*Review* **Green and Renewable Energy Innovations: A Comprehensive Bibliometric Analysis**

**Grzegorz Mentel 1,\*, Anna Lewandowska 2, Justyna Berniak-Wo ´zny <sup>2</sup> and Waldemar Tarczy ´nski <sup>3</sup>**

	- 35-225 Rzeszów, Poland <sup>3</sup> Department of Sustainable Finance and Capital Markets, Institute of Economics and Finance, University of Szczecin, 71-101 Szczecin, Poland
	- **\*** Correspondence: gmentel@prz.edu.pl

**Abstract:** Taking into account factors such as unfavorable climate changes, shrinking fossil fuel resources, low energy efficiency, and the pace of population growth, the transformation towards green and renewable energy is one of the most important goals and challenges facing the world. The energy sector is the source of about 75% of global greenhouse gas emissions and energy-related emissions are reaching new record levels. For the energy transition to succeed, innovation at the level of technology, business processes and policies (local, national, and international) are necessary. Therefore, the aim of this article is to analyze the size, structure, and dynamics of research on innovations in the field of green and renewable energy in the last decade in order to identify the main topics and research trends in this field. The authors conducted a bibliometric review based on the PRISMA guidance together with visualization analysis based on the VOSviewer software. For this purpose, the Web of Science Core Collection (WoS CC) database was used, and based on defined inclusion criteria, the authors selected 1144 records for bibliographic analysis. The database was subjected to a performance analysis from the perspective of the number of publications per year, dominant countries, and journals. Further, science mapping was employed to analyze such features of the publications as co-citations, co-occurrences, and bibliometric coupling. Based on the results, gaps in green and renewable energy innovations were identified and issues for future research were defined and recommended.

**Keywords:** green energy; renewable energy; innovation; trends; bibliometric analysis

#### **1. Introduction**

Population growth and the accompanying socio-economic development increase the demand for energy and energy-related services, as all societies need such services to meet basic human needs and improve human well-being, and to develop and support production processes [1]. In 2014, the total global consumption of primary energy amounted to approximately 160,310 million MWh, and it was predicted that this value would increase to 240,318 million MWh in 2040 [2]. Global reserves of fossil fuels are depleting very quickly: based on average global usage forecasts, it is assumed that oil and gas may last for 50 more years, and coal and uranium for about 100 more years [3]. Due to the long-term and very intensive use of non-renewable energy sources, there are also harmful effects on the environment, such as air pollution, climate change, and irreversible loss of natural resources.

The UN states that to keep global warming below 1.5 ◦C, emissions must be reduced by 45% until 2030 and to net zero by 2050 [4]. It is estimated that the energy sector is the source of about three-quarters of global greenhouse gas emissions [5]. Thus, the energy sector plays a fundamental and growing role in achieving the decarbonization of the economy [6]. Therefore, in May 2021, the International Energy Agency (IEA) published its monumental

**Citation:** Mentel, G.; Lewandowska, A.; Berniak-Wo ´zny, J.; Tarczy ´nski, W. Green and Renewable Energy Innovations: A Comprehensive Bibliometric Analysis. *Energies* **2023**, *16*, 1428. https://doi.org/10.3390/ en16031428

Academic Editor: Benjamin McLellan

Received: 7 January 2023 Revised: 19 January 2023 Accepted: 28 January 2023 Published: 1 February 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

Net Zero by 2050 report, which assumes that the electricity sector must move from being the highest emitting sector in 2020 to the first sector to achieve net zero emissions by 2040 in the world [7]. At the same time, the IEA emphasizes that achieving this goal requires unprecedented efforts by all actors.

Decarbonization of the electricity sector is at the heart of the response to the threat of climate change. Therefore, the Paris Agreement underlines the urgent need for action in this area—in particular, the shift from fossil fuels to renewable energy and increasing energy efficiency [8]. This problem has also been included in the UN Sustainable Development Goals [9]. Goal 7 is to achieve universal access to affordable, reliable, and modern energy and to significantly increase the share of renewable energy in the energy mix. People's dependence on energy has increased significantly, but energy poverty remains an international development challenge. As energy is a prerequisite for many aspects of modern life, lack of access reflects social and economic inequalities. However, it must be based on low-emission technological solutions that reduce greenhouse gas emissions, and thus improve living and health conditions and ensure sustainable development of life on the planet [9].

