**4. Discussion**

In this section, we analyze and discuss the information from the sample, starting with a temporal reading of the evolution of the publications in the years investigated. The following Figure 3 informs us of the annual amount of articles published on the subject from 2008 to May 2021.

The *X*-axis represents the years of research, while the *Y*-axis represents the number of articles published. A growth trend is easily noticeable, with the exception of 2010, 2011 and 2016. The number of articles published annually grew by the year. The considerable increase in publications in the last 5 years is remarkable; these years concentrate 78.39% of the papers published in that period. The decrease in the number of articles from 2020 to 2021 is most likely due to the sampling period of the research since it does not include

the year 2021 as a whole; therefore, we cannot consider it as an indictment of a drop in publications. It is possible that by the end of the year 2021, there will be a number of publications similar to 2020, providing the theme continues with the growth trend.

The growth of publications in the second half of the decade of the 2010s may be the result of the first cycle of commitments of the Kyoto Protocol (2008–2012), which should have fostered research to analyze the effects. Within the scope of this research, in the sample raised, many studies consider emissions and effects on economic activity. It is believed that the first cycle of responsibilities of the Kyoto protocol has a fundamental role in increasing research on renewable energy consumption, non-renewable and which way these matrices are less harmful to the environment affect economic activity.

In Figure 4, we chose to make a geographical analysis, that is, to identify how many and which countries have the most publications on the subject in that period. At first, when considering any number of publications, we obtained 63 countries with research published on this theme of the 194 existing countries. This reveals that only 32% of nations developed research on renewable energy, economic growth and economic development up to the moment of this research. However, it should be noted that this does not mean that only 30% of the countries in the world were investigated in relation to this theme, but that the research is concentrated on around 30% of the countries. In order to facilitate understanding, we did not consider all 63 countries; we chose to make a minimum count of publications, which is five. Thus, the following graph considers only those countries that had more than five publications during the period of the development of this study.

**Figure 4.** 25 Countries with more publications between 2008 and May 2021.

Only 25 countries have more than five articles published; China is noticeably an outlier. The number of Chinese publications is greater than the other countries; consequently, China is responsible for 22.11% of the publications in that period. Another attention-calling factor is that on all continents, there is at least one country with at least five publications on the subject, except Latin America.

Being a multidisciplinary research area, many journals publish about this theme. Seventy-four periodicals were published in that period. In Table 1, the periodicals are ranked according to the metrics stipulated by the WoS and Scopus databases.

Table 2 above shows us the number of articles in the area that were cited in some way in the research period. There are a total of 167 articles. It should be noted that this number is lower than the total sample, which is 199. This is because some articles (32 or 16.080%) have not ye<sup>t</sup> been cited. When analyzing the citations, it seems that the number is low when compared to other research areas in which there are articles that have more than

1000 references. In this sample, no article reached such a number. It was clear that most of the published papers have less than 50 citations, which should change in the future as there is expected to be an increase in articles with more than 50 citations since the increase in publications on this subject is notorious in recent years.


**Table 1.** Source Ranking.


**Table 1.** *Cont.*

\* Listed since 2009; \*\* Listed since 2011; \*\*\*\* Listed since 2013; \*\*\*\*\* Listed since 2014; \*\*\*\*\*\* Listed since 2015; 1 Coverage period 2016–2019; 2 Listed until 2017; 3 Listed until 2018; R = Ranking; >200 Number of articles with more than 200 citations; >100 Number of articles with more than 100 citations; >50 Number of articles with more than a 50 citations; <50 Number of articles with less than a 50 citations.

> Taking the total h-index (34) of this research into account, it is noted that it is not a high value as it only comprises 17.085% of the sample. The number of articles with more than 400, 200, 100 and 50 citations is expected to increase since, as previously mentioned in this study, a growth trend is observed in research on renewable energy, economic growth and economic development.


**Table 2.** General Citation on Renewable Energy, Economic Growth and Development Economic on Scopus.

Source: prepared by the authors with data from Scopus.

Table 3 shows us the most cited articles in the research period, in one of the criteria selected to determine relevance. These are the 20 most relevant papers of that period. One is able to notice a good distribution in the journal ranking, which may be an indication that good studies on the subject can be found in most journals listed in this research. Another point is that most of these 20 articles are post-2015, which reinforces the hypothesis that research on the subject still has a horizon of growth.

