Hydrogen as a panacea for decarbonising everything? Exploring contested hydrogen pathways in Germany

Technological change is often seen as part of the solution to problems of global sustainability. A wide-ranging literature on how path dependent—often fossil fuel-based—socio-technical configurations can be overcome by more sustainable configurations has emerged over the last two decades. One potential transition pathway to transform electricity, heat and mobility systems as well as industrial production is the use of hydrogen. In recent years, hydrogen has received increasing attention as part of decarbonisation strategies in many countries as well as by international organisations such as the International Energy Agency or the International Renewable Energy Agency. Also in Germany it has become a central component of climate change policy and is seen by some actors almost as a kind of panacea, where the use of hydrogen is expected to decarbonise a wide range of sectors. Policy makers have the ambition for Germany to become a leader in hydrogen development and therefore help to contribute to what Grubler called ‘grand patterns of technological change’. The aim of this paper is to analyse whether relevant actors share expectations for transition pathways based on hydrogen, which would foster wide diffusion. Our empirical analysis shows that there are multiple contested pathways, both in terms of how hydrogen is produced as well as in which applications or sectors it is to be used. This causes uncertainty and slows down hydrogen developments in Germany. We contribute to an emerging literature on the politics of contested transition pathways and also critically engage with Grubler’s ‘grand patterns’ argument. Results support the idea that the concept of socio-technical pathways allows to expose tensions between competing values and interests. The German government is under considerable pressure regarding competing visions on hydrogen transition pathways. A targeted political prioritisation of hydrogen applications could mitigate tensions and support a shared vision.


Introduction
The use of fossil fuel technologies has increased human wellbeing, but also caused tremendous negative effects in terms of local social and environmental issues as well as global climate change.Academic and policy attention has therefore focussed on how transitions occur and how they can be supported through policy (Geels et al 2019, Truffer et al 2022, OECD 2023).Based on historical case studies, Grubler (2012) proposed four 'grand' patterns that characterise technological change and energy transitions: (1) there are no 'silver bullet' technologies, but there are important clustering and spillover effects leading to technology clusters which can foster transitions.(2) New technologies are typically expensive, but extended periods of learning and experimentation can lead to price reductions.(3) The history of energy transitions emphasises the importance of enduse as energy supply has historically followed energy demand in technology applications.(4) Energy transitions and associated technological changes are slow to materialise for a number of reasons, including capital intensity as well as slow learning and capital-stock turnover.Others have argued that governed energy transitions can be quicker than historical ones (Kern andRogge 2016, Sovacool 2016), which has been contested by Grubler et al (2016).
In current discussions about energy transitions, hydrogen has received increasing attention.According to the International Energy Agency (IEA), global hydrogen production is expected to reach more than 30 Mt/a in 2030 (2022b).Hydrogen is meant to help decarbonise a wide range of sectors, including industry, heating, transport and provide energy storage (see e.g.Parra et al 2019).Our analysis focusses on Germany, where hydrogen has become a central component of climate policy.The government has published a National Hydrogen Strategy in 2020 (Bundesregierung 2020), aiming to promote hydrogen as a core energy carrier within the German energy transition to decarbonise the economy and meet the net zero 2045 target.Stakeholders in Germany see great potential for hydrogen to support carbon reductions, and a range of academic reports and roadmaps voice this expectation (Kruse and Wedemeier 2021).We argue that the high level of interest in hydrogen as a transition pathway in Germany is an interesting case.Due to its industrial structure and size of the economy, national developments will have significant international impact.Germany wants to establish itself as an international lead market, technology providers are hoping for exports (e.g. of electrolysers) and significant imports of hydrogen or ammonia are likely.
The aim of this paper is to understand whether relevant actors have developed shared expectations for hydrogen, which would foster wide diffusion.This case study of a globally relevant potential energy transition technology is an opportunity to revisit some of Grubler's grand patterns.