However, as the International Renewable Energy Agency (IRENA) highlights in its 2022 Tracking Report on Sustainable Development Goal 7 [10], the latest available data and selected energy scenarios show that at the current pace of progress, the world does not stand much chance of achieving any of the goals and metrics under SDG 7. This is especially true for the most vulnerable groups of countries, which from the beginning have been significantly lagging behind in this area. Worldwide, 91% of the population had access to electricity in 2020, still leaving 733 million people without access to electricity. According to forecasts, the problem of lack of access to electricity in 2030 will still affect 630 million people [11,12].

Renewable energy is defined by the IPCC [13] as:

*'(* ... *) any form of energy from solar, geophysical, or biological sources that is replenished by natural processes at a rate that equals or exceeds its rate of use. Renewable energy is obtained from the continuing or repetitive flows of energy occurring in the natural environment and includes low carbon technologies such as solar energy, hydropower, wind, tide and waves and ocean thermal energy, as well as renewable fuels such as biomass'*.

In many cases, the terms *renewable energy* and *green energy* are used interchangeably, but there are important differences between the terms. Green energy is a subset of renewable energy and includes resources that provide more environmental benefits as they come from natural sources such as the sun, water, and wind [14].

The International Energy Agency (IEA) proposes the following classification of renewable energy technologies based on their stage of development:


Globally, it is estimated that in 2008 renewable energy accounted for 12.9% of the total 492 exajoules (EJ) of primary energy supply [14]. Moreover, as the WHO report [16] shows, in 2010–2019 the share of renewable energy sources in total final energy consumption increased by only 2.7%. It was a good sign that although the COVID-19 pandemic had a bad effect on the energy transformation and stopped many green energy projects, in 2020 the use of renewable energy sources continued to grow and accounted for over 80% of all new electricity capacity added that year [17]. However, in 2021, the share of renewable energy sources in global electricity production reached only 28.7% (after a slight increase of 0.4%) resulting from the global electricity demand reaching its all-time high, the slowdown

in economic activity caused by COVID-19, and drought in several regions that reduced hydropower production [18]. According to Our World in Data [7], global primary energy consumption is still largely based on fossil fuels such as oil (33.1%), coal (27%), and gas (24.3%). The dominant renewable energy sources include hydropower (6.45%), wind (92.2%), and solar (1.1%). Nuclear power, delivering 4.3% of energy, is not classified as a renewable source as it uses radioactive fuel, but it is defined as a low-carbon source [19].

If we are to reach the milestones of a net zero emissions scenario by 2050, thus increasing the share of renewables in power generation from almost 29% in 2021 to over 60% by 2030, then global efforts must be doubled and annual production of green and renewable energy must grow by more than 12% on average between 2022 and 2030, which is twice the 2019–2021 average [20]. This requires a complete change in the way energy is produced, transported, and consumed, and a significant acceleration in the implementation of available technologies, as well as the development and dissemination of technologies that are not yet on the market. We need innovative techniques to respond to climate change. On the one hand, we need innovation to reduce costs, improve efficiency, and enable the integration of renewable technologies in energy systems. On the other hand, innovation is also needed to discover and develop fourth-generation renewable energy technologies that will revolutionize the entire energy system. In other words, incremental improvements are necessary and will continue to make significant progress but may not be enough to drive a complete transformation of the energy sector that requires disruptive technologies and processes. However, this is a large undertaking that requires huge investments and a significant acceleration of innovation and implementation work. Innovations are also necessary in the entire energy system, such as in market design and accompanying policies and regulations, infrastructure integrating renewable energy sources with energy systems, and new business models [21].

