Renewable and Sustainable Energy Reviews

Renewable and Sustainable Energy Reviews 127 (2020) 109879
Contents lists available at ScienceDirect
Renewable and Sustainable Energy Reviews

journal homepage: http://www.elsevier.com/locate/rser
Solid oxide fuel cell technology paths: National innovation system

contributions from Japan and the United States
Marina Domingues Fernandes a, Victor Bistritzki a, Rosana Zacarias Domingues a, b,
Tulio Matencio b, Ma
�rcia Rapini a, c, Rub�en Dario Sinisterra a, b, *
a
Universidade Federal de Minas Gerais, Technology Innovation Graduate Program, Belo Horizonte, Brazil
b
Universidade Federal de Minas Gerais, Chemistry Department, Belo Horizonte, Brazil
c
Universidade Federal de Minas Gerais, Economics Faculty, Belo Horizonte, Brazil
A R T I C L E I N F O A B S T R A C T
Keywords: This study discusses the solid oxide fuel cell (SOFC) technology paths in the United States and Japan under the
National innovation system national innovation system (NIS) framework using the available literature and a patent landscape. By examining
Solid oxide fuel cell technology trajectories, it is possible to identify and justify the patterns of key players and institutions from the
Technology path
NISs of the two countries that shaped the development of these technologies. These patterns are especially
Patent landscape
relevant to the analysis of the role of institutional arrangements in policymaking. This study presents the concept
Renewable energy
of a NIS and explores the main aspects of the Japanese and U.S. NISs regarding the SOFC technology path. This
study analyzes historical patent evolution, patent applicants and their industrial sectors, international patent
classifications (IPCs) and international patent activity. Moreover, this study highlights the correlations of the
SOFC manufacturing and operation with patent data. This study examines the role of NISs in SOFC technology
shaping from two main aspects: through independent historical events that motivated the establishment of
institutional arrangements from which SOFCs have benefited and through shaping policies and efforts that are
intended to promote the development of SOFC and related technologies. The results of this study demonstrate
differences in terms of the sectors that are involved in the SOFC patenting activity, the IPCs of the filed patents
and the international patent activity, which support the role of NISs in technology shaping.
Such complex and research-intensive technologies rely on policies to

1. Introduction support their development. Policies can be formulated by analyzing the
trajectory of a technology, which includes observation of historical as
Solid oxide fuel cells (SOFCs) are devices that convert chemical to pects, technological problem-solving and interaction among players that
electrical energy with high efficiency and reduced CO2 emissions, influence the technological development. Studies that are related to fuel
thereby generating power from hydrogen, natural gas or other fuels. cell technology paths can be divided into three main groups: The first
Since the discovery of the phenomenon behind fuel cells, more than a group consists of technical contributions that investigate the develop
century has passed and technical obstacles persist [1–3], which pose ment of novel techniques, materials, compounds, manufacturing
challenges in bringing the technology to maturity in a convincing methods and applications [1,7–15], or present market accomplishments
commercialization phase. Although SOFC developers understand the and challenges [16–18]. The second group covers studies that consider
operational principle of these cells, they still struggle with the expensive the historical aspects of the technology and emphasize the events and
catalysis materials, the high operational temperature, the durability of turning points along the technological development trajectory [19–26].
the cells, the complicated and expensive balance of plant and the The third group is comprised of methodological contributions that
immature hydrogen infrastructure [4,5]. More recent advances have develop indicators for justifying technological changes of fuel cells [6,
demonstrated the potential application of SOFCs in a renewable energy 27–35]. They often focus on technological forecasting via comparative
generation context to increase the market interests and accelerate the studies and on proposing indicators that are based on price, patent or
development of relevant technologies [6]. paper analysis, for example.
* Corresponding author. Universidade Federal de Minas Gerais, Chemistry Department, Av. Pres. Ant^
onio Carlos, 6627 - Pampulha, Belo Horizonte, MG, 31270-
901, Brazil.
E-mail address: sinisterra@ufmg.br (R.D. Sinisterra).
https://doi.org/10.1016/j.rser.2020.109879
Received 10 July 2019; Received in revised form 25 March 2020; Accepted 20 April 2020
Available online 27 April 2020
1364-0321/© 2020 Elsevier Ltd. All rights reserved.
M.D. Fernandes et al. Renewable and Sustainable Energy Reviews 127 (2020) 109879
2. Conceptual framework: national innovation system

