Tagging ‘green’ patents at the EPO

Everyone who has used patent data to study ‘environmental’ innovation knows that identification of the relevant inventions is complicated. Fortunately, thanks to the European Patent Office (EPO) this task has recently become much easier! A team of patent examiners at the EPO has developed a tagging scheme of selected climate change mitigation technologies, first presented in 2010. Initially available only through EPO’s public search engine espacenet, the tags are now included also in its PATSTAT database.

To fully appreciate why tagging is such a major development, one needs to understand the structure of the existing patent classification systems and the nature of ‘environmental’ technologies. While patent data have become ubiquitous in studies of innovation, they have been used mostly to study innovation in general (in all technological fields together), with applications to specific fields limited to ‘thick’ fields such as ICT, biotechnology, or chemistry. The use of patent data to study ‘environmental’ innovation is rather recent. However, using patent data for this purpose poses additional challenges because the nature of patent classification systems renders the identification of such inventions difficult. Patent classification systems have been designed to categorize inventions with respect to their scientific and engineering characteristics, while classification according to the purpose or motivation for the invention has been less of interest; until recently.[1]

There are two major difficulties in identifying the relevant inventions – the nature of environment-related innovations (defined primarily by application, not by engineering characteristics) and the ‘narrowness’ of the technology fields (and hence the need to use classifications at a very fine level of disaggregation). In fact, only a restricted number of environmental domains lend themselves for identification using the IPC system alone, those characterized by engineering aspects (e.g. wind power) or those where the environmental benefit is correlated with other potential applications (e.g. insulation materials).

Most importantly, identification of inventions that reduce environmental impacts is often complicated by the wide variety of uses and benefits associated with the application of the underlying technology. In such cases, only a subset of inventions within a given patent class may be relevant for environmental purposes (e.g., semiconductors for ICT versus those specific to solar photovoltaics; CO2 separation in industrial processes compared to CO2 capture specifically for CCS).[2]

In general, there are two alternative ways of addressing this issue. The first approach, is to break down the technology fields into domains that are small enough that they can be identified using IPC. However, this approach is unlikely to be widely applicable for the reasons discussed above. While using the more disaggregated ECLA classification system – in which there are 130,000 classes – may increase the number of fields for which this approach is helpful, identification of relevant classes within the ECLA scheme is a true challenge for a non-specialist.

The second approach is through special tagging by experts in the field.  Indeed, in order to facilitate identification of prior art in the domain of climate change mitigation, a team of patent examiners at the EPO developed a tagging scheme (ECLA: Y02 class) covering a selected set of climate change-related technologies in energy supply (incl. renewable energy, biofuels, efficient combustion, energy storage, etc.). This has already proven useful not only to patent professionals but also to researchers and policy makers.

To be clear, the new tagging scheme does not substitute for the standard IPC/ECLA classification codes, rather it is complementary. Technically, the tagging does not involve examination of each individual patent application (as it is sometimes assumed). It is constructed as a set of search algorithms that exploit the full stock of EPO’s patent information.

The underlying approach is thus essentially the same as that of a researcher using the PATSTAT database to construct counts of environmental patents in specific fields (using IPC classes or keyword searches). The main (but essential) improvement of the tagging scheme is the greater depth and breadth of the searches conducted (thanks to the expertise of professional patent examiners and the richness of descriptive data available at the EPO). The advantage of such an approach is that it yields a broad set of relevant inventions. However, as with many aspects of patent data, thoughtful use of the new tags is advisable. Researchers should pay attention to the fact that population from which the searches draw is unknown (imperfectly defined), but work is on-going to address this issue in the near future.[3]

To conclude, the new tagging scheme greatly facilitates identification of relevant climate-related inventions, and its careful application will no doubt enhance our understanding of environmental innovation. EPO’s efforts have provided a valuable public service! Let’s hope that these promising developments continue.

(For more background on the scheme see here.)

[1] In fact, patent applicants would try to avoid listing specific applications of their invention in an effort not to restrict the potential applicability of the patent protection in the future. Introduction of fast-track rules for “green” patents at some patent offices may change these incentives.

[2] The examples used are specific to the IPC but the principle is similar to other systems.

[3] For example, this is why the counts of environmental patents provided on OECD.STAT have been restricted to searches on patents filed at the EPO or registered under the Patent Cooperation Treaty.