Sustainable Development Objective 8 (Decent Work and Economic Growth) includes the sustainable development objective of tourism. This goal specifically strives to develop and implement policies by 2030 to support sustainable tourism that supports local products and culture while also creating jobs. To reduce environmental effects, promote conservation activities, and guarantee that tourism development helps local communities while advancing global sustainability goals, this goal places a strong emphasis on responsible travel behaviors. Tourism has grown over time as a phenomenon and has been observed as one of the major drivers of economic development. According to the United Nations World Tourism Organization (UNWTO, 2020), it creates 319 million employment and accounts for 10.5% of the world GDP, or more than $7.6 trillion. Sustainable tourism is essential for environmental sustainability, biodiversity protection, socioeconomic development, economic wellbeing, and ecological development. The potential significance of international tourism has made it imperative to investigate the fundamental aspects of tourism relevant to various industries (Baloch et al., 2023).

A tourist's fundamental right is to have access to renewable energy use (RE), a healthy environment, and activities based on their preferences (Naseer et al., 2024). The purpose of tourism (TOR) and sustainable development goals (SDGs) centers on the achievement of equal, general, and sufficient TOR resources for visitors. The SDGs include several goals aimed at minimizing carbon emissions, environmental degradation, and the availability of safe water at global TOR locations (Naseer et al., 2024; Voumik et al., 2024). Despite substantial advancements in tourism development in the most visited nations, the world's poorer or less visited countries require aid to present basic services to travelers and preserve a balance between the climate, economy, and cultural components of TOR. People must live without access to necessities, such as clean water and jobs while visiting tourist destinations (Naseer et al., 2024; Voumik et al., 2024).

As a result, local populations must encourage tourism more in their areas, which could lead to an abrupt drop in the number of visitors, their money, and the number of job chances that arise. This could have a negative impact on the local economy and the environment (Gupta et al., 2021). As a result, local populations must encourage tourism more in their areas, which could lead to an abrupt drop in the number of visitors, their money, and the number of job chances that arise. Subsequently, this could have detrimental effects on the local economy and environment. As the COVID-19 pandemic has shown, locals lost their employment, and millions of tourist destinations closed (Rasheed et al., 2021; WHO, 2020). Moreover, environmental problems such as inadequate sanitation and unsafe water in tourist destinations cost the US economy 7% of GDP, or around 250 billion dollars, annually. Thus, it is imperative to manage a healthy environment and fundamental tourist amenities to promote sustainable tourism development (Robinson, 2019). Figure 1 shows the trend of tourism in BIMSTEC nations.

In addition, concerns about the environment, human health, and safety are very important in foreign travel. Research such as those conducted by Torabian and Mair (2022) supports the idea that, despite the attractions and financial benefits, travelers do not choose to visit places that have health and environmental problems (Ahmad et al., 2024). Therefore, factors such as the environment, top health, and quality tourist attractions are important while making trip options. Before making any vacation plans, travelers always consider several critical concerns, including ecology, sanitation, and hygiene (Ahmad and Sheikh, 2024; Naumov et al., 2021).

While significant advancements have been made in tourism development within frequently visited nations (Igoumenakis et al., 2024), there remains a critical gap in understanding how sustainable tourism and renewable energy intersect within the BIMSTEC countries. The Bay of Bengal Initiative for Multi-Sectoral Technical and Economic Cooperation (BIMSTEC) includes seven countries: Bangladesh, Sri Lanka, Bhutan, Myanmar, Thailand, India, and Nepal. These nations are strategically located at the intersection of South and Southeast Asia, encompassing diverse ecological landscapes, ranging from the Himalayas to coastal regions, making them uniquely suited for tourism activities. However, the region also faces substantial environmental and socio-economic challenges (BIMSTEC, 2023; SAIS Review, 2024). BIMSTEC countries are among the most vulnerable to climate change, grappling with rising sea levels, deforestation, and extreme weather events that threaten both natural ecosystems and tourism-dependent economies (Roy, 2017). Moreover, these nations exhibit varying degrees of economic development, infrastructure quality, and renewable energy adoption, which further complicate efforts to balance tourism growth with sustainability objectives (Ridwan et al., 2024).

