Start-Up Accelerators and Their Impact on Sustainability: Literature Analysis and Case Studies from the Energy Sector

Abstract

Start-up accelerators are units supporting entrepreneurs (substantively, financially, legally, and organizationally) in establishing and running young and innovative companies such as start-ups. The commencing energy crisis has led to the need for energy savings, as well as the need to change energy policies and implement energy transformation, creating a wide field for start-ups and start-up accelerators. Making full use of potentially innovative solutions developed by start-ups is, in turn, essential for energy giants and related accelerators in the market. This has created the need for specific research in this direction. Therefore, in this paper we review the literature for 2011–2021 with respect to the role of accelerators supporting start-ups. A survey based on the Scopus database resulted in the identification of 76 papers on accelerators. Particular attention was paid to aspects of sustainable development (economic, social, and environmental). The analysis indicated that 75 works dealt with the economic aspects, 35 focused on social aspects, and only 5 focused on environmental aspects. Due to the perceived gap related to the small number of works dealing with environmental aspects, a decision was made to analyse the energy sector and the methods of operation of accelerators in this sector. Three models found in the market that were used by energy companies to cooperate with start-ups were characterized, along with their goals, in an attempt to enable an improved understanding as to which acceleration model best fits a manager’s organization. The models were supported by case studies—a model of commercial cooperation between a corporation and an external accelerator, a model of creating a corporate accelerator within an internal structure, and a hybrid model.

1. Introduction

A well-defined business model, human resources, and financial means are crucial for the survival and growth of start-ups. Attracting capital investment and winning business contracts is not an easy task, especially for young innovative companies that lack market traction or the business foundations to develop a start-up and its product in compliance with market expectations. In many cases, companies at an early stage of development do not have a precise business model or correctly defined revenue streams, and the business knowledge of start-up managers is not at a high level. In this context, start-up accelerators, which operate within the market, are considered an appropriate choice in the context of development, the finetuning of solutions, and the acquisition of customers and capital investors. The first accelerators and acceleration programs were established in the USA in 2005–2006 (Y Commbinator, Techstars). Accelerators provide intensive support for start-ups in their rapid development. Accelerator programs usually last several months, during which a start-up’s product or service is intensively developed with the support of resources, mentors, experts (both technical and business), partners’ infrastructure, a workspace, networking, and promotional activities. Depending on the operational model adopted, the accelerator program may be share-based, i.e., the accelerator charges the start-up a price ranging from a few to several percent of its shares for its participation. Another model is an equity-free accelerator program, in which no fees or shares for participation are charged. Another solution found on the market is the performance-based model, in which the accelerator can take up shares once the acceleration program in selected companies has been completed if the start-up has achieved certain business objectives.

Energy transitions have entered an era characterized by accelerated technological innovation. The World Energy Council highlighted the significance of new measures related to the humanization of the energy transition. The activities bring together actors such as start-ups, large energy companies, and investors [1]. Companies follow two distinct external and internal growth strategies. The external growth strategy is based on mergers and acquisitions (M&S), whereas the internal strategy aims at the expansion of the utilization of available internal resources [2]. Companies adapt their strategies in order to survive and thrive in rapidly changing environments [3]. During the implementation of an external growth strategy, barriers emerge due to a lack of a shared vision for the organization’s development and business externalities. The acquisition of start-ups minimizes the risk of failure due to the risk of evaluating the young company’s previous activities. The integration of acquired start-ups, as well as the acquisition of features, patents, research work, qualified personnel, and innovation in regard to start-ups, is much easier than developing them from scratch within the structures of a large business [4].

Sustainable development has become a major priority for the modern economy, so decision makers are taking steps to improve its operation in connection with the growing demand for greater diversity, the need for innovative solutions, and the diversification of energy sources. The fundamental improvement drivers include innovation and entrepreneurship [5]. Start-ups are considered to be the major driving force of change and innovation [6,7]. During the sustainable transformation of industries, start-ups play an essential role; therefore, the transformation cannot be carried out by industry tycoons alone. The interaction of these two market players is key for success [5,8,9]. Start-ups are more inclined to test innovative approaches and are characterized by creative thinking [10], speed, flexibility, and risk-taking approaches [11]. The above-mentioned factors are the main reasons that corporations establish business relationships with innovative start-ups, as it enables large companies to obtain access to innovations, new technologies, and the entrepreneurial thinking specific to teams in young companies. The energy sector identified innovation as a key driver of survival in the rapidly changing market environment caused, for instance, by the war between Russia and Ukraine or by ongoing climate change. However, in order to establish such business relationships, both energy companies and start-ups need to plan carefully and manage the change process. In order to ensure the desirable effect of such cooperation, both sides have increasingly noted the need to cooperate with start-up accelerators.

Despite the variety of support offered, the popularity of business environment institutions such as accelerators is constantly growing. The rapid growth in the last 10 years of start-up ecosystems with accelerators operating within them raised the need for in-depth studies to be conducted in this area [12,13,14]. The current resources in the scientific literature do not provide a broad analysis of this topic; there is a lack of structured knowledge collected in one place. Given their significance, it is surprising to find only a few studies focusing on the operations of start-up accelerators [15,16,17]. This issue is relatively new; thus, a lack of a structured studies on the current state-of-the-art research in relation to this topic is perceptible, as signalled by many authors in their scientific articles [18,19,20,21,22]. For instance, A.C. Carvalho et al. focused on structuring the knowledge on the types and kinds of entrepreneurial support [18]. T. Gutmann, in his study, attempts to structure the issue of corporate venturing [19]. In 2019, M. Guijarro-García et al. conducted an analysis of 21 articles to approximate the current state-of-the-art research regarding start-up accelerators and noticeable trends [20]. In turn, authors such as U. Gür or E.L. Crișan et al. focused their research on technology transfer solutions in corporate accelerators [22] and their role in supporting entrepreneurship [21]. There is a particularly noticeable gap in the reviewed literature regarding the operation of accelerators and acceleration programs focused on start-ups offering innovative solutions to the energy sector. This is all the more puzzling given the significant acceleration of the pace of change in this sector due to initiatives taken at least at the European Commission level.

Given the above, this paper systematises the knowledge on start-up accelerators within the body of available literature collected in the Scopus scientific database and provides new information on start-up acceleration programs in the energy sector. Special focus should be given to the presentation and comparison of three models of cooperation supported by the following case studies: a model of commercial business relationship between the energy corporation and an external accelerator, a model of independent operation associated with setting up a corporate accelerator as an internal structure in an energy company, and a hybrid model.

This paper is structured as follows. The first part is an introduction. The second part presents the research methodology. The third part presents a literature review, an analysis of sustainability aspects raised in the context of start-up accelerators, and an analysis of important characteristics presented by start-up accelerator publications. The next part is a discussion of start-up accelerators in the energy sector, the models developed, and case studies. The last part of the paper contains closing remarks and conclusions.

2. Research Methodology

This paper aims to analyse and systematise the knowledge on start-up acceleration in the context of sustainable development and to provide new knowledge on accelerator models in the energy sector. To attain this goal, the research methodology used in this paper consists of the following steps:

1.

