Functional evolution and

accumulation of technological

innovation systems: The case of

renewable energy in East Africa

Aschalew D. Tigabu1,*, Frans Berkhout2 and Pieter van Beukering1

1Institute for Environmental Studies (IVM), Faculty of Earth and Life Sciences (FALW),

VU University Amsterdam, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands2Department of Geography, King’s College London, King’s Building, Strand Campus,

London WC2R 2LS, UK

*Corresponding author. Email: a.d.tigabu@vu.nl.

This paper compares the historical development of innovation systems related to biogas andimproved cooking stove technologies in Rwanda and Kenya by applying the ‘functionsapproach’. It argues that the accumulation of functions in these four renewable energy techno-logical innovation systems (TISs) differed substantially. We find that the accumulation of TISfunctions at early stages of development is determined more by national and international con-textual factors than by specificities related to technologies or internal dynamics (interaction offunctions). Further examination of the functional patterns of TISs suggests that differences in theaccumulation rates of functions explain the differences in diffusion rates, with broader and morebalanced TIS functional accumulation being related to higher diffusion rates. The paper concludesthat systematic support, including well-directed international development assistance, wouldenable the development of mature and balanced TISs that nurture the diffusion of renewable

energy technologies.

Keywords: technological innovation systems; innovation system dynamics; functions approach toinnovation systems; renewable energy technologies; East Africa.

1. Introduction

The introduction of renewable energy technologies toaddress energy poverty and environmental challenges,such as deforestation, has been a focus of much interna-tional development policy in least-developed countries.Since renewable energy technologies are often newlyintroduced, they should be considered as innovations.Modern innovation theory suggests that innovations aredeveloped and diffused in the context of an innovationsystem—a social system composed of actors and institu-tions, whose actions and interactions directly or indirectlycontribute to the process of introducing, developing,diffusing and utilizing a new technology (Freeman 1987).

In recent years, the innovation systems approach hasbeen applied extensively to understand the determinantsof the successful development and diffusion of sustainable

technologies (Jacobsson and Bergek 2004; Alkemade et al.2007; Hekkert et al. 2007; Negro 2007; Negro andHekkert 2008; Hillman et al. 2008; Negro et al. 2007,2008). These studies apply the so-called the ‘functionsapproach’ to innovation systems, which holds that techno-logical innovation systems (TISs) perform crucial activitiesand processes that enhance the generation and absorptionof new technologies (Hekkert et al. 2007; Bergek et al.2008a). Example functions include: knowledge develop-ment, market formation and guidance of search.

In this approach, researchers often map the provision ofseven functions by innovation systems from a historicalperspective, generating patterns of functional dynamicsover time. They show that a balanced accumulation offunctions and their positive interaction leads to systembuildup and improved deployment and diffusion of

Science and Public Policy (2015) pp. 1–18 doi:10.1093/scipol/scu073

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technologies (Jacobsson and Bergek 2004; Alkemade et al.2007; Hekkert et al. 2007; Negro et al. 2007, 2008; Tigabuet al. 2013b). Since the accumulation of functions is im-portant in explaining technology diffusion, insights intothe patterns and speed of functional accumulation are es-sential. As yet, few studies have compared the functionalaccumulation patterns of different TISs, or explainedobserved similarities and differences, particularly in de-veloping country settings.1 If patterns in the accumulationof TISs can be established and/or lessons are learnt, thiscould have important consequences for the development ofpolicies to encourage the development of innovationsystems as a way of enabling the diffusion of newtechnologies in developing countries.

This paper compares the functional evolution of TISs ofRwandan and Kenyan biogas reactors and improvedcooking stoves (hereafter cookstoves). We chose thesefour cases because they allow for the comparison of TISsthat are emerging around two technologies in the institu-tional settings in two East African nations. This allows anassessment of similarities or differences, and can inform anassessment of whether these should be attributed totechnological, national or other factors. The paperaddresses two questions: are the rate and pattern inwhich TIS functions accumulate similar or differentacross technologies or institutional settings? And, what isthe relative importance of external factors, internaldynamics and technological characteristics in explainingobserved accumulation patterns of functions? Insightsinto these questions are critical for the design of effectiveinternational and national policies that support the devel-opment of balanced and mature innovation systems tosupport the diffusion of sustainable energy technologiesin developing countries.

The remainder of this paper is organized as follows:Section 2 provides a concise conceptual framework thatforms the foundation of the empirical analysis. Section 3outlines a methodological overview, describing how thedata on which this paper is based were collected and pro-cessed. Section 4 presents an overview of the functionalevolution of the four TISs. Section 5 provides comparativeanalyses of observed functional patterns and diffusionrates. Finally, Section 6 presents conclusions.

2. Theoretical background

Innovations are now accepted as being the outcome ofindividual and collective efforts, characterized bycomplex, non-linear interactions, and contributions andfeedbacks involving diverse actors and institutions(Saxenian 1994; Edquist and Hommen 1999; Smits 2002).This social system, which is composed of interacting actors(such as governmental organizations and firms) and insti-tutions (norms, rules and laws) that determine the degreeand direction of the innovativeness of firms and other

agents is called an innovation system (Edquist 2004,2005). The innovation systems framework has been in-creasingly adopted as an analytical and policy tool toexamine and influence the rate and direction of techno-logical innovations. Edquist (2001) argues that the innov-ation systems framework captures the most importantorganizational, political, social and economic determinantsof the development, diffusion and use of innovations; andthat innovation policy should draw on empirical insightsfrom this perspective (Edquist and Hommen 1999).

Many perspectives have been developed about innov-ation systems, including national, regional, sectoral andtechnological innovation systems. The variations of theseapproaches mostly lie in the delineation of the systems andpurpose of analysis (Edquist 2004; Markard and Truffer2008). The national innovation systems framework,drawing its contours along the geographic boundary of acountry (Freeman 1987; Lundvall 1992; Lundvall et al.2002), argues that national features, such as actors andinstitutions within a nation-state, determine the innovativeperformance of firms. A related framework is the regionalinnovation system. This approach takes a territorial delin-eation and focuses on cultural and resource conditionswithin a particular sub-national region (Maskell 1997).Other scholars have developed a non-geographical delin-eation called a sectoral innovation system. In thisapproach, the focus is on firms active within a particularsector (Breschi and Malerba 1997).

Hekkert et al. (2007), Negro et al. (2008) and Suurs(2008) have argued that, due to the vast number ofactors within national, regional and sectoral innovationsystems, the analytical focus has often been on structures.These are assessments related to institutions such as:

. . . qualities of educational systems, university–industry collab-orations, and availability of venture capital. (Hekkert et al.2007: 417)

This has led to limited insights into the dynamics of theinnovation systems themselves. These authors suggest thata technology-specific innovation system is appropriatesince the complexities of the relevant systems are analytic-ally more manageable than national, regional or sectoralinnovation systems.2

A TIS is defined by Carlsson and Stankiewicz (1991:111) as:

. . . network(s) of agents interacting in a specific economic/in-

dustrial area under a particular institutional infrastructure orset of infrastructures and involved in the generation, diffusion,and utilization of technology.

One of the major features of the TIS framework is its flexi-bility for analysis of system dynamics. Reconstructing theevolution of TISs is possible by mapping the activities andprocesses within the system. The activities and processesthat are contributed by the system can be clustered into‘system functions’ (simply labelled as functions here)

2 of 18 . A. D. Tigabu et al.

(Hekkert et al. 2007). Table 1 presents a list of these func-

tions along with brief definitions based on Hekkert et al.