Growing interest in energy transformation accelerated by the climate change and energy crises has led to the emergence of a research stream on green and renewable energy innovations. Scientists are working on many innovations in the field of renewable energy aiming to achieve high efficiency with less pollution and to integrate existing and new technologies. They are also analyzing political and financial frameworks as well as new business models necessary to achieve the energy transformation required and define critical areas. Therefore, the aim of this article is to analyze the size, structure, and dynamics of research on innovations in the field of green and renewable energy in the last decade in order to identify the main topics and research trends in this field. More detailed knowledge on this issue will give a helicopter view of the current state of the art. Scientific relationships on the international and authorship level will also prompt research agendas for the years to come that would support the green transformation. There are three key research questions (RQs) regarding this aim:

RQ1.What is the structure of the research on green and renewable energy innovations?


The article is structured as follows. In Section 2 the methodology and data sets are defined. In Section 3, the main findings of reviews and the results of additional analyses are presented. Section 4 discusses the implications of the empirical results and concludes the paper.

#### **2. Materials and Methods**

In order to achieve the aim and answer the research questions posed in the previous section, the authors used a bibliometric review with visualization analysis, well-established methods presenting an overview of research trends in a selected area [22].

The bibliometric review is based on the use of various approaches to the characterization of quantitative, qualitative, and structural changes in scientific research and the

profile of publications in a selected subject area [23]. The main publication classification factors used by bibliometrics are journals, authors, institutions, countries, keywords, and references [24]. According to Bjork et al. [25] the key advantage of bibliometric analysis is gaining a helicopter view of a specific research field. Bibliometric research, very popular in the information and natural sciences, has become equally popular in other fields over time, including the social sciences, and its popularity can be attributed to the development of scientific databases such as Scopus, Web of Science, and Google Scholar, as well as the advancement, accessibility, and affordability of bibliometric visualization software such as Gephi, Leximancer, and VOSviewer. According to Corsini et al. [26], there are several arguments in favor of using bibliometric methods, such as the possibility of obtaining a review of extensive scientific literature, objective results (as opposed to narrative reviews based on a critical and subjective summary of selected scientific papers), and the possibility of using modern solutions in the field of large database analysis.

Bibliometric research techniques can be divided into three groups: review, evaluation, and relational techniques [27].


Zupic and Cater [32] recommend the following workflow guidelines for mapping selected research filed with bibliometric methods: (1) research design, (2) compilation of bibliometric data, (3) analysis, (4) visualization, and (5) interpretation. The workflow of this study can be mapped as follows: The research design is outlined as Section 2.1; the compilation of bibliometric data comprises Section 2.2; and the analysis, visualization, and interpretation are detailed in Section 3.

#### *2.1. Research Design*

At the research design stage, we define research questions and select optimal bibliometric methods. In this paper, three research questions are put forward.

**RQ1.** *What is the structure of the research on green and renewable energy innovations?*

**RQ1.1.** *What is the volume of published articles on the topic of green and renewable energy innovations?*

**RQ1.2.** *What are the most impactful journals, authors, and countries in the field?*

**RQ2.** *What are the research dynamics and the most important activities carried out within the green and renewable energy innovations?*

**RQ2.1.** *What is the intellectual structure in the field?*

**RQ2.2.** *Which are the research topics most addressed in the domain?*

**RQ3.** *What are the future research directions related to green and renewable energy innovations?*

To answer RQ1, we used performance analysis, which aims to examine the impact of selected metrics on a given field [33], explore and define leading research actors in a field [34], and recognize the importance of different factors in that research field. The most common analysis metrics are the number of publications and citations per year, or the source of publications, with the number of publications being an indicator of productivity, while citation being an indicator of impact.

To answer RQs 2 and 3 we have employed the following three mapping science techniques:


#### *2.2. Compilation of Bibliographic Data*

The compilation of bibliometric data covers the selection of the database(s), filtering the bibliographic data, and refining them. The next step was the selection of analytical software and the decision on how to visualize the results of the analysis. We followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and procedures [35]. We decided to use the Web of Science Core Collection (WoS CC), which is considered as the leading database for classifying scientific research. The Web of Science Core Collection (WoS CC) contains over 21,100 peer-reviewed journals published worldwide in over 250 scientific disciplines.

