Numerous academic studies have used various econometric techniques to analyze a single country or country groups in the literature on the relationship between energy consumption, economic growth, and environmental pollution. It is possible to narrow down this vast literature within the scope of our research and examine it in three different categories. In the first part of the literature, the relationship between energy consumption and economic growth, in the second part, the relationship between economic growth and environmental pollution, and in the last part, the relationship between energy consumption, economic growth, and environmental pollution will be examined.
While environmental pollution is generally measured by the change in CO2 emissions in the relevant literature (Mughal et al., 2022; Zhang et al., 2022; Han et al., 2022; Armeanu et al., 2021; Xiong and Xu, 2021; Abdollahi, 2020; Ashraf et al. 2020; Youssef, 2020; Ssali et al., 2019; Zhang et al., 2019; Akadiri et al., 2019; Al-Mulali et al., 2015; Shabbir et al., 2011, Apergis and Payne, 2009), studies using EF as a proxy, including carbon emission, to provide a broader perspective (Ahmed et al., 2022; Murshed et al., 2022; Eregha et al., 2022; Alper et al. ., 2022; Ahmed et al., 2021; Kutlar et al., 2021; Majeed et al., 2021; Nathaniel et al., 2021; Baz et al., 2020; Support and Sinha, 2020; Gülmez et al., 2020; Usman et al., 2020; Alola et al., 2019; Support et al., 2018; Caviglia-Harris et al., 2009) have increased in recent years. In addition to the studies that include energy consumption only in the form of renewable energy(Zhang et al., 2022; Murshed et al., 2022; Androniceanu et al., 2021; Ahmet et al., 2021; Akadiri et. al, 2019; Özcan and Öztürk, 2019; Koçak and Orgsunshi, 2017; Fotis and Pekka, 2017; Al-Mulali et al., 2015; Ocal and Aslan, 2013) or non-renewable energy (Abdollahi, 2020; Ashraf et al. 2020; Zhang et al., 2019; Wang et al., 2018) in the models, there are also studies including energy consumption per capita consisting of the sum of both energy sources (kg of oil equivalent (Zhang et al., 2022; Han et al., 2022; Alper et al., 2022; Eregha et al. al, 2022; Güzel, 2021; Nathaniel et al., 2021; Baz et al., 2020; Gülmez et al., 2020; Ssali et al., 2019; Support and Sarkodie, 2019; Apergis and Payne, 2009) and also studies, as ours, evaluating the different effects of both types of energy on economic growth and environmental pollution (Mughal et. al., 2022; Saqib, 2022; Xiong and Xu, 2021; Usman et al., 2020; Youssef, 2020; Support and Sinha, 2020; Alola et al., 2019; Armeanu et al., 2019; Support et al., 2018; Narayan and Doytch, 2017; Shahbaz et al., 2011; Shabbir et al., 2011; Tugcu et al., 2011). The distinction between renewable and non-renewable energy sources is vital in understanding their effects on EG and EF. For example, in their study on China, Xiong and Xu (2021) concluded that using electricity produced from renewable sources is less efficient than using non-renewable sources. High production rates have a beneficial effect on GDP but a negative effect on pollution in the environment. It is crucial to take the appropriate actions to lessen environmental pollution without sacrificing output volume or quality.
In studies examining the causal relationship between energy consumption and economic growth in the literature, four different hypotheses are investigated: growth, conservation, feedback, and neutrality. According to the growth hypothesis, there is unidirectional causality from energy consumption to economic growth. According to studies supporting this hypothesis (Aydın, 2019; Özcan and Öztürk, 2019; Wang et al., 2018; Support and Aslan, 2017; Öncel et al., 2017; Koçak and Şarkgüneşi, 2017; Narayan and Doytch, 2017; Raza et al. al, 2016; Tugcu et al., 2011; Narayan et al., 2008; Wolde-Rufael, 2006) while an increase in energy use contributes positively to economic growth, economic growth is negatively affected in case of a restriction (or shock) in energy use. The conservation hypothesis expresses the unidirectional causality between economic growth and energy consumption. According to studies supporting this hypothesis (Aydın, 2019; Wang et al., 2018; Support and Aslan, 2017; Öncel et al., 2017; Yaşar, 2017; Narayan and Doytch, 2017; Fang and Chang, 2016; Ocal and Aslan, 2013), with the increase in output, there is an increase in people's demand for energy-powered goods and services, which further increases the energy demand. However, it should be stated here that policies to protect energy consumption in countries that are less dependent on foreign energy will not negatively impact the country's economic growth, or this effect will be limited (Öncel et al., 2017). The feedback hypothesis is based on the claim that the causality relationship between energy consumption and economic growth will be bidirectional. In the studies supporting this causal relationship (Akdiri et al., 2019; Aydın, 2019; Wang et al., 2018; Yaşar, 2017; Jaiyesimi et al., 2017; Koçak and Şarkgüneşi, 2017; Support and Aslan, 2017; Öncel et al., 2017; Tugcu et al., 2011; Odhiambo, 2009; Apergis and Payne, 2009), it was concluded that economic growth and energy consumption mutually feed each other. The neutrality hypothesis predicts no causal relationship between energy consumption and economic growth. According to studies supporting this hypothesis (Destek and Aslan, 2017; Özcan and Öztürk, 2019; Yaşar, 2017; Koçak and Şarkgüneşi, 2017; Menegaki, 2011; Tugcu et al., 2011; Payne, 2009), the policies applied for energy consumption (protective or expander) has no direct impact on economic growth.
