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3.1.2 Institutional Patenting Trends
To illustrate the institutional bases of this patenting effort over time, we categorize
institutional sources of invention as private firms, government agencies, universities, and
independent inventors (the latter are patents without an assignee and are typically owned
by the listed inventors) and characterize whence the innovations came (Table 2).

Table 2. Market Sources of Patents

As an example of why this analysis is useful, one might think that wind power is the
province of mechanically inclined tinkerers in their garage, while biofuels innovations
come from large corporations because of the technical complexity and experimental
requirements for discovery. This theory appears to hold true with independent inventors
responsible for 54.5% of patents in wind and only 22.1% in biofuels. Hence, independent
inventors appear to be a substantial source of technology in wind power and firms in
biofuels. A modest proportion of solar patents (33%) also appear to come from
independent inventors, which may be counter-intuitive considering the advanced
materials chemistry required with most photovoltaic technologies. However, the time
series of bulk patenting activity also shows high levels of independent invention during
periods when entrepreneurial semiconductor activity was on the rise (1985–1995), and
our definition of solar also includes solar thermal technologies that do not require
advanced laboratories to fabricate. The technology with the lowest proportion of
technologies coming from independent inventors is nuclear (11.9%), which may be due
to (1) the inherent dangers of the technology, (2) the lack of market for new innovations
because of diminished new construction since the 1980s [63], or (3) the dependence on a
limited pool of large corporations for essential equipment manufacturing [64].

Before the early 1980s in solar, independent inventors and corporations were equally
dominant patent producers. Since then, however, corporations have produced the
majority of patents, with independent inventors contributing only about 25% of patents.
From 1995–2008, corporations have extended their dominance, responsible for up to
three quarters of the granted solar patents. This transition may be due to the transition of
technology dominance from solar thermal to photovoltaics, which are much more
experimentally complicated technologies and more the provenance of corporations than
of independent inventors.

Wind energy demonstrates a somewhat similar pattern. Independent inventors
contributed the most patents in the late 1970s and early 1980s, after which large firms
supplanted them. Since then, corporations and independent inventors have contributed
about equally to the patent pool. In terms of gross number of patents, universities and
national laboratories never figure prominently in prolifically producing wind energy

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