**Journal JR TC Title Author(s) Year** Energy Strategy Reviews 23 405 The role of renewable energy in the global energy transformation Gielen, Dolf Boshell, Francisco Saygin, Deger Bazilian, Morgan D. Wagner, Nicholas Gorini, Ricardo 2019 Journal of Industrial Ecology 6 332 How circular is the global economy? An assessment of material flows, waste production, and recycling in the European Union and the world in 2005 Haas, Willi Krausmann, Fridolin Wiedenhofer, Dominik Heinz, Markus 2015 Global Environmental Change 2 228 Energy, land-use and greenhouse gas emissions trajectories under a green growth paradigm Van Vuuren, Detlef P. Stehfest, Elke Gernaat, David E.H.J. Doelman, Jonathan C. (... ) 2017 Science of the Total Environment 9 131 Dynamic impact of trade policy, economic growth, fertility rate, renewable and non-renewable energy consumption on ecological footprint in Europe Alola, Andrew Adewale Bekun, Festus Victor Sarkodie, Samuel Asumadu 2019 Energy Policy 8 127 China in the transition to a low-carbon economy Zhang, Zhong Xiang 2010 Cogent Economics and Finance 57 112 Effect of economic growth on CO2 emission in developing countries: Evidence from a dynamic panel threshold model Aye, Goodness C. Edoja, Prosper Ebruvwiyo 2017 Science of the Total Environment 9 103 Modelling coal rent, economic growth and CO2 emissions: Does regulatory quality matter in BRICS economies? Adedoyin, Festus Fatai Gumede, Moses Iga Bekun, Festus Victor Etokakpan, Mfonobong Udom Balsalobre-lorente,Daniel2020

**Table 3.** Most Cited Articles in the Period (2008–May/2021).


**Table 3.** *Cont.*

JR = Journal Ranking; TC = Total Citations.

The taxonomy of the publication was another aim in this research, hereby, the studies selected through the PRISMA methodology were qualified in four subgroups by the authors, I being—Renewable and Non-Renewable Energy Consumption, Economic Growth and Economic Development; II—Transition to a low-carbon economy and energy efficiency; III—Environmental Degradation; IV—Others. Most of the articles in this sample fall into category II—Renewable Energies, Economic Growth and Economic Development, and the expected result, according to the Scopus database, 127 of 199 (63.819%), is in this category. Although category II relates to the keywords used in the scope, it is not the focal point of the publications. These are more related to energy efficiency and countries with the objective of reducing their carbon emissions and cover around 15.075% (30 documents) of the research. The Environmental Degradation is responsible for 8.04%, in other words, 16 documents. Finally, the other category, with fewer studies, encompasses researches that relate to the subjects but are very specific cases and covers 13.065%, or 26 published papers on that period. When analyzing the methodologies applied in the researches that are part of the sample of this study, a prevalence of quantitative methodologies is observed of the 199 studies. One hundred and sixty-one, or 80.904%, apply quantitative methods to obtain the results of their studies. In the following paragraphs, an analysis of the studies within the given subsamples is performed.

