Technological lock-in has been a standard explanation for the slow take-off of clean innovation, but is hard to reconcile with forward-looking investors who anticipate the eventual switch to clean technologies. We provide an alternative explanation: strategic investment complementarities shape innovation and self-fulfilling prophecies can lead to delayed low-carbon transition. We analyze a standard directed technical change model with clean and dirty inputs. Under good input substitutability, two stable steady states co-exist, each allowing multiple transitional paths. Optimal low-carbon transition requires a Pigouvian tax rule combined with a coordination device; commitment to a Pigouvian tax trajectory cannot solve a coordination failure. (JEL H23, O31, O33, O44, Q54, Q55)
Smulders et al. (Mon,) studied this question.