List of abbreviations
This section has two objectives: (1) present the concept of a NIS and
DOE Department of Energy (2) explore relevant aspects of the Japanese and the U.S. NISs regarding
IPC International patent classification the SOFC technology paths.
MITI Ministry of International Trade and Industry
NEDO New Energy Development Organization 2.1. Concept of a national innovation system
NIS National innovation system
SECA Solid State Energy Conversion Alliance The concept of NISs emerged in the late 1980s and has been com
SOFC Solid oxide fuel cell plemented and explored since then. The main contributions to the
SWP Siemens Westinghouse Power emergence of the concept were made by Freeman [38], Lundvall [39]
U&RIs Universities and research institutes and Nelson [40]. NISs relate to how key players interact to promote
technological changes and innovation on a national level, and they
emphasize the mechanisms that enable these interactions. Fig. 1 illus
trates the NIS framework. Typically, an NIS consists of three main types
The publications that are discussed above address the evolution of of entities: government, university and company. The players (GovPj,
fuel cell technologies from various perspectives. However, contributions UniPj, ComPj) within the NIS entities are typically public or private
regarding the historical perspectives lack quantitative empirical evi firms, government agencies and universities and research institutes
dence, and methodological studies often neglect possible historical (U&RIs) [41] and constantly change over time (t) (e.g., government
events behind the data. The national innovation system (NIS), which is a transitions, research agenda shifts, company development and new
framework that was established based on an a posteriori historical comers). The interactions are called institutions (or mechanisms), which
analysis of how key players in a country interact to promote innovation, follow the “rules of the game”, namely, the set of routines or norms that
is useful when trying to understand the determinants of a technology regulate the relationships in the society [42,43]. In an NIS, technology
path within a country. This framework is applied to emphasize impor refers to the development or diffusion of technological learning [44].
tant elements that support policymaking by differentiating the innova NISs are useful for understanding the institutional aspects of a
tion performances of economies [36]. country that relate to a specified technology path. NIS research focuses
To the best of our knowledge, no studies in the literature link the on, for example, innovation of R&D performance or learning and
SOFC technology path with the NIS framework. Under this framework, capability building [45]. Some of these studies elucidate the historical
the SOFC technology paths in the United States and Japan provide useful construction of NISs and provide useful insights into the development of
insights for policymaking. Their NISs have unique structures and technologies in specified countries.
mechanisms that enabled them to rapidly catch up with the SOFC Governments in NISs play an essential role in the development of
development, despite a late kick-off compared to pioneering European high-risk complex technologies. If a technology has not yet been proven
research. and the demand conditions have not been established, its development
The present work aims at observing the SOFC technological devel typically relies on government policies [46], which emphasizes the
opment that placed these two countries in technology leadership posi importance of national institutions (e.g., laws, regulations, bank
tions (e.g., largest SOFC unit shipment worldwide [37]), thereby leading conduct, and instructions) [47]. Governments are responsible for
to the following research questions: (1) how have the NIS mechanisms building such institutions, which are often perceived in a
(institutions) of Japan and the U.S. shaped SOFC development and social-economical context, which enables them to coordinate diffuse
(2) to what extent have they induced technological development players that are involved in the innovation process [48]. Their role also
paths that differ between these countries? An NIS analysis can pro includes R&D investments in basic and applied research in U&RIs, which
vide useful insights into why similar technologies have paths that differ are later appropriated by the industrial sector. Government R&D is also
among countries, which is particularly relevant to the recognition of the conducted within governmental establishments that are not directly
role of institutional arrangements in policymaking, instead of assuming related to research, such as military, energy and health departments.
a deus ex machina technological development based on the optimization Therefore, the government plays a major role in the NIS in the context of
of technical specificities and external scenarios. The strengths of the NIS high risk and complexity, by coordinating, financing and signalizing
approach are numerous [36]. It endogenizes innovation by acknowl directions for private firms, researchers and other NIS players.
edging the interdependency and nonlinearity of innovation, the rela
tional links among key players and the knowledge production and 2.2. Japanese and U.S. NIS determinants for SOFC technology paths
recombination as a result of the innovation process.
To address the research questions, this work discusses the technology The main aspects of the Japanese and U.S. NISs that shaped the SOFC
paths of SOFCs in Japan and the U.S. through a patent landscape and development are historical pathways that were constructed to promote
available literature (e.g., scientific contributions and company and technological innovation within each country. This section focuses on
governmental reports), and it highlights the previously constructed in broader systemic aspects that were not intentionally constructed to
stitutions of the NIS that shaped the technological development. The address fuel cell technologies but were critical to the enabling of SOFC
analysis considers 4889 patents that were filed between 1985 and 2016. development.
To discuss the technology paths of SOFCs, the main characteristics of the
Japanese and American NISs that propitiated the environments in which 2.2.1. Government and technology policies
SOFC technologies could thrive are presented. The remainder of this Fuel cell technologies have benefited from strong government
manuscript is organized into six parts: presentation of the conceptual participation in Japan and the U.S. When British scientist William Grove
framework of NISs, detailed description of the methodology, analyses of observed the fuel cell electrochemical phenomenon in 1839, neither
the SOFC complexity, examination of how the technology paths were Japan nor the U.S. had the prowess to conduct similar experiments. As
shaped by the NISs from a historical perspective, discussion of the results latecomers compared to European countries, the governments were
and presentation of the conclusions of this study. decisive in establishing institutions and promoting the R&D and indus
trial activities that were necessary for the economic and technological
development in both countries.
Much of the infrastructure that was needed for fuel cell development
2
Fig. 1. NIS framework. Own figure.
was developed during the 19th and 20th centuries. In this period, both and the U.S. during the 19th and 20th centuries. These industries, which
governments established basic and superior education, thereby were primarily unrelated to SOFC development, encompassed knowl
enhancing the body of qualified labor that was required for absorbing edge and techniques in complementary niches that were required for the
worldwide technological advancements. After World War II, to assist fabrication, mounting and integration of fuel cells.
with the high R&D costs that were necessary for industrial competi Metal, chemical, shipbuilding, and other heavy industries are some
tiveness, they directly financed various forms of research, created reg of these strategic industries that were consolidated into Japanese public-
ulations and mechanisms for industrial and academic research private large vertical oligopolies (zaibatsu) prior to World War I [49]
interactions and defined the grounds for market competition (e.g., and later embraced fuel cell R&D. In the U.S., these industries included
antitrust law in the U.S. and restriction to foreign currency in Japan) the steel, chemical and electrical industries, and their early industrial
[49,50]. success was more related to mass production than to innovation [55].
Additionally, the U.S. and Japanese governments promoted different The automotive industries in both countries also constitute valuable
policies that have motivated and shaped their fuel cell technology paths. technological assets from which SOFCs have benefited.
In the U.S., the Space Race programs of NASA and the military expen Industrial requirements led to the training of scientists and engi
ditures were important mechanisms of the NIS through which many neers, thereby facilitating the diffusion and utilization of advanced
technologies were developed [51], such as fuel cells. In Japan, the scientific knowledge [50]. Meanwhile, industrial activity also led to the
government sustainability and energy safety policies after the petrol strengthening of capabilities that were necessary for technological
crises have enabled a trustful dedication to the development of energy progress, especially regarding its potential to spill over into comple
and environmental technologies, such as SOFCs. The Japanese Ministry mentary industries.
of International Trade and Industry (MITI) and the New Energy Devel
opment Organization (NEDO) are effective institutions within the 2.2.4. R&D institutions
country’s NIS through which the government communicates and directs Japan and the U.S. developed interactions between the private sector
long-term strategies and guidelines [52,53]. and research institutes, as major industrial sectors required intensive
research for maintaining competitiveness. These interactions differ be
2.2.2. Scientific research tween the two countries despite common players in the NISs, thereby
At the time Grove detected electrical current in his experiments using suggesting differences in the institutions.
platinum electrodes, aqueous sulfuric acid and tubes that contained In the U.S., university-industry interactions expanded after the in
oxygen and hydrogen, the U.S. and Japan lacked scientific research in crease of public research funds in universities, as industries perceived an
frastructures in industry and U&RIs. opportunity to reduce R&D costs and to accelerate their scientific
Most of the technological advancements until the 19th century in research. Public procurement and R&D investments within the federal
both countries were not related to scientific knowledge. The higher establishment, such as military expenditures that generate spillovers
education institutes that were established in Japan and in the U.S. at this into the society, have also been a mechanism for fostering technological
time left scientific and research missions out of their objectives. In the U. development [50]. Moreover, the sophisticated financial system and the
S., the early focus of higher education was to reinforce the republican post-World War II antitrust law contributed to the formation of new
values of liberty and self-government [54] only after World War I did startups. These young firms profited from public and private R&D in
public universities support educational matters [55] and scientific vestments, more noticeably from “seed money” (often public) and ven
research, regardless of its quality [50]. In Japan, during the Meiji Era, ture capital [46].
higher education institutes focused on qualification in engineering The private sector in Japan did not experience the mass production
areas, and in the mid-20th century, the private sector created basic growth in the beginning of the 20th century like the U.S. After World
