VANCOUVER, British Columbia - TransAlta Corp said on Monday it is planning a C$100 million ($97.1 million) expansion to its New Brunswick wind farm after winning a 25-year power supply contract in the Atlantic Canadian province.

TransAlta, Canada's biggest independent power producer, said it was awarded the 25-year contract to provide another 54 megawatts of wind power to the New Brunswick power utility.

The Calgary-based company will now expand its 96 MW Kent Hills wind facility to 150 MW. Kent Hills, which is located southwest of the city of Moncton, New Brunswick, started commercial operations in December 2008.

TransAlta plans to start work on the expansion early this year, subject to regulatory and environmental approvals, and expects it to be in commercial operation by the end of 2010.

Once finished the facility is expected to provide 160,000 megawatt hours of power per year, enough electricity for about 9,000 homes.

With the completion of the Kent Hills expansion next year, we will have over 1,000 MW of wind power and over 2,000 MW of renewable energy in operation across Canada and the United States, said Steve Snyder, TransAlta's president and chief executive.

TransAlta's stock was 11 Canadian cents, or 0.5 percent, firmer at C$23.47 on the Toronto Stock Exchange early on Monday afternoon.

Last year TransAlta bought green power producer Canadian Hydro Developers for C$1.6 billion to expand its renewable power assets as it tries to balance its own, mostly coal-fired, generation business.

($1=$1.03 Canadian)

(Reporting by Nicole Mordant; editing by Rob Wilson)