While the relationship between economic growth (energy consumption) and environmental pollution is discussed in the literature, the theory is usually expressed by the environmental Kuznets curve (EKC). According to EKC, environmental quality and income per capita have an inverted U-shaped relationship. According to this theory, environmental degradation and income growth coexist because environmental concerns are not well understood during the early stages of economic development, and environmental technology is not readily available. The level of damage then slowly reduces as environmental consciousness rises, environmental regulations are implemented, better technology is used, and more funds are used to protect the environment. Consequently, there is a link between environmental degradation and income per capita that is inverted U-shaped (Abdollahi, 2020: 276). Some studies in the related literature (Mughal et al., 2022; Murshed et al., 2022; Nathaniel et al., 2021; Ssali et al., 2019; Zhang et al., 2022; Support and Sarkodie, 2019; Support et al., 2018; Ulucak and Bilgili, 2018; Osabuohien et al., 2014; Apergis and Payne, 2009) reached results confirming the EKC hypothesis, while some other studies (Destek and Sinha, 2020; Wang et al., 2018; Stern, 2004; Caviglia-Harris et al., 2009) did not find sufficient evidence to confirm the EKC hypothesis. Studies in the literature (Ashraf et al., 2020; Allard et al., 2017; Güzel, 2021) show that the relationship between economic growth and environmental pollution may be N-shaped (which suggests environmental degradation will start to rise again beyond a certain income level). Gülmez et al. (2020), on the other hand, concluded in the form of U-Shape EKC between EC and EF in their study using ARDL Models and ECM-Based Granger Causality for the 1961–2016 period in the case of Turkey. On the other hand, some studies try to determine whether there is a relationship between the variables, the direction of the relationship, and whether the relationship is significant or not without emphasizing the EKC.
In our study, we focused on the relevant literature about the relationship between energy consumption, economic growth, and EF variables, but we could not find a panel study in which countries importing energy from Russia were discussed. In the literature, in addition to the studies involving different country groups, there are also studies in the form of time series in which single country examples are included. Caviglia-Harris et al. (2009), one of the selected studies in which all three variables our study were used together, examined 146 countries with different development levels for the 1961–2000 period. According to the study results, the reason for the increase in EF was not economic growth but a CO2 increase. They concluded that countries should pay attention to their energy consumption policies for sustainable development. Ahmet et al. (2021), in their study on G7 countries for 1985–2017, stated that EG increased EF. However, environmental regulation and democracy contributed positively to ecological sustainability by reducing EF, and they also found that EG created a feedback effect with renewable energy. In a study conducted on 16 EU member states, Alola et al. (2019) concluded that using non-renewable energy reduces environmental quality. Still, the use of renewable energy improves environmental sustainability. Having reached similar results, Destek et al. (2018) examined the relationship between NRE REC, trade openness, EG, and EF using second-generation panel data methodologies for the 15 EU countries from 1980–2013. They found that the validity of the EKC and NRE increases the environmental degradation while RE and trade openness decrease the environmental degradation. Destek and Sinha (2020), in their study on 24 OECD countries using second-generation panel data methodologies for the period 1980–2014, concluded that an increase in renewable energy consumption reduces EF and an increase in non-renewable energy consumption increases environmental degradation. The study findings also point to results that do not support the inverted U-shaped EKC between economic growth and EF. Again, Usman et al. (2020), for the period 1994–2017, used FMOLS, DOLS, FGLS, and AMG, Dumitrescu, and Hurlin non-causality tests on 33 upper-middle countries (including China and some Europe countries). Their study found evidence that the increase in renewable energy use decreases EF in Asia and Europe.
In contrast, primary energy use increases EF in Asian countries. Alper et al. (2022) researched the top 10 countries causing the highest CO2 emissions (including China, Germany, Japan, South Korea, and the USA)for the 1970–2017 period, using the Fourier bootstrap ARDL cointegration method and the Fourier bootstrap Toda–Yamamoto causality method. The study concluded that EG and EC (total energy consumption) generally negatively affect EF (EG and EC have adverse effects). The GMM and FMOLS approach was used by Zang et al. (2022) to perform research on the E5 (5 developing economies) countries, including China, between 1990 and 2019. The results demonstrate that EG has a positive and significant impact on environmental degradation (ED). The results show that rising ED results from increased geothermal and hydro energy generation.
Furthermore, it has been discovered that raising energy output from nuclear and wind sources decreased the ED. Nathaniel et al. (2021) researched N11 Countries (the eleven fastest emerging economies), including Turkey and South Korea, using Westerlund cointegration, Dumitrescu and Hurlin causality, and FMOLS analysis methods throughout 1990–2016. According to the study results, EC increases the EF, and the EKC hypothesis is verified for these countries. In another study on N11 countries, Eregha et al. (2022), in the period 1990–2017, used the cross-sectionally augmented autoregressive distributed lag (CS-ARDL) model, augmented mean group (AMG), and the common correlated effects mean. They used group estimators (CCEMG) and concluded that EC (total energy use) and EG promote environmental degradation in all the N11 countries. In summary, it is seen that the increase in the use of renewable energy generally has a positive effect on EF.
As it can be understood from the literature summary we focused on within the scope of our study (analyzing EC, EG, and EF simultaneously in the same study), the findings obtained from these studies differ according to the country or country groups studied, the period covered by the research, the variables used and the methods used in the study. Therefore, in summary, it is understood that a complete consensus has not yet been reached on whether there is a significant relationship between these variables or what the direction of the relationship is.