The Public Acceptance of Power-to-X Technologies—Results from Environmental–Psychological Research Using a Representative German Sample

Abstract

Power-to-X (ptx) technologies are considered a promising solution for enabling the storage and sectoral integration of renewable energy, playing a vital role in the sustainable transition of industrialized energy systems. This study investigates the public acceptance of ptx technologies in Germany using a quantitative, environmental–psychological framework. Key influencing factors such as social and personal norms, environmental awareness, and openness to innovation are analyzed. A particular focus is placed on generational differences, comparing the perceptions of youth (16–25 years) and adults (>25 years) through a representative online survey. The results reveal a general lack of knowledge about ptx technologies yet a positive assessment of their decarbonization potential. Ecological impact—particularly the ability to reduce CO₂ emissions—emerges as the strongest predictor of acceptance. This is closely tied to conditions such as the use of renewable electricity and sustainable sourcing of carbon and water. Notably, acceptance among youth is also influenced by environmental awareness, prior knowledge, and perceived behavioral control. The results show that, in general, there is still a need for improved science communication to address the existing uncertainties in the population. At the same time, age-specific approaches are required, as perceptions and acceptance factors differ significantly between younger and older age groups.

1. Introduction

To achieve a sustainable energy transition, the entire energy system—from production to consumption across all sectors, including heating, mobility, chemical products, and industrial processes—must be defossilized. In the context of electricity generation from renewable sources, challenges arise concerning their transport and integration into the existing system. In this regard, besides measures like grid extension, hydrogen and other power-to-x (ptx) technologies are a promising component with respect to both storage functions and flexibility [1]. “ptx” is a generic term for various processes that convert electrical energy into other forms or carriers of energy. Ptx technologies comprise a variety of technologies. Different technologies can be distinguished along the process chain (i.e., generation, conversion, utilization) and the technology paths (i.e., hydrogen, synthesis gas, e-fuels). In the process chain, electricity is first generated (“power”), and then another usable substance (“x”) is produced by means of chemical conversion processes (“to”). Thus, gases (power-to-gas) such as hydrogen or methane can be produced. These can, in turn, be converted into chemicals (power-to-chemicals) or even fuels (power-to-liquid). In this way, renewably produced electricity can be used in other forms of transport (e.g., e-fuels, hydrogen cars or buses), industry (e.g., CO₂-free energy for the steel industry), or decarbonizing chemical processes and products (plastics and chemical raw materials). Ptx technologies are relevant to the full range of the energy transition process and significantly contribute to decarbonization [2].

Besides rapid technical implementation, it is important to recognize that technologies are always embedded within social systems; they change people’s living environments and impact existing habits. Thus, public acceptance is a key success factor for the further deployment of renewable technologies, such as wind [3], solar [4], or carbon capture and storage (CCS) [5]. In the literature, there exist different definitions of acceptance. A comprehensive approach is provided by Upham and colleagues [6]; they describe public acceptance as “a favourable or positive response (including attitude, intention, behaviour and–where appropriate-use) relating to a proposed or in situ technology or socio-technical system, by members of a given social unit (country or region, community or town and household, organization)”. Integrating both the range of different technological levels and social responses, this definition provides a valuable starting point for the further exploration of the public acceptance of ptx technologies. Accordingly, citizen acceptance means “behavioral responses to situations where the public is faced with the placement of a technological object in or close to one’s home, which is decided about, managed or owned by others” [7] (p. 526) and, hence, focuses on a rather large-scale technological installation. Consumer acceptance, on the other hand, refers to the “public’s behavioral responses to the availability of technological innovations, that is, the purchase and use of such products” (ibid.) [7] and, thus, tends to focus on smaller technological products or end products in production chains.

The model adapted from Upham et al. [6] (Figure 1) shows the research approach used here to analyze the public acceptance of ptx technologies. Accordingly, technology acceptance relates primarily to the process steps of generation and conversion, while product acceptance comes into play primarily in the process step of utilization. The model integrates the acceptance dimensions according to Wüstenhagen et al. [8], which are local acceptance (e.g., residents of an electrolysis plant), market acceptance (e. g., consumers of e-fuels), and socio-political acceptance (e.g., people as citizens, the broader public).

1.1. Influencing Factors of the Acceptance of PtX

In recent years, there have been several studies on the acceptance of green hydrogen and the factors that are relevant in this context [9,10,11,12,13,14]. The technology acceptance framework by Huijts et al. [7], which integrates aspects of the Theory of Planned Behavior [15], norm activation theory [16], and hedonic aspects, provides an overview of relevant factors for the acceptance of large-scale technologies. According to this theory, social norms, perceived behavioral control, attitudes, and personal norms are the determinants of intention, which in turn predicts acceptance. In this context, attitudes and personal norms are influenced by various factors such as costs, benefits [17], and risks, as well as equity issues [18]. Personal norms have had a significant effect on the acceptance of new technologies (e.g., smart grid technology) in several European countries, including Denmark, Norway, and Switzerland [19]. As large-scale energy infrastructures often imply a significant change to the daily living environment, several studies have highlighted the roles of place attachment and place identity, as well as how landscape–technology fit (LTF) moderates public preferences [20,21]. Additionally, for new technologies, another relevant factor is how strongly an individual is attracted to innovations and their tendency to try them out, commonly referred to as personal innovativeness, a concept with a long tradition in the diffusion of innovation research [22]. This factor has been shown to be relevant for the acceptance of technological innovations [23].

Regarding the perceptions of experts and laypersons, van Heek et al. [24] reported differences concerning CO₂ utilization for plastic production. While, overall, the participants’ general perception of CO₂ utilization was positive as long as personal and direct contact with products was not intended, direct, i.e., bodily, contact with products made from CO₂ was especially rejected by older lay interviewees. Interestingly, experts could not understand at all why CO₂ was perceived as strongly negative by laypersons. Consequently, the complexity of technologies such as ptx seems to be a problem. While the general knowledge about a comparable complex technology (i.e., carbon capture and utilization, CCU) is still very low, knowledge as well as interest are significantly higher when it comes to concrete applications such as CO₂-based fuels [25].