The analysis of group I (Renewable and Non-Renewable Energy Consumption, Economic Growth and Economic Development) shows that most of the articles published in this subsample use quantitative methodology while 89.763% of the studies use some common methodologies in economic sciences. Most studies are analyses of statistical inferences of countries or a country studied in isolation. There are many studies covering various economies [28–34], for example [35–38]. Ref. [35] conducted a study covering 123 countries, 146 countries for Ref. [36], 53 countries for Ref. [37], and in [38], 24 countries are heterogeneous economies. However, when observing the studies that opt for groups, there is a direction to investigate specific groups with some similarities, whether geographical, economic and cultural, among others. Ref. [39] investigated 37 economies considered developed. OCDE member countries were studied from various perspectives by [40–45]. The results obtained by [45] indicate that in the long term, trade openings and technological developments tend to stimulate the consumption of renewable energy in OCDE countries. Emerging economies were investigated by [46–50], still, in the emerging economies, there were more targeted studies, such as papers [51–53]. According to [51], for these economies, the flow of foreign direct investment (FDI) and the development of the financial market are fundamental in promoting the consumption of renewable energies, in addition to reducing emissions and promoting economic growth. The BRICS economies were also investigated in isolation: Brazil was studied by [54–56], Russia by [57], China and India by [58] and China by several [59–65], and there were also investigations for Chinese provinces such as [66,67]. Moreover, Brazil, China and the USA were studied by [68], China and USA in [69], and China, USA, France and Japan by [70]. Continents were also the target of this type of research: Europe was studied by [71–83]. The result obtained by [71] indicates a balance between environmental degradation, economic growth, commercial opening, consumption of renewable and non-renewable energies and fertility rate. Furthermore, it was observed that the consumption of non-renewable energies increases the degradation of the environment, while the consumption of renewables contributes to conservation. As in the case of the BRICS, European countries were studied separately: Portugal by [84]. Portugal, Spain, Denmark and the USA by [85], Ukraine by [86,87], Turkey by [88,89], Romania by [90], Czech Republic and Slovakia by [91], Wales by [92], Poland by [93,94], Estonia, Latvia and Lithuania by [95], Scotland by [96] and Russia [97]. The American continent, to be more precise, Latin America, was also the target of research by [98–101]. The study [99] concluded that the consumption of renewable energies, tourism, and FDI tend to reduce environmental degradation, while foreign trade and economic growth are responsible for the deterioration of the environment. Refs. [102–104] analyzed Bolivia and Ecuador, respectively. Saudi Arabia [105] and Iran [106] were studied in the Middle East. This relationship was studied for the Asian continent, where the Environmental Kuznets' Curve [107] was validated, for the South Asian economies by [108]. Ref. [109] investigated South Asian and Southwest economies, and the results obtained indicate that the consumption of renewable and non-renewable energies promotes economic growth [109].

Belt Road countries were investigated by [110,111], SAARC and ASEAN countries [112], as well as, South Korea [113], Bangladesh [114], Malaysia [115–118], Indonesia [119–123], Vietnam [124], Taiwan [125], Pakistan [126–130], Kazakhstan [131,132], and Thailand [133]. Not many studies dealing with the African continent [134] investigate the continent, [135] sub-Saharan Africa, [136] Rwanda, [137] Cameron, Nigeria [138], [139] Ethiopia and [140] Tunisia. In Oceania, only [141] investigated Australia. OPEC member countries were studied by [142] and concluded that electricity production improves access to energy and promotes the economy. In addition to quantitative methodologies, other methodological approaches were applied; however, they were the minority in this subsample (10.318%). Similar to quantitative studies, there is an analysis of large groups, such as [143,144], which were analyzed a very different group of economies. The research addressed Europe [145,146], the United Kingdom [147] and Russia [97]. Refs. [148,149] analyzed China, while [150] studied India and China together; Islamic countries were studied by [151], and finally Bangladesh, Indonesia and the USA by [152–154], respectively.

The studies of subsample II (Transition to a Low-Carbon Economy/Energy Efficiency) are a total of 30, of which 22, or 73.333%, are quantitative surveys. Quantitative studies in this sample have a broad profile, such as [155,156]. The results of [156] point out that renewable energy and energy efficiency technologies are the central points for an energy transition. Renewable energy is the key to limiting greenhouse gas emissions and limiting the increase in global temperature by 2◦ [156]. The continents were also investigated: Asia was studied in [157–159], and the African continent in [160]. The most localized studies have a concentration on research focused on China [161–163]. The results found by [161] indicate that the targets of electricity production through renewable sources in China contributed to an increase of 1.8% between 2010 and 2020. In addition to these, [164] studied India and China. India was also addressed in [165]. Still, on the Asian continent, Pakistan, Vietnam, Kazakhstan and Japan were studied by [166–169], respectively. In Europe, Ireland was surveyed in [170], Turkey by [171], Netherlands by [172], Germany, United Kingdom and Norway in [173]. Regarding the USA, it was found that by achieving innovation targets, there is a reduction in carbon dioxide emissions [174]. In the Middle East, Saudi Arabia was studied by [175], and finally, [176] proposed to investigate quantitatively the impact of public policy of gradual reduction in fossil fuel consumption given through government subsidies; the results indicate that this contributes positively to the performance of macroeconomic factors [176]. In non-quantitative approaches, [177] investigated trends for the global energy market in the medium and long term and concluded that there is a global interest in renewable and non-conventional energies, as well as in improving energy efficiency to reduce an environmental impact on energy generation [177]. Europe was studied by [178,179], while China was studied by [180,181], Russia by [182], the economies of Mexico and Vietnam by [183] and Nigeria in [184].