(2007).An established conceptualization in the innovation lit-

erature is the product or industrial life cycle (Utterback

and Abernathy 1975; Van de Ven and Garud 1989). It

has been proposed that innovation systems also follow

two stages in their life cycle. The early stage of develop-

ment is called the ‘formative period’ while the later evolu-

tionary period is known as the ‘growth phase’ (Jacobsson

and Bergek 2004; Alkemade and Hekkert 2008). The for-

mative period is generally characterized by: the presence of

many rival designs, low market volume, the entry of entre-

preneurs, high uncertainty about technological and market

growth, weak or absent internal institutions, and the emer-

gence of advocacy coalitions (Jacobsson and Bergek 2004;

Utterback and Abernathy 1975; Kemp et al. 1998).

Conversely, the growth phase is characterized by the de-

velopment of a well-functioning market, the emergence of

a dominant design (Suarez and Utterback 1995), and ma-

terialization of positive interactions among increasingly

institutionalized functions (Jacobsson and Bergek 2004).

In this phase, the interactions of the functions will be

circular, creating a momentum of ‘cumulative causation’

that, in turn, influences the structural configuration of the

TIS (Jacobsson and Bergek 2004).An important question that is frequently raised (but in-

frequently answered) is whether the evolution of functional

patterns of TISs are similar across different technologies or

in different contexts, particularly in the ‘formative phase’

(Markard and Truffer 2008; Jacobsson and Bergek 2004).

Jacobsson and Bergek (2005) and Bergek et al. (2008a)

suggest that while the specific evolutionary functional

patterns can be different, there are likely to be

commonalities. These authors also note that empirical

effort is needed to identify the typology of common

patterns of functional accumulation in TISs.

Suurs (2008) has suggested a ‘succession model of innov-ation’ by observing five case studies related to the Dutchand Swedish energy systems. The model consists of atypology of four distinct but consecutive functionalpatterns characterized by common patterns of interactionbetween dominant functions in the early phase of systemdevelopment, which the author labels ‘motors of innov-ation’. The focus of Suurs’ analysis is on the internaldynamics of TISs by observing the interaction pattern offunctions, while placing less emphasis on the influence ofexternal factors in determining observed patterns. Heargues that:

. . . external factors largely determine the general direction of

TIS development (buildup or breakdown) but underlying theseprocesses there are more detailed dynamics at play that shouldbe uncovered. After all, it is on the level of the internaldynamics of a TIS that important strategic lessons are to be

learnt. (Suurs 2008: 210)

Jacobsson (2008) also suggests that the functionalpattern—the degree to which functions haveaccumulated—is partly explained by internal dynamicsand partly by exogenous factors arising in the environmentoutside of the TIS. This phenomenon was also noted byMyrdal (1957: 18) who observed that:

. . . the main scientific task is to analyze the causal inter-rela-

tions within the system itself as it moves under the influence ofoutside pushes and pulls and the momentum of its owninternal processes.

However, significant internal dynamics are often absentin emerging TISs at their early stage. Jacobsson andBergek (2004: 823) have stated that:

. . . a process of cumulative causation can [. . .] only be set inmotion if the technological system has gone through a forma-

tive period—without it, a response capacity to the underlyingwave will not exist and, indeed, the wave itself may not bethere.3

Table 1. Technology innovation system functions

Function Definition

Entrepreneurial activities Activities of innovation systems that are related to commercial startups, diversifications and experimentation around a

new technology

Knowledge development Activities related to learning about the technical, social and economic aspects of a new technology

Knowledge diffusion Activities and processes of innovation systems focused at diffusion of information, creation of awareness and capacity

and sharing of resources among actors

Guidance of search This function involves creaction of expectations and optimism about the future of a new technology. This is also aimed at

reducing uncertainties and risks associated with a new sector

Market formation This function covers activities and processes that can create or induce the creation of a niche for a new technology. This

function enhances market development of a new technology by providing protection measures from competition by

existing (mature) alternatives

Resource mobilization Financial and human resources are typical economic variables for the emergence and success of an innovation. This

function captures resources that are mobilized for a new technology development and diffusion

Creation of legitimacy New technologies often fail to obtain the approval of major actors and policymakers leading them to lack a level playing

field. This function captures those activities that legitimize a new technology

Functional evolution and accumulation of technological innovation systems . 3 of 18

Therefore, the functional accumulation pattern of an

emerging TIS may be determined more by exogenous

factors than internal dynamics in the early period of

developmentThe relative importance of external and internal factors

may change as an innovation system evolves. At an early

stage of development, the buildup of an innovation system

is likely to be influenced by whether or not there are

properly functioning institutions supporting diffusion of

the technology (Jacobsson and Bergek 2004). As Geels

et al. (2008: 530) have observed:

Especially in early phases of development, when [innovationsystems] are weak and fragile, favorable external contexts(or expectations of it) play important roles.

If this is the case, functional accumulation processes might

reflect antecedent institutional characteristics. In turn, this

may shape the functional growth path of an emerging TIS

once mutually-reinforcing processes of growth take hold

later in development (Jacobsson and Johnson 2000).The driving mechanisms may go beyond those rooted

within a national context. Influencing mechanisms, such

as energy prices and international development assistance,

are part of the international context of technology devel-

opment and deployment (Geels et al. 2008; Jacobsson and

Johnson 2000; Negro 2007). Technological characteristics

may also determine the functional accumulation processes

of TISs. Negro (2007: 128) has stated that:

. . . a well-functioning, reliable and profitable technology islikely to gather more support and enthusiasm from entrepre-

neurs, investors, and policymakers than a technology that isexpensive and unreliable. Thus, positive technological charac-teristics may result in an easier fulfillment of system functions.

Suurs (2008), Markard and Truffer (2008) and Bergek

et al. (2008a) have also suggested that the functioning and

evolution of innovation systems may be influenced by

technological attributes, as these enable or constrain the

decision of actors to provide supporting functions.Overall, existing studies suggest that, while there may be

general similarities, emerging TISs are likely to be different

one from the other. Innovation functions accumulate as

historical sequences of events, driven by specific actors

and historical moments within particular multi-level insti-

tutional contexts. Factors, both internal and external to

the innovation system, as well as blockages deterring

the functioning of an emergent TIS, may explain such

differences. Since renewable energy innovation systems

in Africa are generally immature, weak and fragmented

(Gallagher et al. 2012; Szogs et al. 2009; Muchie et al.

2003), internal dynamics or ‘cumulative causation’ may

not materialize as they would in national settings with

mature science and policy systems. Thus, we expect

broader contextual factors to play an important role in

the dynamics of the TISs.

More generally, however, further insights into whether

patterns of functional accumulation are generic (similar

across all types of TISs nationally or technologically) or

specific (unique to each TIS) are important for the design

of policies to support the buildup of innovation systems in

general, and renewable energy technology innovation

systems in particular. This may be especially important

in developing countries. By comparing functional accumu-

lation patterns for the TISs of different renewable energy

technologies in different East African countries, we will

lend empirical evidence to the question of whether or not

the functional accumulation of ‘infant’ TISs of renewable

energy technologies is unique and is largely determined by

external factors during its early stage of development.

3. Methodological overview

The major purpose of this study is to gain insights into the

similarities and differences, as well as the determinants, of

the functional accumulation of TISs by analysing the

accumulation of functions in the Kenyan biogas reactors

and improved cookstoves and Rwandan biogas reactors

and improved innovation and diffusion of cookstoves.

We now provide an overview of how the functional

patterns were developed.First, we mapped major historical activities and

processes around improved cookstove and biogas technol-

ogy in Kenya and Rwanda by adopting the so-called

‘process approach’ (Van de Ven and Huber 1991; Van

de Ven and Poole 1990). We reviewed archival sources,

such as published and unpublished documents, and inter-

viewed key informants, including technology providers,

entrepreneurs and national and international policy-

makers. Table A.1 in the Appendix provides the list and

categories of actors interviewed for the four case studies.The data from different sources were triangulated to

ensure accuracy (Yin 2003). Efforts were also made to

collect as much event data as possible. These event data

were coded into the functions by using a coding scheme

composed of specific indicators for each function (see

Table A.2 in the Appendix).4 Finally, cluster diagrams

showing the accumulation of functions by historical

period were generated. For this purpose, we reasoned

that the fact that an event was classified under a given

function represented evidence that this function existed

and that once a function had been established, its impact

persists through time. Functions are therefore seen as

being additive and as accumulating over time, building

the capability of actors and the capacity of the system as

a whole to fulfil functions. The cluster diagrams therefore

represent the aggregate intensity of functions in each

period (i.e. the size of a circle shows the relative magnitude

of the observed accumulation of the function with respect

to other functions and over time).

