The paper analyses whether and to what extent regional related and unrelated variety matter for the development of green technology, and whether their influence differs over the technology life-cycle. Using patent and socio-economic data on a thirtyyear panel of US States, we find that unrelated variety is a positive predictor of green innovative activities. When unpacked over the life-cycle, unrelated variety is the main driver of green technology development in early stages while related variety becomes more prominent as the technology enters into maturity.

The present study provides an analysis of empirical regularities in the development of green technology. We use patent data to examine inventions that can be traced to the environment-related catalogue (ENV-Tech) covering technologies in environmental management, water-related adaptation and climate change mitigation. Furthermore, we employ the Economic Fitness-Complexity (EFC) approach to assess their development and geographical distribution across countries between 1970 and 2010. This allows us to identify three typologies of countries: leaders, laggards and catch-up. While, as expected, there is a direct relationship between GDP per capita and invention capacity, we also document the remarkable growth of East Asia countries that started from the periphery and rapidly established themselves as key actors. This geographical pattern coincides with higher integration across domains so that, while the relative development of individual areas may have peaked, there is now demand for greater interoperability across green technologies.

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