The search was based on the keyword combination "green energ\*" or "renewable energ\*" and "innovat\*". We searched for articles that have this phrase in the title. A total of 5897 records were found by searching the WoS CC database. In the screening phase we excluded papers:


The WoS CC database was limited to open access papers only, as a result of which another 1908 papers were excluded as not relevant for this research. After the data search and selection process was completed, the qualified records were subjected to bibliometric analysis as shown in Figure 1, and the final database consisted of 1144 documents.

The database was downloaded in TXT format because the authors planned to use it for visualization in VOSviewer software, which requires CSV or TXT files. Since WoS CC has built-in analyzer functions, an initial descriptive analysis was performed using these functions and then the analysis functions of Excel were used. Tables were created to provide quantitative data. Additionally, VOSviewer software, version 1.6.18, was employed to quantitatively and visually analyze selected publications on green and renewable energy innovations, using such techniques as co-citations, co-occurrences, and bibliometric coupling maps.

The analysis, visualization, and interpretation are presented in the next section, Results.

**Figure 1.** PRISMA flowchart [36].

#### **3. Results**

As already signaled in the Introduction, innovation is one of the key elements of achieving SDG 7 and accelerating the development of green and renewable energy. Both from the perspective of science and practice, an in-depth understanding of scientific achievements in the field of green and renewable energy is of key importance [37]. In order to make an in-depth analysis of this research area and identify current topics and directions of scientific research, bibliometric research was used [38], under which 1144 documents selected from the WoS CC database were evaluated.

The basic criterion for assessing the interest of researchers in a given scientific area and the dynamics of this interest is the number of publications and its distribution over the years [39–43]. Figure 2 shows the number of published documents on green and renewable energy and innovation in 2012–2022. It is worth noting that there is an increasing trend in the number of scientists researching the topic of innovation in the field of green and renewable energy. This increase is particularly noticeable in the last three years, i.e., during the period of intensified discussions on the climate and energy crisis and the green transformation. As the problem of climate change and dwindling fossil resources becomes more urgent, the authors predict that this trend will continue into the future.

**Figure 2.** The number of documents on green and renewable energy and innovation and the number of citations of documents (2012–2022).

Table 1 presents the researchers who published at least four papers on green and renewable energy and innovation. The most productive authors in this rating with six articles are Jahid (University of Ottawa, Canada), Anser (Super Univ, Pakistan), and Alsharif (Sejong University, North Korea), followed by Cabeza (University of Lleida, Spain), Ahmad (Shandong University of Technology, China), Dincer (Instanbul Medipol University, Turkey), and Yüksel (Instanbul Medipol University, Turkey) with five papers on green and renewable energy innovation. Meanwhile, twelve authors each published four studies.


**Table 1.** The leading authors of documents on green and renewable energy and innovation.

As Table 2 shows, the most popular journals in the field of green and renewable energy and innovation are *Energies* (MDPI, IF: 3.252) with 19 publications and 961 citations, *Sustainability* (MDPI, IF: 3.889) with 91 publications and 650 citations, and *IEEE Access* (IEEE, IF: 3.476) with 40 published articles and 551 citations. They are followed by the *Environmental Science and Pollution Research* (Springer Heidelberg, IF: 5.19) with 36 articles and 281 citations and the *Frontiers in Environmental Science* (Frontiers Media SA, IF: 5.411) with 31 papers and 83 citations.


**Table 2.** Top 20 journals with articles on green and renewable energy and innovation.

The essential subjects of the research are publications by country, including their social networks [44–46]. Table 3 presents the most important countries in accordance with the number of published papers on green and renewable energy innovations. The most productive authors in this area are from the People's Republic of China with 363 papers (which is 31% of all papers on green and renewable energy innovations). Moreover, important study in this area has been carried out in the USA and England (approximately 10% and 8% of review articles, respectively). Figure 3 shows a geographical map of 93 countries in accordance with the number of published articles.

**Table 3.** Documents on green and renewable energy and innovation by country.


**Figure 3.** A map of countries in accordance with the number of published articles on green and renewable energy and innovation.

The analysis of the organization's bibliographic links is very interesting due to its complementarity with the results of the citation analysis of authors, institutions, and countries. Figure 4 shows data with a minimum of three documents and 100 institutions meeting the thresholds.