This underscores the importance of surveys of the general population to understand the perception and appraisal of relatively new technologies by laypersons, providing a basis for the sensible and sustainable development and use of these technologies. This is especially relevant as ptx technologies are still at an early stage of deployment, leaving considerable scope for designing the technologies. Particularly at this early stage, it can be helpful to investigate fundamental design requirements for ptx processes, which can be understood as necessary preconditions for acceptance (i.e., conditional acceptance). These design preconditions include decisions on how the basic materials for ptx processes (i.e., energy, water, carbon) are to be obtained.

1.2. Who Is Accepting? Why Young People Are Central for the Energy System Transition

For research on the acceptance of ptx technologies as a prospective approach to a technology in its early stages of development, one group of actors plays a special role: youth and young adults. This group represents the generation that will be most affected by future changes and for whom the course is currently being set in the research and transformation processes.

The Fridays for Future movement has demonstrated that young generations often feel their concerns are insufficiently taken into account when it comes to future-related issues, especially questions of sustainability. In particular, young women emphasize the absolute necessity of unconditional environmentally friendly behavior and, in this context, also perceive social justice as a relevant goal [26]. Comparing age groups shows that young adults, on average, are more strongly in favor of implementing the energy transition and rapidly expanding renewable energies than older people [27]. In rankings of the importance of social problems, environmental and climate protection received the most votes from youth and young adults in Germany—80% of 14- to 22-year-olds considered environmental and climate protection to be an important or rather important social issue in 2020 (45% very important, 33% rather important) [28]. In politics and science, this cohort has so far been insufficiently considered and involved. In the existing studies, the age range defined as youth varies from 12 to 25 years [26] and 14 to 22 years [28]. For these reasons, this study specifically focuses on the youth or young adult group, including the age range of 16 to 25 years [27]. This age group corresponds approximately to the United Nations’ definition of youth (aged 15 to 24 years) [29].

Derived from the described approaches and theoretical background, this research aims to gain insight into current public acceptance perceptions of ptx technologies in Germany and the related influencing acceptance factors. As this is early-stage research and given the limited number of tangible ptx projects at the local level, the study focuses on the level of public acceptance in terms of both socio-political acceptance—referring to the triangle model of Wüstenhagen et al. [8]—and public acceptance as part of general acceptance, referring to Upham et al. [6]. Specifically, the following research questions are addressed:

1.

What is the current level of public knowledge regarding ptx technologies?

a.

Which characteristics or perceptions are associated with this perception?

2.

To what extent are ptx technologies accepted by the public overall, and how do perceptions vary across different fields of application?

a.

What conditions must be met for ptx technologies to be accepted by the public (i.e., what constitutes conditional acceptance)?

b.

Which factors—technical, psychological, or socio-demographic—influence the public acceptance of ptx technologies? How do these factors differ across specific sectors such as mobility, industry, and chemical production?

3.

In what ways do the acceptance levels and influencing factors differ between younger individuals and adults?

2. Materials and Methods

2.1. Data Collection and Sample Characteristics

The study took the approach of a representative German population study to answer the research questions described above and was preregistered on 26 February 2021 (https://doi.org/10.23668/psycharchives.4627).

The recruitment and data collection were conducted by a professional data provider (i.e., UZBonn) with high standards in privacy and data quality. The data were collected in November and December 2020 in the form of an online survey. N = 2300 participants from Germany were recruited consisting of two subsamples: N1 = 1150 (16 to 25 years old, “youth sample”) and N2 = 1150 (25+ years old, “adult sample”). Both subsamples were sampled by the data provider according to population statistics of the Statistisches Bundesamt (German Federal Statistical Office) from the year 2020 and were representative of Germany in terms of age, gender, and spatial distribution (in relation to the federal states).

Participants were fully informed about the conditions of participation and their rights (e.g., that participation is voluntary and can be terminated at any time without consequences and that data are collected anonymously) prior to their participation. Only when they indicated that they understood and agreed to the information could they participate in the study. The participants were financially compensated for their participation by the provider of the data (EUR 1.50).

In the first step, the data was screened to obtain an impression of the data quality (e.g., looking at answer patterns, comments of the participants, answer speed). For the initial screening, statistical procedures were used to automatically calculate the means and standard deviations for groups of items with different content (e.g., items from the fair value creation and environmental awareness scales) but the same response format (e.g., response scale with values from 1 to 5). If the mean values here were natural numbers (e.g., 2) and standard deviations were zero at the same time, cases were selected for deeper analysis by at least two researchers. These cases were then inspected in terms of both the answer speed (below 5 min) and comments of the participants (i.e., nonsense comments). Cases were excluded only with the consensus of the researchers. If there was no consensus between the researchers, a senior researcher in the research team was consulted to decide. Twenty-seven cases in the youth sample (age: M = 21.78, SD = 2.47; gender: 56% female) and sixteen cases in the adult sample (age: M = 41.44, SD = 9.36; gender: 50% female) were excluded by the described procedure. Finally, the youth sample consisted of N = 1123 cases (exclusion rate: 2.35%), and the adult sample consisted of N = 1134 cases (exclusion rate: 1.39%). The participants took an average of M = 12:58 min (youth sample) and M = 15:23 min (adult sample) to complete the entire questionnaire.

The mean age of the youth sample was M = 21.53 years (SD = 2.51 years), and that of the adult sample was M = 51.84 years (SD= 14.91 years). In the youth sample, female respondents were slightly overrepresented (60.91%); in the adult sample, gender was balanced (

Table 1. Sample characteristics of the youth sample and the adult sample.

