Exchange rate stability in the emerging economies: does renewable energy play a role—a panel data analysis

Due to the high and rising rates of carbon emissions, the use of renewable energy sources has been encouraged to help achieve carbon neutrality goal. However, renewable energy sources are said to be expensive than fossil fuels. Major studies have been undertaken to ascertain the association between renewable energy and many economic indicators, such as gross domestic product, employment rate, and inflation rate. The current study is aimed at investigating whether renewable energy use helps stabilize the foreign exchange rate of emerging economies, which has not been widely examined in the past, hence the study originality. Stability in the foreign exchange rate of a nation is very crucial as this helps to stabilize the inflation rate. This study employs the fully modified ordinary least and dynamic ordinary least square methods to analyze panel data of emerging economies. The findings indicate that high real interest rate and gross domestic product causes appreciation in the currency exchange of a country, while high balance of payment, inflation rate and renewable energy consumption are found to cause currency depreciation. The Pedroni and Kao cointegration tests are employed and the results show that a long-run relationship exists among the variables examined. This research recommends balance of payments and inflation rate to be minimized if exchange rate stability is to be achieved, while gross domestic product and real interest rate should be increased.


Introduction
The United Nations (UN) have, in recent years, came up the Sustainable Development Goals (SDGs), for the purpose of achieving carbon neutrality in the future. This has led to many researches being done, the world over, to ascertain the impact of renewable energy (RE) (which is considered as a friendly source of energy to the environment) on carbon emissions (CE) (Banga et al. 2022;Shahbaz et al. 2020;Akadiri & Adebayo 2021); on economic growth (Chen et al. 2020;Apergis & Payne 2010;Ivanovski et al. 2021;Zahid et al. 2021; among others); on employment (Ge & Zhi 2016); and on currency stability Deka & Dube 2021). The current study is motivated by the work of Filippidis et al. (2021) who postulated that RE use helps in reducing income inequalities and the environmental stress of nations. If RE use has the significant effect of reducing income equality and greenhouse gas emissions, one could ask whether RE use may also help in stabilizing the exchange rates (ER) of nations. Currency depreciation is not healthy for nations, as this erodes the buying power of Responsible Editor: Roula Inglesi-Lotz the currency, thus causing inflation to rise. Thus, nations seek to keep their currencies as stable as possible.
The studies on the ER determinants have been undertaken by various researchers and different findings have been given, Bouraoui & Phisuthtiwatcharavong (2015); Dogru et al. (2019); Vural (2021); Rodriguez (2016); Kilicarslan (2018); Kia (2013); Beckmann et al. (2020). The research by Vural (2021) in Turkey gave oil prices as a new and significant determinant of ER. The first studies to examine the impact of RE on ER are by Deka & Dube (2021);  in Mexico and Brazil, and the findings indicated that RE use did have a significant effect on stabilizing foreign ER. Moreover, in another study by  in the OECD countries, high use of RE energy is observed to promote the appreciation of ER. Therefore, from these past researches different findings are observed, hence more work is required to ascertain this association. The question of how RE consumption affects the economic activities of nations has been answered through the studies of (Chen et al. 2020;Chica-Olmo et al. 2020;Dogan et al. 2020;Eren et al. 2019;Ivanovski et al. 2021;Rahman and Velayutham, 2020). Other studies have been conducted to analyze the impact of renewable energy on employment (see Ge & Zhi (2016)). The literature provides mixed results on the impact of RE consumption on economic growth, with some studies postulating a positive impact, some a negative impact and others allude that the relationship is not significant (Chen et al. 2020).
The current research is an addition to the existing literature on the effects of RE use on currency exchange. Unlike past studies that have examined the impact of RE use on exchange rate, the current study examines this relationship among emerging economies popularly known as the E7 economies. The current study also differs from past studies in that it uses panel data of 7 emerging economies whose ER has not been stable; for example, Turkey has had high depreciation rates in the lira in recent years, together with the Russian ruble. The research makes use of cointegration regression methods in the presence of unit root, such as fully modified ordinary least square (FMOLS) and dynamic ordinary least square (DOLS). The FMOLS and DOLS models give robust long-run results on panel data that is cointegrated, not stationary at level, and stationary at first difference. Hence, in this study, as there is cointegration among the variables and they are integrated of order one, these models are used. The Johansen and Kao cointegration tests are also applied to ascertain the long-run relationship among the variables, while the augmented Dickey Fuller and Phillips Peron tests are used to check the unit root of the individual variables. The study findings shows that balance of payments, RE, and the rate of inflation positively affects ER, while GDP and real interest rate negatively affects ER in the E7 countries. This research also concludes by giving the policy implications.