4 of 18 . A. D. Tigabu et al.

This simplifying assumption has weaknesses. First,events may contribute to a number of different functions.For instance, a policy statement may contribute toguidance of search function, while also bringing legitimacyto a technological activity (i.e. to the creation of legitimacyfunction). Here we have sought to avoid the analyticalcomplexity of associating single events with multiple func-tions. Second, the assumption that perhaps unrelatedevents can be seen as constituting the fabric of anevolving ‘system’ may be questioned. Events may not beconnected over space and time, and even a sequence ofevents may not have a lasting or general impact, especiallyin the early formative phase of an innovation systembefore processes of cumulative causation have been estab-lished. Nevertheless, this conceptualization captures theinsight common to evolutionary studies of innovationthat past activities have an impact on later outcomes. Italso captures the path dependency of innovation activities.

4. Functional overviews of the Rwandan andKenyan biogas and improved cookstoveinnovation systems

We now summarize the development of the Rwandan andKenyan biogas and improved cookstove innovationsystems. We discuss and illustrate the evolution of func-tions. Functions corresponding to events within thesummaries are indicated in brackets.

4.1 Biogas TIS in Rwanda

We start by summarizing the evolution of biogas TISs inRwanda. In the late 1990s, Kigali Institute of Science andTechnology (KIST) installed biogas in prisons to addressthe waste challenge of overcrowded prisons [entrepreneurialactivities] (Munyehirwe and Kabanda 2008; Uwizeye 2011;Rwigema 2011). Positive feedback from these experiencestriggered the development of institutional awareness,raising the legitimacy of the technology among policy-makers (Uwizeye 2011). This led biogas to be reflected inmajor development plans, such as the Poverty ReductionStrategy Paper (PRSP), generating early guidance of search(Ruzigana 2011; Uwizeye 2011; Dekelver et al. 2006).Subsequently, the government showed interest in expand-ing the introduction of biogas to the domestic sector, prin-cipally as a way of reducing pressure on rural firewoodresources. This was exemplified by its request for donorfunding and technical assistance in December 2004[guidance of search] (Dekelver et al. 2006). In March2005, the Ministry of Infrastructure, with the support ofthe SNV Netherlands Development Organization,assessed the feasibility of promoting domestic biogas inrural areas [knowledge development]. The results indicatedthe presence of over 100,000 households that could poten-tially adopt small-scale biogas plants [guidance of search]

(Ruzigna 2011). Most importantly, the assessment con-firmed that existing infrastructures and institutionalcapacities are reasonably mature (Ruzigna 2011). This ledto the launch of the National Domestic Biogas Program(NDBP) in 2006 with a target of building at least 15,000small-scale digester units by the end of 2010 [guidance ofsearch] (Dekelver et al. 2006). Introduction of biogas wasin line with the governments focus on environmental pro-tection and clean energy use and production. Existingpolicies, such as the environmental protection law (LawNo. 4/2005 of 08/04/2005)5 and ‘zero grazing’ and ‘stricttree cutting monitoring’ and agricultural development pro-grammes, such as: ‘one cow per family’ and ‘send a cow’served as foundations (National Domestic BiogasProgramme 2009). The Netherlands Directorate-Generalof Development Cooperation provided funding forrunning the NDBP [Resource mobilization] (NationalDomestic Biogas Programme 2009; Ndahimana andDekelver 2007). This was followed by the entry of anumber of governmental and non-governmental actorsand entrepreneurs who conducted a large number ofactivities. For example, NDBP conducted informationcampaigns about biogas and, with the support of SNV-Rwanda and the Rwanda Workforce DevelopmentAuthority, trained masons, both contributing to know-ledge diffusion (Deutsche Gessellschaft fur TechnischeZusammenarbeit (GTZ) (transl: German TechnicalCooperation Organization) and SNV 2010). In 2008, a com-prehensive biomass energy strategy was formulated,providing further legitimacy for biogas. An association ofbiogas companies was formed and, in collaboration withNDBP, lobbied key sectors for incentives, resulting in a20% discount on the price of biogas accessories [creationof legitimacy] (Shingiro 2011). While increasing guidancefrom central government (SNV-Rwanda 2008) as well aspublic campaigning from NDBP had caused the entry ofa number of governmental and non-governmental actorswithin a short period, their activities were constrained bymany barriers. For example, companies soon discoveredthat profitability in the biogas sector was low and left thesector due to unmet expectations (Timothy 2011).

The pattern of functional accumulation in the Rwandanbiogas TIS for the period 2000–10 is represented in Fig. 1(top left). The diagram illustrates that all functions hademerged within a decade with guidance of search beingdominant. Within the narrative, we have observed thatthe emergence of the guidance of search, favoured by thealignment of biogas to existing policies and programmesand increasing development assistance, led to the rapiddevelopment of most functions in the later period of theobserved evolution of the TIS.

4.2 Biogas TIS in Kenya

The Kenyan biogas TIS has a much longer history thandoes the Rwandan one. The first introduction of biogas in

Functional evolution and accumulation of technological innovation systems . 5 of 18

Kenya began in the mid-1950s when a farmer first builta digester on a coffee plantation. Biogas activities inthe 1970s were limited to sporadic commercial construc-tions by private entrepreneurs generating an early entre-preneurial activities function (Kenya National DomesticBiogas Programme 2009; Deutsche Gesellschaft furTechnische Zusammenarbeit-Special Energy Programme1987). This early experimentation failed to trigger substan-tial interest in the technology in Kenya. No governmentpolicies were initiated to support biogas (DeutscheGesellschaft fur Technische Zusammenarbeit 1994).

However, in the 1970s, issues of growing firewood andcharcoal consumption, and associated pressure on thebiomass supply emerged, triggering a biomass use studyby a Swedish Institute in 1980 [knowledge development].The study forecast a biomass fuel shortage within twodecades [guidance of search]. This result, along with theUN Conference held in Nairobi in 1981,6 stimulated abiogas introduction programme (Gichohi 2009) whichwas followed by a Special Energy Programme (SEP)promoted by the GTZ, in collaboration with theMinistry of Energy. The major focus of the programmewas increasing capacity through training and informationdissemination using existing infrastructures, such as theagro-forestry centres and agricultural and health eco-nomics officers [knowledge diffusion]. Selected individuals

were trained as construction workers (Gitonga 1997;Gichohi 2009). The expectation was that public awarenesswould bring about demand for the technology and thattrained technicians would build digesters on a commercialbasis. While the potential contribution of the technologyto addressing the biomass crisis was acknowledged, theguidance created did not lead to the expected entry ofentrepreneurs and the provision of other functions. As aresult, mobilization of resources, market-forming schemesand cost-sharing mechanisms were limited. Due to a lackof user awareness, the functionality of installed digesterswas poor, damaging the legitimacy of the technology in themarket (Gichohi 1992, 1997).

By the end of the 1990s (see Fig. 1 top right, period1979–99), only the knowledge diffusion function was rela-tively well served, mostly funded by development partners,while most other functions remained relatively weak.However, compared to previous periods, a higher accumu-lation of functions and some interactions between some offunctions were observed. This was driven by higher insti-tutional guidance created following the increasing aware-ness of the impact of deforestation. However, thisguidance was not sustained as public policies were notdeveloped.