	Youth Sample	Adult Sample
N	1123	1134
Age [Years]
M	21.53	51.84
SD	2.51	14.91
Range	16–25	26–87
Gender [%]
Male	38.74	47.88
Female	60.91	51.85
Diverse/non-binary	0.36	0.27

Note: N = sample size; M = mean; SD = standard deviation.

).

2.2. Questionnaire

The questionnaire was implemented as an online questionnaire. A challenge in this questionnaire was to obtain a valid picture of the acceptance considering the novelty of the ptx technologies. Therefore, after general information and information on data protection, there was a one-page content-based introduction to the topic of ptx (see Appendix A.1), since ptx technologies were still very new and subsequently very abstract.

The study deals with the degree of general acceptance [6] and socio-political acceptance [8], i.e., the question of how the topic of ptx is perceived by the population, which is why we chose the methodological approach of a representative survey. The acceptance factors from the models described above were used; only procedural justice was not taken into account in this study, as this is an important factor for local acceptance and specific projects, which is not the subject of this study. To assess the constructs of interest for the study, we used already-established scales from other publications as far as possible. This has the advantage of these instruments being already proven to be appropriate in other studies, e.g., regarding their factorial structure and reliability. Only some items had to be constructed for this study to answer the study questions (e.g., items to assess prior knowledge and sector-specific acceptance). We opted for a five-point scale because the criteria of simplicity with regard to the high number of items in our questionnaire and familiarity with five-point rating in German society were important to us. In addition, many of the scales used are already in 5-point format. In the following, we present an overview of the instruments used; the complete item list can be found in Appendix A.2.

Prior knowledge: Prior knowledge on ptx was assessed using one item. Participants were asked to rate their prior knowledge on ptx technologies on a five-point scale from 1 = “I have never heard or read about it” to 5 = “I would describe myself as an expert on the subject of ptx”.

Public acceptance of ptx technologies: The acceptance of ptx technologies was assessed with four items which were adapted from Kortsch et al. [30] (“biomass plant” was replaced by “power-to-x technologies”) with a five-point scale from 1 = “do not agree at all” to 5 = “agree completely”. A sample item is “All in all, I support the use of power-to-x technologies in Germany.”

Sector-specific acceptance of power-to-x technologies: The sector-specific acceptance was assessed in each case with an item based on the items from Kortsch et al. [30] with a five-point scale from 1 = “do not agree at all” to 5 = “agree completely”. The basic form “All in all, I support the use of power-to-x technologies in [the transportation sector/the energy sector/the chemical sector] in Germany” was varied depending on which sector was targeted.

Ecological impact of ptx technologies: The ecological impact of ptx technologies was assessed with five items adapted from Arning et al. [31]. These items could be answered on a scale from 1 = “do not agree at all” to 5 = “agree completely”. An example item is “Generally, power-to-x is a relief for the environment.”

Fair value creation: The four items on fair value creation were adapted from Kortsch et al. [30]. This involved first presenting an overarching question “How do you assess the distribution of costs and benefits of power-to-x?”. Four items could then be rated on a five-point scale from 1 = “do not agree at all” to 5 = “agree completely.” An example item is “The use of power-to-x has a positive effect on Germany as a business location”.

Environmental awareness: Environmental awareness was assessed using a scale developed by Arning et al. [31]. This scale consists of four items, each of which was surveyed in a five-point response format ranging from 1 = “do not agree at all” to 5 = “agree completely.” An example item is “I think environmental problems are becoming more and more serious in recent years”.

Personal innovativeness: Personal innovativeness was assessed using the three positive formulated items from the scale of Herrenkind et al. [23]. The negative formulated item “In general, I am reluctant to try out innovative technologies.” was excluded for statistical reasons, resulting in an increase in the Cronbach’s Alpha from 0.63 to 0.79 (youth sample) and from 0.59 to 0.87 (adult sample). A five-point scale from 1 = “do not agree at all” to 5 = “agree completely” was given to rate the items. A sample item is “Among my colleagues, I am one of the first to try out new technologies.”

Social norm: To elicit the social norm, a scale by Wang et al. [32] consisting of four items was transcribed into German and adapted (“HEV” was replaced by “sustainable product”). A five-point scale ranging from 1 = “do not agree at all” to 5 = “strongly agree” was given as the response format. A sample item is “Most people who are important to me think I should buy sustainable products.”

Personal norm: To measure the personal norm, an adaptation of the scale developed by Wang et al. [32] was used (“HEV” was replaced by “sustainable product”). For the three items included, e.g., “Because of my own principles I feel an obligation to use a HEV to reduce carbon emissions and improve air quality”, a five-point scale was given as the response format.

Perceived behavioral control: To assess perceived behavioral control, the scale of Fielding et al. [33] was translated into German. The three items used ask how difficult it is for participants to behave in a sustainable manner and how much control they feel over it. The five-point scale varied in wording depending on the question from “very difficult” to “rather very easy” and from “none at all” to “a lot”; a sample item is “How much control do you have over the extent to which you behave sustainably?”

For all included scales, the descriptive statistics are reported in

Table 2. Descriptive statistics of the included scales separated by sample.

Scale (No. of Items)	Youth Sample			Adult Sample
	M	SD	Cronbach’s Alpha	M	SD	Cronbach’s Alpha
Prior knowledge (1)	1.44	0.74	- a	1.35	0.69	- a
Public acceptance of ptx technologies (4)	3.85	0.73	0.78	3.87	0.80	0.82
Ecological impact of ptx technologies (5)	3.85	0.70	0.85	3.90	0.76	0.91
Fair value creation (4)	3.63	0.70	0.76	3.69	0.83	0.86
Environmental awareness (4)	4.18	0.76	0.82	4.24	0.72	0.82
Personal innovativeness (3)	3.13	0.72	0.79	2.94	0.74	0.87
Social norm (4)	3.18	0.84	0.81	2.99	1.01	0.89
Personal norm (3)	3.56	0.89	0.86	3.45	1.02	0.93
Perceived behavioral control (3)	3.34	0.70	0.70	3.36	0.73	0.77

Note: M = mean; SD = standard deviation; alpha = Cronbach’s alpha; ^a alpha could not be computed because this is a single-item measure.

