(Bloomberg) — The venture capital model honed and perfected in Silicon Valley is proving a bad fit for the clean tech industry, and investors should instead accept that theyāll need to commit much bigger sums of money for longer periods of time.Most Read from BloombergWhere the Wild Childrenās Museums AreBillionaire Steve Cohen Wants NY to Expand Taxpayer-Backed FerryThe Economic Benefits of Paying Workers to MoveAt Londonās New Design Museum, Visitors Get Hands-On AccessLA City Council PassesRead More