Here Comes a Cleantech IPO Parade

The list of cleantech start-ups heading for the public markets is rapidly lengthening: Two have recently filed for initial public offerings, and a handful of others are rumored to be contemplating them. On Dec. 28, biofuel start-up Codexisfiled for a $100 million IPO. This came hard on the heels of a $300 million IPO filing by solar-energy start-up Solyndra on Dec. 18. Tesla Motors, the sexy electric-car company, is likewise rumored to be heading for an IPO, and smart-grid integrated-technology maker Silver Spring Networks is also said to be in the chute for a public debut. (Silver Spring has denied these rumors).