research institutes to improve science and technology education, with War II, significant time and resources were required for the recon
the objective of enhancing industrial technological assets [49,56]. struction of the country, and only in the 1960s, when the Japanese
Hence, in both countries, the formation of scientific research was dis economy started competing internationally, were efforts made to
associated with the higher education that was initially promoted by the develop national technologies via public policies that were orientated
government, but it evolved as industries and governments recognized its toward the promotion of domestic R&D [52]. While such government
role in technological development. R&D incentives were modest, private firms financed most of their own
research activities to cope with international competition. Govern
2.2.3. SOFC-related industries mental research associations promoted long-term and large-scale
Although fuel cells relied on scientific advancements, a significant research, which was technologically and financially unfeasible for in
part of their development occurred in industries that emerged in Japan dividual firms. Later, with the gradual increase in the number of jointly
3
funded research institutions by companies, the government shifted its In addition, patent applicants were classified according to the
role toward the promotion of basic research [49]. Table 1 summarizes Bloomberg Industry Classification System [57].1 This index tracks the
the main differences between the U.S. and Japanese NISs regarding company’s main business by measuring primarily the source of revenue
SOFC technological development. and secondly the operating income, other assets and the company’s
market perception [58]. The eleven sectors on level one branch out to 65
3. Methodology industry groups on level two. To record a greater differentiation and to
provide a more detailed insight on the SOFC industry structure, the
3.1. Patent landscape companies in this study were classified on the second level.
Patents are a form of intellectual property that grant the applicant 3.2. Documentation analysis
exclusive legal rights to commercialize an invention in a designated
geographical area and time. Patent offices categorize inventions ac The patent data were complemented with information available
cording to an international patent classification (IPC) system, which is a from the scientific community, government and industries. Information
universal code structure that classifies patents according to the on the historical development of the technology paths, technical infor
described technology. mation, events, companies and fuel cell programs was collected through
A patent analysis reveals valuable information on countries and official organization websites, presentations from companies and
companies holding patent rights, key years of the technological devel governmental organizations, and academic publications such as journal
opment, patent family and technical aspects of the protected technology. articles, books, conference proceedings and technical reports.
Patent data for this study was obtained from the intellectual property
database Orbit intelligence by Questel® by using following search
4. SOFC complexity
string:
4.1. SOFC fabrication steps and system operation
� IPC: “H01M8/00 OR H01M4/00”
� Title and abstract keyword search: “solid oxide fuel cell” OR “sofc”
Understanding of the SOFC operation and fabrication steps is
essential for comprehending the capabilities that were necessary for
The patent search provided 4889 patents from the years 1985–2016.
SOFC development. Fig. 2 illustrates the operation of an SOFC.
Patents without country codes were excluded, for example patent ap
An SOFC consists at least of two electrodes, which are separated by
plications published by the World Intellectual Property Organization
an electrolyte. The fuel (hydrogen or fossil fuels) oxidizes at the anode,
(country code: WO) or by the European Patent Office (country code: EP),
while the oxidizing material (typically oxygen) reduces at the cathode.
which resulted in a total of 4308 patents that constitute the basis for this
The dense electrolyte, which is between two porous electrode layers,
study.
ensures that only O2 passes from the cathode to the anode. The elec
trons that are formed at the anode transit to the cathode through an
Table 1 external circuit, which is responsible for generating electricity. Each cell
Main NIS differences between U.S. and Japan in relation to SOFC technological
unit contains an anode, a cathode and an electrolyte. The stacking of
development. Own table.
multiple cells, which are interconnected by ceramic or metal plates,
Main NIS differences in relation to SOFC technological development results in a modular power system, of which the intensity varies with the
United States Japan number of stacked cells. As the cell operates via an exothermic elec
Government & Space race programs of NASA Sustainability and energy
trochemical reaction, the heat that is generated within the cell operation
technology and military expenditures safety policies after the petrol can be combined with the electric energy.
policies crises Fig. 3 illustrates the simplified steps of the development of an SOFC
Scientific After World War I, public During the Meiji Era, higher system. There are many frameworks for fabricating a fuel cell system,
research universities supported education institutes focused
education matters and on qualification in engineering
scientific research, regardless areas; In the mid-20th century
its quality private sector created basic
research institutions to
improve science and
technology education, aiming
at enhancing industrial
technological assets
SOFC related Mass production within steel, Public-private large vertical
industries chemical and electrical oligopolies (zaibatsu) focusing
industries on metal, chemical,
shipbuilding, and other heavy
industries
R&D institutions Public research funds Initially, private firms
expanded university-industry financed own research to
interactions; Investments compete internationally;
within the federal Government initiated long-
establishment (e.g. military); term, large-scale research
antitrust law contributed to projects; After private
the creation of small companies jointly funded
businesses research institutions, the
government shifted to invest
in basic R&D Fig. 2. SOFC operation. Figure from Tar^
oco et al. [59].
1
accessible over Bloomberg’s Private Company Information platform.
4
Fig. 3. SOFC manufacturing process and power generation. Own figure.
and each SOFC developer has its preferred process. The intention of automatized system for the injection of fuel, water, and heat; and iv) the
Fig. 3 is not to present the state of the art of these frameworks but to catalyst industries, for preparing the cell and reforming materials.
illustrate the capabilities that are needed for the production of a com Various industries support the SOFC assembly and operation, which
plete working system. demands a high technological level.
Fig. 3 illustrates six development steps that are necessary for the These technological niches are reflected by the IPCs. In the data that
system to generate energy, which are divided into two main phases: The were collected for this study, the patents belong to 10 IPC groups, which
first phase (1–4) is the fuel cell stack production; the second (5–6) is the relate to the technological development steps. Table 2 presents the IPCs
completion of the system and the production or reforming and supply of and their groups according to the data of the present work.
the fuel. The first groups, namely, separation and shaping, and chemistry and
The first phase, namely, the fabrication of the stack, initiates with the metallurgy, which provide details on the materials, focus on the first
preparation of fine ceramic powders that have specified properties, such step of the SOFC manufacturing process (Fig. 3): the stacking of the cell.
as high electrical conductivity, well-defined grain size and chemical The other categories correlate either to the application of the technology
stability in hostile environments, such as high temperatures and or to its system integration and fuels. The categories of measuring
reducing or oxidative atmospheres. Via the addition of specified poly controlling and computing, power generation and conductors and cables
mers and oils, the powders are transformed into three ceramic pastes correspond to the system operation.
that differ in terms of the properties of the anode, the cathode and the
electrolyte. The added materials provide the desired mechanical prop 5. NISs and SOFC technology paths from a historical perspective
erties to the final pastes, such as plasticity, and create green, well-
dispersed and homogeneous ceramics. Then, the pastes are shaped The distinct SOFC technology paths in Japan and the U.S. developed
using diverse methods such as serigraphy printing, spraying and tape through the mechanisms of the countries’ NISs. This section correlates
casting. Strict and controlled steps of drying and sintering are conducted the SOFC patent activity with the historical development of SOFC
until the end of this process. The first phase of SOFC production requires technologies in the U.S. and Japan.
various capabilities: Chemistry is fundamental to the development of In the U.S., the background of the Cold War intensified the devel
fine ceramic powders, additives and coating materials; ceramics are opment of fuel cell technologies with strong government participation,
indispensable for the development of pastes of porous SOFC anodes, especially after NASA’s fuel cell projects in the 1960s [60] which funded
cathodes and dense electrolytes; and deposition film techniques are part award-winning projects [61]. For realizing the objectives of NASA’s
of the process of transforming ceramic pastes into solid cell units. Apollo-series missions, fuel cell systems were the most promising tech
The second phase consists of uniting the three cell components, nologies as they presented beneficial properties such as efficiency, light
stacking them, and integrating them into a system so that the SOFC weight, reliability and supply of potable water [60]. The U.S. space
system can operate with specified types of fuels. At this step, the metallic missions encouraged worldwide fuel cell R&D efforts, which included
or ceramic interconnectors are added to ensure the homogeneous dis efforts regarding SOFCs. The advancement of the U.S. SOFC develop
tribution of the fuel over the anode and to collect the current from the ment in the late 1970s relied almost exclusively on the investments of
system. A background in heavy machinery is essential for understanding the Department of Energy (DOE), which financed the development of
the specificities of the metal parts and the integration and engineering SOFC systems by a company, namely, Westinghouse, with the objective
processes. Know-how in reforming and energy distribution is necessary of integrating them into the power grid [20].
for comprehending the technical challenges that are related to SOFC In Japan, the advancements in fuel cell R&D are partially explained
fueling and applications. by the lack of natural resources that were available for energy genera
tion and the government policies for stimulating the development of
4.2. SOFC production and related IPCs new renewable energy technologies [62]. In 1980, the MITI established
NEDO, which was an important semi-governmental institute for the
Fig. 3 provides insights into the main technological niches that are development of fuel cell technologies, to emphasize energy and global
crucial for the manufacturing and operation of an SOFC. They are i) the environmental problems and to improve industrial technology. NEDO
ceramic and chemical industries; ii) the steel industries, for preparing promoted fuel cells for mobile and stationary applications; in the case of
the interconnectors and reformers; iii) the integration industries, for SOFCs, NEDO focused on stationary cogeneration systems [63].
putting together all the ceramic and metallic parts and providing an
5
Table 2 Table 2 (continued )