A systematic literature review on start-up accelerators [23]. This methodology was chosen because of its precise and transparent paper-searching process [24]. The paper uses Tranfield’s guidance [25] and adopts main steps:

(a)

Planning the review: In this paper, the authors focus on start-up accelerators and analyse the state-of-the-art research about them. The systematic literature review searched only for articles that use the following terms: a (“startup*” OR “start-up*” OR “startup compan*” OR “start-up compan*”) AND (“start-up* accelerator*” OR “startup* accelerator*”).

(b)

Conducting the review: The authors searched (in title, abstract and keywords lines) for the term “start-up accelerator” or its synonyms in the Scopus database. The database is characterised by high-level publications relative to quality posted therein and has a high reputation in the scientific community. Scopus is one of the most frequently used databases by both theoreticians and practitioners. The authors took into consideration papers written in English appearing in journals, conference monographs, and books.

(c)

Reporting and dissemination: An analysis was carried out on start-up accelerators. According to the guidelines, 81 publications dating back to 2011 to 2021 were obtained. Based on the manual verification of publications (reading whole papers), 76 articles focusing on start-up accelerators and their impacts on the sustainable economy were obtained for further analysis.

2.

In this stage of the study, the analysed publications were classified. The selected 76 articles were coded based on the type of acceleration program or accelerator type they described. Six groups were distinguished: (1) general approach to start-up accelerators, (2) corporate accelerators, (3) seed accelerators, (4) academic accelerators, (5) many types of accelerators, and (6) other types of accelerators.

3.

Then, the authors focused on the analysis of sustainability aspects and material features of start-up accelerators in the context of sustainability aspects raised in 76 publications. This allowed the determination of which aspects of sustainability (economic, social, or environmental) are most often taken into account in this research area. This systematises the knowledge on start-up accelerators and provides an excellent summary of the ongoing literature review in the context of sustainable development.

4.

Acceleration of start-ups in the energy sector: In this research phase three models of cooperation of start-up accelerators with start-ups and corporations were presented: a model of commercial cooperation between the corporation and an external accelerator, a model of independent operation related to the establishment of a corporate accelerator being an internal structure in an energy company, and a hybrid model comprising a mixture of the two previous models. Each of the presented models was supported by case studies of companies operating in Europe.

3. Literature Review

3.1. General Analysis

Under the literature review, the authors covered the 2011–2021 period, when 76 publications were found. Figure 1 shows the publications in each year in the reviewed area. From 2015 to 2019, a steady upward trend can be observed. In the consecutive years, a decrease in interest in the question of start-up accelerators is visible. The likely reason for this is the breakout of the COVID-19 pandemic and the focus of many research areas on this topic. Nevertheless, the number of publications in 2020 overall and the first seven months of 2021 was the same (12 publications) and did not fall below the level recorded in 2019. In the consecutive years, we believe that a return to an upward trend should be expected.

The consecutive figure (Figure 2) shows the geographical breakdown of start-up accelerator research. The highest number of scientific publications on this topic was recorded in the United States (19 publications accounting for 20.21%). However, the majority of publications was written in Europe (58 publications accounting for 61.70%). Research was carried out in 131 international R&D centres. Figure 3 shows the R&D centres that are quoted most frequently in the papers under study. The distribution among numerous continents, countries, and institutions shows that the topic discussed is of global significance and relevance. Additionally, the accelerator programs supporting the development of start-ups implemented by many governmental institutions and accelerators established at universities are factors that underline the significance of this research.

A total of 159 authors wrote papers on start-up accelerators according to the Scopus database (Figure 4). The author who has written the highest number publications on start-up accelerators to date is Dominik K. Kanbach [26,27,28,29]. The runner-up group of authors (Gutmann T., Jackson P., and Richter N.) are authors who have contributed to three publications. Another group consists of twelve authors. Each is involved in two publications. The last group consists of 144 authors. Each has contributed to one publication.

The thematic areas of the publications under study are presented in Figure 5. The publications covered by the study are categorized in 12 research areas. The studied literature is dominated by business, management, and accounting focuses (50 publications). This shows that authors have focused on issues related to the acceleration of start-ups, and start-ups and corporation’s business liaison management via accelerators and the results obtained by doing so play pivotal roles. Consecutive thematic areas include technical studies (25 publications). This may indicate that these papers focused on accelerator programs for technical solutions. This is followed by a series of papers on economics, econometrics, and finance, which highlight the economic efficiency of solutions developed by accelerators. This is followed by social sciences (12 publications), focusing on issues of start-up and accelerator management. The last large set of publications (11 publications) falls into the area of computer science. They focus on the acceleration of new IT start-up solutions.

In relation to their research, the authors of this paper developed a Sankey diagram, shown in Figure 6, supplementing the quantitative data shown earlier with the following: (a) the association of the main authors, (b) keywords, and (c) sources. Flows are expressed in streams, with widths proportional to the popularity of a phrase in its category. At the same time, the total width of the input streams is equal to the total width of the output streams of a given element. The developed diagram shows that, for instance, the most intensively explored aspect of the studied topic was corporate acceleration programs, which is probably driven by the fact that, on the one hand, corporations face the greatest difficulties in sufficiently efficient in-house innovation activities, but, on the other hand, they have the largest resources for acquiring ideas using various forms of open innovation. Consequently, this type is becoming the most common, and along with these types of start-ups research opportunities, research demands are growing.

3.2. Literature Analysis

As accelerators are gaining popularity, many entities such as private organizations, universities, or government agencies decided to run this type of activity. Universities view this as a method to promote student entrepreneurship and an opportunity to connect with industries. Organizations view this method as a way to accelerate innovation and their commercialization. In turn, agencies view this method as a way to create jobs and create favourable conditions for the development of entrepreneurship in the region. Accelerators provide support in the form of mentoring, networking, office space, infrastructure, and, more often than not, additional funding in connection with the identified needs of start-ups. They provide intense workshops and training sessions to support young innovative companies in developing their products, undergoing market validation, and procuring financial resources for further development from investors centred around an accelerator [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45].

The conducted literature research in the field of start-up accelerators resulted in the collection of 76 articles, which were subjected to further analysis. All works were sorted into six groups:

• The general approach to start-up accelerators group comprises papers covering start-up accelerators and acceleration programs of general interest. The authors of these publications will not identify a specific accelerator or acceleration program. This group comprises 22 articles, written by 54 authors from 46 R&D centres located in 13 countries. In total, all publications in this group were cited 125 times [30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53].
• The corporate accelerator category comprises papers covering start-up accelerators and acceleration programs run by multinational corporations. This group consists of 27 articles written by 56 authors from 34 research centres located in 13 countries. In total, all publications included in this category were cited 274 times [19,22,26,27,28,29,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74].
• The category of seed accelerators comprises papers covering start-up accelerators and accelerator programs covering seed activities. The authors of these publications will not identify a specific accelerator or acceleration program. This group consists of 9 papers written by 17 authors from 11 R&D centres that are located in 3 countries. In total, all publications falling into this category were cited 106 times [75,76,77,78,79,80,81].
• The academic accelerators category comprises papers on start-up accelerators and acceleration programs of academic significance. The authors of these publications presented mainly university projects aimed at the implementation of solutions developed at R&D units into industrial practice and supporting entrepreneurship in the academic environment. This category consists of 10 papers written by 23 authors from 10 R&D centres that are located in 8 countries. In total, all publications included in this category were cited 24 times [34,82,83,84,85,86,87,88,89,90,91].
• The “Many types of accelerators” category comprises papers covering start-up accelerators and acceleration programs with a broad view on the subject. The authors of these publications presented many forms of support for start-ups. This category comprises 6 papers written by 11 authors from 18 R&D centres that are located in 7 countries. In total, all publications included in this group were cited 24 times [18,20,21,92,93,94].
• The “Other types of accelerators” category comprises papers comprising new or less popular start-up accelerators and acceleration programs. This category consists of three papers written by six authors from five R&D centres that are located in two countries. In total, all publications included in this category were cited 3 times [29,95,96].