Exchange rate theories
There are basically two major kinds of exchange rate regimes that exist, which countries ought to choose on the best one to pursue. These two kinds of exchange rate regimes are flexible and fixed exchange rate (Mankiw 2010). Fixed exchange rate regime entails that the government dictates the currency rate of their own economy's currency to that of other countries. With fixed exchange rate, the rate of currency exchange is not subject to change; it is pegged at a certain rate, as per the government's decision. Flexible exchange rate regime, on the other hand, is when the economy leaves the exchange rate to be determined by the market forces of demand and supply, prevailing in the economy. There is no government intervention, and the rate of currency exchange is determined by the decisions of many buyers and sellers in the economy. Unlike, the fixed exchange rate, the flexible exchange rate is always subject to change. Proponents of the fixed exchange rate regime argues that the flexible exchange rate is subject to high volatility, which in turn causes market uncertainty. Consequently, proponents of flexible exchange rate regime argue that intervention of the government in pegging currency exchange results in market inefficiency since the pegged rate will not reflect true decisions of buyers and sellers. In that regard, the fixed exchange rate has been proved as ineffective; hence, nations have long resorted to the flexible exchange regime. There are basically, four major theories of foreign exchange, that is, the purchasing power parity, interest rate parity, international fisher effect, and unbiased forward rate.
The purchasing power parity (PPP) was proposed, through the work of Fisher (1930). According to Dornbusch (1975);Fisher (1930); Stockman (1980);Dornbusch (1980), it gives that the prices of two trading countries and their rate of currency exchange are closely related. Under the PPP proposition, various economic assumptions are considered, such as zero transportation costs, trade barriers don't exist, and the costs of currency conversion doesn't apply. Given these assumptions, the PPP proposition is simplified, hence its ability to determine the rate of currency exchange of two nations. There are generally two major subdivisions of the PPP proposition, that is, the relative and absolute PPP propositions. According to the absolute PPP theory, the law of one price exists among two different trading countries on the same identical good. This entails that the price of say bread in the UK happens to be the same sterling price of bread in Germany. Consequently, if the law of one price, on same identical goods, exists between 2 nations, then their ratio prices become the rate of currency exchange; see , for review. If the law of one price happens to be violated, then this will cause arbitrage opportunities to arise (Fisher 1930). The relative PPP, according to Fisher (1930), states that if in a single country, for instance UK, the rate of inflation increases more than in another; for instance, in Germany, this will cause UK prices to increase at a higher rate in comparison to that of Germany. According to , the country whose prices have risen more, say the UK in our example, will have their currency depreciating relative to that of the other country whose price has not risen much, say German in our example. Therefore, this shows that the relative PPP proposition provides for a connection between currency exchange, price, and the rate of inflation ; , Deka & Dube (2021)). This entails that the factors which raise the rate of inflation in a nation have a tendency of exacerbating exchange depreciation. The studies of Nasir & Simpson (2018); Nasir & Vo (2020); ; Pham et al. (2020); ); Nasir (2020) provides for the opposite of the above, known as the exchange rate pass-through, which shows that currency undervaluation of a nation has a tendency of affecting changes in the prices.
The interest rate parity (IRP) theory or the covered interest parity (CIP), according to Fisher (1930), alludes that the rate of currency exchange and the rate of nominal interest are significantly connected. The assumptions of the IRP theory are that the cost of changing from one currency to the other is zero, there is full capital mobility, and that investors have free choice either invest in securities denominated in the foreign or home currency, for review see, Deka & Dube (2021). According to the IRP proposition, nominal interest rate and the spot rate remain the major factors that impact the currencies' forward exchange rate. It also follows that, in the event that, if the interest rate differentials are smaller than the spot and forward rate differences of two nations, then covered interest arbitrage will exist. A dilemma is always faced on which security to invest in if the quoted rate equals the calculated forward rate; see  for review. When the forward rate is higher than the spot rate that is expected, then market participants will be induced to sell currency forward hoping to buy the currency at spot rate in the spot market at the maturity of the forward contract. The sale of the currency forward results in a fall in the forward rate, hence equalizing the spot rate expected. The opposite of the above scenario also happens when there is a forward rate which is below the expected spot rate; see  for review. The unbiased forward rate (UFR) proposition, according to Jaffe & Mandelker (1976) and Fisher (1930), gives that the forward rate is the unbiased predictor of the spot rate expected. The actions of participants in the market ensure that the forward rate is equal to the spot rate expected in the future; see  for review.