Despite tourism's economic potential, BIMSTEC nations face challenges such as inadequate renewable energy infrastructure, poor waste management, and limited access to clean water and sanitation, exacerbating ecological degradation (Chaudhary and Paudel, 2024; Yin and Qamruzzaman, 2024). While sustainable tourism is vital for the BIMSTEC region, existing research has largely overlooked the synergistic role of renewable energy in mitigating tourism's environmental impacts and promoting sustainability (Yin and Qamruzzaman, 2024). Most prior studies have independently examined either the economic benefits of tourism or the environmental advantages of renewable energy, without adequately exploring their combined influence on environmental sustainability within this unique regional context (Baloch et al., 2023).

For instance, Naveed et al. (2023) examined the association between economic development, transportation, tourism, renewable energy, and ecological footprint in the BIMSTEC region. Although their findings underscored the positive contributions of tourism and renewable energy to ecological integrity, the study did not delve into the long-term impacts of these factors on overall environmental quality or provide a comprehensive framework for their integration. Similarly, Bano et al. (2021) examined the nexus between tourism, renewable energy, income, and environmental quality in Pakistan. However, their focus was confined to a single country, limiting the applicability of their findings to the broader BIMSTEC region. Moreover, Gupta et al. (2021) study focuses on tourism and stakeholder satisfaction within the Pushkar region of Rajasthan, examining sustainability. While this provides valuable localized insights, it is limited to a single destination and does not address broader regional dynamics or the interplay between tourism and renewable energy.

This study seeks to bridge these gaps by investigating the long-term impacts of tourism and renewable energy on environmental quality across BIMSTEC economies. It adopts a holistic approach, integrating economic, technological, and environmental perspectives to capture the complex interplay between these sectors. By incorporating an interaction term for tourism and renewable energy, this research provides novel insights into how their combined effects drive environmental sustainability (Li et al., 2024)—an area overlooked in previous studies. This comprehensive analysis offers a valuable contribution to understanding and promoting sustainable development in the BIMSTEC region.

Furthermore, the application of second-generation panel regression and wavelet analysis allows for a nuanced understanding of cross-sectional dependence and policy implications, offering practical recommendations for sustainable tourism development in the BIMSTEC region.

Therefore, by comparing the ecological footprint (EF) per capita and bio-capacity, the current study investigates the LCC hypothesis considering TOR and RE on environmental quality (LCF). We use the CS-ARDL approach on data from the BIMSTEC economies from 2000 to 2022. To achieve this goal, a model for TOR is built that includes eco-advancements, per capita income, and access to green energy as variables.

This work adds to the body of knowledge on the financial and ecological factors driving international tourism in several ways. This study investigates the long-run effects of TOR on the environment in the economies of the BIMSTEC region. Second, raising the standard of RE and technological advancements can also raise income, promote the growth of sustainable tourism, and boost traveler demand. The economies of the BIMSTEC region are dealing with decreased levels of ecological footprint and green energy consumption, and previous research has not considered the influence of high-quality institutions on tourism. Moreover, this work includes an interactional term of TOR^*RE to check its impacts on environmental quality. Third, a second generation of panel regression was used in this work to address cross-sectional dependence because these economies consist of various countries and behavioral patterns. Fourth, the results show that technical advancements, ecological footprints, and green energy use can all significantly boost foreign travel. Fifth, the application of wavelet analysis provides important policy options to promote sustainable tourism in the BIMSTEC region. Ultimately, the study's conclusions offer several policy recommendations that support the SDGs and help the region's tourist industry grow.

The Environmental Kuznets Curve (EKC) hypothesis and Load Capacity Curve (LCC) theories examine economic growth (GDP) and environmental effects from different angles. According to the EKC hypothesis, environmental degradation increases with economic development, but after a certain level of income per capita, technology, and more stringent laws to improve the environment. In contrast, the LCC hypothesis compares GDP to the load capacity factor, which is the greatest environmental strain an ecosystem can tolerate without degrading. The LCC theory emphasizes keeping economic activity within ecological limitations to avoid exceeding the environment's load capacity, unlike the EKC, which focuses on economic development to lessen environmental effects. The EKC holds that economic success will automatically improve the environment, whereas the LCC theory emphasizes the necessity for deliberate management to achieve sustainable growth within Earth's ecological constraints.

Second Section will address the review of literature, 3rd Section will address the methodology and materials, 4th Section will record the anticipated outcomes, and 5th Section will end the study with the conclusion and policy suggestions.