In each of the analysed publications, the authors emphasize the following:

• As most researchers emphasize in their studies, irrespective of the model and the type of accelerator, its functioning contributes to the increase in entrepreneurship and innovativeness in the economy on the local, regional, and macro-scale [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95].
• There are many types of accelerators and acceleration programs, they are considerably diversified, and their mode of operation are embraced in various types of models, which include, among other things, economic or marketing aspects [40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65].
• A prevailing part of the studied papers comprises statistical analyses, case studies, ethnographic studies, interviews, and surveys [34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91].

Within the scope of the typology of programs and accelerators defined by authors, the following significant conclusions were formulated:

1.

In the group of papers referring to accelerators in general [30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53]:

• The research is focused mainly on the priorities of accelerators, and the needs of start-ups are omitted.
• The role of accelerators in the development of entrepreneurship and innovativeness is emphasized, but no criteria are recommended to enterprises for applying for a given accelerator.

2.

Corporate accelerators [19,22,26,27,28,29,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74]:

• The studies note the sources of disturbances of the corporate-start-up collaboration within the frames of the implemented acceleration programs. The main objective of that type of accelerator is not the growth of start-ups but their incorporation. In that model, accelerators perform the function of an intermediary and administrator between a start-up and a corporation rather than an accelerator of a new business.
• The research of the activities taken by corporations with respect to start-ups indicates that their motives result mostly from corporations’ problems with internal innovativeness and/or creation of its culture.
• The conducted research is focused mainly on corporations and, as such, their expectations for start-ups applying for a program.
• A noticeable objective of the research presented in the papers was also to elaborate directions for designing and positioning accelerators with respect to a corporate strategy.
• Start-ups are treated as suppliers of new ideas and projects or potential investment opportunities.

3.

Seed accelerators [75,76,77,78,79,80,81]:

• The essence of this type of accelerator is to support newly established undertakings and, thus, create jobs.
• The research is dominated by the point of view of an accelerator, where the success of a start-up is treated rather as the success of the accelerator itself, indicating the necessity for accelerators to select appropriate projects at the stage of their evaluation.

4.

Academic accelerators [34,82,83,84,85,86,87,88,89,90,91]:

• In light of the research results, academic accelerators primarily play an educational role and act as an intermediary in providing knowledge and stimulating entrepreneurship and innovativeness.
• The problem of those accelerators is the transformation of the ideas and the completion of programs that become real business projects.
• Most undertaken activities concern the creation of accelerator programs by academic environments, their analysis, and modelling to serve as a model for other academic facilities

5.

Many Types of Accelerators [18,20,21,92,93,94]:

• The prevailing approach is to view accelerators as an ecosystem and situate start-ups as one of its elements.
• It is particularly worth mentioning a study in which the authors present a model of an accelerator as a tool for decision makers to decide on the selection of start-ups and their projects. The authors further indicate that start-ups may employ that model to select an adequate accelerator.

6.

Other types of accelerators [29,95,96]:

• A new type of accelerator was identified by the researchers as a start-up supplier, which confirms the objectification of start-ups even more.
• Establishing accelerators founded by family enterprises and impact (social and environmental) accelerators supporting sustainable development is desired.

The literature shows that accelerators and their acceleration programs adopt various forms of support and are determined by the adopted operation mode, i.e., objectives defined by the management and also general rules of procedure of launched entrepreneur support programs. Those programs are often subject to restrictions resulting from the fact that they are funded by public resources. In connection with the above, a statement of characteristic features was developed for the analysed accelerator types, taking into account the following elements: development stage of the submitted solution, identified problems of the team/start-up, form of offered support, and assumed collaboration objectives (

Table 1. Features of the analysed accelerator types.

Class of Accelerators	Development Stage of the Solution Submitted by the Team/Start-up	Identified Problems of the Team/Start-up	Forms of Offered Support and Their Intensity	Objectives of the Collaboration between the Team/Start-up and the Accelerator	Source
General start-up accelerators	Minimum Viable Product a prototype/basic version of the product	Uncertainty as to market demand	Mentoring	Product validation	[30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53]
	A program with various thematic paths	Lack of financial resources (problems with financial liquidity)	Networking	Procuring financial resources
		Lack of human resources (poorly coordinated and incomplete team)	Access to office space	Providing for an organisational structure
			Additional financing	Confirming the business model
			Moderate intensity of activities	Achieving sales readiness of the product/service
				Gaining a reference client
				Access to investors centred around the accelerator
				Promotion
Corporate accelerators	Product market fit—the product fits the needs of the market in which the corporation operates	Other investment needs	Access to infrastructure and a testing environment	Gaining and broadening technical expertise	[19,22,26,27,28,29,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74]
	The product/solution fits an industry-related acceleration program		Industry-related mentoring	Access to the market
			Partnership with a corporation	Scaling sales
			High intensity of activities	Commercial co-operation
				Optimising the sales channels
Seed accelerators	The product is at the prototype stage and may be used	No sales	Mentoring	Procuring first paying clients	[75,76,77,78,79,80,81]
	A program with thematic paths	Uncertainty as to market demand	Networking	Confirming the business model
		Lack of financial resources (problems with financial liquidity)	Access to space	Access to investors centred around the accelerator
		Lack of human resources (poorly coordinated, incomplete team)	Additional financing	Promotion
		Lack of required permits (if applicable)	Moderate intensity of activities
Academic accelerators	The solution is at the stage of idea	Lack of business model	Mentoring		[34,82,83,84,85,86,87,88,89,90,91]
	Basic assumptions of the product/service operation were verified	Lack of tested solution (it is uncertain whether the market will accept the product/service)	Access to space
			Access to research and development infrastructure
			Access to research personnel
			Low intensity of activities
Many types of accelerators	A product/service at an early development stage	An inadequate pricing model	Mentoring	Confirming the business model	[18,20,21,92,93,94]
	A program with thematic paths	Low product/service utility	Networking	Development of the product/service
			Access to space	Expansion into new markets
			Additional financing	Expansion into new markets
			Low intensity of activities	Access to investors centred around the accelerator
				Promotion
Other types of accelerators	A product/service at various development stages	A new direction for development of the product is searched for without changing the activity (pivot)	Mentoring	Product presentation	[29,95,96]
	A program with thematic paths	An inadequate pricing model	Networking	Development of the product/service
		Low product/service utility	Access to space	Confirming the business model
			Additional financing	Access to the market
			Low intensity of activities	Access to investors centred around the accelerator
				Promotion

).

