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[28]
[29]
net oil-exporting and 14 net oil-importing countries. Idroes et al. for Indonesia, Destek and Sinha for
[30]
[32]
24 OECD countries, Dogan et al. for South Asian countries, Kongkuah for BRI countries, and Pata
[31]
for the USA have all reported the same effect.
Renewable energy Kuznets curve (RKC) hypothesis and its determinants
The RKC hypothesis, developed by Yao et al. as an alternative to the EKC hypothesis, proposes a U-
[10]
shaped relationship between income growth and REN. This hypothesis, contrary to the EKC, posits that
REN decreases in the initial stages of economic development but begins to increase after a certain income
threshold is passed. Many studies in the literature have focused on the mitigating effect of REN on CO
2
emissions, but have not made any inferences about how the widespread adoption of REN would affect the
turning point or the economic rationale behind it . While the economy is under the "scale effect", per
[10]
capita GDP increases, but REN decreases because the energy required during the rapid growth process is
primarily sourced from fossil fuels.

As the RKC hypothesis is relatively new, the literature remains in its developmental stages.
[12]
Nabaweesi et al. , in their study on the East African Community countries, reported that financial
development positively affects REN and found evidence supporting the validity of the RKC hypothesis.
Pata et al. conducted one of the pioneering studies in the field, testing both the RKC and EKC hypotheses
[13]
for the US economy using Fourier-based analyses. The findings of their study are critically important as
they reveal that the RKC turning point occurs before the EKC turning point. Theoretically, a rapid decline
in REN accelerates the emergence of the "structural effect" in the economy, causing the RKC's turning point
to occur relatively earlier. This, in turn, would also pull the EKC's turning point to an earlier stage. Thus, the
U-shaped RKC reaches its turning point before the inverted U-shaped EKC. This finding directly motivates
the core research question our study poses for India.

The literature has also examined the effects of variables such as urbanization and TO on REN.
Urbanization, defined as the migration of rural populations to cities, creates problems related to access to
clean air and water, stemming from NREN [25,33,34] . The impact of urbanization on renewable energy,
however, is ambiguous. Some studies have found a positive relationship. For instance, Khan et al. showed
[35]
that in 48 BRI countries, urbanization reduces carbon emissions and that REN also has a reducing effect on
[36]
[37]
carbon emissions. Chen , for the Chinese economy, and Kusiyah et al. , for 23 industrialized countries,
identified a positive interaction between urbanization and REN. On the other hand, some studies have
reported a negative relationship. Yin and Qamruzzaman for Bay of Bengal Initiative for Multi-Sectoral
[38]
Technical and Economic Cooperation (BIMSTEC) countries and Simeon et al. for Emerging Seven (E7)
[39]
countries showed that urbanization adversely affects renewable energy use. Raihan , however, found that
[40]
for Bangladesh, urbanization increases energy consumption that leads to low carbon emissions.
Xing et al. , in their study on the Group of Seven (G7) countries, revealed that urbanization increases
[41]
energy demand, while green innovations reduce it.
The effects of TO on REN also feature prominently in the literature. A comprehensive analysis by Wang
and Zang , covering 186 countries, revealed that free trade positively affects REN in high and upper-
[42]
middle-income countries but negatively in low-middle-income countries, while Zeren and Akkuş found
[43]
[44]
that increases in energy consumption reduce TO in Bloomberg's Top Emerging Countries. Han et al.
concluded that in the Chinese economy, TO partially increases REN but invariably increases NREN.
Similarly, Khan et al. found that TO facilitates the transition to renewable energy in developed countries
[45]
but has a negative impact in developing countries. In contrast, other studies focused on specific country
groups have generally identified a positive relationship. Alam and Murad , for OECD countries,
[46]