Data IPCs. Own table. steel); treatment in molten state of
Separation B01B Boiling; boiling apparatus ferrous alloys
B01D Separation C22C Alloys
B01F Mixing (dissolving, emulsifying, C23C Coating metallic material; coating
dispersing) material with metallic material;
B01G Chemical or physical processes surface treatment of metallic; coating
(catalysis) methods
B01J Processes or devices for granulating C23F Non-mechanical removal of metallic
materials, in general material from surfaces; inhibiting
B04 Centrifugal apparatus or machines for corrosion of metallic material;
carrying-out physical or chemical inhibiting incrustation; multi-step
processes processes for surface treatment of
B05B Spraying apparatus; atomizing metallic material
apparatus; nozzles C25B Electrolytic or electrophoretic
B05D Processes for applying liquids or processes for the production of
other fluent materials to surfaces compounds or non- metals; apparatus
Shaping B22F Working metallic powder; therefor
manufacture of articles from metallic C25C Processes for the electrolytic
powder; making metallic powder production, recovery or refining of
(making alloys by powder metals; apparatus therefor
metallurgy); apparatus or devices C25D Processes for the electrolytic or
specially adapted for metallic powder electrophoretic production of
B23F Making gears or toothed racks coatings; electroforming
B23P Other working of metal; combined (manufacturing printed circuits by
operations; universal machine tools metal deposition); joining workpieces
B23K Soldering or unsoldering; welding; by electrolysis
cladding or plating by soldering or C30B Single-crystal growth; unidirectional
welding; cutting by applying heat solidification or unidirectional
locally; demixing of eutectoid material;
B28B Shaping clay or other ceramic refining by zone-melting of material;
compositions, slag or mixtures production and after treatment of a
containing cementitious material homogeneous polycrystalline
B28D Working stone or stone-like materials material
B29C Working of plastics; working of Engines or pumps F01D Non-positive-displacement machines
substances in a plastic state or engines, e.g. Steam turbines
B30B Presses in general; presses not F01K Steam engine plants; steam
otherwise provided for accumulators; engines using special
B32B Layered products working fluids or cycles
Chemistry C01B Non-metallic elements; compounds F01N Gas-flow silencers or exhaust
thereof apparatus for machines or engines in
C01F Compounds of the metals beryllium, general; gas-flow silencers or exhaust
magnesium, aluminum, calcium, apparatus for internal-combustion
strontium, barium, radium, thorium, engines
or of the rare-earth metals F02B Internal-combustion piston engines;
C01G Compounds containing metals combustion engines
C02F Treatment of water, waste water, F02C Gas-turbine plants; air intakes for jet-
sewage, or sludge propulsion plants; controlling fuel
C03C Chemical composition of glasses, supply in air-breathing jet-propulsion
glazes, or vitreous enamels; surface F02G Hot-gas or combustion-product
treatment of glass; surface treatment positive-displacement engine plants;
of fibers or filaments made from glass, use of waste heat of combustion
minerals or slags; joining glass to engines
glass or other materials F04D Non-positive-displacement pumps
C04B Lime; magnesia; slag; cements; Engineering F16J Pistons; cylinders; pressure vessels in
compositions thereof, e.g. building general; sealing
materials; artificial stone; ceramics; F17C Vessels for containing or storing
refractories (alloys based on compressed, liquefied, or solidified
refractory metals); treatment of gases; fixed-capacity gas-holders;
natural stone filling vessels with, or discharging
C07C Acyclic or carbocyclic compounds from vessels, compressed, liquefied,
C09B Organic dyes or closely-related or solidified gases
compounds for producing dyes; Lighting heating F22B Methods of steam generation; steam
mordant; lakes boilers
C09D Coating compositions; filling pastes; F23C Methods or apparatus for combustion
chemical paint or ink removers; inks; using fluid fuel or solid fuel
correcting fluids; woodstains suspended in air
C09K Materials for applications not F23D Burners
otherwise provided for; applications F23Q Ignition; extinguishing devices
of materials F23L Supplying air or non-combustible
C10J Production of gases containing liquids or gases to combustion
carbon monoxide and hydrogen from apparatus; valves or dampers
solid carbonaceous materials by specially adapted for controlling air
partial oxidation processes involving supply or draught in combustion
oxygen or steam; carbureting air or apparatus; inducing draught in
other gases combustion apparatus; tops for
Metallurgy C21C Processing of pig-iron (Refining, chimneys or ventilating shafts;
manufacture of wrought-iron or terminals for flues
(continued on next page)
6
Table 2 (continued ) Table 2 (continued )

