Optimism and the Environmental movement

Whenever I read about something like Calera's new CO2 into concrete breakthrough I get excited and hopeful.  In fact, players as diverse as the Sierra Club and Peabody Energy (world's biggest coal company) are feeling that way about Calera's technology.  Without fail, there's always someone around (in this case Stanford and MIT scientists) saying how it just won't work and they can't believe in it.  Now, I am not saying that we should go along and believe in every technology that comes around the corner, especially in the energy space but a belief in  "the art of possibility" has to come into play with the sustainability movement or we might as well give up now.  After reading a case study on the beginning of Sun Microsystems and Vinod Khosla (lead investor in Calera) there is little doubt in my mind that it's this belief in what is truly possible that has driven his success thus far.