Conceptual framework
To analyse the development of hydrogen pathways in Germany, we draw on insights from the literature on sustainability transitions (Grin et al 2010, Markard et al 2012, Geels 2019, Köhler et al 2019).It conceptualises transitions as long-term changes in dominant ways of fulfilling societal needs (such as providing energy or mobility) and analyses the processes through which such systemic changes come about.Furthermore, it aims to develop recommendations about how policy can speed up and influence the direction of transitions (see e.g.Schot andSteinmueller 2018, Kanger et al 2020).
Specifically, our analytical perspective focuses on the notion of transition pathways (Foxon et al 2013, Rosenbloom et al 2018).Research investigates how and under which conditions such pathways emerge, cause and consolidate structural change in reconfigurating or superseding dominant socio-technical systems.The literature conceptualises such paths as the result of decisions by interdependent actors, which collectively influence path development.Policy actors thus cannot manage transition paths top-down but considerably rely on a range of other actors.
Pathways can be conceptualised as unfolding sociotechnical patterns of change within societal systems as they move to meet human needs with minimal carbon intensity (Rosenbloom 2017, p 39). Sociotechnical pathways are context dependent and deeply temporal, shaped by competing actors with fluid strategies and positions, and involve complex feedbacks between structures and agents.Pathways are often contested, triggering conflicts around demanded regulatory changes and infrastructure investments.Powerful incumbents often try to 'close down' future pathways to a small subset that helps them maintain current business models.
One important aspect of pathways gaining momentum is the development of collectively shared expectations (Kriechbaum et al 2021).Developing shared expectations allows actors in technological fields to manage uncertainties and coordinate innovation activities.Shared expectations can play central roles in creating legitimacy for particular pathways and can help attract policy support.The literature finds that various technologies and their future expectations compete with one another in so-called 'arenas of expectations' , i.e. socio-cognitive spheres in which a wide variety of competing expectations accumulate.Competition between emerging technologies involves different stakeholders and a wide variety of exchanges and assessments of expectations (Bakker et al 2012).An important theme in this literature is that expectations are not descriptive statements that are true or false, but that they have a generative or performative function: they may guide actor activities, help attract investment or help mobilise policy support (Borup et al 2006, Van Lente 2012).Technological expectations represent 'wishful thinking' designed to enrol actors in networks aligned around shared expectations and can be seen as a strategic game played by actors interested in pursuing certain pathways.Our research builds on these insights.

Methodology
To gain insights into relevant positions and expectations, a mapping of central actors and their voiced preferences regarding hydrogen was undertaken.Methodologically, the approach draws on Lindberg et al (2019).First, we mapped positions concerning potential hydrogen pathways based on documentary analysis.We analysed publicly available documents, published between 2019 and 2022, such as position papers, roadmaps, strategies, and open letters by 18 actors from industry, research and green nongovernmental organisations (see table 1).Qualitative document analysis identified actor expectations about future hydrogen pathways (for details please see appendix A).Central actors were identified based on their engagement in public debates about hydrogen.This selection criterion was considered fulfilled when an actor had contributed to relevant research, professional hydrogen events, or public debates.The resulting selection of actors is not exhaustive; however, it covers a good range of perspectives and can therefore provide valuable insights into the German hydrogen landscape.
Second, to be able to compare actor expectations with politically envisaged pathways, we looked at key German policy documents.Given that important policy developments also occurred before and after the publication of the 2020 National Hydrogen Strategy, we mapped which hydrogen pathways were politically supported over time, from the 2016 'National Innovation Program Hydrogen and Fuel Cell Technology' (NIP) to the 2021 coalition agreement of the current German government and the 2023 national hydrogen strategy update.Third, for triangulation we also monitored media coverage on hydrogen in, for instance, news articles and press releases by relevant institutions such as the German ministries of Education and Research (BMBF) or the Ministry for Economic Affairs and Climate Action (BMWK) and relevant industry actors.
In addition to the documentary analysis, 15 semistructured qualitative interviews with stakeholders were used to complement our data (see table 2 for an overview).These were recorded, transcribed and coded using the qualitative analysis software MAXQDA (for details, please see appendix B).In order to get a picture of the state of hydrogen developments in Germany, we used data from the IEA (as of October 2022).