F24H Fluid heaters (e.g. Water or air B64D Equipment for fitting in or to aircraft;
heaters, having heat-generating flying suits; parachutes;
means) arrangements or mounting of power
F25J Liquefaction, solidification, or plants or propulsion transmissions in
separation of gases or gaseous aircraft
mixtures by pressure and cold B65B Machines, apparatus or devices for, or
treatment methods of, packaging articles or
F27D Details or accessories of furnaces, materials; unpacking
kilns, ovens, or retorts B67C Filling with liquids or semiliquid, or
F28D Heat-exchange apparatus; heat emptying, of bottles, jars, cans, casks,
storage plants or apparatus barrels, or similar containers; funnels
F28F Details of heat-exchange or heat- B82B Nanostructures formed by
transfer apparatus, of general manipulation of individual atoms,
application molecules, or limited collections
Measuring, testing, controlling, G01B Measuring length, thickness or them
regulating, computing similar linear dimensions; measuring
angles; measuring areas; measuring
irregularities of surfaces or contours 5.1. Historical patent evolution
G01D Measuring not specially adapted for a
specific variable; arrangements for
measuring two or more variables;
After 1980, the patenting activities of SOFC technologies in Japan
tariff metering apparatus; and in the U.S. were related to the results of R&D in both countries.
transferring or transducing Fig. 4 presents the numbers of SOFC patents that were filed in the U.S.
arrangements not specially adapted and Japan between 1985 and 2016; these data provide useful insights
for a specific variable
regarding the technology paths.
G01M Testing static or dynamic balance of
machines or structures; testing of The DOE investments in Westinghouse induced patent growth, not
structures or apparatus only in terms of the company’s patent activity but also by influencing
G01N Investigating or analyzing materials other SOFC developers, even after their acquisition by Siemens in 1997
by determining their chemical or (Siemens Westinghouse Power - SWP). In 1999, the DOE created the
physical properties
G01R Measuring electric variables;
Solid State Energy Conversion Alliance (SECA) with the objective of
measuring magnetic variables making SOFC systems available at low cost. The program aimed at
G05D Systems for controlling or regulating reducing the cost per kW and increasing cell performance using fossil
non-electric variables fuels [64]. In 2001, the program selected companies and research in
Basic electric elements and H02J Circuit arrangements or systems for
stitutes, and it aimed at applications in, e.g., transportation, the military
generation, conversion, or supplying or distributing electric
distribution of electric power power; systems for storing electric and stationary power [64,65]. SECA created independent industry teams
energy that were responsible for designing and manufacturing SOFCs. To sup
H01B Cables; conductors; insulators; port the industry teams’ technical challenges, SECA selected U&RIs and
selection of materials for their small fuel-cell-specialized firms to compose the Core Technology Pro
conductive, insulating or dielectric
properties
gram. The federal government coordinated the interactions and
H01G Capacitors, rectifiers, detectors, information-sharing between the collaboration partners [66]. The pat
switching devices, light-sensitive or ent activity increased in the U.S. with the creation of SECA, collabora
temperature-sensitive devices of the tive efforts of industry teams, and the Core Technology Program.
electrolytic type
At the beginning of the 2000s, U.S. SOFC developers faced technical
H01M Processes or means for the direct
conversion of chemical energy into issues, which slowed the demonstration testing and validation of their
electrical energy (e.g. Batteries) technologies [20]. The Core Technology Program researchers also
H01L Semiconductor devices; electric solid encountered difficulties in realizing consistent advancements due to the
state devices not otherwise provided small-scale, underfunded and short-term research projects. Moreover,
for
H01J Electric discharge tubes or discharge
SECA shifted from a natural gas and oil initiative to a coal-based pro
lamps gram in 2005, thereby leading to budget restrictions, the disintegration
Transporting B60K Arrangement or mounting of of industry teams, and the waiver of important participants. With the
propulsion units or of transmissions end of the initial SECA program in 2011, the funds for SOFC projects
in vehicles; arrangement or mounting
diminished [67] but the DOE continued to support the technology under
of plural diverse prime-movers in
vehicles; auxiliary drives for vehicles; other initiatives [68]. The oscillation of the number of filed patents
instrumentation or dashboards for during this period might be correlated to the uncertainties that sur
vehicles; arrangements in connection rounded the SECA program.
with cooling, air intake, gas exhaust In the following years, at the same time as companies with strong
or fuel supply of propulsion units in
vehicles
SOFC involvement abandoned the technology, others, especially fuel-
B60L Propulsion of electrical vehicles; cell startups, began commercializing small-scale systems [20]. As an
supplying electric power for auxiliary example, the two contrasting cases of SWP and Bloom Energy stand out.
equipment of electrical vehicles; While SWP decided to shut down its fuel cell business in 2010 after
electrodynamic brake systems,
several smaller installations and less successful tests, Bloom Energy,
magnetic suspension or levitation for
vehicles; monitoring operating which was a NASA SOFC spin-off, installed their “Bloom Box”2 nation
variables of electrical vehicles; wide [20,69,70]. Additional SOFC companies3 have been funded by the
electric safety devices for electrical
vehicles
B61C Locomotives; motor railcars
B64B Lighter-than-air aircraft 2
B64C Airplanes; helicopters The Bloom Box is the commercial name of Bloom Energy’s SOFC system.
3
such as Acumentrics, Adoptive Materials, Delphi Technologies and
NexTech.
7
Fig. 4. SOFC patent (priority date) activity in U.S. and Japan. Own figure.
U.S. Army to develop fuel cell vehicles and systems for military appli companies, which was once again financed by NEDO8 [79]. By 2013,
cation [71–74], especially after the department committed to a 20% Japan had installed several systems,9 however, their high costs and low
reduction of its CO2 emissions [74]. durability slowed further commercialization [80]. To address these
In Japan, NEDO launched a three-phase long-term program for SOFC problems, a subsequent project aimed at developing low-cost, high-
development in 1989 [20], which affected the national patent activity. durability cell stacks for the commercialization of SOFC systems by
The program aimed at developing an SOFC system jointly with major 2017. By the end of 2016, program participants improved the durability
Japanese companies4 and research institutes.5 Aside from energy safety, and reduced the cost but not to sufficient levels for commercialization
the government was concerned with catching up with the U.S. in terms [81]. Table 3 summarizes the government programs that targeted SOFC
of technological development6 [20]. Significant investments in basic R&D and commercialization in Japan and the U.S.
research, R&D of materials and basic technology aimed at the realiza
tion of higher reliability, cost reduction, conceptual designs and opti
mization [75]. The investments enabled the development of a 5.2. Sector classification of SOFC applicants
high-performance SOFC module by 2004 [76]. In the following four
years, NEDO initiated a large-scale demonstration by testing the previ The patent applicants have their main businesses in various indus
ous prototypes and identifying market perspectives [76], but many trial sectors, as presented in Fig. 5. This figure presents the percentages
technical challenges were encountered [20]. In the subsequent phase, of patents that were filed in the U.S. and Japan, which are classified
namely, “Development of system and elemental technology on SOFC” according to their industrial sectors10, which include U&RIs.
(2008–2012), several companies and U&RIs7 jointly investigated the In both countries, companies in the automobile and components
cell durability and reliability, the cost reduction of raw materials and the sector have filed a significant number of SOFC-related patents. In the U.
development of a low-cost system [77,78]. The R&D programs in Japan S., Delphi Automotive11 holds 70% of this sector’s patents. Delphi,
have influenced the patent activity and accelerated research after the which has expertise in automotive parts, received investments as a
elemental technology program, which suggests that the government member of the SECA program for its R&D on SOFCs, which focused on
policies had a positive impact. In 2011, the ENE-Farm type S was applications for ground and undersea vehicles [20]. In Japan, the pat
released, which was a result of decades of R&D on the residential ents in this sector belong mostly to Nissan (43%) and NGK Spark Plug
application of SOFCs with the involvement of electric, gas and energy (27%). Nissan was not part of the NEDO program, in contrast to NGK
Spark Plug, which was selected to participate in the most recent project
(FY 2013 – FY 2017) by conducting research on durability issues.
4
such as Sanyo, Fuji Electric, Murata, Mitsui Engineering & Shipbuilding,
Electronic equipment, instruments & components is also a strong
Mitsubishi Heavy Industries, Toto, Nippon Steel and Tokyo Gas. sector in both countries. Companies such as DAI Nippon Printing (42%),
5
such as Japan Fine Ceramic Center, Japan Research and Development
Center for Metals and Institute of Applied Energy.
6 8
A few Japanese companies had researched and developed SOFC technolo The ENE-Farm type S was released in 2011 by JX Nippon Oil and Energy
gies in response to the American progress, but they used different fabrication and 2012 by Aisin.
9
methods and cell shapes than Westinghouse [20]. Approximately 300 units were pre-ordered in 2012 [84].
7 10
companies from the heavy industries, such as the chemical, metal, mining, According to the BICS, described in the methodology.
11
and building product industries. Since December 2017 known as Aptiv PLC.
8
Table 3 Table 3 (continued )