Beginning in the early 2000s, the health hazards of usingtraditional fuel sources were increasingly recognized in

Resource

mobilization

Entrepreneurial

activities

Knowledge development

Knowledge

diffusionGuidance of search

Entrepreneurial

activities

Market

formation

Creation of

legitimacy

Knowledge diffusion

Guidance of

search

Entrepreneurial

activities

Knowledge

development

Knowledge

diffusion

Guidance of search

Resource

mobilization

2000 2004 20072010

Biogas TIS in Rwanda

Creation of

legitimacy

Resource

mobilization

Entrepreneurial

activities

Knowledge

diffusionGuidance of

the search

Knowledge

development

Entrepreneurial

activities

Market

formation

Knowledge

diffusion

Guidance of

search

Knowledge

development

Resource

mobilization Entrepreneurial

activities

Market formation

1979 1999 20101957

Biogas TIS in Kenya

Resource

mobilization

2011

Resource mobilization

Knowledge

diffusion

Guidance of search

Knowledge development

19801994 2000

Knowledge

development

Knowledge

diffusion

Resource

mobilization

Knowledge diffusion

Knowledge

development

activitiesEntrepreneurial

Market formation

ICS TIS in Rwanda

Creation of

legitimacy

Resource mobilization

Entrepreneurial

activitiesResource

mobilization

2011

Resource

mobilization

Entrepreneurial

activities

Knowledge

diffusionGuidance of the search

Knowledge

development Market

formation

Knowledge diffusion

Guidance of search

Knowledge development

Entrepreneurial

activities

19761984 1995

Knowledge development

Knowledge diffusion

Guidance of

the search

ICS TIS in Kenya

Figure 1. Functional accumulation patterns of biogas and ICS TIS in Rwanda and Kenya. It should be noted that each TIS has adifferent timeline, the shortest being the Rwandan biogas TIS, with only a decade of evolution. Patterns are developed on the basis ofthe complete list of functions for the four TIS (see the Supplementary file).Size of each circle is related to mafgnitude of accumulation of function in the period, based on frequency of corresponding events.ICS= improved cookstove.

6 of 18 . A. D. Tigabu et al.

Kenya. Consequently, biogas began to be reflected inenergy policy documents [guidance of search] (Baru2012). This was one of the triggers for a biogas programfunded by the GTZ in 2006. Its focus lay in informationcampaigning and training of masons [knowledge diffusion].It also supported the Association of Biogas Contractors ofKenya with the aim of creating a platform for advocacyabout biogas [creation of legitimacy] (Kinoti 2012). The‘Biogas for Better Life Conference’ was held in Nairobiin 2007 to promote biogas. The conference, alongwith positive results from the biogas programme ofthe Deutsche Gesellschaft fur InternationaleZusammenarbeit (GIZ) (transl.: German DevelopmentOrganization) led to the launch of Kenya NDBP in2009. This nationwide biogas programme carried out in-tensive public awareness efforts, training of biogas masons[knowledge diffusion] etc., which have led to the installationof quality digesters and increased commercial penetrationof biogas.

In this period, a rapid accumulation of functionsoccurred (see Fig. 1 top right, period 1999–2010).Increasing institutional guidance was generated followingawareness among policymakers about the impacts ofindoor air pollution. The guidance created in early 2000swas sustained over the next years, inducing the entry ofseveral governmental actors and entrepreneurs who ful-filled several functions. In this period, the emergence oflimited internal self-sustaining dynamics is observed dueto the increasing entry of local actors and interactions,institutional alignment and availability of funding, sup-ported by development assistance. This means that overtime, the maturity of the TIS increased as local actorsentered and began to balance the intensity of the sevenfunctions.

4.3 Improved cookstove TIS in Kenya

The Kenyan improved cookstove TIS emerged in the mid-970s, following the oil crisis and an increased awareness ofthe impact of deforestation (Kimani 1991). This wasfollowed by a biomass survey conducted by KenyattaUniversity College in 1976, showing that over 90% ofsurveyed households were using biomass sources forcooking inefficiently. This triggered the establishment ofthe Appropriate Technology Centre (ATC) in the sameyear, with the aim of identifying ways of raising the effi-ciency of traditional fuel consumption (Newman 1984;Karekezi and Walubengo 1989).

Stove design activities were initiated by the ATC and theBellerive Foundation (a Swiss-based non-governmental or-ganization (NGO)). During the same period, the BeijerInstitute of Energy and Human Ecology (a Swedish-based NGO) conducted a larger survey of household fueluse, which showed that the country was running a deficitbetween supply and demand of biomass fuel (predictedto be about 30 million tons in 2000) (Miguiyi 1990). The

study suggested the introduction of fuel-efficient stoves asa potential solution to the problem [guidance of search](Kamweti 1983; Kinyanjui and Minae 1982; Karekeziand Turyareeba 1994; Jones 1988). NGOs, such as theUN Children’s Fund (UNICEF) also contributed tocookstove design development [knowledge development](Hyman 1985b).

The UN Conference on New and Renewable Sources ofEnergy (UNCNRSE) was held in Nairobi in 1981.7 Theconference was instrumental in strengthening the govern-ment’s awareness of the importance of developingimproved cookstoves. Soon afterwards, the Ministry ofEnergy launched the Kenya Renewable EnergyDevelopment Project (KREDP) funded by the USAgency for International Development (USAID)[resource mobilization] (Namuye 1990). KREDP conductedsurveys of existing stove production and emerging sectoralinitiatives, such as those by the Kenya Claystoves WorkingGroup,8 which had developed to promote improved effi-cient stoves (Kinyanjui and Minae 1982). KREDP realizedthat focusing on existing practices was critical for success.Therefore, involving traditional stove artisans, knownlocally as fundi, and increasing their technical capability,as well as modification of the existing all-metal charcoalstove became key aspects of the project (Jones 1988). Thiswas followed by the development of an improved charcoalstove prototype and testing activities by KREDP, whichultimately resulted in the Kenyan ceramic jiko (KCJ)[knowledge development] (Kimani 1991). The ATC subse-quently field-tested the KCJ prototype, involving 300 po-tential consumers, resulting in the modification of theprototype [knowledge development] (Karekezi 1993).

When these design activities had been completed, thefocus of KREDP and the Kenya Energy andEnvironment Organization (KENGO)9 turned to market-ing and large-scale introduction (Karekezi and Gathoga1990). The focal activities became training fundis in KCJproduction and public campaigning to raise the awarenessof potential consumers [knowledge diffusion] (Hyman1985a). Production equipment, such as an indoormasonry kiln, was also mobilized for stove producers(resource mobilization). Existing platforms, includingtraining centres for farmers and agricultural shows werepivotal for demonstrating KCJs. At this time, entrepre-neurial activities around improved cookstoves alsobecame visible in Kenya (Karekezi and Ranja 2002).

In this period, the knowledge development functionappears to have played a major role in the developmentof the Kenyan improved cookstove TIS (see Fig. 1, lowerright, period 1976–84). This development was driven byenvironmental concerns generated from the surveyfindings and the UN Conference. Additionally, other func-tions, such as knowledge diffusion and entrepreneurialactivities emerged as cookstove activities became betteraligned with existing practices and built on an existingcommercial technology. The public campaigning

Functional evolution and accumulation of technological innovation systems . 7 of 18

[knowledge diffusion] was necessary since it was important

to increase awareness on the benefits of the KCJ as

opposed to the all-metal traditional stoves.Beginning from 1983, the success of KCJ introduction to

urban consumers began to encourage international devel-

opment agencies to introduce improved cookstoves to

rural and institutional users. The GTZ funded and

launched its SEP10 in collaboration with the Ministry of

Energy. This project developed an improved woodstove

known as the Maendeleo [knowledge development]

(Njenga 1994). Similar to the urban stove project, this

project also focused on utilizing existing skills and

capabilities. Thus, the development of the skills of

existing groups of women who produced pottery, so that

they would be able to produce Maendeleo stoves [know-

ledge diffusion], became an important focus. Other NGOs,

such as CARE International and the Intermediate

Technology Development Group (ITDG) (a development

advisory group based in the UK) began training women’s

groups (Kaduru 1983). The Ministry of Agriculture’s ex-

tension officers in home economics and agriculture also

played an important role in awareness creation (Okello

2010).In this period (see Fig. 1 lower right, period 1984–95),

we see an increasing accumulation of knowledge diffusion

and knowledge development functions supported by an

increasing resource mobilization from development

agencies. The primary drivers of knowledge development

were: the oil crisis, deforestation problems and the UN

Conference on renewables that advocated, among other

topics, the need to develop energy efficient technologies.