The nexus between economic indicators and renewable energy
It is of paramount importance that the impact of RE consumption on economic activities is studied, since nations are shifting to RE use to curb the negative effects of fossil fuels on the environment. Several studies have been undertaken to examine how RE impacts economic growth in various nations, and mixed results have been observed (Chen et al. 2020;Chica-Olmo et al. 2020;Dogan et al. 2020;Eren et al. 2019;Ivanovski et al. 2020;Smolovic et al. 2020;Wang & Wang 2020;Rahman & Velayutham 2020). The studies by Wang & Wang (2020) and Chen et al. (2020) on Organisation for Economic Co-operation and Development (OECD) countries found that RE consumption has a significant positive impact on economic growth. These findings were supported by the studies of Smolovic et al. (2020) and Chica-Olmo et al. (2020), who observed that in Europe, RE positively impacts economic growth. Therefore, this indicates that an increase in RE consumption will increase the growth of economies. Thus, in addition to reducing the greenhouse effect, RE significantly improves nations' economic growth. Therefore, RE consumption has double-positive effects, and nations should be encouraged to use it. Another study by Dogan et al. (2020) that employed quantile regression analysis showed that for lower and low middle quantiles, RE positively affects economic growth and that the effect becomes negative in middle, high middle, and higher quantiles. The study results also indicated that RE has a negative impact on economic growth across all quantiles (Dogan et al. 2020).
Moreover, other studies have suggested that economic growth causes RE consumption (Rahman & Velayutham 2020;Sadorsky 2009). Rahman & Velayutham (2020) found a unidirectional causality from economic growth to RE consumption in five Asian countries, while Sadorsky (2009) determined that economic growth has a positive impact on RE consumption in emerging economies. Therefore, we observe that increases in the growth of an economy cause RE consumption to increase. Thus, if economies are growing and improving economically, this will improve the consumption of RE. Hence, economic growth should be encouraged in emerging economies and other nations to enhance RE consumption, which will in turn result in a reduction in CO2 emissions and global warming effects. Eren et al. (2019) also found a bidirectional relationship between economic growth and RE in India. This implies that economic growth impacts RE and RE also impacts economic growth. Financial development is also found to cause RE (Eren et al. 2019), while RE is also found to positively impact employment in developing and developed countries (Ge & Zhi 2016).
Additionally, several other researchers have been recently conducted to ascertain the association between RE use on the one hand and exchange rate and inflation rate on the other (Deka & Dube, 2021); Deka et al., 2021). The association between RE use and currency exchange has been found to be negative and significant, indicating that relying on the use of RE has the effect of stabilizing the nation's foreign exchange rate (Deka & Dube 2021;Deka et al. 2021;. The association between RE use and inflation rate has been observed to be significant and positive, indicating that RE use has the tendency to increase the prices of products in a nation. This is because RE sources are more expensive than nonrenewable sources. Thus, governments should intervene by providing subsidies on the production of RE.

Major determinants of exchange rate
Many researches have been done, the world over, to examine the determinants of exchange rate. The findings of past researches give that the major determinants of ER are government debt, money supply, investment by the domestic nation, fiscal spending, prices of oil, reserves, rate of inflation, trade, interest rate, net foreign liabilities, income growth, GDP, and productivity per labor work, just to mention a few (Bouraoui & Phisuthtiwatcharavong (2015) (2012)). The impact of various factors that affect ER is observed not to be consistent among many studies. The research by Bouraoui & Phisuthtiwatcharavong (2015) gives that ER is not impacted by interest rate differentials in Thailand, whereas Chowdhury (2012) alludes that interest rate differentials in Mexico do have a significant effect on ER. The differences on the findings of different researches are explained by different conditions prevailing in different countries . Bouraoui & Phisuthtiwatcharavong (2015) and Chowdhury (2012), however, agree that ER is significantly impacted by terms of trade. The research by Vural (2021) gives fiscal spending, GDP, and prices of oil as the major determinants of the lira in Turkey. Moreover, Beckmann et al. (2020) give that the prices of oil and ER are significantly connected, while Kilicarslan (2018) gives that ER is negatively impacted by GDP, FDI and government spending. Kilicarslan (2018) also gives trade openness, domestic investment and the supply of money as the major factors which results in rising ER.

