TPAC - Technology Policy and Assessment Center at the Georgia Institute of Technology

The diffusion of a technology can be analyzed by tracing the rate of discrete individuals and organizations publishing over time. It is assumed that peer-reviewed publication is an indicator of institutional interest in a specific technology. Thus, the number of different authors and affiliations publishing/patenting indicates the relative growth in 'popularity' of the technology. As the number of individuals/institutions publishing increases, the size of the research community and expert knowledge base correspondingly increases. The following indicators were analyzed to better understand the diffusion of information on fuel cell technology:

Affiliation Rate - Size of the Research Community
Analysis of the number of affiliations publishing on fuel cell technology indicates that the fuel cell research community is large, diverse, and relatively young. From 1987 to 1997, a total of 783 different institutions published articles on fuel cell technology. The top 10 affiliations contributed 444 articles representing 18.9% of total publications. Most of the organizations contributed very few articles; only 63 organizations contributed 10 or more articles. In fact, 58% of the affiliations contributed only a single article. These findings suggest that no organization dominates fuel cell research, which has a community consisting of hundreds of players contributing sporadically.

Table 4: Most Prolific Affiliations - Articles (ENGI)

Fig. 9 displays the trends in affiliations publishing and patenting on fuel cell technology. The affiliation rate for ENGI reflects the general publication trend. From 1987 to 1991, the number of organizations fluctuated from a high of 126 to a low of 76. Since 1991, there has been significant growth in affiliations, reaching an apex of 173 different organizations publishing in 1995. Over the last 5 years, the affiliation rate has averaged 156 affiliations per year. Most recently, there has been about a 10% decline in affiliations, perhaps reflecting industry consolidation.

Fig 9: Technology Diffusion Analysis - Affiliation Rate

Analysis of patent affiliations reveals a different pattern. From 1987 to 1997, a total of 368 institutions obtained patents on fuel cell technology. The top 10 patent affliations accounted for 712 patents, representing 61.7% of the total. The number of different organizations patenting on fuel cell technology has steadily increased over the 10-year period. Of the 36 organizations patenting in 1987, only 11 organizations had 2 or more patents (30.6%). This number increased to 26 in 1997, the relative percentage decreased to 17.3% indicating that over four-fifths of organizations had only modest patent activity (only 1 patent).

Table 5: Most Prolific Affiliations - Patents

The analysis of affiliation rates can be extended to examine the diffusion of specific technology types. Fig. 10 compares the trends in affiliation rate for each fuel cell type. Solid oxide fuel cells are diffusing rapidly, increasing two-hundred percent in the five year period from 1992 to 1997. In contrast, the number of organizations publishing on phosphoric acid fuel cells has declined sharply over the last five years; from a high of 24 organizations in 1994 to only 9 organizations in 1997.

The number of affiliations publishing on alkaline fuel cells has been steadily declining; this may indicate that AFC's have already reached a high level of diffusion into the scientific literature. Proton exchange membrane fuel cells experienced consistent growth in affiliation rate until 1996; an indicator of steady diffusion.

Fig 10: Technology Diffusion Analysis - Fuel Cell Technology

Author Rate - Size of Expert Knowledge Base
The number of authors publishing on fuel cell technology was analyzed to evaluate the size of the expert knowledge base. From 1987 to 1997, over 4000 different authors published articles on fuel cell technology. The top 10 authors (Table 3) contributed a total of 262 articles, representing only 11.1% of the total publications abstracted in ENGI. Thus, no individual dominates the literature.

Table 6: Most Prolific Authors

Fig. 11 shows the trend in number of authors publishing on fuel cell technology per year. From 1987 to 1993, the author rate averaged 411 authors per year. After 1993, however, the author rate stepped up to a higher plateau, as the rate jumped from 483 to 712 authors per year, an increase of 47%. These levels are a significant indicator of the size of the expert knowledge base. In other words, over 700 different persons published articles on fuel cell technology, a critical mass of contacts with expertise on fuel cell technology.

Fig 11: Technology Diffusion Analysis - Author Rate

Source Rate - Maturity of Market Communication
The number of sources containing articles on fuel cell technology were analyzed to assess the concentration of market communication. From 1987 to 1997, a total of 396 discrete sources contained articles on fuel cell technology. The top 10 sources (Table 7) represent a 'core' set of journals for fuel cell technology, accounting for over half of all articles (53.4%) and having longevity of over a decade. A few of the sources (rank 8-10) had significant early publication output, yet have very short longevity; these sources have likely been consolidated into other publication vehicles,

Table 7: Most Prolific Sources

Fig. 12 depicts the trend in number of sources publishing articles on fuel cell technology. Total sources declined by nearly 40% in the late 1980's, reflecting the general decline in publications during that period. The source rate leveled off from 1989 to 1992 averaging 42 sources per year during this period. Since 1992, however, the number of discrete sources has increased by 105% over the five year period from 1992 to 1997 (from 40 to 82).