SOFC development in the U.S. and Japan. Own table. United States Japan
United States Japan
Demonstrative study for
Goals of SOFC Develop low-cost, highly Promotion of renewable business use
programs efficient, environmentally energy and energy Form of guiding Projects and funding Full coordination of NEDO.
friendly SOFC technology conservation; Enhance the promoted by the DOE NEDO selected program
for smaller, modular-scale level of industrial technology; participants and sets projects
as well as large-scale power Catalyst for industry- and goals
generation; Initial focus on academia-government Investment 467$/10 years 175.2$/9 years (2001–2010)
tubular design [20,82] collaboration; Promote (2000–2010) [20] [20]
knowledge and idea exchange; Commercialized – ENE-FARM Type S
Projects aim at resulting in the unites 03/2013: 37.000 units sold
market entry; Development of (PEFC and SOFC) [80]
planar SOFC technology by 12/2016: 198.500 units sold
using a “wet” method (PEFC and SOFC) [81]
Motivation Cold War, NASA, reduce Energy independency Total program >41 >29
CO2 emission participants
Application Transportation, military, Vehicles, stationary power,
stationary power infrastructure
Duration Short/Medium erm Medium/Long Term; Kyocera (29%) and Hitachi (16%) contribute to this second-largest
projects; individual project coordinated project execution sector in Japan. Kyocera and Hitachi were both involved in the NEDO
execution
program: Kyocera by providing SOFC stacks for the R&D programs and
Environment Competitive environment; Full coordination over NEDO
SOFC companies without under METI; Most SOFC for the “ENE-FARM type S” [20,80,81,83], and Hitachi by optimizing
SECA involvement; Less research in Japan is connected the system fuel distribution, heat recovery and quick start-up method
coordinated on a national to NEDO’s programs [76]. In the U.S., most of the patents in this sector were filed by Corning
level (83%), which is a ceramic multinational.
Government DOE administered and METI launched SOFC R&D
departments funded all SOC projects in projects under the Moonlight
Except for these two sectors, the distributions differ between the
the U.S. DOE initiated project. NEDO coordination as countries. The figure shows that U&RIs in the U.S. have the third-largest
SECA under the Clean Coal a semi-governmental patent share, in contrast to Japan, where this category is less involved in
Research Program (CCRP) organization under the patenting SOFC-related technologies. Similarly, the sector of electrical
and is administered by the Ministry of Economy, Trade
equipment is the largest in the U.S. but shows low participation in Japan.
Office of Clean coal and and Industry (METI).
implemented by the In the U.S., 52% of this sector’s patents belong to Bloom Energy (32%)
National Energy and Siemens Energy (20%). In Japan, the Mitsubishi Group accounts for
Technology Laboratory 69% of the largest sector, namely, machinery, and participated in many
(NETL) of the government programs.12 In the building products sector, Toto
Tech Phases [20, 1977–2005: Westinghouse 13-year, 3-phase SOFC R&D
66,78,81,83] tubular SOFC development program:
dominates the patent activity with 97%. Toto, which is the world’s
2000–2010: SECA: � 1989–2001: Phase I: largest toilet manufacturer, began participating in the government
Development of SOFC Development of 100 W class programs during the extension program of SOFC R&D Phase II in 1998.
system with costs lower planar SOFC modules
than $400/kW � 1992–1997: Phase II:
� Phase 1: 3–10 kW system Development of planar
5.3. Main SOFC applicants
with costs at $800/kW SOFC modules and 10 kW
(achieved in 2007) class modules (10 kW goal
� Phase 2: costs at $600/ not reached) Frequently, the applicants develop technologies using their own
kW (canceled) o 1998–1991: Extension capabilities, which are related to their primary business. Most of the U.S.
� Phase 3: costs at $400/ Phase II: Improve and Japanese SOFC companies participated in the government pro
kW (canceled) durability and reliability;
grams, and all of them have their main business in at least one core
2009: SWPC tested a 10 kW Development of tubular
SOFC module SOFC modules capability that is necessary for SOFC system manufacturing, as pre
� 1991–2004: Phase III: sented in Fig. 3. Table 4 lists the 15 most frequent companies in terms of
Development of a 5–10 kW SOFC filings, along with their year of foundation, main business and
module (thermally self-
participation in the two main national government programs that pro
supported)
Extension Programs: mote SOFC development – NEDO and SECA.
2004–2007: “SOFC System The table shows a stronger correlation between SOFC developers and
Technology Development”: their program participations in Japan (67%) than in the U.S. (53%),
10–200 kW class cogeneration which emphasizes the role of NEDO in the Japanese SOFC development.
demonstration plant (Failed
The Japanese patents are also more concentrated than the U.S. patents:
partially)
2007–2010: “Demonstrative while the 15 most frequent Japanese SOFC applicants hold 72% of all
Research on SOFC”: patents that were filed in Japan, the overall American patent applicants’
Installation and field tests of participation represents less than 34% in the U.S. Another observation
233 SOFC systems.
from Table 4 relates to the company foundation years: the Japanese
2008–2012: “Development of
System and Elemental
companies’ average foundation year was at the beginning of the 20th
Technologies on SOFC”: Basic century, compared to the 1950s for the U.S. companies. This finding
research program with focus contrasts the foundation years of the Japanese SOFC developers, which
on degradation
2013–2017: “Technology
Development for Promoting
12
SOFC Commercialization”: Early SOFC R&D programs (Phase II FY 1992 – FY 1997) [20] and the
Studies on Degradation; system development program (FY 2004 – FY 2007) [20]. The Mitsubishi Group
has participated in several projects, which range from basic research on dura
bility and reliability and practical utility improvements (FY 2008 – FY 2012)
[80] to commercialization programs (FY 2013 – FY 2017) [81].
9
Fig. 5. Sector classification of SOFC applicants in the U.S. Japan. Own figure.
were all established before 1952 (average foundation year 1914). The U. The IPC frequencies that correspond to the stacked cell and the
S. companies that were founded in or after the 1950s are either the re system and applications differ in terms of their patterns over the three
sults of mergers of other companies (AlliedSignal and Siemens Energy analyzed periods in each country. In the first period, in the U.S.,
Sector) or are directly related to fuel cell development and production. approximately 34% of the patented technologies addressed SOFC sys
In addition, the Japanese companies were established within a narrower tems and applications, while in Japan, such patented technologies
time range (standard deviation of 27 years) than the U.S. companies accounted for approximately 18%. These results are related to the initial
(standard deviation of 52 years). difference in the applications between the countries: the U.S. focused on
In the U.S., the young companies with their main business in fuel cell portable applications (represented by the “transporting” and “engines or
development reflect the NIS mechanisms that promoted such industrial pumps” IPCs), while Japan focused on stationary applications (repre
formation. Moreover, the early commercialization attempts, in combi sented by the “building” IPC).
nation with intensified public policies, have led to the creation of new In the following period, the U.S. IPCs that were associated with the
companies that target SOFC R&D and commercialization. Companies stacked cell increased their relative percentage, especially due to IPC
that were established before the early 1950s developed fuel cell tech “separation”. In Japan, the percentage of the patents that were classified
nologies outside their main business but with capabilities in the fabri as “chemistry” increased while the percentages of the patents that were
cation steps of SOFC devices. This finding holds for all Japanese main classified as “separation” and “shaping” decreased, thereby suggesting a
applicants. As explored in Section 4.1, chemistry, ceramics, printing stronger focus on the materials than on the process. Meanwhile, IPC
techniques, heavy machinery and energy distribution are main busi “capacitor” increased its percentage jointly with the IPCs that were
nesses that are directly related to SOFC system production and related to the system operation.
commercialization. In the final period, the U.S. had the highest percentage for the cell
stack IPC group, and Japan had the lowest. The compositions of the
system and application classifications in Japan and the U.S. show the
5.4. IPC distribution differences in the orientation of the technological development between
the two countries. Aside from the portable and stationary application
The patents that are compiled in this work fall under 13 IPCs differences, the U.S. patents are related to “engineering” and “lighting
(Table 2), which are categorized into two main groups: stacked cell heating”, whereas Japan’s are related to “capacitor” and other IPCs that
manufacturing and system applications (Fig. 3) that are related to the are related to the system operation.
implementation process. Fig. 6 presents the results regarding the IPC
distributions in the U.S. and Japan. The first group, namely, “Stacked
Cell”, is comprised of IPCs “separation”, “shaping”, “chemistry” and 5.5. International patent activity
“metallurgy”, which disclose details regarding the materials and focus
on the first steps of the SOFC manufacturing process in Fig. 3. The sec The last result is the main countries in which SOFC developers filed
ond group, namely, “System and Applications”, correlates either to the their patents. Patent families are subsequent, similar or identical ap
application of the technology or to its system integration and fuels, such plications which were filed either in the same country or internationally
as “transporting”, “building” and “capacitor”. Other IPCs from this to expand the protection of a technology either technically or
group, such as “measuring, controlling and computing”, “generation geographically. An applicant has exclusive rights to commercialize a
power” and “conductors, cables & insulators”, are related to the system patented invention in the country in which the patent was filed. Inter
operation. nationally filed patents often indicate an interest in the commercial use
10
Table 4
Most frequent SOFC patent applicants in Japan and the U.S. Own table.
Company Foundation year National patent share Main business Program participation
SECA
United States Corning Inc. 1851 4.0% Glass & Ceramics No

