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We observe that bulk energy patenting activity is increasingly coming from non-U.S.
sources; the U.S. share of issued clean energy patents has been declining by about 1% per
year since 1975 (Figure 4). The recent observed increase in percentage of patents granted
to U.S. institutions is likely a mathematical artifact created by comparing the largely
declining granted patent trends (Figure 1, Figure 3, and Figure 4). Different countries are
responsible for the majority of international patenting, but in general we observe
significant activity from Germany, Japan, Canada, and France. Interestingly, three major
sources of clean energy activity—India, China, and Brazil [60, 61]—are not even in the
top 10 most active patenting countries, although this may be an artifact of their recent
entry into the field and USPTO granting delays. In keeping with general features of
foreign patents, foreign energy patents have a lower citation count than their U.S.
counterparts, presumably because foreign firms build upon their domestic knowledge
base and do not spend as much time and effort tracking the U.S. intellectual property
landscape [62]. This makes evaluating their impact using patent citations challenging.
Future work should include evaluation of a disambiguated global intellectual property
database as well as publications to truly measure the innovative capacity of the global
economy.

Figure 4. A comparison of renewable energy patents generated by U.S. and non-U.S.
inventors

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