Knowledge Spillovers between Clean and Dirty Technologies
41 Pages Posted: 15 Oct 2022 Last revised: 5 Jul 2023
Date Written: September 29, 2022
Does knowledge from dirty technologies spill over to clean technologies? This answer to this question has implications for the ease of switching from dirty to clean R&D and informing firms’ diversification strategies. We measure knowledge spillovers using the patent citation network. We first examine the proportion of citations in clean patents that directly refer to dirty technologies. Secondly, we systematically explore how clean and dirty technologies are indirectly linked in the citation network and which sectors most frequently “bridge” these two fields. We find that less than one-tenth of clean patents contain a citation to prior dirty patents, but nearly two-thirds are indirectly linked. Geothermal energy, carbon capture and storage, and more efficient industrial processes have the highest proportion of direct connections to dirty knowledge. Patents related to propulsion, chemistry, mechanics, and circuitry frequently serve as “bridges” between clean and dirty technologies in the citation network. We discuss how our results may inform clean industrial policy and firm-level diversification.
Keywords: Knowledge Spillovers, Directed Technical Change, Clean Technology, Dirty Technology, Diversification
JEL Classification: O32, Q55
Suggested Citation: Suggested Citation