Results and Analysis of Bibliometric Study
Figure 5.4 shows that the number of industrial symbiosis papers published in peerreviewed journals has increased from one paper in 1995 (the ﬁrst year of publication of a paper meeting our criteria) to 75 in 2014. In particular, 2007 is the year that shows a notable increase in the publication of papers, which is in line with the observation from Yu et al. (2014a), and, notably, the number of papers more than doubled between 2010 and 2014. It is not yet known whether the large increase of articles in 2014 is an outlier, but in general we expect this output to continue to rise at least in the short to medium term (2–5 years) given the trajectory.
Before 2004, the main topic of inquiry concerned conceptual aspects of industrial symbiosis. Case studies began to grow by 2004 with the most for any year being 11 case study articles in 2007. Later, more papers began to focus on analyzing performance and mechanisms of industrial symbiosis and proposing new ideas or strategies for its implementation. Modeling as a topic in industrial symbiosis emerged in 1998, but more than 90 % of modeling papers appeared after 2006. This implies that the focus of industrial symbiosis research has gradually shifted from introducing the concept and presenting speciﬁc case studies to delving more into performance and mechanisms of industrial symbiosis and presenting new ideas for industrial symbiosis.
Fig. 5.4 The number of industrial symbiosis papers published between 1995 and 2014 divided into the seven thematic categories
According to Table 5.3, publications of industrial symbiosis papers are concentrated in a few journals, most of which also publish industrial ecology articles. Out of a total of 124 journals publishing industrial symbiosis articles, the top six journals published ﬁfty percent of all the papers captured in the analysis. Figure 5.5 represents the number of industrial symbiosis papers published over time and differentiates whether these articles appeared in the top six journals or the others. Figure 5.5 indicates, in general, that the number of industrial symbiosis papers published in journals other than the top six has increased over time: from one paper in 1996 to 36 papers in 2014. This ﬁnding reveals that more industrial symbiosisrelated research has emerged in a wider range of journals outside of the core, indicating that industrial symbiosis research is reaching a broader readership.