(except for sector-specific acceptance; see

Table 3. Acceptance of power-to-x in general and in different sectors and group comparisons (youth vs. adult).

Sectoral PtX Acceptance	Total Sample		Youth Sample		Adult Sample		Group Comparisons (Youth vs. Adult) 1
	M	SD	M	SD	M	SD	t	df	p
General	3.86	0.77	3.85	0.73	3.87	0.80	−0.83	2008	0.405
Mobility sector	3.93	0.86	3.89	0.85	3.98	0.88	−2.25	1990	0.024
Industry sector	3.97	0.86	3.93	0.83	4.01	0.88	−2.05	2007	0.041
Chemistry	3.89	0.92	3.82	0.93	3.98	0.90	−3.88	1881	<0.001

Note: M = mean; SD = standard deviation; ¹ group comparisons by means of an independent-samples t-test; t = t-value; df = degrees of freedom.

for these descriptive statistics). The scales had mostly very good reliability [34].

Associative perceptions: To capture which attributes participants associate with ptx technologies, a semantic differential was constructed containing twelve bipolar pairs. The semantic differential technique helps to visualize mental associations and implicit attitudes connected to the research object and can be used especially when the level of elaborated knowledge is low [6,35]. Each pair could be rated on a ten-point scale (1–10). Exemplary pairs are “environmentally friendly vs. environmentally harmful” or “competitive vs. non-competitive.”

Conditional acceptance factors: Items were developed for this study to survey under which conditions the usage of different ptx technologies and the creation of products would be acceptable. These are divided with respect to three aspects: first, with respect to the source of energy required; second, with respect to the origin of the water used; and third, with respect to the origin of the carbon necessary. The respective places/types of origin/production could be rated on a scale from 1 = “strongly disagree” to 5 = “strongly agree”. For the origin of energy, the overarching question was “Which energy sources should be used to produce the hydrogen?” Different sources (renewable energy, fossil fuels, fossil fuels with carbon capture) could be assessed. For the origin of water, the overarching question was “Where should the water needed in the ptx process come from?” Three conditions could be assessed for origin (water used should not be lacking elsewhere, water used should be available in sufficient quantity at the place where it is needed, water should be used from where it is cheapest). For the source of carbon, the overarching question was “How should this carbon be obtained?” Two sources could be assessed (direct air capture, carbon as a waste product in industry).

Finally, socio-demographic data (e.g., age) were collected with the questionnaire.

2.3. Statistical Approach and Construct Evaluation

To answer the formulated research questions, the following methodological–statistical approach was chosen: First, prior knowledge as a prerequisite for acceptance was investigated and compared between the groups. In connection with this, the associations with ptx technologies were evaluated in the form of semantic differentials and analyzed with regard to group differences. This answers research question 1. Subsequently, to answer research question 2a, the acceptance conditions and the sector-specific acceptances of the groups were investigated. For research question 2b and research question 3, the influences of potential influencing factors on the general acceptance of ptx technologies were then examined using a regression analysis.

The statistical software JASP version 0.14.1 was used for descriptive and simple statistical analyses (group comparisons, multiple regressions). For confirmatory factor analysis, R (version 4.1.0) [36] and the package “lavaan” (version 0.6-8) [37] were used.

For group comparisons, a Mann–Whitney U-test (prior knowledge, which had an ordinal scale level) and independent-sample Student t-tests (all other group comparisons) were performed, which is a robust procedure even for deviations from preconditions in the case of equal sample sizes and large samples with conditions [38]. Multiple linear regressions were used to investigate the influencing factors of ptx acceptance.

First, an evaluation of the constructs was carried out to prove their separability. A confirmatory factor analysis was conducted to prove that the items from the item list in Appendix A.2 loaded on their respective factors. The scales in Table 2 were included except for the “prior knowledge” scale because it is a single-item measure. Thus, an eight-factor model (i.e., the factors general acceptance of ptx technologies, ecological impact of ptx technologies, fair value creation, environmental awareness, personal innovativeness, social norm, personal norm, and perceived behavioral control) was used in which each item was an indicator of the assumed factor. The CFA results support the assumed eight-factor model (Χ² = 2292.62, df = 377, p < 0.001, CFI = 0.90, RMSEA = 0.07, SRMR = 0.06). The separability and validity of the scales used can therefore be considered confirmed. Therefore, a mean value was calculated as a scale value for each construct from the respective item values in order to use these scale values in multiple regressions.

3. Results

3.1. Prior Knowledge

Concerning prior knowledge on ptx technologies, it was found that 67% of the youth sample and 74% of the adult sample had never heard about ptx technologies (see Figure 2). Comparing both groups regarding this variable using the Mann–Whitney U-test, it was found that the difference between both samples (youth: M = 1.44, SD = 0.74; adult: M = 1.35, SD = 0.69) was significant (U = 679,586, p < 0.001).

Despite the relatively low degree of knowledge and experience across the total sample, there is substantial interest in terms of the intention to use ptx-based fuels such as synthetic fuels in aviation or cars; for hydrogen in cars, there is even a slightly higher intention (67% as a sum of agree and strongly agree) (Figure 3).

Correspondingly, 40%–45% of the respondents stated that there is a willingness to pay higher prices when purchasing airline tickets or cars using ptx-based fuels, and the willingness to pay more for airline tickets is higher (Figure 4).