Knowledge diffusion was primarily driven by the tendency

of development agencies to exploit existing capabilities and

societal structures (women’s groups involved in pottery)

and the importance of raising the awareness of user

benefits of improved cookstoves. Public information cam-

paigns were important since most people had the cost-free

three-stone stove alternative available to them (households

could build their own traditional stoves using materials

that were freely available). Karekezi and Turyareeba

(1995: 12) observed that:

. . . a major difficulty that has been encountered [in the promo-tion of rural improved cookstove] is the fact that traditionallyrural households have paid for neither fuel nor stove.

In the early 1990s, development agencies recognized that

KCJ production and market penetration had become well

established. Their support therefore shifted to rural stoves,

which had failed to achieve similar results (Namuye 1990;

Okello 2010). ITDG launched rural stove programmes

principally focusing on training women and conducting

public campaigns [knowledge diffusion] (Okello 2010).

The government changed the focus of its agro-forestry

centres towards renewable energy technologies, renaming

them as energy centres. These subsequently served as key

demonstration sites for the improved cookstoves(Murianki 2012; Baru 2012; Macharia 2012).

A new biomass use study by the Ministry of Energy in2002 suggested increasing pressure on forest resources ofthe country [knowledge development] (Ministry of Energy2002; Karekezi 2002). This was also reflected in a MinistryWhite Paper which specified biomass conservationstrategies, including the promotion of improvedcookstoves (Ministry of Energy 2003). Scarce forestbiomass resources were also signalled in the Energy Actof 2006 [guidance of search]. A key development in thisperiod was the formation of the Improved StovesAssociation of Kenya (ISAK) [creation of legitimacy]with the support of the GIZ. This aimed to empowerstove producers whose social prestige was limited bytheir low economic power (Djedje et al. 2008). In termsof functions, this period saw an increased accumulation ofknowledge diffusion, guidance of search and resource mobil-ization with a clear TIS structure emerging (see Fig. 1lower right, period 1995–2001).

Overall, although relatively strong, the functional accu-mulation of the improved cookstove TIS in Kenya wasrelatively slow (taking place over a period of about 30years), with many functions performed by internationaldevelopment agencies. This could be attributed to thelack of government policy which could have guided theentry of other agents. With the emergence of nationalpublic policies and greater accumulation of functions, afully fledged TIS is seen clearly to emerge in subsequentyears.

4.4 Improved cookstove TIS in Rwanda

In Rwanda, an improved cookstove TIS began emerging inthe early 1980s, following the recognition (instigated by theinternational environmental movement) that biomasssources were dwindling at a rapid rate. In 1984, theEnergy Directorate of Rwanda appointed a foreign con-sultant who suggested the promotion of improved, ruralcookstoves by training skilled artisans who were involvedin pottery and ceramic producing activities (World Bankand UN Development Programme 1992). Public awarenesscampaigns were conducted by Ministry of Public Worksand Energy, funded by the SNV [knowledge diffusion](Hategeka and Karenzi 1997). However, influenced bythe success of the Kenyan charcoal stove, the WorldBank’s Energy Sector Management Assistance Program(ESMAP) decided to focus on urban charcoal stoves(World Bank and UN Development Programme 1992).ESMAP conducted performance testing of stove models,including the Kenyan KCJ [knowledge development].Whereas the KCJ showed a higher fuel-saving efficiency,households did not prefer it due to a perceived mismatchbetween the stove and their cooking pots. Participants in aRwandan trial preferred a stove model known as theRondereza (ESMAP 1991; USAID 2007). ESMAP

8 of 18 . A. D. Tigabu et al.

subsequently trained women groups in Rondereza produc-

tion and conducted extensive public campaigning [know-

ledge diffusion] (ESMAP 1991; USAID 2007; Hategeka

and Karenzi 1997).The early development of the improved cookstove TIS in

Rwanda was, therefore, characterized by the emergence of

knowledge development and knowledge diffusion functions,

mainly through resources mobilized by international devel-

opment agencies (see Fig. 1, lower right, period 1980–94).

The major forces driving the emergence of the TIS were

declining wood resources, stove developments in Kenya

and development assistance. The focus on the knowledge

diffusion function seems to be related to decisions by the

Ministry of Public Works and Energy and SNV to

upgrade traditional capabilities among ceramic artisans.

Despite the apparent effort to align with existing practices

and incorporate user preferences, there was insufficient in-

stitutional embedding with existing public policies and

strategies. The ‘infant’ Rwandan cookstove TIS effectively

collapsed as stove activities were halted as a result of the

political and economic turmoil during, and in the aftermath

of, the genocide war of 1994 (USAID 2007).Stove activities were revived in the early 2000s, following

a dramatic increase of wood and charcoal fuel prices due to

deforestation and an increasing population. This triggered

two notable events. The first was the rural stove campaign

of the Rwanda Defence Forces in collaboration with the

Ministry of Local Government, which installed thousands

of stoves in rural households, increasing the penetration of

improved cookstoves to over 40% of rural households.

However, due to insufficient awareness and persuasion,

almost all of these stoves were immediately destroyed by

their owners (Nkurikiyumukiza 2011). The second was

a fuel-use evaluation study by the KIST, which showed

that Rwanda was running a fuel wood deficit of 4.5

million cubic metres per year [Knowledge development]

(Nkurikiyumukiza 2011). The study results triggered the

government to focus on fuel-use efficiency and to request

assistance from donors [guidance of search] (USAID 2007).

The USAID responded positively and agreed to provide

support to develop and implement a market-oriented

stove promotion programme. But USAID’s activities were

limited to undertaking comparative efficiency tests of stove

models, disregarding the earlier efforts of selecting models.

Based on these new test results, USAID recommended the

Canamake stove (a local name for theKCJ stove, which hadbeen rejected in the 1980s) for promotion (USAID 2007).

The government showed continued interest in promotingimproved cookstoves. For example, beginning from themid-2000s, targets for improved cookstove diffusion wereset in key government plans and strategies, such as inEconomic Development and Poverty Reduction Strategyand Biomass Energy Strategy [guidance of search](Nkurikiyumukiza 2011). CARE International-Rwandalaunched its Community Assisted Sustainable Energyproject in January 2008, focusing on the training of ruralstove making and installation, as well as awareness raising[knowledge diffusion]. In 2010, the government launched theNational Urban and Rural Cookstove DisseminationProgrammes. The major activities of the programmeincluded training of existing traditional stove producers(ceramists and metal workers) [Knowledge diffusion].

In the final period of the improved Rwandan cookstoveTIS, new functions could be observed, driven by growinggovernment policies which favoured their introduction.The knowledge diffusion function was relatively well de-veloped, while most other functions remained compara-tively weak.

