Manufactured in Denmark, the turbine stands 117 meters (384 feet) tall, with 39-metre (128-foot) blades. It is part of a C$50 million ($33 million) strategy by the provincially owned company to develop new sources of renewable energy as it prepares for deregulation of the Ontario power sector.

"We are very serious with our green energy program because we know that the people of Ontario see it as a market that they would like to tap into," said spokesman John Earl.

"When the market opens, people will be able to choose their kind of energy ... and we want to make sure that we have sufficient renewable energy on hand to meet that market."

Earl said his company wants to quadruple its green energy supply by 2005, using a mix of wind, solar, hydro-electric and biogas sources.

Ontario Power is also studying the idea of a 10 MW wind farm in the Bruce Peninsula, on Lake Huron. One small turbine, about one-third the size of the Pickering unit, is already operational there and the firm is in talks with manufacturers to buy eight to 15 more, he said.

The head of the Ontario Clean Air Alliance, an environmental lobby group, said the Pickering windmill should help reduce Ontario's dependency on coal-fired power plants.

"But because of Ontario's silly emissions trading system - allowing the power suppliers to increase certain emissions while reducing others - building wind turbines can lead to a net increase in pollution and make things worse," Jack Gibbons told Reuters.