Results
Based on existing literature (Belova et al 2023, Ohlendorf et al 2023) as well as inductively from our documentary analysis, the analysis identified two important fault lines of differing expectations across actors.One concerns the production of hydrogen: While some actors argue that for decarbonisation only green hydrogen is permissible, other actors are in favour of using other forms as well, e.g.hydrogen from natural gas with carbon capture (blue) or methane pyrolysis (turquoise).A second fault line relates to expectations about hydrogen use: Some actors advocate a prioritisation of a few applications (e.g.steel production), while others see hydrogen as a 'silver bullet' decarbonising a whole range of sectors.Taken together, expectations on production and usage allow us to analytically differentiate four 'archetypical' potential hydrogen pathways (see figure 1).
The resulting matrix was used to map actor positions on the four hydrogen pathways (section 4.1) as well as government positions over time (section 4.2).Section 4.3 reflects on respective findings and interprets them in light of their impact on hydrogen developments in Germany.

Mapping stakeholder positions regarding envisaged hydrogen pathways
The results of the actor mapping based on the documentary analysis shows a heterogeneous picture across types of actors as well as within the group of industrial actors in particular (see figure 2).
The mapping indicates that most industry associations are in favour of a 'maximum diffusion pathway' , in which multiple technologies to produce hydrogen are utilised and where hydrogen is used across various sectors.For example, the German Association of Energy and Water Industries envisages a broad spectrum of production technologies, stressing that it would be necessary to 'take all options for decarbonisation into account' (BDEW 2020).Regarding the range of hydrogen uses, a tendency against prioritising hydrogen applications is apparent among industry.Such a broad pathway enables building broad coalitions of actors as all potential producers and users are included.It is therefore not surprising that broad-based industry associations (such as BDI) are in favour of a maximum diffusion pathway to maintain buy-in from their diverse membership1 .VKU and DVGU largely represent municipal utility and gas industry interests which are unsurprisingly in favour of a widespread use of hydrogen since this will help maintain one of their assets: the gas distribution network.
However, two industry actors are strongly in favour of using green hydrogen only: unsurprisingly, the German Renewable Energy Federation (BEE) criticises recommendations for blue hydrogen as counterproductive for decarbonisation and advocates for green hydrogen only (BEE 2021).Also, the German Hydrogen and Fuel Cell Association considers blue hydrogen as a 'risk to a market launch of a hydrogen economy' (DWV 2020).This strategic positioning makes sense given their interest in developing a hydrogen economy, which depends on hydrogen being seen as sustainable, while blue hydrogen production involves residual carbon emissions (IRENA 2022).The association argues for a use of hydrogen across various applications, including fuel-cell vehicles (DWV 2019).This is understandable as the association inherently promotes the use of hydrogen and also represents members interest in fuel-cell technology.The German association of Renewable Energy is the only industry actor which advocates hydrogen usage only in selected sectors, arguing that the focus must be on the few sectors 'in which the use of renewable energy is not possible' (BEE 2020).Source: own illustration, for full names of the actors please see table 1.
The mapping of green NGO expectations shows a clear positioning in favour of a 'targeted green diffusion pathway': a preference for green hydrogen is not surprising as its production method is considered carbon-neutral, which matches with such actors' inherent interests.Their clear positioning for politically prioritised hydrogen application areas is mostly grounded in considerations of climate protection, energy efficiency and economic efficiency.The screened NGO documents largely advocated on the basis of academic studies that show the use of hydrogen to be economically inefficient (Agora Energiewende 2022) or energetically inefficient in applications where direct electrification is possible (Matthes et al 2021).
Finally, the expectations of scientific actors regarding hydrogen production were mixed and evenly distributed between commitments to using blue hydrogen and unclear or open statements that could neither be interpreted as in favour nor against an exclusive focus on green hydrogen.Voices for a wider range of production technologies were mostly accompanied with clear restrictions such as the provision of 'strict requirements' (Agora Energiewende 2022), a 'vision of a full green hydrogen supply' and references to technologies expected to be usable 'until 2050' (Hebling et al 2019).In fact, only the Öko-Institut has a relatively clear position whereas many of the other actors are 'sitting on the fence' regarding our 'archetypical' pathways.
The mapped actor positions depict an curious state of debates in Germany: while wide agreement exists among green NGOs on a pathway that is based on green hydrogen and frugal deployment for selected applications, other stakeholders are not committed to such a targeted approach.Research and think tanks often refer to complexity and a range of uncertainties and therefore avoid clear positioning.Due to divergent interests, the least coherent expectations regarding future hydrogen pathways are found among industry.The expectations of some of the stakeholders within this group are diametrically opposed to others.Broad-based industry associations (e.g.BDI) voice support for the maximum diffusion pathway as it includes all possible users and producers to build a broad coalition, but this strategy is so far unsuccessful given the observed variation even amongst industry associations and even less so with regard to other actor groups.The overall result of our stakeholder mapping is that there is a significant degree of disagreement and uncertainty about desirable hydrogen transition pathways voiced among central actors.