3.2. Level of Acceptance of PtX and Associative Perceptions

Regarding the question of acceptance, at a general level (see Table 3), the mean ratings for the acceptance of ptx in general as well as for the more specific acceptance foci are considerably above the scale midpoint, thereby indicating positive acceptance. Regarding the group comparisons between the young people and the adults, there were no differences in the acceptance of ptx technologies in general (p > 0.05). However, significant differences were found for all three sector-specific acceptances: the acceptance of adults was higher on average for ptx in the mobility sector (p < 0.05), ptx in the industry sector (i.e., energy for industrial applications) (p < 0.05), and ptx in chemistry (p < 0.001).

To capture the image of ptx technologies and content-related attributes more precisely, a semantic differential was utilized. The perceptions of ptx technologies of the respondents fall towards the positive endpoint of the scale, as indicated by values below 5.5, which is the midpoint of the scale (see Figure 5). The values in the total sample ranged from M = 3.11 (innovative–backward) to M = 4.68 (land-saving–land-intensive) on a scale from 1 (the positive endpoint of the scale) to 10 (the negative endpoint of the scale). Overall, concerning the total sample, the respondents tended to rate ptx technologies as innovative (M = 3.11), sensible (M = 3.28), clean (M = 3.78), and environmentally friendly (M = 3.86).

With regard to a comparison of the youth and the adult sample concerning the associative perceptions, significant differences were found for the pairs “environmentally harmful–environmentally friendly” (t = −4.04, df = 1927, p < 0.001), “backward–innovative” (t = −3.85, df = 1974, p < 0.001), “land-intensive–land-saving” (t = −3.60, df = 1739, p < 0.001), “dirty–clean” (t = −4.10, df = 1897, p < 0.001), “harmful to health–beneficial to health” (t = −4.08, df = 1732, p < 0.001), “dangerous–harmless” (t = −4.06, df = 1757, p < 0.001), and “unreliable–reliable” (t = −3.75, df = 1769, p < 0.001). All other pairs differed non-significantly (p > 0.05).

3.3. Conditional Acceptance of PtX

In addition to general acceptance, conditional acceptance was investigated, i.e., under which conditions ptx technologies are acceptable; the main acceptance criteria can be derived from this. For the technical conditions, it was investigated which energy sources should be used to generate hydrogen:

• “Green” hydrogen (i.e., hydrogen produced by using renewable energy sources) clearly received the highest level of acceptance here (mean value M = 4.29 for the youth sample and M = 4.39 for the adult sample on a scale of 1 = “do not agree at all” to 5 = “agree completely”; significant difference: t = −2.52, df = 2064, p < 0.05).
• Fossil fuels (youth sample: M = 2.27; adult sample: M = 2.39; significant difference: t = −2.21, df = 2021, p < 0.05) received low agreement, even in the case where the CO₂ emissions were captured (youth sample: M = 2.84; adult sample: M = 2.93; difference was not significant: t = −1.671, df = 1936, p > 0.05). Thus, most agreement values of the youth were significantly lower.

Concerning the water in the process, different options were given:

• Only water that is not lacking elsewhere should be used (youth sample: M = 4.30; adult sample: M = 4.48; significant difference: t = −4.91, df = 2112, p < 0.001).
• Water is sufficiently available on site (youth sample: M = 4.25; adult sample: M = 4.45; significant difference: t = −5.57, df = 2100, p < 0.001).
• Compared to the two options above, the option “Water should be used from where it is cheapest” received lower agreement values (youth sample: M = 2.71; adult sample: M = 3.31; significant difference: t = −11.71, df = 2018, p < 0.001). Thus, again, the adults’ consent scores are significantly higher with respect to all options.

In terms of carbon sources, the two options reached a similar level of agreement:

• Direct air capture (youth sample: M = 3.787; adult sample: M = 3.936; significant difference: t = −3.47, df = 1745, p < 0.001).
• Capture in industrial processes (youth sample: M = 4.02; adult sample: M = 4.18; significant difference: t = −3.94, df = 1982, p < 0.001). Here, too, the same picture emerged when comparing young people and adults: the adults’ approval ratings were significantly higher.

3.4. Influencing Factors of the General Acceptance of PtX Technologies

The multiple regression on the general acceptance of ptx technologies in the total sample showed a significant model fit (F = 127.29, df1 = 10, df2 = 1800, p < 0.001); the ecological impact of ptx technologies, fair value creation, environmental awareness, and personal innovativeness variables were significant positive predictors of the general acceptance of ptx technologies; prior knowledge, social norm, and perceived behavioral control were significant negative predictors (see

Table 4. Results of the multiple regression analyses on the public acceptance of ptx technologies in the total sample and separately in the youth sample and in the adult sample.

Predictor	Total Sample	Youth Sample	Adult Sample
Prior knowledge	−0.07 ***	−0.11 ***	−0.04 n.s.
Ecological impact	0.51 ***	0.47 ***	0.54 ***
Fair value creation	0.13 ***	0.12 ***	0.15 ***
Environmental awareness	0.10 ***	0.15 ***	0.04 n.s.
Personal innovativeness	0.08 ***	−0.04 n.s.	0.11 **
Social norm	−0.13 ***	−0.06 n.s.	−0.19 ***
Personal norm	−0.03 n.s.	−0.02 n.s.	−0.03 n.s.
Perceived behavioral control	−0.05 *	−0.09 **	−0.02 n.s.
Age	−0.01 n.s.	0.01 n.s.	0.02 n.s.
Gender 1,2	0.07 ***	0.05 n.s.	0.10 ***
R2	41.1%	39.4%	44.9%

Note: Reported are the standardized regression coefficients (β) and the significance levels using asterisks (*** p < 0.001, ** p < 0.01, * p < 0.05, n.s. = not significant); ¹ 7 respondents who indicated “diverse/non-binary” gender were excluded from these analyses for statistical reasons; ² gender was coded as 1 = male and 2 = female; a positive beta value indicates that women’s acceptance values are higher than men’s acceptance values.