Nexus between foreign exchange rate and other economic indicators
The relationship between exchange rate and economic growth has been examined in the studies by Fraj et al. (2018); Ribeiro et al. (2020); Tang (2015); Papanikos (2015). Exchange rate appreciation (currency overvaluation) negatively affects economic growth (Papanikos 2015), whereas exchange rate undervaluation, or depreciation, has the effect of increasing the growth of nations since this stimulates technological progress and knowledge spillovers (Ribeiro et al. 2020). They showed that to enhance economic growth, the currency should not be overvalued as this will hinder growth. In China, low real exchange rates have not induced any growth benefits (Tang 2015).
However, Wesseh & Lin (2018) postulated that in Liberia, the depreciation of the Liberian dollar has caused the gross domestic product (GDP) to fall, indicating that currency depreciation negatively impacts economic growth. The findings of Wesseh & Lin (2018) concurred with Ribeiro et al. (2020) that currency undervaluation has the effect of raising income inequality, which will harm output growth. This shows that currency appreciation should improve an economy's growth, and thus, nations should improve and maintain their currency values. The studies by Deka & Dube (2021) and Deka et al. (2021) examined the relationship between foreign exchange rate and inflation rate. In the case of Mexico, Deka & Dube (2021) ascertained that there is a significant positive link between the nation's rate of currency exchange and its rate of inflation. This shows that currency depreciation will tend to cause a high rate of inflation and currency appreciation stabilizes inflation rate in the country. Deka et al. (2021) also supported the findings of Deka & Dube (2021) that the two indicators are positively related. This is in line with the postulations of the relative purchasing power parity theory by Fisher (1930), which states that a high inflation rate causes currency depreciation. Therefore, any factors that stabilize the exchange rate will indirectly stabilize the rate of inflation, and vice versa.

Research model
The major determinants of ER are government debt, money supply, investment by the domestic nation, fiscal spending, prices of oil, reserves, rate of inflation, trade, interest rate, net foreign liabilities, income growth, GDP, and productivity per labor work, just to mention a few (Bouraoui & Phisuthtiwatcharavong (2015) (2012)). In addition to that, interest rate and inflation rate are considered as the major factors that affect ER (Fisher 1930). In this research, we follow the model specification given in the research of  in research of the OECD. Therefore, this research specifies ER as a function of balance of trade, inflation rate, GDP, RE, and real interest rate. The model specification of this research is given in Eq. 1 below: ER represents the exchange rate, RE is the renewable energy, INFL represents inflation rate,BOP is the balance of payment, GDP is the gross domestic product, and RIR is the real interest rate. The statistical representation of this model is also given in Eq. 2 below: In Eq. 2, et is the error term, while β0 to β5 are the model's coefficient values, and ln is the log value of a variable.

Data and sample
In this research study, we specify the variables exchange rate, inflation rate, RE, BOP, GDP, and real interest rate of the emerging economies for the period 1990 to 2019. The data employed in this study is secondary data and is retrieved from https:// www. data. oecd. org, except for real interest rate data which is retrieved from https:// data. world bank. org. In this study, we use a study sample of seven countries known as the emerging seven (E7 economies): China, India, Brazil, Mexico, Russia, Indonesia, and Turkey.
The exchange rate is the price of one country's currency expressed as a ratio of that of another country. Thus, the exchange rate shows the value of one country's currency related to that of other countries. The exchange rate values used in this study are expressed as the home currency per one US dollar. Thus, an increase in the exchange rate value means that the home country's currency is depreciating and vice versa. Inflation is a continuous increase in a country's prices of goods and services and is not suitable for the country's economy since it erodes the currency's buying power. In this research, inflation rate is measured as a percentage of consumer price index (CPI). RE is referred to as the contribution of renewables to the total primary energy supply, and it comes in the form of hydro, tidal, geothermal, wind, solar, and wave sources. RE in this research is measured as a percentage of total primary energy supply. GDP refers to the total value of all products produced within the boundaries of a country and is measured in million dollars. Balance of payment is the current account record of one nation's international transactions with those of other countries in the Real interest rate, in this research, refers to the rate of interest that is adjusted for the effects of inflation and is in percentage form.