Mapping hydrogen pathways supported by federal policy
To compare stakeholder positions with politically envisaged transition pathways, we looked at central policy documents and mapped the government's position according to the same analytical matrix to analyse which hydrogen pathways are supported (figure 3).The government's position in the 2016 NIP was strongly in favour of using hydrogen across various sectors (including transport), but made no claims regarding expectations about how hydrogen should be produced.The 2020 National Hydrogen Strategy argued that while only green hydrogen is sustainable in the long run, over the next ten years there will be a global and European market for carbonneutral (blue or turquoise) hydrogen which-given Germany's energy import dependency and close European integration-may also be used for a transition period.Although focusing funding on green hydrogen, the strategy claims a technology-neutral approach.
The 'Emergency Climate Program' (2021a) adopted in June 2021 only speaks of the use of green hydrogen and only mentions the use of hydrogen in industry as well as for aviation.No other sectors are explicitly mentioned, which could be interpreted as a gradual move towards a 'targeted green diffusion pathway' .
The new government's coalition agreement (2021b) by Socialdemocrats (SPD), Greens and Free Democratic Party (FDP) argues that to accelerate the development of a hydrogen market, it will fund future use technologies even if the availability of green hydrogen is currently insufficient and therefore is open to the use of other 'colours' .It also argues that fields of application should not be restricted, while also acknowledging that hydrogen should primarily be used in sectors in which it is not possible to become climate-neutral through direct electrification.
This positioning may be a compromise between the Green party and the liberal party, between strong commitments to climate protection (Greens) and technology-neutral policy as well as pushes for using hydrogen to produce e-fuels (FDP) respectively.In order to achieve its climate goals, the German government plans to cover future hydrogen demand in a climate-neutral way, both through imports and domestic production.One component of this strategy is the target of installing 10 GW of electrolysis capacity in Germany by 2030, as set out in the coalition agreement (SPD, Bündnis 90/Die Grünen, and FDP 2021, p 47), which is significantly more ambitious compared to the previous government's National Hydrogen Strategy (5 GW target).
The 2023 update of the national hydrogen strategy adopted the 10 GW target and continued the line of argument of preferring green hydrogen, but acknowledged that blue hydrogen may be used for a transition period.It also suggests that hydrogen should not be used in sectors where direct electrification is more efficient and economical.
Our policy documentary analysis shows that the government tended to support a 'maximum diffusion pathway' , but recently moved slightly into the direction of a targeted diffusion pathway, where blue hydrogen may be used for a transition period in addition to green hydrogen, but hydrogen use is focussed on areas where direct electrification is not possible.