In the literature, there is a research gap related to the role of start-ups in the accelerator ecosystem. Research studies are conducted mainly from the point of view of accelerators or corporations themselves. They make little reference to start-ups and investors themselves (venture capital funds and business angels). With respect to corporate accelerators, it is justified as corporations may also act as investors; with respect to other types of accelerators, there is no such justification. It was observed that a great number of analyses was devoted to success factors in terms of the quality of submitted projects and the mechanisms of operation and management of accelerators, but on the other hand, little attention is given to other participants. Thus, attempts to embrace the accelerator operation model require learning the needs of all collaborating entities to a similar degree. As emphasized by the researchers themselves, the quality of acceleration processes is relevant to the success of new undertakings.

These processes are driven by the occurrence of strengths, weaknesses, weaknesses, and communities that affected start-up workers (

Table 2. Strengths, weaknesses, opportunities, and threats of the analysed accelerator types.

Class of Accelerators	Strengths	Weaknesses	Opportunities	Threats	Source
General start-up accelerators	Co-operates	Rapid changes in institutions implemented by start-ups	Updating the business model	Collecting, processing, and sharing information about projects and companies participating in them	[30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53]
	Maximizing the likelihood of a start-up’s success	Transaction and bureaucratic costs	Investment risk reduction	Information policy
	Know-what, know-how, and know-who	Insufficiently strong ties between partners to effectively commercialize technologies and promote them effectively	Developing an official start-up incubation policy	Bad decisions can damage the accelerator’s reputation
	Innovation	No specialization of accelerators in a specific economic sector	Digitization
	High level of knowledge unattainable in traditional cooperation	The large number of supported acceleration programs may affect the quality of acceleration	Generating more businesses
	Business education and mentoring	No prioritization of activities	Increasing the number of full-time employees
	Undertaking activities that disseminate ideas and experiences to create breakthrough change	Carrying out many activities at the same time that do not bring expected results	Educating enterprising engineers who will have the potential to establish innovative start-ups
	Strengthening human capital through social capital	There are no schemes for selecting business partners	Sustainable growth of start-ups
Corporate accelerators	Open innovation	No prioritization of activities	Organizational culture	Collaboration can be disrupted by conflicts over beliefs, authority, personal goals, and competition	[19,22,26,27,28,29,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74]
	Development of new technologies	Mentoring	Tips for managers
	Large network of committed external partners	Networking	Emphasis on the greatest possible use of start-up innovativeness
	Development of knowledge and skills		Faster product development and product sales
	Competitiveness		Checklists
	Increasing innovative performance		Reduce resources and risk while maximizing the chances of reaping the benefits of innovation
	Fast flow of information Specialization of accelerators in a specific economic sector		Guarantee that the interests of start-ups and corporations align
			Faster market entry
Seed accelerators	Development of technology and entrepreneurial ecosystems	Lack of experience of entrepreneurs	Taking into account geographical and cultural specifications	Information policy	[75,76,77,78,79,80,81]
	Access to the resource network	Emphasis on management skills	Real-win-worth table
	New work places		Tips for policymakers, shareholders, entrepreneurs and investors on development prospects
	Prioritizing criteria when selecting projects		Cohesion
			Quick market debut
Academic accelerators	Partnership between universities and business	Little business experience	Inter-university expansion	Acceptance of business failures	[34,82,83,84,85,86,87,88,89,90,91]
			Activation of entrepreneurship of young people	The conflict between the information collected from clients and the authority of entrepreneurs
	Using digital channels to develop business ideas		Motivating innovation among scientists and students
	Classification of projects		Attracting talent
	Formulated set of design parameters		Digitization
Many types of accelerators	Pipeline model	No prioritization of activities	Organizing knowledge about supporting start-ups	Information policy	[18,20,21,92,93,94]
	Innovation		Identifying the future challenges of acceleration programs
Other types of accelerators	Economic development	The large number of supported acceleration programs may affect the quality of acceleration	Access to innovation	High profit orientation	[29,95,96]

). The analysis aims to ensure that the utilised accelerators are focused on research, and the acceleration of start-ups is recommended for development and for eliminating weaknesses and management. The search results, weaknesses, and threats are results of ineffective activities that may lead to activities aimed at a smooth strategy. Therefore, weaknesses and threats must be systematically reduced, and the risks associated with the power of accelerators and development plans must be eliminated by launching. The diagnosis of the strengths of start-up accelerators is aimed at identifying tendencies and phenomena that need to be acquired, because they can become stimuli for development. It should be mentioned that in carrying out the analysis, reference is made to virtual enterprises that can have an impact on actions, and accelerators and enterprises carry out the action. Solutions for appropriate solutions and solutions for specialists and solutions were taken.

3.3. Analysis of Sustainability Aspects and Material Features Appearing in the Publications about Start-Up Accelerators

In the next phase of the analysis, the authors focused on analysing aspects of sustainable development mentioned in the publications on start-up accelerators. The analysis allowed grasping which aspects of sustainability (economic, social, or environmental) are most often taken into account in this research area. Such a presentation requires an analysis of the available literature to indicate what aspects are most often taken into consideration. In addition, on the basis of the literature review, the authors analysed relevant features in the context of sustainability aspects on which the examined publications focus. This allowed the systemization of knowledge in the field on start-up accelerators and provides an excellent summary of the carried out literature review.

Table A1. Analysis of sustainability aspects and material features in publications about start-up accelerators.

