Knowledge spillovers from renewable energy technologies, Lessons from patent citations

This paper studies the knowledge spillovers generated by renewable-energy technologies, unraveling the technological fields that benefit from knowledge developed in storage, solar, wind, marine, hydropower, geothermal, waste and biomass energy technologies. A <a href="http://www.cpb.nl/en/publication/on-which-technologies-do-renewable-energy-innovations-build-on">CPB Background Document </a>accompanies this CPB Discussion Paper. Using citation data of patents in renewable technologies at seventeen European countries over the 1978-2006 period, the analysis examines the relative importance of knowledge flows within the same specific technological field (intra-technology spillovers), to other technologies in the field of power-generation (inter-technology spillovers), and to technologies unrelated to power-generation (external-technology spillovers). The results show significant differences across various renewable technologies. While wind technologies mainly find applications within their own technological field, a large share of innovations in solar energy and storage technologies find applications outside the field of power generation, suggesting that solar technologies are more general and, therefore, may have a higher value for society. Finally, the knowledge from waste and biomass technologies is mainly exploited by fossil-fuel power-generating technologies. The paper discusses the implications of these results for the design of R&D policies for renewable energy innovation.