5. Comparative analyses of the functionalpatterns

We now compare the observed patterns of functional ac-cumulation in the four cases. The comparisons are con-ducted systematically across countries and technologiesto address one of this paper’s research questions: is theemergence of TISs shaped primarily by technological orby institutional factors? (see Table 2). The cross-countryand cross-technology comparisons can only be seen if thepattern is similar or different. If similarities are observedeither for a technology or for a country, it suggests thatpatterns may be generic to a technological field in allcountries or to countries for all technologies, respectively.It may also reflect whether technological or nationalfactors are relatively more important in shaping the func-tional patterns. However, it does not confirm if interna-tional factors are important or if internal dynamics havean influence. The narratives (provided in Section 4) shedadditional light on the role of international factors andinternal dynamics in the evolution of the TIS. Taken

Table 2. Comparison matrix of functional patterns and expected implications of similarities and differences of functional patterns

Biogas TIS in Rwanda Improved cookstove TIS in Kenya

Biogas TIS in Kenya If similar, patterns may be generic to technology

(addressed in Section 5.1)

If similar, patterns may be generic to institutional

contexts (addressed in Section 5.4)

Improved cookstove in Rwanda If similar, patterns may be generic to institutional

contexts (addressed in Section 5.3)

If similar, patterns may be generic to technology

(addressed in Section 5.2)

Functional evolution and accumulation of technological innovation systems . 9 of 18

together, we aim to capture the relative importance ofexternal factors (both national and international),internal dynamics and technological characteristics in thedynamics of TISs at their early stages of development.With data on technology diffusion for each country, wealso aim to draw preliminary conclusions about the impactof particular patterns of functional accumulation on tech-nology diffusion.

5.1 Comparison of the Rwandan and Kenya biogas TISs

The Rwandan and Kenyan TISs demonstrate differenttrajectories and rates at which functions accumulate. InRwanda, the guidance of search is a core function,whereas in Kenya knowledge diffusion dominates. We alsoobserve that functional accumulation in Rwanda was com-parable to that observed in Kenya, but over a much shorterperiod (one decade, compared with about five decades in theKenyan case). This was due to the favourable institutionalconditions that prevailed in Rwanda, creating strong andcontinued guidance for actors to enter the TIS and begin toperform biogas activities, while in Kenya such guidance wasabsent for a much longer period.

In the Rwandan biogas TIS, the key drivers for the ac-cumulation of functions were the involvement of technol-ogy research and training institutes, such as KIST, whoseearly experiments with biogas technology was instrumentalin the emergence of the guidance of search function. Otherdrivers included: favourable policies and regulations,committed government support and international develop-ment assistance in the late 2000s, as well as a track recordin solving a pressing environmental challenge (humanwaste in prisons). Blockages have also played an importantrole in determining the fulfilment of functions. An exampleis the presence of other profitable and competitiveindustries, such as the housing construction sector,deterring the entrepreneurial activities of biogas construc-tion companies. The driving forces and blockages thatwere observed are related to the external (national or inter-national) context of the TIS.

In the Kenyan case, major drivers included: the envir-onmental movement of the 1980s, development assistanceand the perception among national and international pol-icymakers in the early 2000s of biogas as a potentialsolution to the health impacts of indoor air pollution.Blockages included the absence of government policy, es-pecially in the early period. Again, the external environ-ment appears to be a more important driver of TISfunctioning than internal dynamics.

Overall, we observe two significantly dissimilar func-tional patterns over time for a biogas technology inRwanda and Kenya. This suggests that the evolutionof the functional patterns of a particular technology isnot generic across countries. Contextual institutionalfactors have influenced the evolution of functions in bothcases.

5.2 Comparison of the Rwandan and Kenyan improvedcookstove TISs

When comparing the Kenyan and Rwandan cookstoveinnovation systems, we see that both evolved over about30 years. The Kenyan TIS has achieved comparativelybroader functional development than its Rwandan coun-terpart. There are major differences in the accumulation ofmost functions, with the exception of knowledge diffusion.This resemblance appears to be driven primarily by theinfluence of international development assistanceagencies, who have focused on capability development ofindigenous artisans with related skills, such as pottery andmetalwork. This confirms the finding for biogas: that thefunctional accumulation pattern of TISs is not genericacross technologies. The two systems exhibit clear differ-ences in patterns of accumulation for most functions, whilethe major driving factor for their similarity is not related totechnological characteristics. Contextual factors, such asincorporation of the all-metal traditional stove producersand fundis, development assistance, as well as internationalevents, played an important role in shaping the develop-ment of the Kenyan improved cookstove TISs. InRwanda, factors such as the 1994 civil war and eventsthat are fragmented in time and space have had a negativeeffect on the emergence of the innovation system. In bothcountries, the environmental movement following the oilcrisis in the 1970s was an important factor.

5.3 Comparing the Rwandan biogas and improvedcookstove innovation systems

During an early phase of development, in the Rwandanbiogas TIS, we find that the guidance of search isdominant, while knowledge diffusion dominates in theRwandan improved cookstove TIS. This appears to bean important difference. However, since 2000 thereappears to be a convergence in the pattern of accumulationof functions in the two innovation systems, with guidanceof search playing an important role in both. This appearsto be mainly driven by a common framing by governmentof deforestation as the problem being addressed by the twotechnologies. However, it is clear that the accumulationpattern of functions is not identical, due to differences inthe national and international driving actors and to thespecificity of historical moments. Thus, the functionalpatterns in different technological fields do not appear tobe generic to the national context.

5.4 Comparing the Kenyan biogas and improvedcookstove innovation systems

In the Kenyan biogas innovation system, the dominantfunction is knowledge diffusion, whereas in the improvedKenyan cookstove system more balanced development isobserved, with knowledge diffusion, knowledge developmentand resource mobilization all featuring significantly. Both

10 of 18 . A. D. Tigabu et al.

TISs share the knowledge diffusion function. Over periodsof several decades, there has been a focus on capabilitydevelopment through the creation of awareness and thetraining of traditional craftspeople involved in activitieswith related capabilities. For example, international devel-opment assistance in Kenya has focused on trainingwomen in the production of improved rural cookstoves.On the other hand, information campaigning was neededsince there was lack of awareness about alternatives inurban and rural households.

While the functional maturity of the two TISs was com-parable by 2010, their accumulation pathways are differ-ent. In the biogas system, the accumulation rate wasinitially slow, with acceleration occurring in later years.This was due to the limited entry and diversification ofactors in the early years. This can be explained by thelack of enabling policies, particularly before the year2000. In contrast, in the improved cookstove TIS, a sig-nificant rate of accumulation occurred early on, with de-velopment slowing from the mid-1980s to the mid-1990s.With both biogas and improved cookstoves gaining polit-ical legitimacy in addressing pressing societal challenges(deforestation and the health impacts of indoor air pollu-tion) in the 2000s, new government policies to support thetechnology, such as the knowledge diffusion, resource mo-bilization and market formation emerged. This resulted ingreater business participation.

In general, despite the importance of the knowledge dif-fusion function across the two cases, the accumulationpattern of other functions is dissimilar. These results alsosubstantiate the finding that functional patterns of TISs indifferent technological fields are not generic to a nationalcontext.

5.5 Comparing functional patterns and diffusion rates

Tigabu et al. (2013b) have discussed the relationshipbetween the functioning of innovation systems and the dif-fusion of sustainable technologies. They find that as morefunctions develop and positive interactions are generated,an increased rate of diffusion of biogas plants is observedin Rwanda and Kenya. Here we extend the analysis ofpatterns of accumulation of functions and their influenceon diffusion rates.

Table 3 presents estimates of the diffusion rates ofbiogas and improved cookstoves in Rwanda and Kenya.The rate of diffusion of both technologies is calculated bytaking the estimated total units of biogas digesters installedand improved cookstoves sold to households,11 andcomparing these figures with the total technical potentialor number of buyers available at a specific period of timeand period of diffusion (see footnotes to Table 3 for detailson methods). This allows us to observe the relative rates ofpenetration of the two technologies and associate themwith the functional accumulation pattern of the corres-ponding TIS (see Fig. 1).