		Aspects of Sustainable Development				Analysis of Important Features Appearing in Publications
Group	Publication	Economic	Social	Environment	Total	Accelerator	Start-up	Entrepreneurship	Innovation	Corporate Accelerator	Incubator	Start-up Accelerator	Open Innovation	Engineering	Ecosystem	Education	Corporate Entrepreneurship	Corporate Venturing	Accelerator Projects	Design	Venture Capital	Investment	Seed accelerator	New venture	Innovation management	Student	Lean Start-up Methodology	Academic Start-up Accelerator	Accelerator Design	Business Idea	Commerce	Corporate-Start-up Collaboration	Engineering Education	Internet of Things	Best Practices	Established Firm	Value Proposition	Entrepreneurial Ecosystem	Entrepreneurship Education	Total
General Approach to Start-up Accelerators	[30]	X			1	X	X					X							X	X							X		X											7
	[31]	X	X		2		X	X	X																															3
	[32]	X			1	X	X					X																												3
	[33]	X			1	X	X																																	2
	[34]	X	X		2	X		X																							X									3
	[35]	X			1	X	X	X													X	X	X																	6
	[36]		X		1			X			X			X		X										X							X							6
	[37]	X	X		2		X	X																																2
	[38]	X	X		2			X	X																															2
	[39]	X	X		2	X	X	X				X				X				X							X													7
	[40]	X	X		2	X	X				X												X																	4
	[41]	X			1	X		X							X																							X		3
	[42]	X	X		2		X																																	1
	[43]	X			1	X	X	X						X					X	X				X																7
	[44]	X	X		2	X		X	X				X																					X						5
	[45]	X	X		2	X	X																																	2
	[46]	X			1																									X										1
	[47]	X	X	X	3	X		X							X																							X		3
	[48]	X	X		2		X	X								X											X			X									X	5
	[49]	X			1	X	X	X				X									X																			5
	[50]	X	X	X	3				X						X																			X						3
	[51]	X			1	X	X					X										X																		4
	[52]	X	X		2				X							X																								2
	[53]	X	X		2	X	X		X																															3
Corporate Accelerators	[54]	X			1	X	X																																	2
	[55]	X			1			X	X					X											X						X									5
	[26]	X			1	X	X	X		X							X																							5
	[56]	X			1	X	X	X	X	X	X		X					X																						8
	[57]	X	X		2	X	X		X	X			X																											5
	[58]	X	X		2	X	X		X		X		X																											5
	[59]	X			1	X	X			X					X																									4
	[60]	X			1	X		X	X						X					X					X				X											7
	[61]	X			1	X	X	X	X	X							X															X								7
	[62]	X			1	X			X				X	X				X																		X	X			7
	[63]	X	X		2		X																																	1
	[64]	X	X		2	X			X	X																														3
	[19]	X			1			X	X				X				X	X							X															6
	[27]	X			1	X		X		X							X	X																						5
	[65]	X			1	X	X		X	X	X																			X							X			7
	[66]	X			1	X	X		X	X			X											X												X				7
	[67]	X			1	X	X		X	X			X		X																									6
	[68]	X			1	X	X	X	X	X							X															X								7
	[69]	X	X		2									X								X									X									3
	[28]	X			1	X	X			X								X																						4
	[70]	X			1	X		X	X	X	X			X			X		X																					8
	[29]	X	X		2	X				X										X									X											4
	[71]	X			1	X			X	X			X																											4
	[22]	X			1	X	X			X		X																												4
	[72]	X			1	X	X		X	X															X															5
	[73]	X			1		X		X				X																			X								4
	[74]	X			1	X		X	X	X							X	X																						6
Seed Accelerators	[75]	X	X	X	3		X	X	X																															3
	[76]	X	X		2	X	X																																	2
	[77]	X			1	X	X	X	X		X										X	X																		7
	[78]	X	X		2	X	X	X			X	X							X	X			X	X																9
	[79]	X			1	X	X	X	X		X												X																	6
	[80]	X			1	X	X	X													X		X																	5
	[81]	X			1	X			X	X																														3
Academic Accelerators	[82]	X	X		2			X																																1
	[34]	X	X		2	X		X																							X									3
	[83]	X	X		2						X			X		X										X							X							5
	[84]	X			1	X	X																																	2
	[85]	X	X		2		X	X			X			X		X																	X	X						7
	[86]	X	X		2	X	X	X				X																X							X					6
	[87]	X	X		2	X	X	X				X		X		X			X							X		X							X					10
	[88]	X	X	X	3	X	X	X				X				X																								5
	[89]	X	X		2	X	X	X				X		X					X								X													7
	[90]	X	X		2	X	X					X																X												4
	[91]	X	X		2			X							X											X														3
Many types of Accelerators	[18]	X			1	X																																		1
	[92]	X			1	X	X	X							X																									4
	[20]	X			1	X	X	X		X	X	X									X																			7
	[93]	X	X	X	3	X										X																								2
	[94]	X			1	X	X				X				X																									4
	[21]	X			1	X	X	X			X				X							X																		6
Other types of Accelerators	[95]	X			1		X		X				X					X						X																5
	[29]	X	X		2	X				X										X									X											4
	[96]	X	X	X	3	X																																		1
	Total	75	35	5		55	48	38	29	20	14	13	11	10	10	9	7	7	6	6	5	5	5	4	4	4	4	3	3	3	3	3	3	3	2	2	2	2	1

(Appendix A) presents the full and complete analysis.

Out of 76 analysed publications, as many as 75 considered the economic aspect of sustainable development, 35 considered the social aspect and only 6 considered the environmental aspect. Only the authors of five publications considered all aspects of sustainability simultaneously [47,50,75,88,93,96].

The environmental aspect of the publications focuses primarily on the impact of technological developments with respect to the natural environment. The authors pay attention to activities compliant with the sustainable development concept. Acceleration programs for environmentally friendly solutions play an important role [47,50,75,88,93,96].

Attention is also focused, to a large extent, on the social aspects associated with accelerators [40,52,53]. The significance of accelerators as a key factor in social learning [39,76,78] and their relevance in educational development is highlighted [52]. The role of accelerators [36,86,87,88,89] as an important element in developing entrepreneurship and innovation by combining expert and business knowledge is recognized and studied. Providing access to internationalisation tools as well as investors and funding [26,37,39,41,69,74,75,82,83,85,92] also contributes to this end. The key to the functioning of accelerators is collaboration in accelerators and the mechanisms of their operation [39,45,47,57,58,61,63,64,67], contributing to the development of entrepreneurship and innovation ecosystems [19,35,38,44,47,48,50,75,76,85,90,91,96]. The authors emphasise that accelerators are not only used by corporations or start-ups for business purposes but also to finance projects with high social relevance for sustainable development as in the case of health care [38,50] or the activation of urban areas [93]. Much attention is also paid to social drivers of start-up accelerators, particularly the impact of the culture prevailing in a certain region on the development of accelerators [31,53,75] and relations with government bodies and agencies [42,45,50]. The way accelerators contact communities, through the choice of a digital marketing strategy that enables accelerators to enhance their social added value, is highlighted [34,69].

In the economic aspect, the authors refer to the profits generated by start-ups carrying out commercial activities under accelerator programs [41,48,55,82,92,96] and the success of companies cooperating with accelerators in a broad sense [30,36,58,59,62,63,64,69]. Attention is paid to the effectiveness of acceleration programs implemented both from the perspective of enterprises and investors [32,33,45,51,70,71,76]. Many authors emphasise the importance of the availability and effectiveness of their use within the implemented programs and the significance of their accessibility for the development of innovation and entrepreneurship [28,42,47,49,55,57,60,70,72,73,78,80,90]. Business models are being developed [31,39,40,45,47,55,75,77,86,88,92], as well as models explaining the operation of accelerators and the processes taking place in them and the interaction between accelerators and the environment [21,22,49,52,67,68,79,87,89,90,91,95], which enables the transfer of good practices to other countries. These models help mitigate the project risks related to investment projects and start-up failures [30,55,57]. The relationship between accelerators and their impact on development [47,52,76,82], employment levels, and job creation [31,37,39,40,56,58,79] is studied and analysed. In this respect, research is carried out both across local, regional, national, and international markets [18,29,42,44,75,76,84,94]. The aim of this research is to determine, beyond cultural and social influences, the influence of economic and institutional factors on the development of start-up accelerators [37,93]. The growing efficiency of accelerators enhances, according to the researchers, the competitive edge of the economy and its long-term growth [27,34,84,95]. The technological aspect is important both in the context of the operation of accelerators themselves, as well as the industries and sectors in which accelerators are particularly strong and their impact on the creation and development of new technologies [22,45,46,47,54,56,59,69,70,75,78,85].

