Spiegel: Europe’s wind energy sector is currently experiencing a major transformation. New massive offshore wind parks are soon expected to crop up off Europe’s coastline. Big companies like Siemens and General Electrics are increasing their stakes in a market worth billions. But experts warn that a new energy oligopoly may soon emerge. Vestas is going and Siemens is coming. Danish market leader Vestas announced in April that it would close its wind turbine factory in Britain and relocate it to the United…