The diffusion of biogas in Rwanda shows that an annualinstallation rate of 0.006%, 0.05% and 0.3% of technicalpotential in the three evolutionary phases: 2000–4, 2005–7and 2008–10, respectively. This is associated with a rela-tively rapid accumulation of functions in each phase, mostnotably with the guidance of search (see Fig. 1). In Kenya,a similar observation can be drawn from Table 3 andFig. 1, where an increase in the annual rate of installationof bio-digesters (0.002%, 0.005% and 0.03%, respectively,of the technical potential) is associated with an increasingaccumulation of functions over time. However, the patternof functional accumulation is dominated by the knowledgediffusion function and the relative rate of diffusion is lowerthan in Rwanda.

On the other hand, the penetration rate of improvedcookstoves in Kenya shows a relative decline up to theyear 2000 and a steep increase thereafter. This is associatedwith a relative increase in the accumulation rate of func-tions, particularly the knowledge diffusion function. Theannual rate of penetration of improved cookstoves inKenya shows continuous growth. This is associated witha broader functional accumulation.

These results suggest that higher diffusion rates areassociated with the development of a more balanced andmature TISs, with a number of functions sufficiently de-veloped. This may be because a higher accumulation offunctions provides increased guidance, awareness, re-sources, incentives, capability to users and producers ofnew sustainable technologies, as well as legitimacy forthe new technology, which strengthens its acceptance andadoption. This implies that agents wishing to increase thediffusion of renewable energy technologies need to facili-tate the functional buildup of the TIS.

In summary, we have shown that the evolutionary func-tional buildup and accumulation of functions is unique toeach of the TISs analysed here. This is consistent with theviews of Negro et al. (2008: 413) that:

. . . the dynamics of innovation systems are complex and thatthere is certainly no single ideal development.

Additionally, we have found evidence that functionalpatterns in the early years of development are determinedprimarily by external (national and international) context-ual features, such as alignment to government policy,which shape the entry of producers, traders and users ofthe technology, in turn constituting the innovation system.For the four systems compared here, local realities, histor-ical moments, national institutions and development as-sistance seem to dictate the activities of actors,generating unique sequences of events which describeunique patterns of functional accumulation. Under favour-able external conditions, functional momentum appears toemerge over time that also contributes to the differences inthe functional patterns among different TISs. The findingthat TISs are likely to evolve along different pathways, andare prone to changes in the external context in the early

Functional evolution and accumulation of technological innovation systems . 11 of 18

phases of development, suggests that external policymeasures are critical in shaping the later development ofinnovation systems. The improved functional performanceof TISs may be ensured by aligning technical options toexisting challenges, expectations, policies, skills, resources,infrastructures and preferences. Other scholars, such asGallagher et al. (2012) and Byrne et al. (2012) have re-flected similar views.

The results also suggest that a balanced accumulation ofseveral functions leads to higher diffusion rates. An im-portant goal of public policy would be to foster andsupport weak functions. In doing this, the ultimate goalshould be to create a mature and balanced TIS, allowingfor processes of cumulative causation to emerge.

6. Conclusions

To increase the dissemination of renewable energytechnologies in developing countries and ultimately con-tribute to energy security and environmental sustainability,the emergence and development of balanced and matureinnovation systems supporting these energy technologies isvital. Interventions to shape the buildup of these systemsrequire a number of policy questions to be answered. For

instance, it is useful to know if the rate, pattern and degreeof functional accumulation are similar or different acrossTISs. It is also important to know the relative importanceof external factors, internal dynamics and technologicalcharacteristics in influencing the functional developmentof TISs in less-developed country settings. To generateinsights into these issues, we undertook cross-case com-parative analyses of the evolution of biogas andimproved cookstove innovation systems in Rwanda andKenya (see Table 4 for the evolutionary periods of eachcase).

The comparison of biogas TISs in Rwanda and Kenyashows that the two innovation systems have different ratesand unique patterns of accumulation. The evolution ofinnovation systems across different national contextsappears to differ, with a variety of functions playing adominant role. The comparison of the Kenyan andRwandan improved cookstove innovation systems corrob-orates this finding (see Table 4 for overviews of thedominant functions).

Further comparisons of Rwandan biogas and improvedcookstove innovation systems show that accumulationpatterns are quite dissimilar, where in the biogas TIS theguidance of search is consistently dominant and in theimproved cookstove case, knowledge diffusion has played

Table 3. Estimation of annual rates of penetration of bio-digesters and improved cookstoves in Rwanda and Kenya

Periods of TIS

evolution (years)

Units installed

or diffusedaTotal

populationbTechnical potential

or potential buyerscRate of installation or

penetration (%/year)d

Biogas in Rwanda

2000–4 (5 years) 35 9,202,000 110,424 0.006

2005–7 (3 years) 150 9,321,000 111,852 0.046

2008–10 (3 years) 1,200 10,624,000 127,488 0.314

Biogas in Kenya

1957–79 (23 years) 200 16,268,000 542,267 0.002

1980–99 (20 years) 1,100 3,125,4000 1,041,800 0.005

2000–10 (11 years) 4,500 40,513,000 1,350,433 0.030

Improved cookstoves in Rwanda

1980–94 (15 years) 30,400 5,570,000 1,114,000 0.18

1995–2000 (6 years) 15,000 8,098,000 1,619,600 0.15

2001–10 (10 years) 255,000e 10,624,000 2,124,800 1.20

Improved cookstoves in Kenya

1976–84 (9 years) 40,700 19,655,000 3,853,922 0.12

1985–95 (11 years) 600,000 27,426,000 5,377,647 1.01

1996–2011 (16 years) 3,100,000 40,513,000 7,943,725 2.44

aSources: Tigabu et al. 2013b; USAID 2007; ESMAP 1991; Hategeka and Karenzi 1997; Wanjohi et al. 2011; Namuye 1990; Karekezi and Ranja 2002; Hyman 1985;

Wulubengo and Kimani, 1993; African Energy Policy Research Network 1996)bTotal population at the last year of the period. Source: UN (2012)cThis is the number of households that can potentially adopt the technology at that specific time. It is calculated on the basis of total population and average household size

(for Rwanda and Kenya the average household size is taken to be 5 persons and 5.1 persons, respectively. For biogas, only a percentage of total households are estimated to

adopt biogas (6% in Rwanda and 17.2% in Kenya; see Dekelver et al. (2006) and Heegde and Sonder (2007)). The technical potential percentage for both cases is assumed

to remain constant over the years, which allows calculations of the technical potentials in each period by taking total number of households in those periods. For improved

cooktoves, we simply assumed that all households (100%) at a specific time are potential buyers and a single household has only one stoved%/year= ((units diffused)/(potential buyer� years))� 100eReports indicate that non-commercial rural stove installations were carried out by the Rwanda Defense Forces in 2005, reaching to over 40% of rural households (about

850,000 households). However, most households destroyed these stoves immediately, thus drastically reducing the effective adoption rate (see Section 4.4). Since exact figures

are not available, we estimated the effective adoption to be 30% of installed stoves

12 of 18 . A. D. Tigabu et al.

a significant role (see Table 4). Similarly, the comparisonof the Kenyan biogas and improved cookstove TISs showsthat patterns are different. The exception is knowledge dif-fusion, which appears to be important in both cases.

These dissimilarities imply that functional accumulationpatterns of TISs are neither generic to national factors norto technological fields. While accumulation processes offunctions are not generic to national contexts, the resultsdo suggest that the functional accumulation rate andpatterns at the early stages of TIS development are likelyto be primarily influenced by contextual drivers andbarriers within the national and international contexts.Example factors include: government policies, develop-ment assistance, existing infrastructures, and existing prac-tices and capabilities. For example, in the case of theRwandan biogas TIS, rapid functional accumulation isobserved due to the alignment of the technology toexisting policies and the availability of supportive infra-structural and institutional conditions in the early years.There are signs that, due to this alignment, positive inter-actions of functions and clear TIS structures emerged inlater years.12

The final analysis was the comparison of the historicalfunctional patterns with observed levels of diffusion. Theresults show that TISs with more balanced and maturefunctions are associated with higher rates of diffusion oftechnology (see Table 4).

