on the investment is much reduced."
Mainstream then sells projects to utilities or others, Maguire said.
"There are a number of tax equity providers, and a lot of them are waiting in the sidelines," he added. "We're confident that for the right projects, you will find people who are willing to invest."
Global wind power capacity grew 29 percent in 2008 to some 120,798 MW, with the United States surpassing Germany to become the world's leading generator of wind power. The sector now provides 1.5 percent of global energy demand, versus a paltry 0.1 percent in 1997.
Maguire said 16-month-old Mainstream bought the three projects, located within 80 miles of Chicago, from FPC Services for a fraction of the cost of developing them.
The most advanced of the projects was Shady Oaks, in Lee County, which will produce 120 megawatts when completed in 2010. Mainstream said it expected to employ 120 people in the development and 12 people to operate the farm.
Green River, also in Lee County, is slated to produce 467 megawatts. Construction is scheduled to begin in 2010.
A project in Boone county, set to produce 200 megawatts, is at an earlier stage. No time schedule was given.
About half of the more than 80 employees at Mainstream, which builds and operates wind, solar, thermal and ocean current plants from South America to Europe, worked formerly at Airtricity. which was sold in 2008 for 1.8 billion euros.
The Illinois project is Mainstream's second North American deal in three months. It signed an $840 million (Cdn) joint venture deal with Canadian wind farm developer Alberta Wind Energy Corporation to build an initial portfolio of over 400MW of wind energy plants in Alberta by 2013.
The company has also announced plans to build a wind farm in Chile in the forthcoming months.