). Gender had a significant positive beta weight (β = 0.07, p < 0.001), indicating that women’s acceptance values are higher than men’s acceptance values. The ecological impact of ptx technologies had the highest beta weight (β = 0.51, p < 0.001). The model accounted for 41.1% of the variance in the general acceptance of ptx technologies.

Concerning the multiple regression on the public acceptance of ptx technologies in the youth sample, the model was also significant (F = 63.93, df1 = 10, df2 = 982, p < 0.001). The same variables except for social norm, personal innovativeness, and gender (which all had no significant effect) were significant predictors to a similar extent. In contrast to the adult sample, environmental awareness (β = 0.15, p < 0.001) and perceived behavioral control had a significant negative effect (β = −0.09, p < 0.01). Here, again, the ecological impact of ptx technologies had the highest beta weight (β = 0.47, p < 0.001). The model accounted for 39.4% of the variance in the general acceptance of ptx technologies.

Concerning the multiple regression, in the adult sample, the model was also significant (F = 65.84, df1 = 10, df2 = 807, p < 0.001). The same variables as in the total sample except for environmental awareness and perceived behavioral control (which both had no significant effect) were significant predictors to a similar extent, with the ecological impact of ptx technologies again being the strongest predictor (β = 0.54, p < 0.001). In contrast to the youth sample, in the adult sample, personal innovativeness (β = 0.11, p < 0.01) and gender (β = 0.10, p < 0.001) had a significant positive effect, while social norm had a significant negative effect (β = −0.19, p < 0.001). The model accounted for 44.9% of the variance in the general acceptance of ptx technologies.

4. Discussion

4.1. General Discussion

As tackling climate change is one of the greatest challenges of our time, climate-friendly technologies such as ptx must be deployed on a large scale as quickly as possible. Large, industrialized nations such as Germany, with their high CO₂ emissions, have a particular responsibility in this regard. The study focuses on public acceptance as a key success factor for the introduction of ptx technologies and uses Germany as an example for many industrialized countries. The study therefore examined the general and sector-specific acceptance of ptx technologies, the necessary prerequisites for acceptance, and the factors that are important for achieving acceptance. In answering these questions, particular attention was paid to how young people differ from adults, as this group is particularly affected by decisions on the energy transition. The answers to these questions provide important insights for the design of innovative technologies such as ptx technologies as an important pillar—besides reducing energy consumption—for combating climate change in industrialized countries with high energy consumption. The example of Germany, with its relatively far-reaching technological progress in the development of ptx technologies, offers insights that could also be of interest to other industrialized nations that want to rely more on ptx technologies in the future.

In the following, the results are discussed according to the formulated research questions. For the questions of acceptance, the relevant factors, and conditional acceptance, the differences between the youth and adult samples are considered in an integrated manner.

4.1.1. Current Level of Public Knowledge Regarding PtX

Concerning the first research question, like in other studies [25], it was found that the current public knowledge about ptx technologies is rather low. This should be considered when reflecting on the other results of this study. Even though the media coverage of hydrogen and ptx technologies is slowly increasing due to specific decisions and events at the political level in Germany (e.g., the announcement of the national hydrogen strategy [39,40]), there still is only little information about ptx technologies and their relevance within the energy transition for the general German public. Despite the low level of knowledge, the respondents show a principal interest in the form of a willingness to use hydrogen and e-fuels, both in individual mobility decisions and in public transport. There is also a basic willingness to pay, but this should only be understood as a trend due to the low level of knowledge and still limited availability [41,42,43].

Currently, discussions about the technology and its specific conditions predominantly remain at the expert level [44]. The challenge of conducting research with laypersons or the public at a very early stage with a corresponding low degree of knowledge has been discussed in science and is linked to the questions of “pseudo-opinions” and “non-attitudes” [6,35]. It is argued that because of the low degree of elaborated knowledge and thus ability to derive differentiated opinions, the expressed answers are not stable or reliable. Nonetheless, as it is crucial to involve the perspectives of the public also in early stages, some measures can be taken to address the described challenges. On the one hand, it is mandatory to provide neutral and non-reactive information to the participants about the technology as a precondition for the poll. Following this, regarding the methods used, the analysis of automatic mental associations and implicit attitudes, for example, by applying semantic differentials or association tests, can help to capture instinctive reactions to attitudinal objects. Last but not least, while interpreting the results, one should be sensitive to the specific context of the study.

As mentioned above, knowledge is important as a framing condition for the process of acceptance formation [7]. An understanding of a technology becomes even more important for complex and abstract new technologies such as ptx. Therefore, in the context of the introduction of new technologies such as ptx, how the new technologies are framed communicatively, i.e., how information about the new technologies is presented, seems to be quite essential. A one-sided presentation of arguments for new technologies such as ptx technologies can lead to a “boomerang effect” [45] and cause oppositional behavior. De Vries [46] therefore suggests that actors consider different psychological mechanisms (e.g., cognitive biases) when communicating to the public on the topic of new technologies. Additionally, it should be considered that in the study the adults reported being less informed about ptx technologies than the youth, which should be taken into consideration in the choice and design of communication tools and invites more differentiation by target groups.

4.1.2. Public Acceptance of PtX: General Level, Factors, and Conditional Acceptance

Regarding the second research question, the results revealed high values in public acceptance in general. This is in congruence with other acceptance studies on new energy technologies (e.g., smart grid technology [19]; hydrogen storage [47]) where high approval ratings were consistently found at the general level. The fact that adults show a higher acceptance of ptx technologies than the youth in all three fields of application could possibly be related to lower and therefore possibly less differentiated knowledge about these technologies. With increased knowledge, the complexity and challenges of the technology also become more apparent.