There is subsample III, in which the documents relate to the keywords used in the research, but the focus of the research is on the degradation of the environment. Having said this, this group has 16 articles, 12 of which are quantitative papers, while the rest applied other methodologies. In the field of quantitative studies, [185] studied 32 countries considered in development. While [186] focused on the BRICS, for these economies, the consumption of renewable energies and the FDI tend to reduce carbon dioxide emissions, the opposite relationship found for GDP, and bank credit with CO2, the increase in these variables is accompanied by an increase in environmental degradation, as well as exports [186]. In addition to this research, South Africa was also studied by [187,188], and India, together with Malaysia, Indonesia, Kenya, Mexico, Colombia, and Poland, were investigated by [189]. The European Union was addressed by [190], and concluded that economic factors accelerate environmental degradation; only Turkey was analyzed in isolation from Europe by [191,192]. ASEAN member countries were investigated by [193] and showed that macroeconomic factors contribute to degradation. Still, in Asia, Vietnam and Taiwan were studied by [194,195], respectively. The African continent was studied by [196] and Ghana by [197]. The study with non-quantitative approaches by [198] focuses on the

possibilities of development in the global use of energy, land exploration, emissions and climate change in order to maintain constant sustainable development. The results indicate that a combination of these factors by opting for sustainable alternative, can lead to a strong energy transition towards renewable sources; however, in addition, it is also necessary to apply strict climate policies to reduce the trend of the rising global temperature [198]. Ref. [199] studies how the banking sector can contribute to decarbonization. Finally, [200] is the only country study that investigates Nigeria.

Lastly, in category IV (Others), unlike the aforementioned, where there is a clear predominance of quantitative methodologies, there is a balance. Of the 26 papers falling into this category, 13 (50%) are quantitative, while the other half use other approaches. In this category there are comprehensive studies, which do not necessarily work with continents/countries, for example [201–205], moreover [206] conducted a micro study. In studies dealing with territories for the European continent [207], it was concluded that renewable energy development policies improve the social factors studied (government policy, general public awareness, the market, lobbying activity) [207]. Russia was studied in [208], and the United Kingdom and Germany in [209] together with the USA and Brazil. On the Asian continent, Iran, China and Cambodia were investigated by [210,211] and [212], respectively. Ref. [213] studied the decision-making between financing and not financing renewable energy matrices on the African continent and concluded that investor confidence in regulatory effectiveness is the main concern, besides local construction capacity and political instruments [213]. In non-quantitative approaches, there are also studies without a sample directed to country/continent, such as [214–219]. Ref. [219] proposes two scenarios, a conservative one in which there is no change in the current situation of energy production and a transition, which assumes ambitious targets in the evolution and incentives of renewable energies. The results show that renewable sources may be responsible for providing between 35 and 50% of the world's electricity production by 2040, while the share of fossil fuels tends to decrease [219]. Ref. [220] demonstrated that common law adept countries responded better to renewable energy investment opportunities; in other words, the study points out that legal and regulatory institutions are to blame for the global imbalance in the development of energy [220]. In Europe, only Italy and Macedonia have surveys in this category, [221] and [222] respectively. While only Chinese provinces were surveyed in [223–225], and at the country level, in Asia, only Nepal in [226].

Due to the diverse results obtained in the studies, there is no academic/scientific consensus on the way in which energy consumption affects economic dynamics. There are economies in which the influence is positive, others negative and even economies in which the results are not statistically significant. This is likely to be the effect of specific characteristics of each sample observed in the studies. Despite this, a conclusion regarding the consumption of renewable energies was possible. They are fundamental in mitigating greenhouse gas emissions; therefore, there is evidence that they are essential in conserving the environment.

The prevalence and varieties of quantitative approaches in the studies are an indication that information is available so that decision-makers and policymakers can formulate strategies based on statistical evidence.