Method
Based on the findings of Deka & Dube (2021); Deka et al. (2021) who found a significant link between currency appreciation and the use of RE, in this study, we seek to further examine whether the association really holds. Cointegration regression analysis, including fully modified ordinary least square (FMOLS), by Phillips and Hansen (1990) and dynamic ordinary least square (DOLS) by Stock and Watson (1993), is used as the study methodology to ascertain the relationship between exchange rate as the dependent variable and the explanatory variables (RE, GDP, BOP, money supply, population size, trade, and inflation rate) of the E7 economies. The FMOLS and DOLS models provide robust long-run results on panel data that is cointegrated, not stationary at level, and stationary at first difference. Hence, in this study as there is cointegration among the variables and they are integrated of order one, we employ these models. FMOLS and DOLS are cointegration regressions that require two essential prerequisites to be met: the variables should be nonstationary at level and stationary at first difference (integrated of the same order 1), and they must have at least one cointegration equation.
In this study, we employ the augmented Dicker Fuller (ADF) test and Phillips Peron (PP) test to check the stationarity of the variables (Box & Jenkins, 1976;Granger 1986;Engle & Granger 1987). The ADF test was pioneered by Dickey & Fuller (1979), and it is an extension of the Dickey test developed by Dickey (1976). The Dickey test is only capable of checking the stochastic trend of a variable but not the deterministic trend, and the ADF test can identify both stochastic and deterministic trends in a time series (see Gujarati 2004). The other test of unit root in a variable is the PP test by Phillips and Peron (1988). The PP test is used together with the ADF test for robustness (Gujarati 2004;Granger 1986). Granger (1986); Engle & Granger (1987) suggested that if the variables are nonstationary at level and stationary at first difference, then a relationship such as Z t exists that is stationary, and this is known as the cointegration relationship. Granger (1986) stated that if variables Yt and X t are connected through a relationship that contains a constant term, then the following cointegration relationship that is stationary will be obtained.
where Z t is the cointegration relationship between Y t and X t that is stationary at level and a is a unique constant term connecting Y t and X t , in a cointegration relationship; see Granger (1986). The relationship expressed in Eq. 1 above may contain some seasonal problems (Granger 1986). However, another relationship such as the one below may exist that has no seasonal issues.
If variables are cointegrated, this means that a long-run relationship among them exists. They have a long-run association, and this association can be ascertained by employing cointegration regressions such as FMOLS and DOLS models, among others.

Descriptive statistics
The results of this study's descriptive statistics are provided in Table 1. The total number of observations per each variable, ER, BOP, inflation, RE, GDP, and real interest rate is 210. In Table 1, we also provide the mean, median, maximum, standard deviation, and total value of every indicator under study. It is shown that in the E7 (4) Y t = aX t economies for the period under study, the average values of BOP, ER, GDP, inflation, RE, and real interest rate are − 0. 1191, 1190, 9164.9, 58.77, 21.38, and 6.76, respectively (see Table 1 below). For the median, maximum, minimum, and standard deviation values of the indicators under study, please see Table 1 below. Table 2 below provides the correlation results of ER, BOP, inflation, RE, GDP, and reap interest rate for the E7 economies. The results of the correlation analysis show that RE use is negatively correlated with BOP, inflation rate, and GDP but positively correlated with ER and real interest rate. Real interest rate is also observed to exhibit for a significant negative association with BOP and inflation rate. The other pair of variables are not significantly related as shown in Table 2. A negative significant correlation shows that the variable has an inverse association such that a rise in one variable will cause a decline in the other, whereas a positive significant correlation implies that the variables move in the same direction such that a rise in one causes the other to rise as well.

Unit root test results
In this section of the study, we provide the findings of the ADF and PP unit root tests. In Table 3 below, the results of the unit root test are given for all the variables that have been employed in this research. The findings of both ADF and PP tests show that all variables are stationary at first difference, and hence, they are integrated of order one. They are nonstationary at level and become stationary after first difference. It is only inflation rate and real interest rate that are stationary at level at 1% level of significance according to the results of both tests. However, they are stationary again at first difference. Cointegration regressions such as FMOLS, DOLS, and VECM require that variables should be stationary at first difference (Granger, 1986;Engle & Granger 1987).