The associative evaluations regarding ptx technologies were all towards the positive endpoint of the scale, which underlines the principally positive perception of ptx technologies. However, it must also be noted that the profile of ptx technologies was not (yet) particularly pronounced; the values ranged between M = 3.11 (innovative–backward) and M = 4.68 (land-saving–land-intensive) on a scale from 1 to 10, which speaks for a not yet consistently well-founded assessment on the part of the respondents. Besides the principally low degree of elaborated knowledge about ptx technologies, it becomes evident that the polled persons attribute a large potential for energy transition: Looking at the associations of being innovative (M = 3.11), sensible (M = 3.28), clean (M = 3.78), and environmentally friendly (M = 3.86), it can be stated there are some opportunities in the public perceptions connected to this technological pathway. Compared to the current discussions regarding renewable energies, the attributes of being innovative and clean especially are dimensions that integrate economic and ecological potential and thus are relevant for public acceptance. Likewise, the current risk perception (being harmful or dangerous) is rather low; there is consequently no salient negative counterpart within the associations [48,49]. Surprisingly, the adults showed fewer positive evaluations in seven of the associative contrast pairs, even though they showed no difference in the general acceptance of ptx technologies and higher acceptance for the different application areas than the youth. It can be assumed that the results will become more differentiated and, in part, more critical with more elaborated knowledge and concrete experiences with ptx technologies in the future. This is part of a necessary and valuable learning process to establish well-informed citizens making differentiated evaluations and decisions. Nevertheless, it should be stressed that the principally positive public perception illustrated by the results of the rated associations underlines the perceived potential of ptx at this early stage, with positive beliefs and emotional responses dominating. Other comparable technological approaches in an early stage were evaluated rather negatively in public discourse, e.g., carbon capture and storage (CCS) [5].

Furthermore, the results concerning conditional acceptance (i.e., the technical conditions that should be fulfilled when implementing the technology) reveal that different aspects in the ptx phases of generation and conversion are differently evaluated by the youth and adults. It was found that the respondents advocated for the sustainable production and use of the necessary energy (highest values for green hydrogen), water (using only water that is not lacking elsewhere and is sufficiently available on site), and carbon (high agreement to capture it directly from the air or in industrial processes). However, generally, the following was observed for all questions concerning conditional acceptance: The adults’ approval ratings were significantly higher than those of the youth. So, the youth are more cautious—or maybe a bit more skeptical—with their assessment of the design of ptx technologies.

4.1.3. Differences Between Youth and Adult Samples

Combining all respondents into one sample, the ecological impact of ptx technologies, fair value creation, environmental awareness, personal innovativeness, and gender variables were significantly positive, whereas prior knowledge, social norm, and perceived behavioral control were significantly negative predictors for the general acceptance of ptx. The ecological impact of ptx technologies was by far the most important predictor indicating that ptx technologies are mostly seen as an environmentally friendly solution to the challenge of the energy system transition, which is in line with results of other studies showing clear support for green hydrogen [11,50]. This fits in with the fact that environmental issues have once again become a much greater priority in Germany in recent years having already been highly relevant in the 1980s with the environmental movement and subsequently losing importance [51]. Interestingly, the results turned out to be more differentiated when looking at both samples separately. In both samples, ecological impact and fair value creation are relevant factors. While for the youth sample general environmental awareness was important, in the adult sample, personal innovativeness played a role. Consequently, for the youth, the technology is seen as a relief for the environment; for the adults, the technology itself plays a more important role. These results illustrate very well the importance of the context and the different life worlds in different life phases.

Looking at further differences, prior knowledge is only relevant in the youth sample, in a direction which might be surprisingly at first glance: more knowledge is associated with lower acceptance. However, with a closer look at the context, this result becomes more reasonable. In fact, some studies indicate that higher knowledge correlates with higher acceptance [52,53]. But those studies investigated existing energy infrastructures like wind energy turbines, where concrete application experiences were provided and potential prejudices could be revised. Ptx technologies are still at an early stage of development. Rather than being based on well-established knowledge, public perceptions are largely shaped by positive beliefs and attributes [54]. The perceived opportunities and potential of these new technologies—along with the associated hope that they may contribute to solving current energy supply challenges—can lead to a certain degree of overestimation, which is reflected in very high levels of acceptance. Accordingly, it is plausible to assume that acceptance may decline or become more differentiated as knowledge increases, ultimately stabilizing at a more realistic and reflective level of evaluation. This could explain the negative correlation found in this study. Nonetheless, it is worth noting that public acceptance remains at a relatively high level overall. Future research would have to examine more closely what prior knowledge was already present among the respondents and also how it develops over time with increasing media coverage regarding the technology.

Social norm as a predictor is only relevant in the adult sample. The relation was unexpectedly negative, i.e., a higher social norm is connected to lower acceptance values. One explanation for this might be a reactant reaction [46] to the feeling of being socially influenced. Here, again, the low level of knowledge on the technology could be important: people nowadays may not feel informed enough to form an opinion about the new technology and therefore react with resistance to perceived social influence. Another explanation could be that the social norm is addressing more sustainable consumption behavior, hence a less technological focus, which is more relevant in the adult sample.

Perceived behavioral control, on the other hand, was a significant predictor only in the youth sample, but contrary to the assumption, it was negative. The young people with low perceived behavioral control for sustainable behavior had high acceptance scores and vice versa. Youth generally appear to report lower perceived and actual control not only in political but also in personal domains [55]. Climate challenges are considered enormously relevant by young generations [27] but beyond their control, causing feelings of despair and grief. The positive valuation of ptx technologies might possibly be seen as a form of compensation. The less one can achieve as an individual, the more one yearns for more far-reaching changes, such as the adoption of sustainable technologies. The fact that this effect is only found in the youth sample is in line with the idea that the young generation as an age group has hardly been involved in decision-making to date.

4.2. Limitations and Future Directions

Even though the study was carefully planned and conducted, some limitations must be acknowledged.