It is worth noting that when observing the countries taken into account in the abovementioned studies, they are developed economies. There are many studies for Europe, USA, OCDE member countries, and many studies for developing economies, such as the case of BRICS, but little is investigated for less wealthy economies, as most African and Caribbean economies are countries that find themselves at the bottom of a low point of economic development. Thus, there are indications of a gap to be explored, develop, or even replicate studies already conducted for the most relevant economies, for these countries with lower economic power, in order to ascertain how the consumption of renewable energies affects the economy of these nations.

Along with, according to the analysis of the articles in this sample, a focus on relating energy consumption, whether renewable and non-renewable, with macroeconomic indicators, such as labor force, trade, foreign direct investment, with economic growth, not taking into account variables or socioeconomic indicators, is noticeable. This marginalization of metrics to evaluate economic and social development may be an indication, as it was previously pointed out that there is a growth horizon in the studies of this theme. It is natural that socioeconomic development is promoted from economic growth. Therefore, academia is on the way to understanding the various effects of renewable energies on economic activity, and from this understanding to expand into economic development.

Figure 5 informs us of the most used keywords. A universe of 637 keywords was obtained; however, when we limit it to a minimum of five occurrences, this number drops to 17, thus, following relevance criteria previously stipulated that Figure 4 was made with the existing relationships between these 17 words that were most used by the authors as keywords.

Immediately, it is possible to observe that there are four clusters (given the different colors on the image), all of which somehow connect with the keyword "economic growth", which is the most used term by researchers, followed by "renewable energy". It is noted that, of the three terms selected in this work, two stand out. This may be an indication that the academy is focused on investigating the relationship between economic growth and energy consumption, a subject that was already investigated, however not overdone, since the focus is now on renewable energy matrices. With regard to the term of economic development, this subject, although extremely relevant, when related to economic growth and renewable energy, appears to be marginalized; that is, there is not much targeted research, so it is possible to conclude that there is a gap that should be explored by researchers.

It is also noted in the keywords with more occurrences there is a certain emphasis on CO2 in conjunction with keywords that relate to sustainability. This implies an apparent interest in studying how greenhouse gas emissions may be impacting growth and or economic development. To a certain extent, the rise in the temperature of the planet may be one of the factors that have driven research to understand how renewable energies affect economic dynamics.

In addition, Figure 6 shows us that there are indications (given the yellow color) that these keywords, in sets, date to 2015 post surveys, once more, another indication that there is still much to be explored. Finally, China is noted as one of the most cited terms, and this may be one of the reasons why the country has greater prominence in the number of publications on the subject.

When the links between renewable energy, economic growth and economic development are observed, it is noted that there is no evidence of research relating to economic development and renewable energies, as can be seen in Figure 7 below. According to Figure 7, the existence of two clusters is clear; one between economic growth and renewable energies and the other between economic growth and economic development. The research gap that can be explored is even more evident since there is no direct link between economic development and renewable energies.

However, if we use energy consumption instead of renewable energies, a link is noted with economic development, as can be seen in Figure 8. Once again, this result reinforces the hypothesis of the absence of studies relating the consumption of renewable energies with development.

Finally, an analysis of the possible clusters and links between the researchers was also performed. The number of citations is a relevance indicator, even though it is not an accurate metric. In VOSviewer, the software to perform such analysis only considered authors with more than five citations, so the number of authors analyzed is 404 (instead of 665), which is the total number of researchers in this sample. Even though the number of researchers was reduced to 404, a link was found between only 46 of them, as can be seen in Figure 9.

**Figure 8.** Link Between Energy Consumption, Economic Growth and Development Economic.

**Figure 9.** Authors' Network Visualization.

By observing the number of colors, one can see 10 clusters. However, although there are 10, only 4 clusters stand out because they have more branches; therefore, they are connected to more researchers. These are one led by Bekun in blue, followed by Sarkodie in yellow, then Ozturk is in purple, and finally, the cluster formed by the Shahbaz in red. Notoriously, this relationship does not occur randomly since they are the authors with the highest number of documents published on the stipulated criteria. Sarkodie has eight publications based on the topic in that period, while Bekun has five publications, Shahbaz four publications, and Ozturk three publications.