This research investigates the effects of renewable energy, international tourism, environmental assessment computations, and GDP on the LCF in the BIMSTEC nations (Bhutan, Bangladesh, India, Myanmar, Nepal, Sri Lanka, and Thailand). For the requirements, data were gathered between 2000 and 2022. This paper measured the amount of RE consumed as 1 kW of power. World Development Indicators were used to obtain this variable. This study has chosen GDP in US dollars that were also obtained from the World Bank's World Development Indicators (WDI). This study has chosen to focus on foreign tourism, as indicated by the number of arrivals (Tiwari et al., 2021). The UNWTO tourism monitor is the source of this information. The ecological footprint, expressed in metric gha per capita, is used to determine the load capacity factor (LCF) or environmental quality, which is derived from data collected from the Footprint network. Table 1 lists the definitions, measuring units, and data sources.

The following is a possible formulation for the study's base model:

Another way to express Equation 1 is as follows:

The LCC theory states that GDP2 and GDP coefficient are expected to have positive values (γ₂ = GDP2 > 0) and negative signs (GDP < 0), respectively, Pata and Samour (2022). The hold LCC theory might be disproved if the signs of the coefficients were switched. According to the coefficient of TOR and RE, we predict that, in the panel nations, renewable energy will have a positive impact on LCF (Dogan and Pata, 2022), whereas tourism will have a negative impact (Mohanty et al., 2021).

All variables' summary statistics are displayed in Table 2. For LCP, the mean is 0.492, while the remainder of the series shows positive values. It is evident that the TOR standard deviation is greater than the GDP change than the LCF.

A non-symmetric series was also revealed by the skewness aspect deviating from 0 and the kurtosis displaying surplus values; Table 2 exhibits significant values and significant leads for the Jarque-Bera test, proving that the data is not normal. The correlation statistic among the panel countries is shown in Table 3.

0.607% is the correlation coefficient between LCF and TOR. in a similar vein, there is a minimum connection of roughly −0.175 between TOR and RE and a moderate link of roughly 0.560 between TOR and RE. ultimately, there is a moderate relationship between LCF and RE, with a 0.666 correlation. the CD test enables us to assess whether to apply the first method and how dependent certain nations are on one another. Table 4 displays the test results from the tests.

The findings disprove the null hypothesis, which states that the residual has no cross-section or association. They provide credence to the data showing a relationship between energy and tourism and environmental quality. The cross-sectoral dependency results in the panel data among BIMSTEC nations, however, support the applicability of the 2nd-generation stationarity test. Table 5 displays the results of the CIPS unit root test.

The results show that LCF, GDP, and TOR are stationary at level and first difference, rejecting the alternative hypothesis and accepting the null hypothesis at the level. The Westerlund (2005) in Table 6 shows a strong correlation among the variables of BIMSTEC countries.

The results obtained using the sophisticated CS-ARDL technique, which effectively addresses cross-sectional dependence and heterogeneity in panel data, are presented in Table 7.

Environmental quality (LCF) is negatively impacted by GDP at the 1% significance. A standard deviation of the GDP method is an ~0.017 drop in the LCF change. The GDP² is favorable, though, and this results in a roughly 0.021 decrease in LCF, supporting the validity of the LCC hypothesis. These outcomes corroborate with Awan and Azam (2021) study examines the validity of the Environmental Kuznets Curve (EKC) hypothesis for G-20 economies and finds an N-shaped relationship between CO₂ emissions and GDP per capita. It suggests that while GDP growth initially leads to environmental degradation, higher levels of GDP can mitigate these impacts and promote sustainability. The findings also show that, for every 1% increase in RE, the amount of renewable energy per person considerably increases LCF by around 0.04%. It's interesting how our findings relate to the task. A 1% increase in TOR due to tourism causes a 0.003% increase in environmental degradation in the chosen countries. Villanthenkodath et al. (2022) investigated the impact of tourism development on environmental degradation in India using the autoregressive distributed lag (ARDL) approach and wavelet coherence analysis. Their findings also indicate that tourism development significantly contributes to environmental degradation, with changes in tourism development leading to variations in pollution levels at different frequencies and periods. It is worth noting that the interactional term TOR^*RE enhances the environmental quality. This means that the interaction of TOR with clean energy is vital for these nations. This result is consistent with that of Zhang et al. (2023). Using the Q-ARDL model, their findings highlight the positive contributions of renewable energy and tourism to sustainability in OECD economies from 2000 to 2021. The CS-ARDL model in the current study seems to be occurring well, with furthermore, to extract true figures, the ECT (−1) signifies the equilibrium's adjustment speed. Finally, Table 8 presents the empirical results of the AMG models, which are utilized to ensure robustness by effectively addressing cross-sectional dependence, slope heterogeneity, and structural breaks in the data.