First, this population study on social acceptance was carried out at an early technology stage of ptx in Germany, where the first points of contact for ordinary citizens—primarily through increased media coverage—were just beginning to emerge. Thus, it was challenging to enable respondents at such an early stage of the technology to answer a comprehensive questionnaire on a new and little-known technology. Inevitably, simplifications had to be made. Regarding the assessments of carbon sources in particular, it should be noted that the survey did not provide information on the different climate impacts or further details about the various carbon, energy, and water sources. Accordingly, the results should be understood as initial indications and starting points for more in-depth information and communication on these alternatives, serving as a basis for societal discussion. However, Germany can be seen as a country with relatively advanced development of ptx technologies, and in this respect, the findings can provide a basis for further research in other countries that also aim to develop ptx technologies in the future. Likewise, it will be useful to compare how acceptance factors and criteria are shaped in relation to different socio-political and socio-cultural contexts.

Second, there are some limitations concerning the sample. We compared the youth sample and the adult sample, which allowed conclusions about differences between these two groups (youth aged 16–25 years and adults aged over 25 years). Since the youth group was as large as the adult sample, this study provides a counterpoint to most studies and overrepresents a group that is otherwise mostly underrepresented. However, it may be interesting for future research to compare additional age groups to gain a better understanding of how acceptance changes with age. Furthermore, in the youth sample, women were slightly overrepresented (about 61 percent).

Third, data collection took place at the end of 2020. Since then, technological development has continued, and the context has changed—for example, due to Russia’s war against Ukraine, which has brought the issue of energy and supply security to the forefront of public attention. Nevertheless, the present study offers a good starting point for comparative research, as the actual number of installed ptx plants is still small, so there are few actual points of contact. Changes in external conditions, in turn, may influence perception, making comparative studies an option for the future. In this respect, it is important to note that the study was cross-sectional, providing a snapshot of public acceptance of ptx technologies at an early stage of technological development. This is helpful and can be used to influence the development process to achieve a more widely accepted technology. However, conclusions should be drawn with caution, especially causal conclusions. Future studies should apply mixed-method and longitudinal designs to overcome these limitations and contribute to advancing these new technological components [11].

5. Conclusions

Early-stage analyses of the acceptance of ptx technologies in Germany generally show a high level of approval for the basic ptx approach, although considerable uncertainty remains in the assessments. On the one hand, this uncertainty stems from individuals’ varying levels of information and knowledge; on the other hand, it reflects ongoing scientific debates about the potential and future development of ptx technologies.

Individual environmental awareness is a relevant predictor of ptx acceptance across all areas of application. Accordingly, this general endorsement is closely linked to the expectation that ptx will be based on green hydrogen—i.e., the underlying renewable energy source constitutes a central criterion for public acceptance. This implies that, in the future, ptx technologies must demonstrate their positive impacts across the three dimensions of sustainability—ecological, economic, and social—over their entire life cycle. In current public perception, these positive impacts represent the core promise of ptx; however, as with any high expectations, this also entails the risk of disappointment and rejection in the event of unmet goals.

Therefore, in order to fully realize the potential of ptx approaches, a key systemic implication is the need for the broad national expansion of renewable energy sources to ensure sufficient renewable electricity is available for hydrogen production within ptx processes. Additional global strategies may arise at the regulatory level, potentially including accounting and financing rules linked to low-carbon standards across the entire value chain—verified through certification schemes. This issue is partly addressed in the ongoing debate about hydrogen color classification and the EU’s sustainable finance taxonomy [56]. A possible further and promising approach is the “EESG Framework for PtX”, which comprises four basic dimensions: economic, environmental, social, and governance [57]. Further specifying these dimensions and securing them with corresponding binding regulations would increase distributive justice along the value chain, thereby contributing to sustainability and thus also to the acceptance of ptx in the global perspective.

Another key finding of this study is the difference between the two main study groups: young people and adults. These results highlight the importance of surveying young people as a distinct target group, rather than drawing conclusions from studies in which they are typically underrepresented. Even within the adult sample, the results and conclusions diverge when focusing exclusively on this age group. Thus, a more age-differentiated approach can contribute to a more nuanced understanding of the factors influencing the acceptance of ptx technologies, lead to more targeted recommendations for future interventions, and help shape technology development.

Looking ahead, and considering social movements such as the globally active Fridays for Future, along with changing lifestyles, norms, and values, it can be assumed that the observed differences may diminish over time, as greater environmental awareness becomes the dominant social norm—not only in Germany. This trend is likely to be accompanied by the increased acceptance of innovative technological solutions, as well as social innovations and new behavioral routines. In the mobility sector, in particular, the close link between the acceptance of ptx technologies—as one alternative technological pathway—and broader societal discourses (e.g., the need for a transformation of the transport sector, including a general reduction in traffic volumes) becomes especially evident.

One important challenge will be the future of science communication: conveying the complexity of ptx technologies and their potential relevance within the broader energy system transformation in a way that is both accessible and understandable to the public. In this respect, which parts of the value chain remain in Germany and which parts are imported and under what conditions should be explicitly described and discussed (see EESG framework above). As ptx technologies span a wide range of applications across sectors such as transport, industry, and chemical production, science communication must transparently present the advantages and disadvantages of each pathway, as well as comparisons with potential alternatives. One example is the decarbonization of the transport sector, where ptx-based synthetic fuels offer a promising option for more sustainable aviation, while in the case of individual transport, e-mobility may represent a more efficient alternative. Consequently, comprehensive and balanced communication strategies are essential to enable the public to form informed opinions—an important prerequisite for the empowered evaluation of ptx technologies. In this way, the foundation is also laid for the population or individual stakeholder groups to actively participate in the transformation process towards a sustainable energy supply. Science communication is therefore an important accompanying measure for participation and, by increasing transparency, has an impact on the perceived procedural justice, especially if there will be more concrete ptx projects on site in the future.