Westinghouse Electric Company 1886 1.4% Nuclear power Yes
General Electric 1892 4.8% Variety of industries Yes
Honeywell 1906 1.5% Variety of industries Yes
Phillips 66 1917 1.1% Oil & Gas No
Hewlett-Packard 1939 0.9% Hardware components & Software No
UTC Power 1958 1.5% SOFC Yes
FuelCell Energy, Inc. 1969 0.9% Fuel cells Yes
AlliedSignal 1985 1.2% Aerospace & Automotive No
Acumentrics 1994 0.7% Clean power electronics Yes
Adaptive Materials Inc. 1999 1.4% SOFC No
Versa Power Systems, Inc. 2001 2.5% SOFC Yes
SOFCo-EFS Holdings LLC 2002 1.1% SOFC No
Bloom Energy 2002 6.5% SOFC No
Siemens Energy Sector 2008 4.1% Power generation Yes
Average year 1954 Yes ¼ 53%

Standard Deviation of years 52
Sum national patent share 33.7%
NEDO
Japan Mitsubishi Group 1870 11.4% Variety of industries Yes

Dai Nippon Printing Co., Ltd. 1876 6.4% Printing No
Tokyo Gas 1885 4.0% Natural gas Yes
JXTG Nippon Oil & Energy 1888 2.9% Petrol Yes
Osaka Gas 1897 2.7% Gas Yes
Noritake 1904 1.6% Ceramics No
Hitachi 1910 2.5% Variety of industries Yes
TOTO 1917 9.8% Ceramics (toilets) Yes
NGK Insulators 1919 3.2% Ceramics (insulators) Yes
Nissan 1933 5.1% Automobile No
Kyocera 1934 4.5% Ceramics and Electronics Yes
NGK Spark Plug Co., Ltd. 1936 3.2% Ceramics (spark plugs) Yes
NIPPON SHOKUBAI Co., Ltd. 1941 2.1% Chemicals No
Kansai Electric Power, Inc. 1951 5.0% Nuclear power Yes
Nippon Telegraph and Telephone 1952 7.1% Telecommunications No
Average year 1914 Yes ¼ 67%

Standard Deviation of years 27
Sum national patent share 71.6%
of a technology in foreign countries; thus, countries that do not 6. Discussion

