TPACTechnology Policy and Assessment Center
 
 

Technology Growth Rate

Table of Contents

This section describes trends in fuel cell technology, with particular emphasis on the question: "How rapidly is fuel cell research growing?"

Publication Profile

Table 1 profiles the total articles published on fuel cell technology each year from 1987 to 1997.

Table 1: Publication Profile

Database 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 Total Articles
ENGI 214 152 111 173 193 205 207 289 280 241 290 2,355
PATS 95 86 95 80 82 95 116 134 123 120 128 1,154
SCI N/A N/A N/A N/A N/A 149 126 175 189 269 241 1,149
BUSI N/A 0 0 2 1 15 29 35 25 29 74 210

Fig 4: Publication Profile - Fuel Cell Technology

The trend in publications from Engineering Index (ENGI) exhibits two interesting phenomena (Fig. 4):

  • A marked decline in publication rates during the late 1980's reversing in 1990.
  • Significant publication growth from 1989 to 1997.

Equally compelling is the consistent trend in U.S. Patents (PATS). Despite the decline in publication, the trend in patent production has been relatively level from 1987 to 1992, followed by steady growth.

Data from Science Citation Index (SCI) and Business Index (BUSI) are limited to 1988-1997 and 1992-1997 respectively, yet these trends support the general growth trends.

Fig 5: Trends in Fuel Cell Technology

The publication trends for the five fuel cell types in ENGI mirror the general trend with fuel cell technology (Fig. 5).  All five types display sharp declines in the late 1980's reaching the nadir in 1988-89. This time period marks a turning point for the specific fuel cell technologies. Following are some observations:

  • Publication on solid oxide fuel cells has increased over ten-fold since 1988.
  • Publication on alkaline fuel cells has steadily declined to none in 1997.
  • Both phosphoric acid fuel cells and molten carbonate fuel cells have experienced an up-and-down trend in publication rates.
  • Proton exchange membrane fuel cells have slowly increased during the late 1990's.1

Growth Rate Indicator The rate of growth in publications was analyzed for each of the fuel cell types.  The growth rate indicator is calculated by the formula: sum of { articles in year i+1 / articles in year i }.  Table 2 presents the ranking of 10-year growth and 5-year growth rates for each fuel cell type.

Table 2: Fuel Cell Growth Rate

Rank 10-year Growth 5-year Growth
1 SOFC (12.51) SOFC (6.98)
2 PEMFC (12.09) AFC (5.83)
3 AFC (10.83) MCFC (5.16)
4 MFC (10.14) PEMFC (4.92)
5 PAFC (9.61) PAFC (4.58)

Solid oxide fuel cells (SOFC) are the fastest growing fuel cell technology over a 5-year and 10-year period. Proton exchange membrane fuel cells (PEMFC) follow closely in growth over the 10-year period. Molten carbonate fuel cells (MCFC) and alkaline fuel cells (AFC) had slightly higher growth than phosphoric acid fuel cells (PAFC) over the same period.

Significant fluctuations publication levels for AFC's and MCFC's over the past 5 years create a misleading picture of their overall growth. The 5-year growth rate ranks them both ahead of PEMFC's and PAFC's.

Communication Rate Indicator Another indicator of growth is the ratio of conference to journal articles.  The communication rate is calculated by taking the ratio of the total conference articles divided by the total journal articles. It is assumed that conference publications tend to publish the most recent technological advances, while journals are hindered by their inherent review process. Thus, a higher rate indicates a 'hotter' technology in terms of the interest in publishing topical information more rapidly.  Cross-field comparisons must be made with care as publishing practices do vary by field.

Fig 6: Fuel Cell Communication Rate

For the period from 1987 to 1997, the communication rate averaged 0.434. The communication rate for fuel cell technology declined sharply in the late 1980's. It rebounded in 1990 and fell in the early 1990's. Since 1994, the rate has remained steady averaging 0.258; this indicates that conferences contributed only one-fourth (25.8%) of the total articles from journal sources.

Table 3:  Fuel Cell Communication Rate

Rank Communication Rate
1 PAFC (.665)
2 PEMFC (.497)
3 MCFC (.397)
4 AFC (.309)
5 SOFC (.181)

From 1987 to 1997, the communication rate for specific fuel cell types is surprising. PAFC's had the highest rate of 0.665, suggesting that many conferences have addressed these fuel cells. Only PAFC's and PEMFC's had higher than average rates. The lowest rate is attributed to SOFC's, over 3 times less than PAFC's.

1The total 1997 items in ENGI as of this analysis was XXXX.  This is somewhat less than the average for years XXX.  We chose not to normalize so that counts are actual.  Were one so inclined, multiplication of 1997 values by XX would eliminate the downward tendency for 1997.