In 2009, there were an estimated 505 clean-technology M&A transactions globally, totaling $31.8 billion, according to the Cleantech Group, a research firm based in San Francsico. In North America, Europe and Israel, the number of clean technology M&A deals was up from 2008, but the total value of those transactions was down. In China, however, M&A activity in the sector was red hot. The country reached a historic high with 29 transactions totaling $5.5 billion. Click ahead to see the biggest cle
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