San Diego's blend of resources, technical expertise and supportive policies has turned it into a hub for advanced-biofuel startups such as Sapphire Energy and Cellana. "San Diego has developed as the Mecca of algae technology development, as well as a model community for the cleantech movement," according to David Schwartz, editor of an online algae-biofuels trade publication. "This is largely due to a remarkable convergence of ... resources and brain trust [that] has resulted in the development of pioneering companies," Schwartz said.