The research carried out mainly focused on the significance of accelerators for entrepreneurship, innovation, collaboration with business [19,20,21,26,27,29,31,34,35,36,37,38,39,41,43,44,47,48,49,50,51,52,53,55,56,57,58,60,61,62,63,64,65,66,67,68,70,71,72,73,74,75,77,78,81,82,85,86,87,88,89,90,91,92,95] (comprising 67 items), and start-ups [18,20,21,22,26,27,29,31,35,36,37,38,40,44,45,46,48,49,50,51,53,55,56,57,59,60,62,64,65,67,69,72,73,74,75,76,77,78,79,80,83,84,85,86,87,88,89,91,94,95] (48 items in total). The relevance of the accelerator’s model to the type of projects supported and the life cycle phase of enterprises [28,35,41,42,48,57,60,63,64,77,86,88], i.e., 18 items from the publications, were also analysed. An important area of research is the mechanism of accelerator operations. Attention is drawn to related problems concerning the effective selection of projects for accelerator programs, relations with investors, and the evaluation of the effectiveness of the programs themselves [19,30,39,41,48,53,54,57,60,64,67,75,80,82,84,85,86,88]. Numerous studies focused on case studies on such program operations and aim to develop models that could be used by emerging programs and companies planning to use this form of venture funding [29,30,36,38,44,47,48,50,53,57,60,65,67,74,75,76,77,79,85,86,87,88,89,95]. Much attention is also focused by the authors on the projects themselves and the factors affecting their quality, noting the significance of academic accelerators in the process of their creation [19,21,22,26,28,30,33,35,36,37,41,43,45,47,54,56,57,61,64,68,74,75,77,78,80,82,84,85,86,87,89,91,95]. Via accelerators, companies have opportunities to develop a project and transform it from a concept to a commercial venture and can marketize it. Researchers highlight the impact of accelerator programs on macroeconomic aspects such as the labour market, regional development, and technological aspects [44,50,85]. The analysis shows that the main focus of research is the relationship between originators and accelerators, enterprises, and accelerators to a lesser extent between investors and accelerators [19,20,21,22,26,27,28,29,30,32,33,34,35,36,37,38,39,40,41,42,43,44,45,47,52,55,57,59,61,62,64,91,95,97]. The examples of academic incubators and accelerators presented in the research also illustrate well their importance in facilitating the flow of knowledge between business and academia [30,54,61,64,66,82,84,86,90].

Based on the literature review carried out above, an accelerator ecosystem model emerges. Its participants are investors, companies, accelerators themselves, originators, and the market. The relationships between them are presented in Figure 7.

The type of interactions taking place between participants in light of the literature research can be described as follows: (1) the presentation of ideas in the accelerator program and their selection; (2) attracting investors and the evaluation of ideas and teams by investors; (3) the validation of the solution with respect to the corporation’s infrastructure and acquiring funds for the implementation of the idea in the business sphere; (4) the marketization of the concept, including expansion and scaling of the solution [27,28,37,56,58,66,76,80,90,94].

The authors of the analysed papers focused their research on accelerators, thanks to which the originators—which can be either companies, start-ups, or projects coming out of universities—can develop the offered solution and obtain funds for financing the project [36,39,53,60,74,75,77,78,79,80,91] and scaling it up.

4. Start-Up Acceleration in the Energy Sector

Due to a perceived gap in the literature related to the lack of analysis of the functioning of the offered support for the acceleration of solutions in the energy sector, the authors decided to examine this question by presenting main forms support offered on the market in this area. They compared models of accelerator operation on the example of case studies of large players in the energy market in Europe.

Start-ups in the energy sector work closely with investors, technology providers, and funding agencies [97]. Large energy market players recognise the increasing value of external innovation projects to improve innovation processes within the organisation [11,98]. Consequently, in recent years, energy sector giants engaged in activities to support start-ups by creating their own accelerator programs or joining as a partner of existing accelerator programs. The acceleration program is a form of support that plays an Important role in the initial stage of a start-up’s development. Investments are characterised by a limited duration [99]. The purpose of the program is to accelerate the creation process, the implementation of products, and to increase the sustainability of the start-up [78]. Most acceleration programs guarantee start-ups: intensive mentoring, the possibility to cooperate with corporations, and a shorter time to raise capital from investors [41,99].

In contrast, a hackathon is a short, intensive event where participants develop innovative products, services, and solutions. Participants develop innovations in interdisciplinary teams [100]. A hackathon is a type of competition [101]. The event lasts from one day to even a week [102]. A hackathon refers to the implementation of a project from the concept phase to a working prototype that meets the key objectives and expectations of future technology adopters. The creators develop an innovative business model for the solution and have an opportunity to test the innovation using start-up working methods [100].

Another type of support is corporate venture capital (CVC), which is an equity investment by corporations in start-ups and is treated as a corporate investment vehicle in companies. Corporations allocate funds for investment and are entities that indirectly influence investment decisions [103,104]. The purpose of CVCs is financial returns on investment [105] and “exposure to new technologies and markets”, according to managers of CVC programs [106].

Meanwhile, corporate venture building (CVB) is an alternative solution for large corporations interested in bringing innovation to the organisation. Compared to corporate venture capital, CVB involves building a solution from scratch [107]. Venture building involves the establishment of an independent entity by a corporation to act as an innovation centre. The CVB allows the start-up to leverage speed, flexibility, and agility [108]. In turn, the management team has large corporate resources at its disposal, which guarantees fast and agile decision-making (without the barriers of corporate hierarchy) [109].

4.1. Model of Cooperation between an Energy Corporation and a Third Party Independent Accelerator

In this model, the corporation cooperates with an accelerator, for which its aim is to support start-ups by providing conditions for the rapid development of the designed or offered solution and its testing in conditions similar to real ones (e.g., in a test environment or on a small sample of consumers, e.g., retail buyers of electricity). Accelerators under this model provide multifaceted support and mediation between start-ups and corporations (Figure 8). Accelerators are the link between corporations and start-ups because of the differences between corporations and start-ups. Accelerators create space to reduce and/or eliminate barriers to cooperation with corporations. Organisations are specialised in acceleration processes and have proprietary start-up support programs. Many energy corporations lack experience in acceleration activities and knowledge about start-ups, which is why they choose to cooperate with an external accelerator [66]. The cooperation of the corporation is mainly focused on facilitating the development of the solution offered by the start-up by providing their own industry experts and possibly providing test infrastructure. On behalf of corporations, accelerators recruit start-ups from the market, usually according to the expectations and challenges defining the needs of the corporation [110]. The acceleration program lasts for a set period of time and additionally provides workshops, pilot implementation, funding, and support from accelerator mentors at each stage of the acceleration process [111].

An external accelerator has its own board and team dedicated to working with start-ups [112], and it has its own leaders experienced in launching, funding, and scaling a start-up.

An example of such cooperation is the involvement of the Tauron Group (a key player in the energy sector and an important link in Poland’s energy security system) in an external acceleration program operated by the Kraków Technology Park (KPT ScaleUp). KPT ScaleUp is a program that supports start-ups from the area of Industry 4.0. The program guarantees support, mentoring, pilot implementation, financing up to EUR 50K, and the possibility of cooperation with a large energy company. Start-ups that want to take advantage of the offer must have at least a prototype solution and has not been on the market for more than 5 years [110].

The Equinor & Techstars Energy Accelerator, on the other hand, is a global, 13-week accelerator program operating in the energy sector. The program combines support from the international consultancy company Capgemini and a partnership with Equinor (a broad energy company with more than 21,000 colleagues committed to providing affordable energy for societies worldwide and taking a leading role in the energy transition). Equinor’s corporate partnership with Capgemini and Techstars aims to streamline start-up development by providing access to more than 100 mentors and energy-sector experts from around the world, and this is hosted at the Equinor office and supported by Capgemini consultants. The program supports companies with solutions that contribute to helping the energy transition. The program focuses on four thematic areas: energy generation, net zero future, digital and operational enablers, and disruptors [113].