Comparing stakeholder positions and federal policy: lack of shared expectations and implications for hydrogen developments in Germany
Our analysis reveals an interesting conundrum: on the one hand, there is significant policy and industrial interest in hydrogen to decarbonise the economy.There is also significant contestation about the direction of travel.The current government's position towards hydrogen is at odds with many of the green NGOs, but aligned with some of the major industrial interests.However, even within industry, there are contested positions and varying perceptions and also academia and think tanks have varying expectations about the best route towards a hydrogen economy.
On the other hand, progress on the ground has been slow.There are a number of local and regional developments, numerous R&D or pilot projects.However, there has been no significant investment in infrastructure for the production (or import) of hydrogen or its use (Interview #12).The National Hydrogen Council therefore calls for urgent action (Nationaler Wasserstoffrat 2022).According to the IEA Hydrogen Projects Database (IEA 2022a), electrolysers with a maximum capacity of up to 10 MWel and a total capacity of 63.3 MWel are currently in operation in Germany.As of October 2022, projects with a total capacity of 26.6 MWel are under construction.Final investment decisions (FIDs) have been made for a further 438 MWel.Feasibility studies were carried out for electrolysis plants with a further 4.3 GWel of capacity.Progress towards achieving the government's 2030 10 GW target is therefore relatively limited.Even if, following the adoption of the EU Delegated Acts on the definition and certification of renewable hydrogen (a major bottleneck for projects according to interviewees), several projects should receive a FID in the next few months, it is difficult to imagine that the 2030 target will be met.
Based on the interview evidence, we explain this finding by pointing to a range of uncertainties, including major disagreements between core actors about desirable hydrogen pathways, but also delayed policy decisions at the EU level.Many actors thus adopted a 'wait and see' strategy.So far, both industry actors as well as policy makers have pursued rather broad visions of a hydrogen economy, while green NGOs and some scientific actors have argued for a more targeted approach.In large part this difference it due to the expectation that renewable electricity will remain scarce given the need to decarbonise electricity and electrify transport and heating systems, which will not allow for major investments in large scale domestic electrolysers for lack of sufficient quantities of renewable electricity.There is currently very little in the way of import infrastructures or international supply of green hydrogen.While all actors expect that in the long term only green hydrogen will be used, there are diverging expectations about the next 5-10 years and whether to use also blue hydrogen as a transition fuel.This is strongly contested across actors.Most supportive of blue hydrogen are actors from the gas industry which is hardly surprising since it is produced by means of gas steam reforming and would prolongue the use of gas grids.The economic interests are therefore obvious.Blue hydrogen is presented as a possible bridging technology.This disagreement is reflected in our stakeholder mapping and interviews.The most significant division can be seen between environmental NGOs and industry associations for fuel cells and renewable energies on the 'green only' side and parts of the research community and industry (e.g. for gas, water, heating, and chemistry) on the 'more than green' side.This ongoing controversy influences actors' future expectations and thereby led to a rather cautious approach towards hydrogen.
A second major point of contestation is the use of hydrogen in applications such as heating.An ambitious first draft legislative proposal to amend the German building energy act ('Gebäudeenergiegesetz') became public in spring 2023.Critics saw it as making it very difficult to have installations of hydrogen-fuelled heating in German buildings from 2024.Accompanied by controversial debates in the media, a hefty exchange between the ruling parties revealed significant disagreement about heatpumps versus hydrogen playing a major role in the decentralised heating transition.Especially the green and liberal parties were publicly perceived as taking diametrically opposed positions on the potential future of hydrogen as a heating fuel.Some interviewees pointed to the impression of the BMWK having clear priorities for the use of hydrogen in selected sectors (interview #6), while some also point out that this vision is not necessarily shared across government, where the finance and transport ministries, which are both led by the liberal party, argue for a technology-neutral approach and see a potential use of hydrogen also in transport or heating (interview #7).This lack of a shared vision across government is considered problematic and is partly seen as a result of sustained lobbying by interested industries (e.g.gas or boiler manufacturing, but also municipal utilities).
This debate exemplifies an ongoing struggle in Germany about the future of the gas grids, with network companies pushing for hydrogen to be used to heat homes.Such actors therefore are strongly against a prioritisation of hydrogen.Other actors push for a wide roll-out of heat pumps as the main technology to heat homes, which would mean a discontinuation of existing gas grids and involve major regulatory changes.
Our overall argument is that the contestation and lack of shared expectations across important actors contributes to the uncertainty and thereby slows down hydrogen developments in Germany.