contribute directly to the technological development can still present
market features that will enable an invention to prosper. Fig. 7 presents The SOFC technology paths in Japan and in the U.S. are inseparable
the destinations of patents with international filings, which exclude the from the unique institutional arrangements of the countries. NISs are a
priority country. Patents that have no family or for which subsequent historical construction that promoted innovations in these countries,
patents were only filed in the priority country were also excluded from which emphasizes the importance of a consolidated institutional infra
this representation. Thus, the figure shows where SOFC applicants structure for fostering and shaping technology pathways. The presented
choose to protect their inventions outside their home country. results provide sufficient grounding for discussing the research ques
Approximately one quarter of all compiled patents were filed inter tions: (1) how have the NIS mechanisms of Japan and the U.S. shaped
nationally. For international filings, the U.S. (22%) is the preferred SOFC development (Section 6.1) and (2) to what extent have they
designated location for SOFC patents, which leaves behind Japan (13%), induced technological development paths that differ between these
which is the world leader in terms of the overall number of filed patents countries (Section 6.2)?
of SOFC technologies. In terms of patent share, Japan loses the most
participation compared to international filings. Although Japan filed
6.1. Role of NIS in technology shaping
47% of SOFC patents, only 13% of the international patents were
designated to Japan, which is almost half the percentage for the U.S.
By examining technology trajectories, it is possible to identify and
Another observation is that the overall patent distribution is more ho
justify patterns of key players and institutions that have continually
mogeneous, as other countries such as Brazil, Mexico, South Africa,
enabled the development of new technologies. The present work has
Russia and India also have market potential. Canada receives 9% of all
explored the historical conditions that resulted in the engagement of
internationally filed patents, which represents a greater share than
players and the creation of institutions that promoted SOFC develop
South Korea and is closing in on China (13%). We attribute this finding
ment. The presented results demonstrated two main factors that affected
to the proximity and similarity to the U.S. market. Comparing to other
the shaping of SOFC technology by NISs:
countries, Australia (7%) and Germany (6%) have attracted the atten
The first is the role of independent historical events that motivated
tion of SOFC developers.
the establishment of institutional arrangements from which SOFC
technology has benefited. They include the NIS determinants for SOFC
development that are presented in the conceptual framework in Section
2.2 that either preceded the technological development or were not
11
Fig. 6. IPC frequency separated in three periods. Own figure.
Fig. 7. Patenting activity of SOFC applicants outside their headquarters’ countries. Own figure.
intentionally designed to promote SOFCs. Examples include the strong established between industry and researchers. Such unintended ar
industry-university interaction since the consolidation of the scientific rangements of each NIS have reverberated in the SOFC applicants and
research on and the development of industrial knowledge and tech their related sector classifications. The results demonstrate that a
niques in complementary industries of SOFC technologies, such as the consistent share of the patent owners, especially in the case of Japan, are
metal, chemical, electrical and heavy industries, which were founded in companies that were founded long before SOFC development began and
the 19th and early 20th century. Despite the late emergence of the core businesses that were unrelated to fuel cells (Table 4). From the
research mission in university and educational institutes, in both industry side, key industrial sectors of the U.S. and Japanese NISs have
countries, the research objective was to respond to industrial needs to also been responsible for developing SOFCs, as major patent applicants
increase competitiveness; hence, collaboration pathways were come from sectors that have pushed industrial and innovation policies
12
(e.g., the chemical, steel and electronic sectors) (Fig. 5). zaibatsu, such as “machinery”, “electronics”, “petrol and gas”, “build
The second is the role of NISs in shaping policies and efforts with the ing” and “telecommunication”, have demonstrated stronger patenting
objective of promoting SOFC and related technologies, such as the SECA activity in SOFC development. In contrast, in the U.S., the creation of
(U.S.) and NEDO (Japan) programs. Both policies unfolded from an university spin-offs that are related to the SOFC business has reflected in
already constructed modus operandi that was unique to each NIS. The the high participation of the “electrical equipment” sector, which is
SECA program has been conducted with strong participation from U.S. composed of firms that are new to the fuel cell business and R&UIs.
federal departments (Energy, NASA, Army and Defense), which pro Another high-performing sector in terms of patenting activity in the U.S.
moted a competitive environment by providing more resources to is “aerospace and defense”, which is associated with U.S. federal de
awarded projects and by government procurement (via mission- partments’ procurement and vehicular application of SOFCs.
orientated projects). Meanwhile, Japan has promoted a national tech The IPCs of the filed patents (Fig. 6) suggest different development
nological development strategy with the long-term objective of energy focuses in SOFC manufacturing steps (Fig. 3) between the two countries.
independency, with milestones throughout the process. The industrial Dissimilarities in the initial application of the technology between the U.
R&D budget for SOFC development has not only been complemented by S. (portable) and Japan (stationary) are related to the technological
robust government subsidies and investments but also benefited from development orientation in each country, namely, the military in the
solid coordination with NEDO to realize technological development in a American case and energy independency in Japan. In Fig. 6, the IPCs are
cooperative environment. categorized into technologies that are related to the cell production until
stacking (“stacked cell” in Fig. 3) and technologies that are related to the
6.2. Differences in the technology development application or use of the fuel cell system (“system and applications” in
Fig. 3), which affects how the components are being mounted around
The pathways for producing SOFC devices in the U.S. and Japan the cell. The results demonstrate that the technological development of
consistently differ, despite technical similarities in terms of comparable SOFCs and the patent filings correlate with the context and NIS of each
parameters, such as power generation, efficiency and used materials. As country. In the U.S., the enthusiasm in the early phases with the success
much as SOFCs are a bundle of technical specificities, they are also a of the Westinghouse prototyping led to stronger patenting activity of
convergence of multiple trajectories of efforts that have enabled fuel cell “system applications”, as further impediments to cell production were
production. Key players have constructed SOFC trajectories according to not foreseen at the early phase. When the DOE launched the SECA
the “rules of the game”, namely, “what is possible” and “how it is done” program, the objective was to solve production scale issues; the program
in each country’s institutional arrangement. Thus, different rules inev was not necessarily orientated toward improving the cell technology. In
itably result in differences in technological development, as in the case contrast, Japan focused on the development of basic technologies for the
of SOFCs in the U.S. and Japan. cell, as Japan was behind the SOFC frontier of knowledge and opted for a
Such differences are already observed in each country’s motivation different cell design (planar, not tubular, as was used by Westinghouse).
to engage in fuel cell development, as presented from a historical The objective of the NEDO projects was twofold: to develop a solution
perspective in Section 5.1. In the American case, the space race and for the country energy supply and to catch up with the American tech
military orientation provided the initial resources and incentives for fuel nical advancements. Therefore, the projects were more orientated to
cell R&D. In Japan, especially after the petrol price oscillation in the ward the development of stationary SOFCs and the expansion of the cell
1970s, energy dependency and safety provided the institutional grounds knowledgebase.
for fostering SOFC development. Such motivations aligned with larger The reframing of the SECA program from an oil and gas to a coal
country projects (unrelated to SOFC), which were inextricable from coordination has also influenced the IPC composition. Changing the fuel
their NISs. Moreover, differences in terms of technological maturity led type directly affects the SOFC manufacturing process and the materials
to differences in terms of the objectives, the structures of the programs, that are used, as embedded technologies consider the whole system
and the development strategies. For an instance, when Westinghouse operation and its application (e.g., internal or external reforming).
began delivering SOFC prototypes, no Japanese company understood Similarly, in Japan, when the participants had difficulties in realizing
the technological production. Thus, instead of high government budgets the demonstration-phase objectives, NEDO called for elemental tech
that were directed to a single company, as in the case of Westinghouse, nology research [20], thereby leading to a major IPC share that was
the Japanese program focused on a national development of fuel cell related to the stacked cell (Fig. 6) despite already being in the demon
technologies with participants from industry and academia since their stration phase (Fig. 4).
early development. Finally, the results regarding the international patent activity (Fig. 7)
The management and design of direct policies for SOFC development clarify the role of NISs in absorbing technologies. Although Japan holds
have emerged from each NIS institutional arrangement in alignment the majority of SOFC patents, the U.S. has attracted more foreign pat
with the policy goals. Similar to other policies in the U.S. [55] and Japan ents. The larger market size of the U.S. compared with Japan justifies the
[49], the SECA promoted the creation of new companies, which were international interest in the American territory; however, other large
mostly spin-offs from U&RIs, and the Japanese policies promoted market economies, such as China, India and Brazil, have not received the
technology enhancement and diversification of well-established con same attention. The market potential of the U.S. is also related to its
glomerates. The SECA structure was synergetic: it assigned basic and capacity for absorbing and diffusing technology. Incentives for techno
applied research tasks primarily to U&RIs and the development of SOFC logical development and commercialization, for a competitive envi
systems to industrial players. In contrast, in Japan, companies and ronment and for partnership promotion among key players are
universities contributed with their main capabilities to the SOFC characteristics of the American NIS that favors patent filings in the
manufacturing steps (Fig. 3) – such as TOTO and Kyocera with ceramics, country. Japan received as many patents as China, which is a much
Tokyo Gas with gas distribution and universities with basic and applied larger economy, thereby highlighting the importance of public policies
research – to address issues under the coordination of NEDO. This for SOFCs and NIS mechanisms for fostering technological development.
contribution is reflected by the most-frequent Japanese SOFC appli
cants, which have their main businesses outside hydrogen technology 6.3. Implications for policy making
niches but in fundamental steps of the system manufacturing, in contrast
to the U.S., where many companies are exclusively developing and NISs and technology trajectories facilitate the comprehension of
commercializing SOFC and related technologies (Table 4). technological development and are, ultimately, instruments that facili
Another difference in the technological development is the sectors tate policymaking. Technology trajectories provide important insights
that are involved in the SOFC patenting activity. The sectors of Japanese into knowledge accumulation over the development process. They
13
facilitate the identification of the sector that gathered the technological (306076/2017-9, 307538/2017-6, 407186/2013-1, 303487/2018-6),
information and experience, the soft skills that were improved, and, Ministry of Education MEC/FNDE (PET-UFMG 5751292) and Minas
most importantly, the mechanisms that enabled the learning processes. Gerais State Agency for Research and Development-FAPEMIG (APQ-
With this analysis, it is possible to identify the strengths and weakness of 03623-17).
technology production, the roles of various sectors in technological
development, and the motivations of key players for participating in the References
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Renewable and Sustainable Energy Reviews 127 (2020) 109879

Contents lists available at ScienceDirect

Renewable and Sustainable Energy Reviews

Solid oxide fuel cell technology paths: National innovation system

Such complex and research-intensive technologies rely on policies to

2. Conceptual framework: national innovation system

Fig. 1. NIS framework. Own figure.

Fig. 3. SOFC manufacturing process and power generation. Own figure.

Table 2 Table 2 (continued )

Table 2 (continued ) Table 2 (continued )

Table 3 Table 3 (continued )

United States Corning Inc. 1851 4.0% Glass & Ceramics No

Average year 1954 Yes ¼ 53%

Japan Mitsubishi Group 1870 11.4% Variety of industries Yes

Average year 1914 Yes ¼ 67%

of a technology in foreign countries; thus, countries that do not 6. Discussion

Fig. 6. IPC frequency separated in three periods. Own figure.

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