4.2. A Model for Setting up an In-House Structure in an Energy Company as a Corporate Accelerator (Model In-House Accelerator)

Corporate accelerators (Figure 9) can take different forms of operation, the most common being a dedicated innovation centre. The common feature in this model is the direct use of corporate assets to influence the faster implementation of start-up innovations in the corporation [112]. The priority of the corporate accelerator in this case is not profit but more importantly the development of innovation in the corporation and the added value for the portfolio companies from the supported start-ups [12].

Corporate accelerators differ from accelerators developed by private investors, universities, or public institutions [114]. Corporate accelerators are programs characterised by a limited duration and selective collaboration with start-ups. The programs are created and run as part of a corporate entrepreneurship strategy. Corporate accelerators, in addition to providing direct and indirect financial support, strive for self-development and support the energy and digital transformation of corporations [26]. Via acceleration, corporations strive to realise strategic objectives related to corporate rejuvenation and the acquisition of innovative solutions, sometimes including start-up employees [74]. What corporations have to offer, inter alia, is direct access to the resources of the energy company, including the organisation’s financial resources, a strong brand and market recognition, sales channels, and a large customer and supplier base, often numbering in the tens of thousands of energy consumers [112]. A corporate accelerator involves corporate stakeholders in its activities. Executives (e.g., directors of business units interested in new technologies) are involved in the selection process of start-ups. The involvement of executives involves the selection of projects that should contribute to the improvement of the corporation in different spheres of activity, e.g., customer service, sales, research. Corporate experts offer intensive support for start-ups in product development [12]. In a corporate accelerator, one can notice a barrier in the form of the mentoring offered. This is due to the fact that experts are usually experienced corporate employees who do not necessarily have experience in scaling a start-up’s solution [112].

A market example of such a model is the ORLEN Skylight accelerator, which is a program run by Polski Koncern Naftowy Orlen Spółka Akcyjna (integrated multi-utility company that operates in Central Europe and Canada: provider of energy and fuel to over 100 million of recipients). The acceleration process lasts approximately 6 months and consists of three phases: the recruitment and selection of projects for the accelerator, signing a contract, and piloting [115]. The accelerator offers benefits such as: funding for technology development, pilot implementation (testing and scaling the innovation on the company’s infrastructure), and expert support. Orlen offers knowledge exchanges within business lines of the PKN Group and provides networking with relevant employees. The biggest advantage of the accelerator is the possibility of further commercial cooperation after the end of the acceleration with the business units of the corporation [116]. The company aims to accelerate start-ups that respond to current business challenges. It seeks solutions from start-ups that link their activities to Industry 4.0, methods for removing pollutants from industrial wastewater, automating gas station services with robots, and using sustainable packaging methods [117].

Meanwhile, the Enel Start-up Supports accelerator was developed to drive energy transformation through open collaboration with start-ups, investors, industry leaders, researchers, and internal and external experts [118]. Enel (Italy’s national entity for electricity) offers the scaling of an innovative solution on an international scale using a global corporate network after the testing phase. Enel leverages the Enel Open Innovability team and global centres and laboratories. Enel Open Innovability is integrated into all business lines in the Enel Group. In order to identify the best projects, managers systematically search for new business solutions. The centres and labs work with start-ups and the SME sector. The cooperation results in new technological solutions and pilot projects. Access to the corporation’s centres, labs, mentoring, database, and customers influences the start-up’s development throughout the acceleration process. In order to accelerate a start-up’s development path, Enel uses a simplified qualification, a standard and flexible contract, upfront funding (30% down payment upon signing the contract), reduced payment times, and further support after a successful PoC at the corporation [119].

4.3. Mixed Model of Cooperation between Energy Companies and Start-ups (MIX Accelerator Model)

The MIX accelerator model (Figure 10) is characterised by a combination of the energy company’s management of its own acceleration program according to the model described in Section 4.2 and, in addition, its involvement in collaboration with independent, external accelerators. The model aims to combine development activities for the start-up and to provide a relationship between the corporate accelerator and the collaborating external accelerator. An external accelerator provides a proven acceleration program with a defined structure, leaving freedom for the corporation to adjust its own preferences. The tasks of the external accelerator include screening and scouting activities, while the corporation usually decides on the selection of the start-up for acceleration and takes over the main cooperation with the start-up on the development of the innovative solution. The MIX model is perceived by energy corporations as increasing the chance of acquiring a larger number of valuable projects that fit the needs of the technology recipient. Thus, cooperation under the mixed model is perceived as supporting innovative activities of corporations.

The Polish Oil and Gas Company (Polish acronym PGNiG) is a leader in the Polish natural gas market, operating in the exploration for and production of natural gas and crude oil. The company offers cooperation to small- and medium-sized enterprises, including start-ups, through its own corporate acceleration program InnVento. The aim of this program is to connect established multinational corporations with start-ups by offering support to micro-companies and small companies. The accelerator guarantees support from external mentors and its own experts and provides office space and access to databases and business units of the corporation. In addition, support is offered in the areas of law, accounting, and obtaining financing [120]. The accelerator program targets projects that demonstrate a competitive advantage over current solutions on the market. The solution submitted by the start-up must have at least a fabricated prototype of the solution and an implementation potential in the corporation. The corporation focuses on the following topics: new RES technologies and systems, digital technologies, natural gas extraction materials and technologies, and new energy sources and environmental protection in the energy sector [121]. The Polish Oil and Gas Company, in order to support small- and medium-sized companies, and previously mentioned InVento additionally cooperate with external accelerators such as Space3ac and IDEA Global—Huge Tech [122]. The joint program under the model aims to provide funding for the pilot, as well as testing using the infrastructure of a major energy company [123]. In the mixed model, the corporation also interacts with an external accelerator managed by the Kraków Technology Park. The organisations create a joint program that is geared towards helping start-ups in the areas of IoT, AR/VR, artificial intelligence, robotics and automation, and energy efficiency. Start-ups can benefit from funding, workshops, and mentoring [124].

4.4. Classification of Energy Accelerator Models

In relation to the noticed gap in the literature of the presented models of operation of acceleration programs in the energy sector, in the

Table 3. Comparison of corporate accelerator models in the energy sector.