Discussion and conclusion
This paper aimed at analysing whether relevant actors have developed shared expectations about hydrogen pathways in Germany.Our analysis shows that there are multiple contested pathways (see figures 2 and 3), which causes uncertainty and slows down hydrogen developments.Even though academic research broadly agrees on a set of priority applications for expectably scarce hydrogen (Clausen 2022), there are incumbent interests that (at least rhetorically) pursue hydrogen pathways, which may be economically and in terms of technical efficiency, suboptimal or could divert attention away from alternative decarbonisation options (e.g.electrification of heating or mobility) (Kern et al 2023).
Our results echo findings from earlier studies.Eames et al (2006) and Eames and McDowall (2010) already showed that the notion of a hydrogen economy encompasses multiple contested sociotechnical futures, value judgements and problem framings.Drawing on an extensive review of UK, European and US hydrogen futures, many contested futures were identified among relevant actors.Interestingly, this is very similar to our findings in Germany: rather than having developed shared expectations, hydrogen pathways are contested.The potential versatility of hydrogen may well both be an asset as well as a 'curse' .Given our findings are very similar to earlier studies of hydrogen developments from 15 years ago, one can argue that actors supportive of developing hydrogen as a transition pathway have made very little progress in this endeavour.This is a stark contrast to other transition pathways such as the roll-out of renewable energy or the electrification of individual mobility.
Our findings therefore nuance Grubler's 'grand' patterns.He argued: 'Historically energy supply has followed energy demand in technology applications, and energy end-use markets have been, and remain, the most important market outlets for new energy technologies.In other words: new energy technologies need to find consumers, and better many of them' (2012, p 2).While this may be important in later stages of the global diffusion of hydrogen, at the moment the uncertainty about the utility of certain hydrogen applications vis a vis alternatives, and the corresponding lack of infrastructure and production or import capacity means that having many different applications in early stages of deployment may be more of an obstacle than an asset.Grubler's point about new technologies initially not competing on price but on performance before learning makes them more competitive, is also interesting to think about here.Where for certain applications there are no feasible alternatives, hydrogen is set to diffuse based on its low carbon performance.However, developments in Germany illustrate that while new technologies may not outcompete incumbent technologies based on price, they may early on compete with alternative niches (such as electric vehicles or heatpumps) that are more competitive in terms of performance or cost (Kern et al 2023).This in turn may limit the diffusion of hydrogen in these domains.The phenomenon of what Lin and Sovacool (2020) call inter-niche competition therefore merits more research.
In summary, our empirical contribution is to shed light on the emergence of contested hydrogen futures in Germany in order to understand which actors pursue hydrogen and with what future expectations.It became clear that the government finds itself under considerable pressure regarding competing positions that need political governance to support the development of shared hydrogen pathways.Our analysis highlighted that beyond the widely shared notion that hydrogen can be a major contribution to decarbonise the German economy, there are at least four majorly distinct pathways which vastly different implications in terms of investments, political and policy choices as well as infrastructure needs.
a similar approach for their analysis of EU renewable energy policy.We used this approach analogously for the analysis of the actor expectations regarding hydrogen.
From our preliminary analysis we inductively, as well as based on previous literature (Belova et al 2023, Ohlendorf et al 2023), identified two important faultlines on which actors disagree: one concerns the production of hydrogen.While some actors argue that for climate change reasons only the use of green hydrogen is permissible, other actors are in favour of using other means of producing hydrogen as well.The second dimension concerns expectations about the use of hydrogen.Some actors advocate a prioritization on a few important use applications (such as steel production), while others see hydrogen as a 'silver bullet' which can decarbonise a whole range of applications and sectors.Taking these two dimensions together, this allows us to differentiate four basic hydrogen pathways (see figure 1).These two dimensions were then used to map actor positions (incl.policy makers) on these different hydrogen pathways.
In practical terms, the analysis involved the following steps: 1. Identifying central actors which engage in the public debate about hydrogen developments in Germany: This was done by desktop research.This selection criterion was considered fulfilled when an actor had contributed to relevant research, professional hydrogen events, or public debates (e.g. through press releases, interviews, etc).The 18 identified actors were collected in an Excel spreadsheet and clustered into the following categories: industry, research/think tanks and NGOs/civil society organisation (see table 1). 2. For each actor, we then screened publicly available documents published between 2019 and 2022 (such as position papers, roadmaps, strategies, and open letters) in order to map the voiced positions along the two identified fault-lines.This information was collected in an Excel spreadsheet which contains the name of the actor, the title of the document(s) analysed as well as the main verbatim statements referring to positions on both of the two dimensions (hydrogen production and use).3. On this basis, the actors were placed in the 2 by 2 matrix according to their voiced positions.The positioning in the matrix is illustrative based on the qualitative statements identified and not based on metric scores.The allocation regarding supported H2 type was mostly obvious.For example, it is precisely written whether a certain actor is of the opinion that 'all processes for the climateneutral production of hydrogen and every energy source should be used for this' (means preference for all H2 types/colours) or whether 'only hydrogen produced from renewable energies may be part of a climate-neutral energy mix' (means preference only for green H2).The allocation in terms of application sectors was a bit more difficult.For example, if the document said that 'the use of hydrogen and PtX materials must be limited to sectors where there is no alternative for defossilisation' , then we interpreted that to mean that the actor is in favour of prioritisation and H2 is only to be used in selected sectors.

