All variables were verified for stationarity using the Levin, Lin, and Chu (LLC) (Levin et al. 2002), Im, Pesaran, Shin (IPS) (Im et al. 2003), ADF-Fisher Chi square (ADF) (Dickey and Fuller, 1979), and PP-Fisher Chi square (PP) (Phillips and Perron, 1988) techniques. At both the I(0) and I(1) levels, Table 2 displays the unit root results for all of the data.
Table 2
Tests | Results | Variables |
I (0) Unit Root |
REC | GDP | Energy Con. | Electricity Power Con. | RE Policies | R&D | CO2 |
LLC | Statistics | 25.0561 | 1.07355 | -5.95230 | -2.24346 | -2.22841 | -8.50488 | 3.95355 |
Prob. | 1.0000 | 0.1415 | 0.0000 | 0.0124 | 0.0129 | 0.0000 | 1.0000 |
IPS | Statistics | 32.7107 | 1.16024 | -2.75445 | -2.28630 | -2.15436 | -4.35891 | 9.21060 |
Prob. | 1.0000 | 0.8770 | 0.0029 | 0.0111 | 0.0156 | 0.0000 | 1.0000 |
ADF | Statistics | 2.38740 | 65.5851 | 120.205 | 339.717 | 84.3336 | 134.732 | 22.4472 |
Prob. | 1.0000 | 0.8409 | 0.0015 | 0.0000 | 0.0312 | 0.0000 | 1.0000 |
PP | Statistics | 2.62659 | 84.5302 | 128.863 | 345.394 | 167.810 | 130.504 | 20.7120 |
Prob. | 1.0000 | 0.2871 | 0.0003 | 0.0000 | 0.0000 | 0.0000 | 1.0000 |
Tests | Results | I (1) Unit Root |
LLC | Statistics | -1.70975 | -3.12788 | -23.5704 | -26.0043 | -21.8347 | -20.7843 | -15.0819 |
Prob. | 0.0437 | 0.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 |
IPS | Statistics | -2.12585 | -6.53014 | -20.0169 | -22.1564 | -16.6522 | -22.0332 | -16.4365 |
Prob. | 0.0168 | 0.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 |
ADF | Statistics | 132.182 | 173.605 | 469.457 | 628.988 | 423.198 | 493.745 | 391.733 |
Prob. | 0.0001 | 0.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 |
PP | Statistics | 128.754 | 157.807 | 878.791 | 1153.25 | 540.303 | 843.394 | 413.461 |
Prob. | 0.0003 | 0.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 | 0.0000 |
* p value < the significance level of 0.1 |
**p value < the significance level of 0.05 and 0.1 |
*** p value < the significance level of 0.01, 0.05, 0.1 |
As seen in Table 2, all variables are stationary at the first level, and to avoid spurious regression, a first-order unit root test was used in the study. As a result, for the investigated countries, all exogenous variables have become stationary, and a regression analysis is conceivable. Table 3 summarizes the results of numerous estimations of the fixed-effect and random-effect models (equations 2 and 4).
Table 3
Estimation Results from Fixed and Random Effects Models
Dependent variable | REC (Installed cumulative RE capacity) |
Explanatory variables | Fixed Effects Model Estimation1 | Random Effects Model Estimation |
Coefficient | Standard Error | p-value | Coefficient | Standard Error | p-value |
GDP per capita | -0.019633 | 0.044664 | 0.6604 | -0.055385 | 0.132484 | 0.6760 |
Energy consumption | 0.074423 | 0.027066 | 0.0012 | -0.143386 | 0.067211 | 0.0398 |
Electricity Power Consumption | -0.004263 | 0.001676 | 0.0519 | -0.032617 | 0.013348 | 0.0046 |
Renewable Policies | -0.000935 | 0.003275 | 0.7754 | -0.033690 | 0.008305 | 0.0008 |
R&D | 0.007003 | 0.003403 | 0.0479 | 0.020400 | 0.007284 | 0.0052 |
Carbon Emission | -0.076127 | 0.030003 | 0.0114 | -0.167991 | 0.076408 | 0.0338 |
R-squared | 0.813648 | 0.693023 |
Probability (F-Statistic) | 0.0000000 | .129078 |
Notes: Standard errors are corrected for country/state-level serial correlation. The variance inflation factor (VIF) was used to check for colinearity between independent variables. |
* p value < the significance level of 0.1 |
**p value < the significance level of 0.05 and 0.1 |
*** p value < the significance level of 0.01, 0.05, 0.1 |
1 In addition, the study performed weighted least squares (WLS) statistical analysis to obtain more robust results. The WLS method overcomes the problems of autocorrelation and varying variance from panel data (Javeed et al., 2021). The results of the robustness test confirm the previous panel regression results. The robustness test panel enables data autocorrelation and varying variance to be overcome (Lu and White, 2014; Prokhorov and Schmidt, 2009). |
The findings of the fixed effects panel data regression are shown in Table 3, which identify a few variables as significant drivers of RE investment. The R square value of 0.813 suggests a satisfactory fit for the fixed effects model, according to the panel regression findings for the fixed effects model. As a result, all exogenous variables combined could account for about 81 percent of the variation in REC. Even though all coefficients are nonzero, an F-statistic probability of 0.000 suggests that the overall panel regressions are significant (F < 0.05). A positive link between REC and energy usage and R&D was discovered using panel data fixed effects regression. In other words, a 1% increase in energy consumption and R&D spending results in a 0.007% rise in REC growth. This finding is supported by recent research by Khezri et al. (2021) and Wu et al (2020). The findings suggest that R&D spending has a favorable impact on RE sources such as solar, wind, bioenergy, and geothermal.