Cointegration analysis
In this study, we employ the Johansen and Kao cointegration tests to analyze the cointegration relationship among the variables specified in the research model of this study.  (Granger 1986;Engle & Granger 1987;Granger & Weiss 1983). Therefore, the variables move together in the long run.

FMOLS and DOLS results
At this juncture, we have ascertained that the variables under study are integrated of the same order I(1), and they are cointegrated, indicating that they have a long-run relationship (Granger 1986;Engle & Granger 1987). In Table 5 below, we provide the FMOLS and DOLS results. In this research, for both FMOLS and DOLS techniques, ER is the explained variable, while BOP, inflation, RE, lnGDP, and real interest rate are the explanatory variables. The results of the FMOLS model in Table 5 below show that BOP, inflation rate, and RE consumption have a significant positive impact on the foreign ER of the E7 nations. Therefore, when BOP, inflation rate, and RE use increase in these nations, then this will have the effect of causing a depreciation in the nation's currencies. A rise in BOP, inflation rate, and   Table 5 above also show that GDP and real interest rate have a significant negative effect on ER. It follows that an increase in the gross domestic product and real interest rate of the E7 economies will result in a decrease in their foreign ER, indicating that economic growth and rise in real interest rate in the E7 nations tend to encourage appreciation of the currency value. According to the findings of the FMOLS technique, an increase in lnGDP and real interest rate by 1 unit in the E7 countries has the effect of decreasing the exchange rate by 2522.59 and 28 units respectively. Moreover, the DOLS outcomes also gives that a rise in lnGDP by 1% causes ER to fall by 1940%, while real interest rate has no significant effect on ER in the E7 countries. This is a good sign for the E7 nations as there is no dilemma faced in trying to achieve a high growth rate and stabilize the currency at the same time.

Discussion
In this research we show that BOP and inflation rate remain the major factors that causes currency depreciation. A high rate of inflation rate and high rate of BOP results in the depreciation of the home currency. The positive effect of inflation rate on ER supports the relative PPP theory of Fisher (1930). The results also support the findings of Deka & Dube (2021); ; Deka et al. (2021), who alluded that a high inflation rate has the effect of depreciating the nation's currency. Moreover, the positive effect of BOP on ER in the E7 countries supports the postulations of  who observed the same results. We therefore, in this study provide that, for nations to maintain a stable rate of currency exchange, their inflation rate should be monitored and kept low, while their BOP should be kept at reasonable levels that are not too high.
The positive effect of RE use on ER rate shows that high use of RE sources has the tendency of depreciating the currency in these nations. These findings do not support the results of Deka & Dube (2021); ; , who alluded that RE use enhances currency appreciation. The reason for the differences observed on the findings of past studies and the current study may be explained by the exorbitant prices of RE sources as compared to fossil fuel sources; see Becker & Fischer (2013). Thus, RE sources need to be subsidized by the government to reduce the burden of high priced to the citizens. By doing so, both ER stability and low carbon goal maybe achieved. Moreover, GDP and real interest rate positively impacts ER, showing that high economic growth and high level of interest rate promotes currency appreciation. These outcomes support the results of  who gives that long-term interest rate promotes currency stability. Therefore, economic growth and real interest need to be improved for the purpose of achieving ER stability.

Conclusion
This research provides that stability in the foreign ER of a country is achieved through promoting economic growth and raising the real interest rate. Interest rate, according to the relative PPP theory of Fisher (1930) has a strong link with ER. The findings of  also shows that high long-term interest rate results in currency appreciation. Moreover, the rate of currency exchange can also be stabilized through reducing the rate of inflation of a country as well as by reducing the BOP. High inflation rate is regarded as the major factor that causes currency depreciation (Fisher (1930); Deka & Dube (2021); ; ). As a result, reducing or stabilizing inflation rate of a country helps stabilizing ER too. This research recommends reduction in the inflation rate and BOP of countries, together with promoting GDP and increasing real interest rate, if ER stability is to be achieved. RE sources whose prices are high should also be subsidized by the government. By doing so, both ER stability and carbon neutrality goal is achieved.

Data availability
The data used in this paper is secondary data and were retrieved from the Organisation for Economic Co-operation and Development (OECD) website www. oecd. org

Declarations
Ethics approval Not applicable.

Competing interests
The authors declare no competing interests.

Consent for publication
The authors guarantee that this manuscript has not been previously published in other journals and is not under consideration by other journals. The authors also guarantee that this manuscript is original and is their own work.