	Independent Accelerator Model	In-House Accelerator Model	Hybrid Accelerator Model
Advantages	a proven highly renowned accelerator program and recognition in the marketplace corporation reliance on the experience of an external accelerator an accelerator program independent of the corporation in terms of the corporation’s complex procedures taking advantage of the existing start-up ecosystem financially efficient for corporations, including low costs for verification of start-up projects cooperation not only with corporate experts but also with accelerator mentors low entry and exit barriers into/from the accelerator program ability to work with several accelerators at the same time rapid launch of acceleration program due to use of external accelerator resources low entry and exit barriers into/from the accelerator program	full control over the program and development of the start-up seamless integration with corporate business lines, including easy access to the internal corporate network an option of continuous observation of the start-up team and monitoring of product, service development decision-making capacity in every aspect introduction of a start-up culture into corporations strong association of the start-up with the corporation and the brand strengthening the market position and brand development of the corporation develop your own tools to support the project’s acceleration process achieving its own strategic objectives	a greater flow of information and market good practice low entry and exit barriers for corporations no restrictions on interfacing with accelerators taking advantage of existing accelerator programs and the start-up ecosystem the opportunity for corporate employees to quickly learn how to work with start-ups cultural exchange start-ups between and internal matters greater sourcing of projects
Disadvantages	less control over the structure of the accelerator program and the development of start-ups limited decision-making capacity and prolonged decision-making process delays in communication with the start-up team more difficult cooperation and integration with corporate business units	increased capital expenditure for the organisation of the program and administrative support the need for changes in the company’s organisational structure increased time required to set up the program a strong commitment from the corporation and its business units high risk of losing resources (in case of failure) risk of negative PR due to failure of start-ups less interest from start-ups in participating in the program due to support provided solely by the corporation	limited control over program structure and start-up development high operating and maintenance costs possible delays due to large number of projects preference for start-ups participating in a program organised by a corporate accelerator over start-ups provided by an external accelerator

below, the authors discussed the advantages and disadvantages of start-up acceleration models. The presented overview of the model will help the management of the energy company to make an informed decision on choosing the right model of accelerator operations. Three different corporate accelerator models were identified.

As the above tabular overview shows, there are not only many similarities but also significant differences between the described models. There are noticeable differences in the number of projects filed under the accelerator programs, the management structure of accelerators and the influence of corporations on ongoing programs, the pace of starting-up, and the provision of financial and organisational resources. The above findings provide practical implications for managers in terms of a deliberate decision on choosing the model of cooperation between a large energy company and start-ups.

5. Closing Remarks and Conclusions

The aim of this study was to present the state-of-the-art findings on the operation of start-up accelerators and their impacts on aspects of sustainable development based on resources retrieved from the Scopus database (76 papers) written between 2011 and 2021. Analysing the state-of-the-art findings of the issue under study, the important role that accelerators play was highlighted in the start-up ecosystem and in terms of how they operate in the energy sector, which is considered relatively conservative and difficult to access for innovation. The distribution of accelerators and the programs they run shows that the topic in question has global relevance and is important as a contributor to the success of start-ups, technology transfer, and commercialisation of solutions. The major goal of young innovative companies is to find a repeatable and scalable business model. Therefore, numerous start-ups try to cooperate with accelerators present on the market, counting on their support offered under acceleration programs, which offer a chance to accelerate the development of their technology companies. Accelerators provide assistance not only during the development of the solution offered by start-ups but also by providing support from mentors and experts, acting as a bridge between the world of start-ups and large corporations, including those from the energy sector. Furthermore, accelerators, acting as market makers, fill the funding gap for start-ups and the information gap for potential technology buyers and investors.

The research carried out has shown that the market offers a wide variety of models for corporate involvement in cooperation with start-ups, and corporate accelerator programs in particular. A significant relationship between the functioning of accelerators and economic aspects is noticeable, particularly in terms of the results obtained in the framework of acceleration programs, as well as cooperation with investors. Via the ecosystem, accelerators not only influence social and environmental conditions but also actively meet expectations and trends related to sustainable development by creating programs not only dedicated to business development. Thanks to accelerators, it is possible to develop and finance innovative projects in all areas of the economy; in this way, they create added value not only in the economic area but also in social and environmental areas. From the literature research carried out, an image of start-up accelerators emerges as a new model for start-up financing and development, combining sustainable development aspects as well as a model conducive to the development of enterprises striving for sustainable growth. On the grounds of the literature review, the authors made a tabular analysis of features that are the focus of publications, along with an examination of sustainable development aspects in economic, social, and environmental contexts. It should be noted that of the 76 publications analysed, as many as 75 considered the economic aspect of sustainable development, 35 considered the social aspect, and only 6 considered the environmental aspect, which focused on the impact of technological development on the natural environment.

The analysis carried out further revealed the following interesting findings:

• A growing trend in the number of publications, especially from 2015 onwards;
• Most publications to date have been written in Europe, with efforts in this area carried out in over 100 R&D centres;
• Within the defined twelve (12) thematic areas, the largest number of publications relates to business, management, and accounting (50 publications);
• The developed Sankey Diagram supplemented the quantitative data collected as links among major authors, keywords, and sources;
• Scientific articles published in journals represent the vast majority of published content in the Scopus database;
• Practically speaking, all analysed publications dealt with the question of sustainable development (economic, social, and environmental aspects).

The authors defined an accelerator ecosystem model with the following elements identified: (1) the acquisition of projects along with their selection, (2) investors and their involvement in the project development process, (3) the validation of the solution on the infrastructure of the corporation (the beneficiaries of the start-up’s solution) along with fundraising for further project commercialisation in cooperation with a large enterprise, and (4) the marketization of the solution offered by start-ups with the support of accelerators, including further expansion paralleled by product or service scaling. The accelerator market itself is young and still leaves much room for the development of new operational models. Thus, there is no single recipe for an optimal accelerator program. The analysed publications indicate different approaches to the development of tools with the aim to support start-ups. Differences include the start-up development phase, the readiness of the start-up’s product or service, the duration and intensity of the support offered, funding, equity subscription, market fit, and how start-ups comply with the expectations of corporations and accelerators. These differences are considered to be of great importance for the ultimate success of parties involved in accelerator programs.

In addition, the analyses identified a gap in the acceleration activities provided to start-ups by the energy sector. The research provides little information on the prevalence and characteristics of corporate accelerator programs targeting the energy sector. They do not provide support for corporate entities. The results of the undertaken research will help large energy businesses choose an appropriate model for an acceleration program and help such programs differentiate themselves from their competitors in the market. Accordingly, the authors identified various models of energy companies focused on working with start-ups in the market, which have different strengths. Three models of such cooperation were distinguished: (a) a model of cooperation between energy corporation with a third-party independent accelerator (independent model), (b) a model of independent operation of a corporate accelerator as an in-house unit within the energy company (in-house accelerator model), and (c) a hybrid model of cooperation of an energy company with start-ups (hybrid accelerator model). Specific differences in the operation of the above models, as well as their advantages and disadvantages, are presented in a tabular layout. Each model described differences, inter alia, in the costs of running an acceleration program, the flow of information between the parties to the program, the impact on the acceleration program, its management structure, and decisions made in connection with the program. According to the authors, large energy companies can opt for any model of cooperation with start-ups. This is mainly due to their ability to provide financial and human resources. Managers should take into account when making their decision that the required resources will vary a great deal depending on the chosen model. The in-house accelerator model will require significantly more time and financial resources than operating under the model of cooperation between an energy corporation and a third-party independent accelerator. Similarly, managers should be aware that in choosing an accelerator model, start-ups, when deciding to submit a project to an accelerator program, are guided not only by the company’s brand but also by the scope of support offered by the corporation, which by definition may be smaller in the corporate accelerator model compared to at least the indicated hybrid model. The activities of an in-house accelerator should focus on start-ups that are more mature in the market, have a proven operating model, and are ready to enter the market. A noticeable strength of such an in-house accelerator is that it directly provides access to the market and customers of the energy company and creates a great opportunity for start-ups to find a committed customer who actually needs their solution.

Future research should cover activities related to the evaluation of the indicated models of cooperation between energy companies and start-ups in terms of the effectiveness and efficiency of the acceleration programs conducted in the context of business objectives set by corporations and their impact on sustainable development.