On the other hand, GDP, electricity power consumption, RE policies, and CO2 are inversely correlated to REC. The negative relationship between CO2 and REC was an astonishing outcome. However, recent studies by Ponce and Khan (2021) find that RE and energy efficiency is negatively related to CO2 emissions. Similarly, Zaidi et al. (2018) show that REC has an insignificant effect on CO2 emissions in Pakistan. Another conclusion drawn from the study is that there is no statistically significant link between REC and income or renewable policy. The findings obtained from the analysis are also supported by the literature. According to Hughes (2010), FITs fail in the UK because they prevent local promotion of RE capacity. Likewise, Delmas et al. (2007) established that the quota (RPS) policy system had no effect on RE production.
These findings mean that the current RE policies are insufficient to promote investment in RE. Furthermore, the world's three largest economies (the United States, China, and India) declared net-zero carbon goals, and the United Kingdom hosted the UN Climate Change Conference (UNCCC) of the Parties (COP-26) in October-November 2021, which resulted in new important agreements for UNFCCC implementation. However, it has been accepted that the steps planned will not be sufficient to prevent irreversible climate change. Governments should work harder in partnership with businesses, science, and civil society. Despite the fact that this result shows that countries should devote more resources (policy and R&D) to RE investments in order to attain net-zero ambitions (UNCC, 2022).
The R-square value was 0.69, and the Prob. (F-statistic) was 0.129, according to the random effects model result in Table 3. While REC and R&D have a positive link; GDP, energy consumption, electricity power consumption, RE policies, and CO2 have a negative relationship.
In the regression model that looked at REC in OECD and BRICS nations between 2000 and 2020, the Hausman test was utilized for exogenous variables. Table 4 shows the results of the Hausman test.
Table 4
Hausman Test Results for Random Effects
Test Summary | Chi-Square Statistic | Chi-Square | Probability |
Cross-Section Random | 7.356853 | 6 | 0.0348 |
As seen in Table 4, H0 is rejected because the random effects correlated Hausman test result is p > 0.05, the fixed effect model is more appropriate to estimate the net effect of exogenous variables on REC, and the alternative H1 hypothesis is accepted. In this case, the fixed effect model's R2 score indicates that it is suitable for the GMM model. Table 5 shows the findings of the GMM model.
Table 5
Estimation Results from GMM Model
Dependent variable | REC (Installed cumulative RE capacity) |
---|
Explanatory variables | Coefficient | Standard Error | p-value |
GDP per capita | 0.067107* | 0.009315 | 0.0000 |
Energy consumption | -0.036121* | 0.004213 | 0.0000 |
Electricity Power Consumption | -0.026330* | 0.011304 | 0.0201 |
Renewable Policies | 0.026005* | 0.001003 | 0.0000 |
R&D | 0.023241* | 0.000571 | 0.0000 |
Carbon Emission | -0.236776* | 0.018699 | 0.0000 |
* p < 0.05 |
According to the panel regression results for the GMM model, all variables are statistically significant (p < 0.05), indicating that it is appropriate. The findings are consistent with the fixed effects model's results: there are positive correlations between RE capacity, GDP per capita, RE policies, and R&D. RE policies and R&D spending cause REC to expand by 0.06 percent, 0.02 percent, and 0.02 percent, respectively, with a 1% growth in GDP per capita. Recent research has discovered similar results (Gershon and Emekalam, 2021; Tudor and Sova, 2021). According to Sadorsky (2009), for G7 countries, a 1% increase in GDP per capita boosts RE consumption by 3.5 percent. Recent research has discovered similar results (Gershon and Emekalam, 2021; Tudor and Sova, 2021). According to Sadorsky (2009), for G7 countries, a 1% increase in GDP per capita boosts RE consumption by 3.5 percent. Similarly, Baye et al. (2021) find that a 1% rise in real GDP per capita results in a 0.32 percent increase in REC in African countries. Omri and Nguyen (2014) find that economic development is the key driver for REC growth using a two-stage GMM panel estimate regression technique for 64 nations. In high-income, middle-income, and low-income nations, a 1% rise in GDP per capita improves the REC by 0.199 percent, 0.169 percent, and 0.149 percent, respectively.
Conversely, there are negative correlations between REC, energy use, electricity consumption, and CO2. REC drops by 0.03 percent, 0.02 percent, and 0.23 percent, respectively, when energy consumption, electricity consumption, and CO2 consumption all rise by 1%. These findings are in line with some previous research. For example, Baye et al. (2021) show that CO2 emissions have a negative impact on REC per capita in Sub-Saharan African countries, and they attribute this to energy inefficiency and a lack of environmental awareness.