Among the most referenced studies in the period, Bekun and Sarkodie, of the authors with the highest number of publications, are unique, with works listed among only 20 most referenced in the period. While Shahbaz, already recognized for his academic contribution in research that relates to economics and the environment, as highlighted in [17,18], appears to be relevant in studies relating to renewable energy and economics.

The work developed by these authors in the period investigated also does not study less developed economies, except Ozturk studying energies and ecological sustainability in the Belt and Road Initiative Countries [110], and Sarkodie investigating Ghana's economy in [197], all other studies focus on developed or developing economies. This is a strong indication that these less capable economies are being marginalized in the context of

understanding how renewable energies can affect their economic growth and development, and this negligence may be another factor of delay in their development.

## **5. Conclusions**

This research focused on investigating articles published in the Scopus database that studied the relationship between renewable energy, economic growth and economic development between 2008 and May 2021. The results of screening through the PRISMA methodology provided a sample of 111 articles selected by the WoS database and 199 articles selected by the Scopus database. There is a prevalence of quantitative methodologies to the detriment of other approaches. Regarding the ranking of the journals with the highest impact, Renewable and Sustainable Energy Reviews were in first place, followed by Global Environmental Change and in third was Water Research. However, the journal with the largest number of publications was Sustainability (Switzerland).

Despite the effort to overcome the difficulty in quantitatively measuring an article, journal or author, this is the major limitation of this research. The metrics used for quantifying are susceptible to failure; thus, they are not accurate because there is no defined methodology that is applicable to the type of approach used in this study. In addition to this, the selected sampling period was also considered since it does not take the year 2021 into account. To be more precise, it is only considered until 21 May. Nevertheless, the number of publications found for this year should not be ignored. Another limiting factor of the research is found in the sample used, considering the information available in the Scopus database in the construction of the analyzed sample, not taking into account all the studies that exist in Web of Science (WoS), which may have relevant studies that of course were not taken into consideration.

The analysis of the data obtained among both databases leads us to conclude that studies with respect to renewable energy, economic growth and economic development are just beginning since it is possible to observe a growth trend. Most of the studies published on that period occurred after 2015, and the articles considered to have the greatest impact are publications that date back to more recent years, which appears to be the result of the end of the first cycle of commitments of the Kyoto Protocol.

It is notorious that the topic is being researched on all continents, and surprising that China is a leader in publications, given that it is one of the countries whose economic growth has been the most damaging to the environment.

This research was able to identify research gaps; studies have focused on understanding how renewable energies have affected economies around the globe, but the observed gap is precisely in one of the keywords used in this research. No studies were observed that connect renewable energies and economic development; therefore, it is suggested that it is a theme to be addressed by academia in the future. There is also a lack of studies dedicated to less developed economies, so there is no evidence of how the factors observed in this study can affect the economic activity of these countries; for these economies, there is a lack of information to outline the best strategies and policy development to promote greater growth. In addition, with the possibility of continuing to work with this sample, it is also proposed in future research to analyze the quality of the research reviewed in this article, with the objective of finding unexplored gaps, which can later be addressed.

This type of study, proposed in this research, is strategic for decision-makers and policymakers in demonstrating that the effects of a variable on the economy. In the case of this research, the nexus between economic growth, renewable energy consumption and economic development may be different between economies. Hence, it is an indication that before any strategic decision-making to promote economic growth, consumption of renewable energies or economic development, statistical studies should be promoted, with the aim of having an evidence-based decision and thus making efficient decisions.

**Author Contributions:** Conceptualization, H.O. and V.M.; methodology, H.O.; software, H.O.; validation, V.M.; formal analysis, H.O. and V.M.; investigation, H.O. and V.M.; resources, H.O. and V.M.; data curation, H.O.; writing—original draft preparation, H.O. and V.M.; writing—review and

editing, H.O.; visualization, V.M. Both 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:** Data supporting reported results can be found in Scopus and Web of Science database at https://www.scopus.com/search/form.uri?display=basic#basic, accessed on 21 May 2021, and https://www.webofscience.com/wos/woscc/basic-search, accessed on 23 July 2021, respectively.

**Acknowledgments:** This work was supported by NECE-UBI, Research Unit in Business Science and Economics, sponsored by the Portuguese Foundation for the Development of Science and Technology, project UIDB/04630/2020, funded by national funds through FCT—Fundação para a Ciência e a Tecnologia.

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