Appendix B. Detailed description of the interview analysis
The interview material for this study consists of 15 semi-structured qualitative interviews with stakeholders (see table 2 for a list of interviewed actors).The stakeholders were selected to cover a range of different perspectives from industry, research/think tank, civil society and policy/public administration.
In each case, actors were selected who were actively involved in hydrogen discourses at the time-for example through political work, statements, research work, topic-related campaigns or presence at relevant events.The interviews took place between September and November 2022, were guided by a semi-structured questionnaire and lasted around 45-60 min each.They covered a range of topics from German hydrogen policy and its effects on target groups, to actor positions on the development of the hydrogen economy in Germany (including views about the two fault-lines in terms of how hydrogen is to be produced and used) and expectations about future hydrogen developments in terms of technological developments, implementation challenges, competitive advantage, changes in networks and institutional changes.The interviews were conducted via a video conferencing tool, recorded, and subsequently transcribed using a professional transcription company.The resulting transcripts were manually checked by members of the project team to ensure the quality of the transcripts.In total, the transcripts amounted to 95 000 words of empirical material.The transcripts were then manually coded by the research team using the qualitative analysis software MAXQDA, utilising a code tree which was iteratively developed by the project team based on the core analytical themes of the project.Intercoder reliability checks were conducted in order to increase the validity of the coding.This involved checking coded sequences by another team member in order to achieve a high degree of congruence and also comparing the frequencies of codes appearing across coders.Based on the qualitative content analysis of the codes, main insights were developed by the project team in an iterative fashion.The insights of the interviews were also triangulated with the other sources of evidence, including the documentary analysis, media coverage of events, press releases, the IEA hydrogen project database, etc.

Figure 1 .
Figure 1.Four 'archetypical' potential hydrogen pathways depending on expectations in terms of hydrogen production and use.Source: own illustration.

Figure 2 .
Figure 2. Mapped stakeholder positions regarding envisaged hydrogen transition pathways.Source: own illustration, for full names of the actors please see table 1.

Figure 3 .
Figure 3. Mapping of hydrogen pathways supported by federal policy makers.Source: own illustration.The years mark the following policy documents: 2016-Government Program H2 and Fuel Cell Technology 2016-2026; 2020-National Hydrogen Strategy; 2021a-Emergency Climate Program 2022; 2021b-Coalition Agreement, 2023 National Hydrogen Strategy Update.

Table 1 .
Actors included in documentary analysis.

Table 2 .
Overview of interviews conducted.
The policy documents were analysed in the same way of collecting central quotes in a spreadsheet in order to derive the positioning of the government and to trace how this changed over time.The following five policy documents were analysed: the National Innovation Program Hydrogen and Fuel Cell Technology 2016-2026, the 2020 National Hydrogen Strategy, the 'Emergency Climate Program' for 2022, all of which were published by the previous coalition government, as well as the new government's Coalition Agreement and the 2023 National Hydrogen Strategy Update.They represent the main formal government policy statements related to hydrogen or broader climate policy strategy.