Fig 12: Technology Diffusion Analysis - Source Rate

Analysis of the 40 sources in 1992 and 82 sources in 1997 reveal that the core journals continue to be the leading avenues for publication on fuel cells, with 6 of the top 10 in 1992 still in the top 10 of 1997. The doubling of sources over the last 5 years can be attributed to an increase in the number of conference proceedings (e.g., Materials Research Society Symposium, Proceedings of the American Power Conference) and specialty journals (e.g., Journal of Alloys and Compounds, NTT R&D). New conferences and journals contribute significantly to the diffusion of fuel cell research across publication sources.

Longevity - Track Record
The number of years publishing on a specific technology is an indicator of the individual or institution's track record. Greater longevity in the field infers greater experience and enduring interest in the area.

Fig. 13: Publication Longevity

Only 3 organizations have continuously published on fuel cell technology from 1987 to 1997, and only 8 have over a decade of publication experience.

Rank	Affiliation Name	Total Articles	Longevity
1	NASA, Cleveland, OH, USA	64	8
2	Los Alamos National Laboratory, Los Alamos, NM, USA	58	11
3	Texas A&M Univ, College Station, TX, USA	48	11
4	Westinghouse Electric Corp, Pittsburgh, PA, USA	42	10
5	Energy Research Corp, Danbury, CT, USA	40	10
6 (tie)	Argonne Natl Lab, Argonne, IL, USA	36	10
6 (tie)	CNR Inst for Transformation and Storage of Energy, Messina, Italy	36	10
8 (tie)	Mitsubishi Electric Corp, Amagasaki, Jpn	32	11
8 (tie)	Case Western Reserve Univ, Cleveland, OH, USA	32	8
10 (tie)	Illinois Inst of Technology, Chicago, IL, USA	28	8
10 (tie)	U.S. Dep of Energy, Washington, DC, USA	28	9

Rank	Affiliation Name	Total Patents	Longevity
1	United Technologies Corporation Hartford CT	164	8
2	International Fuel Cells Corporation South Windsor CT	147	11
3	U.S. Department of Energy Washington DC	84	10
4	Westinghouse Electric Corp. Pittsburgh PA	51	10
5 (tie)	Hitachi, Ltd. Tokyo JPX	50	8
5 (tie)	Fuji Electric Co., Ltd. Kawasaki JPX	50	11
7	Energy Research Corporation Danbury CT	45	9
8	Siemens Aktiengesellschaft Berlin and Munich DEX	44	4
9	Mitsubishi Denki Kabushiki Kaisha Tokyo JPX	43	10
10	NGK Insulators, Ltd. JPX	34	5

Rank	Author Name	Affiliation	Total Articles	Longevity
1	Srinivasan, S.	Texas A&M Univ, College Station, TX, USA	45	11
2	Giordano, N.	CNR Inst for Transformation and Storage of Energy, Messina, Italy	34	10
3	Appleby, A.J.	Texas A&M Univ, College Station, TX, USA	30	10
4	Gottesfeld, S.	Los Alamos Natl Lab, Los Alamos, NM, USA	24	10
5	Dokiya, M.	Natl Inst of Materials and Chemical Research, Tsukuba-shi, Jpn	23	8
6 (tie)	Sakai, N.	Natl Inst of Materials and Chemical Research, Tsukuba-shi, Jpn	22	8
6 (tie)	Kawada, T.	Natl Chemical Lab for Industry, Tsukuba Research Cent, Ibaraki, Jpn	22	8
6 (tie)	Yokokawa, H.	Natl Chemical Lab for Industry, Tsukuba Research Cent, Ibaraki, Jpn	22	8
9	Savinell, R.F.	Case Western Reserve Univ, Cleveland, OH, USA	20	9
10	Kordesch, K.	Technical Univ Graz, Graz, Austria	20	7

Rank	Journal	Total Articles	Longevity
1	Journal of the Electrochemical Society	347	11
2	Proceedings of the Intersociety Energy Conversion Engineering	306	10
3	Journal of Power Sources	262	11
4	Solid State Ionics	223	11
5	International Journal of Hydrogen Energy	97	10
6 (tie)	Electrochemica Acta	69	9
6 (tie)	Journal of Applied Electrochemistry	69	10
6 (tie)	Proceedings - The Electrochemical Society	69	3
9	NASA Conference Publications	67	3
10	Electrochemical Society Extended Abstracts	65	1