A key public policy lesson derived from these findings isthat the development of an innovation system at an earlystage of development is sensitive to conditions in itsexternal context. This should be considered in designing

policies, nationally and through international developmentassistance. This insight is consistent with those ofGallagher et al. (2012), Byrne et al. (2012) and Arocenaand Sutz (2005) who have emphasized the implications ofcontextual specificities to policymaking aimed at shapingthe development of innovation systems in developingcountries. If the intention is to influence alreadyemerging innovation systems, it is important to recognizethat different systems are likely to evolve along differentpathways. This is in line with the views of Jacobsson andBergek (2005) and Jacobsson (2008) who have argued thatTISs are often unique in terms of specific weaknesses (ex-pressed in functional terms) at a specific moment of time.This means that policy measures to strengthen TISs needto be tailored to the needs of a particular setting.Therefore, one needs to appraise the strengths andweaknesses of an emerging TIS before intervening.The goal is to strengthen weak functions and ensure thedevelopment of a balanced and mature TIS that ischaracterized by positive interactions among the functions.The application of this finding could have majorimplications for the design of policies to promote a sus-tainable diffusion of renewable energy technologies in EastAfrica.

Acknowledgments

We would like to express our appreciation and whole-hearted thanks to the two anonymous reviewers of thedraft manuscript. Their comments and suggestions havesubstantially improved the quality of the paper. We also

Table 4. Summary of period of TIS development, dominant functions, overall functional accumulation intensity of the four TIS and levels of diffusion

as of 2010/11

Biogas Improved cookstove

Rwanda � Period of evolution: 10 years � Period of evolution: 30 years

� Well-accumulated guidance of search � Fairly well-accumulated knowledge diffusion

� Fairly well-accumulated knowledge diffusion, knowledge devel-

opment, resource mobilization and entrepreneurial activities

� Least accumulated: all remaining functions

� Least accumulated market formation and creation of legitimacy � Achieved diffusion level: about 18.5 % of potential buyers

within period 1980–2011

� Achieved diffusion level: about 1.2% of average technical

potential within period 2000–10

Kenya � Period of evolution: >50 years � Period of evolution: 35 years

� Well-accumulated knowledge diffusion � Well-accumulated knowledge diffusion, knowledge development

and resource mobilization

� Fairly well-accumulated guidance of search, knowledge develop-

ment, resource mobilization, entrepreneurial activities and market

formation

� Fairly well-accumulated guidance of search

� Least accumulated creation of legitimacy � Least accumulated entrepreneurial activities, market formation

and creation of legitimacy

� Diffusion level achieved: about 0.6% of technical potential

within period 1957–2010

� Overall diffusion rate of about 65% of average potential buyers

(households) within period 1976–2011

Functional intensity evaluations are based on relative comparisons among all functions within and across TISs

Dominant functions in TIS development are indicated in bold. Diffusion levels are estimated on basis of data in Table 3

Functional evolution and accumulation of technological innovation systems . 13 of 18

would like to thank Mr. Stephen Karekezi for his usefulguidance, passion and inspiring comments during the datacollection process.

Notes

1. For general insights into the applicability of the TIS

framework in the context of developing countries, see

Tigabu et al. (2013a,b).2. Note that TISs are sometimes conceptualized as global

systems (Bergek et al. 2008a). This may be the case

when the contours of the TISs are drawn around a

newly emerging or a novel technology in the global

context. But, since we are interested in the introduc-

tion of an existing technology to a new context, and

for practical reasons, we conceptualize the TIS as

those actors, their interactions and institutions

around a specific renewable energy technology

within a particular national setting. Other factors

outside of the national TIS will be conceptualized as

a context.3. For simplicity and practical reasons, we conceptualize

internal dynamics as interaction of functions from

the TIS-specific local actors, interactions and institu-

tions. Structural elements of the TIS, contributing

to the functions include: entrepreneurs, associations

and policies emerging around the specific technology

in a focal country. On the other hand, the exter-

nal environment is conceptualized as: national and

international actors, institutions and other

influencing factors outside the emerging local actor-

network and institutions around the specific

technology.4. Although the indicators provide guidance for coding,

interpretation of which events contribute to which

functions holds some degree of subjectivity.5. Dekelver et al. (2006:20) state that:

. . . according to the Organic Law determining the

modalities of protection, conservation and promo-

tion of the environment in Rwanda (Law No.

4/2005 of 08/04/2005), the State is obliged to

promote the use of renewable energy and to discour-

age wastage of sources of energy in general and par-

ticularly that derived from wood.

6. The UNCNRSE was held in Nairobi on 10–21 August

1981 with the aim of deliberating on ways that can

facilitate developing countries to make a transition

to new and renewable energy sources. The major

trigger of the conference was the sharp rise in the

price of oil in the period 1974–81. One result of the

conference was the development of the Nairobi Action

Plan that underpinned six key areas, which require

international support to developing countries to

facilitate a transition to renewable sources of energy(Odingo 1981).

7. This international event has also influenced functionaldevelopments in the Kenyan improved cookstove in-novation system.

8. The Kenya Claystoves Working Group was aninformal group of enthusiasts for improved claystoves. Initially the group was composed of individ-uals, such as Keith Openshaw, Maxwell Kinyanjui andStuart Marwick. Later, it included organizations, suchas UNICEF and the ATC of Kenyatta UniversityCollege. It was established to organize an exhibitionof efficient cookstoves at the UNCNRSE (Hyman1985a; Karekezi 1993).

9. KENGO was a local association working on energyproblems. It was established in June 1981 and formallyregistered in June 1982. It comprized 40 organizationsthat were working on energy issues in Kenya(Newman 1984).

10. This programme has also played a role in Kenyanbiogas.

11. Consistent data on the annual diffusion rates ofthe two technologies in both countries are notavailable. An effort is made to triangulate estimateddiffusion figures from different sources within theperiods studied and capture data as accurately aspossible.

12. Over time, the relative role of external as compared tointernal factors in the development of a TIS seemsto shift. This needs to be examined further in orderto obtain more conclusive insights.

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Appendix

Table A.2. Indicators for functions

Function Indicator activities

Entrepreneurial activities � Commercial technology manufacturing and/or installing

� Entry of firms/producers

Knowledge development � Conducting market surveys/feasibility studies/pilots

� Performance testing, developing promotional materials

� Developing new designs/prototypes

� Adapting or modifying new models

� Developing complementary technologies

� Assessing biomass energy use trends (fuel utilization surveys)

� Assessing presence of biomass resources for fuel

� Assessing availability of raw materials for technology production

� Conducting impact assessments

Knowledge diffusion � Training (of technicians or constructors)

� Conducting awareness campaigns

� Organizing conferences/workshops/seminars/meetings

� Demonstrations and exhibitions

Guidance of search � Setting targets

� Designing favourable regulations and policies

� Setting expectations

� Providing awards

� Providing directions/showing interest

� Publicizing research outcomes

Market formation � Provision of subsidies (sharing cost of investment)

� Standardization

� Setting tax incentives

� Public procurement

� Regulatory reform

Resource mobilization � Providing financial incentives and grants (funding)

� Providing loans (credit)

� Mobilizing human resources (hiring consultants and technical staff )

� Providing improved tools (equipment)

Creation of legitimacy � Conducting advocacy activities (lobbying)

Table A.1. Categories of interviewees in the four TISs

Actor category Number of interviewees

Kenyan and Rwandan

improved cookstove TISs

Kenyan and Rwandan

biogas TISs

Government agency 9 8

NGOs 14 16

Academic and research institutes 5 4

Financial institute 1 1

Technology producer/enterprise (company) 18 18

Technology user 6 5

Total 53 52

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