Despite its bright promise, wind energy has taken a number of years to gain importance with major energy industry concerns. The US conglomerate General Electric was the first to dive into the market wholeheartedly in 2002.

Then German giant Siemens followed suit in late 2004 by buying Danish wind turbine maker Bonus Energy. Now the Munich-based firm is planning to gain customers worldwide with its newly acquired technology.

Such developments have pleased Martin Kühn, a wind energy expert at the University of Stuttgart.

"I see it as positive that another large global player has jumped into this new market," he said. "That makes plain that this market is interesting for companies that have clear expectations for profits and that this sector is finally ready for prime time."

It remains a very concentrated field, with only five firms accounting for more than 80 percent of the world's wind energy market. Besides GE, the German firm Enercon, Denmark's Vestas, Spain's Gamesa and now Siemens dominate the show.

Energy giant

Up until recently, the name Siemens stood for any kind of energy production except for the renewable kind. The firm earns billions with traditional energy technology with large turbines for gas and nuclear power plants.

But that looks set to change now. Andreas Nauen, head of the Siemens wind energy unit, said the company plans to double its business in the sector by 2008 or 2009. That would add up to sales of 600 million euros ($775.5 million). And the company isn't just limiting its plans to Europe. By taking over Westinghouse, Siemens hopes to tackle the US market, which is currently dominated by GE Wind Energy.

"I don't see any major problems," Nauen said. "By taking over Westinghouse we have a fantastic platform for the USA, which we will use to sell wind turbines there."

Alongside wind turbines on land, Siemens also wants to get part of the action in so-called offshore-turbines. There are already two large Danish wind parks that use Bonus Energy turbines in the Baltic Sea.

Wind expert Kühn expects plenty of opportunities for such sea-based parks in the future.

"The firm Bonus has a great reputation internationally, a large export market share and robust technology in the offshore sector," he said, adding that Siemens' financial firepower and the firm's further expertise would only make it a stronger international competitor.