The following list represents the 25 top privately held renewable energy companies as compiled by BusinessWeek in July 2009.  A few of these may just be companies we cover here at GreenStocksCentral.com in the coming years, so certainly worth keeping an eye on.  The latest news results are below the title and description of each company.

Achates Power
Testing a cleaner burning, more efficient diesel engine that gets up to 100 miles/gallon.