**Figure 4.** Bibliographic coupling of organizations.

Table 4 presents the most frequently cited articles from the research area under study. It is worth noting that there is a very good representativeness of studies published in the last decade (2012–2022) [47–56]. This is confirmed by the fact that the topic of innovation in the field of green and renewable energy is a development topic. Moreover, the importance of some studies, such as Richter [54] and Lehr et al. [55], indicate that this topic began to

appear in the 2000s, but a particularly dynamic increase in the number of studies in this field could be observed from 2015.


**Table 4.** Most cited articles.

Based on the co-citations of references analysis, it was possible to define the network of citations. This technique, as reported by Albort-Morant et al. [39] describes the key authors, often cited with other authors. Figure 5 shows a citation map where each circle represents a document, and the size of the circle corresponds to the number of citations [57].

**Figure 5.** Co-citation of references map.

The analysis defined four clusters of papers that cited each other. The red cluster shows research that mainly concerns the environment–competitiveness relationship [58], renewable energy and technological innovations [59], and energy-saving innovations [60]. The green cluster shows studies that relate to the panel unit root test, as described in [61], and diagnostic tests for cross-sectional relationships in panels, as in [62]. The blue cluster covers the topics of green public finance and sustainable green finance [63], CO2 emissions in the context of economic growth and renewable energy production [64] and energy poverty and energy efficiency [65]. The yellow cluster focuses on research methods [66,67].

In the next step, the technique of bibliographic coupling of authors was employed to identify active researchers in the field and provides a view of the research structure of the front of the field. Of the 4194 authors, we selected those with a minimum of three publications and 10 citations. Only 44 authors met the threshold. Figure 6a presents the authors bibliographic coupling map. To make the map more readable we created two more showing the four defined clusters more precisely. Figure 6b presents the first three clusters, and Figure 6c presents the fourth cluster, namely:


Following Phillips et al. [67], in order to illustrate the geographic allocation of knowledge, bibliographic coupling of countries was used. Figure 7 shows three clusters in relation to the network of countries defined as a result of the analysis. The green cluster includes Asian countries under the strong leadership of the People's Republic of China supported by Latin America (Mexico and Brazil), South Africa, and Canada. Another cluster, red, combines research from the United States and European Union (mostly Italy, Germany, Poland, and France) with contribution from Israel and Egypt. In the blue cluster, the most productive countries are England, Saudi Arabia, Spain, Malaysia, and Australia.

The analysis of the author's keywords is also very important due to the fact that the keywords correspond to the context of the publication and thus define the main topics and research trends [68].

Figure 8 shows the most common author keywords and the author keyword network in articles. The minimum number of author keywords for a co-occurrence map is five and the minimum cluster size is specified as 12. The author's most popular keywords are *renewable energy* (131), *energy efficiency* (90), *green energy* (57), *energy consumption* (40), and *sustainable development* (34). The identified 92 author's keywords were classified into four clusters.

**Figure 6.** (**a**) Authors bibliographic coupling map. (**b**) Authors bibliographic coupling map—clusters 1–3. (**c**) Authors bibliographic coupling map—cluster 4.

**Figure 7.** Bibliographic coupling of countries.

**Figure 8.** Co-occurrence map (keywords network).

• The red cluster (38 keywords) encapsulates such terms as *renewable energy* and *green energy* followed by *sustainable development*, *CO2 emissions*, *solar energy*, *green economy*, *environmental sustainability*, *green innovation*, *renewable energy sources*, and *technological innovation*, which led to the naming of this cluster as "renewable technology innovations".


Using the same map, Figure 9 shows the chronological evolution of research topics. Thanks to this, it is possible to identify the most current topics in the researched area, which turn out to be green finance, green innovations, renewable energy consumption, CO2 emission, and carbon neutrality, while energy efficiency related to green construction or energy harvesting have been the main topics of interest in the previous decade.

