Siemens AG announced this morning that it has won an order to supply 448 wind turbines with a total capacity of 1,050 megawatts to Des Moines-based MidAmerican Energy Co. The German engineering group said it was the largest single order for onshore wind power ever awarded, Reuters reported. The wind turbines will be installed in five projects across Iowa as detailed last month by MidAmerican, which announced the expansion project in May. The order is worth more than $1 billion of business to Siemens, Bloomberg Businessweek reported. MidAmerican's purchase of the blades "will be a significant chunk of our overall business," said Markus Tacke, CEO of Siemens Energy's wind power division, who did not provide an exact price. Wind turbines typically cost about $1 million for each megawatt of capacity. Gov. Terry Branstad is expected to make an announcement at 1 p.m. today at Siemens' turbine plant near Fort Madison, where the blades will be manufactured.