**Figure 9.** Co-occurrence map (overlay visualization).

Figure 10 presents the most cited journals. The best three journals in the researched area are *Energies*, *Sustainability*, and *IEEE Access*. These journals appear as the most important sources in green and renewable energy research (in the innovation context) and can be helpful for further research and also to the identification of consistent journals on green energy and renewable energy.

**Figure 10.** Bibliometric coupling of sources.

#### **4. Discussion**

The amount of research into green and renewable energy innovation has been increasing over the last decade, especially in the last three years. Until 2019, the number of publications in this field was about 70 per year, after which there was a significant increase to about 130 published works in 2020 and even 320 in 2022. The increase in 2020–2022 may, among others, be related to changes in EU legislation [69]. This concerns the amended renewable energy directive (Directive (EU) 2018/2001) as part of the "Clean energy for all Europeans" package. EU Member States were obliged to transpose it into national law by June 2021. EU Member States were also obliged to propose a national energy target and establish ten-year national energy and climate plans under the "Horizon 2030" program. The Directive establishes a binding target according to which at least 32% of the final energy must come from renewable sources by 2030 and includes a clause to increase this target by 2023, as well as an increase in the 14% share of renewable energy in transport by 2030. In July 2021, in accordance with the EU's new climate ambitions, the co-legislators were tasked with changing the target to 40% by 2030. An important element that will affect the scale of the use of renewable energy sources will be technological progress, both in terms of currently known methods of generating energy and in completely new technologies, including energy storage technologies [70–72]. The strong increase in the number of publications in 2022 was also significantly influenced by the war in Ukraine and the related energy and fuel crises. This factor caused huge turbulence and caused opposite trends—strengthening the development of green and renewable energy technologies and the return to fossil fuels and nuclear energy. However, the assessment of the impact of the war requires further and in-depth research, which will undoubtedly translate into a further increase in scientific publications. However, regardless of the development of the situation on the energy market, this huge increase in scientific activity in the last decade indicates the importance of the problem and the need for further research in this field.

The study of the most cited references shows that the green and renewable energy innovation bibliography has been defined by various related research areas (such as energy fuels, environmental sciences, ecology, science technology, business economics, telecommunications, and chemistry). The most frequently cited articles concern research methods, the unit root panel test and diagnostic tests of cross-sectional relationships in panels [61,66,67], the environment-competitiveness relationship [62], and green energy solutions in construction [73] as well as technological innovations in the field of green energy [74]. The most productive authors are Jahid (University of Ottawa, Canada), Anser (Super Univ, Pakistan), and Alsharif (Sejong University, North Korea), followed by Cabeza (University of Lleida, Spain), Ahmad (Shandong University of Technology, China), Dincer (Instanbul Medipol University, Turkey), and Yüksel (Instanbul Medipol University, Turkey). Their origin is differentiated both from a geographical perspective and from an institutional perspective. However, globally the most productive scientists in this area are from China, USA, and UK. The research geographical context is very important because green energy innovation is greatly reliant on the macro environment and business ecosystem (including financial support).

According to the analysis of bibliographic coupling of countries, the leading countries are China, USA, UK, Italy, Pakistan, Germany, Poland, Saudi Arabia, and India. In some of countries, especially in Africa, green and renewable energy innovations are barely analyzed. Moreover, the relatively few studies in Southern Europe (except for Italy) or Eastern Europe and Balkans suggests the need for such research and wider cooperation between regional scholars. Additional studies at a regional level are missing to understand green and renewable energy innovation nature.

Some researchers have suggested wider and more intense collaboration in their study on green and renewable energy innovations to share the resulting benefits and costs [75]. Accordingly, the study not only indicated a great deal of cooperation among the different clusters, but also collaboration between Canada and China in the first cluster, collaboration between the USA, Italy, Germany, and Poland in the second cluster, and collaboration between England, Spain, Malaysia, and Australia in the third cluster. Overall, cooperation is happening mainly between developed countries whereas cooperation in developing countries is very poor.

The analysis of the co-occurrence of the author's keywords identified four clusters dominated by four research topics. The first concerns the innovative capacity of green technologies (cluster one), the second relates to energy efficiency (cluster two), the third concerns the macro-environment (cluster three), and the last concerns policies, sources and tools for financing investments in green and renewable energy sources (cluster four).

#### *4.1. Limitations of the Study*

The results of the conducted research are burdened with a number of limitations. First, science mapping is a comprehensive, quantitative method of assessing the structure of the knowledge base, but the emphasis on quantitative information related to publications in a given area is no substitute for review methods that qualitatively analyze the substantive content of scientific publications. Therefore, the review presented in the article is only a helicopter view on research on innovations in green and renewable energy, and thus a starting point for further, in-depth research in this area. In addition, the interpretation of maps prepared with the VOSviewer software is subjective. Second, one specific WoS CC database was selected for the study, while others such as Scopus and Google Scholar were excluded. Therefore, we cannot guarantee that our search strategy was able to cover all relevant articles. Finally, due to our inclusion criteria, we included publications in English only in this study. Undoubtedly, there are valuable studies and publications in the native language of researchers who do not publish in English.

#### *4.2. Future Research Directions*

The results of the analysis of the co-occurrence of the author's keywords show some similarities and links between innovation and green and renewable energy, which requires further research. The trends in the use of the author's keywords show that many current keywords are *green finance, renewable energy consumption, CO2 emissions, innovations in the field of green technologies,* and *green and renewable energy*, i.e., in the area of climate change and financing the development of green and renewable energy sources.

Further research is needed to assess whether this trend in the use of the author's keywords will continue in the future. In particular, the importance of green buildings for the development of energy efficiency has long been recognized in the literature [76,77]. Indeed, energy consumption is a significant criterion of analysis and measure of innovation activities [78–80]. Finally, as an important topic for various organizations, climate change and environmental regulation have become of particular interest to innovation scientists [81–83].

It is worth mentioning that the essential features of green and renewable energy and innovation are not sufficiently emphasized in the clusters. The author's co-cited keywords focused mainly on technology, knowledge, research and development, and management. When it comes to innovations in the field of green technologies or ecoinnovations, these are topics that are much less popular among researchers. Thus, in further research scientists could be more focused on terms such as "green technologies innovation" or "eco-innovations".

Moreover, further analysis of the investments of various funds is needed to better understand innovation as a pilar of climate change policy and to explain the logic of government funding priorities. In future research, it is worth assessing innovation in green and renewable energy from other perspectives, such as public/private sector, financial support, competitiveness. In addition, this study could be supplemented with qualitative methods, e.g., expert panels or focus groups with representatives of various entities.

Finally, this research approach could be continued by, for example, inclusion in the analysis of other databases such as Scopus, Google Scholar, and inclusion of other types of publications, including reviews and conference proceedings.

#### *4.3. Contributions*

The obtained research results filled the knowledge gap in several aspects. In the first place, to the authors' knowledge, this is the first study in which a comprehensive bibliometric analysis was carried out, which: (1) analyzed the number of published articles on innovation in the field of green and renewable energy; and (2) identified the most influential authors, journals, and countries in the field of green and renewable energy innovation.

We answered the research questions posed:


#### **5. Conclusions**

The aim of the article was to analyze the size, structure, and dynamics of research on innovations in the field of green and renewable energy in the last decade in order to identify the main topics and research trends in this area. To achieve this goal, a comprehensive bibliometric analysis of leading authors, journals, countries, and the most frequently cited documents in the field of innovation in green and renewable energy in the years 2012–2022 was carried out. The analysis was based on 1144 articles selected from WoS CC. Performance analysis of the records was supplemented with mapping using the VOSviewer software. The results of the review presented in the article provide scientists with knowledge about the structure and dynamics of research on innovations in green and renewable energy and identify knowledge gaps and future research directions. The most important conclusions from the research are as follows:


**Author Contributions:** Conceptualization, J.B.-W., A.L., G.M. and W.T.; Data Curation, J.B.-W. and A.L.; Formal Analysis, J.B.-W. and A.L.; Investigation, J.B.-W., A.L. and G.M., Methodology, J.B.-W. and A.L., Writing—Original Draft Preparation, J.B.-W. and A.L.; Writing—Review and Editing, W.T., J.B.-W., A.L. and G.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**


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