Table 8 shows the findings of AMG results while checking the impacts of tourism, RE, and GDP on LCF in BIMSTEC countries. The results indicate the existence of LCC hypotheses because GDP is lowering environmental quality, but its squared term is increasing it. This means that in the future, after achieving more economic prosperity, BIMSTEC countries will start to experience better environmental quality due to strict environmental regulations and better awareness. This result is consistent with the findings of Laghari et al. (2022), who demonstrated that while GDP growth can lead to environmental degradation, the square of GDP (indicating higher economic resilience) can mitigate environmental impacts and promote sustainability in 124 nations. Tourism is not good for environmental quality, and green energy is contributing to the development of LCF. These results are validated by Baloch et al. (2023). Their study investigated the relationship between tourism development and environmental sustainability, revealing that tourism activities lead to environmental degradation through land overutilization, pollution, and social vulnerability in Pakistan. When TOR interacts with RE, the impacts of TOR become good for environmental quality in BIMSTEC nations. The findings of the UNEP (2023) study align with the results of the current research, emphasizing the critical role of renewable energy in promoting sustainable tourism. UNEP (2023) also highlights how clean energy sources such as solar, wind, hydro, geothermal, and biomass can power the tourism industry sustainably, reducing environmental impacts, supporting local communities, and often lowering operational costs. These AMG results are validating the findings of CS-ARDL test.

The findings, supported by both CS-ARDL and AMG methodologies, provide a robust basis for policy recommendations. BIMSTEC countries must prioritize renewable energy integration, enforce stringent environmental regulations, and promote green tourism initiatives to achieve sustainable development. This aligns with global perspectives, such as Zhang et al. (2023) and UNEP (2023), which advocate for renewable energy's role in reducing ecological pressure and supporting sustainability. By situating these findings within the unique environmental and socio-economic contexts of BIMSTEC, this study offers actionable insights to policymakers aiming to balance economic growth with environmental preservation.

The outcomes of this study make significant contributions to both theoretical and practical frameworks, particularly the Environmental Kuznets Curve (EKC) and Load Capacity Curve (LCC). The EKC hypothesis suggests that environmental degradation initially increases with economic growth but eventually decreases after reaching a certain level of income due to improved regulations and technology. The results of the current study confirm this progression in BIMSTEC countries, where GDP growth initially lowers environmental quality but its squared term indicates future improvements, validating the EKC. This supports the view that strict environmental regulations and better awareness at higher income levels can mitigate ecological impacts, adding empirical evidence to the EKC's applicability in developing regions.

Similarly, the findings align with the LCC theory, which posits that economic activities must remain within an ecosystem's load capacity to avoid environmental degradation. This is evident from the positive impact of renewable energy on environmental quality, demonstrating that clean energy can reduce the strain on ecological systems caused by tourism and economic activities. Moreover, the interaction term between tourism and renewable energy highlights how integrating green energy with tourism can transform the sector into a driver of environmental sustainability, extending the practical applications of the LCC framework.

The study also challenges some assumptions by showing that tourism alone, without renewable energy integration, contributes to environmental degradation, a nuance that complicates simplistic EKC models. These findings enhance our understanding of both theories by illustrating how sustainable energy and tourism policies interact within diverse economies like BIMSTEC. Practically, the results underline the importance of targeted policy interventions, including renewable energy adoption and sustainable tourism practices, to balance economic growth with environmental conservation in the region. This dual theoretical and practical contribution advances both academic discourse and policy development for sustainable development in BIMSTEC countries.

The sustainable development goal of tourism is included in the eighth sustainable development goal (Decent Work and Economic Growth). Specifically, this target aims to create and execute policies by 2030 to promote sustainable tourism that creates jobs and supports regional goods and culture. This objective emphasizes ethical travel practices heavily to minimize environmental effects, support conservation efforts, and ensure that tourism development benefits local communities while furthering global sustainability goals. The phenomena of tourism have expanded over time, and it has been noted as one of the main forces behind economic development. Even though the BIMSTEC economies are home to the most stunning areas due to their scenic beauty, rich cultural legacy, mountains, oceans, and lakes, as well as diversified biodiversity, these economies see comparatively less international tourism than other regions. The foreign exchange needed for the GDP of the region can be supplied by the tourism industry's revenue. Previous empirical research examined terrorist and economic factors to explain international traveler behavior. This study is an initial assessment that combines environmental and socioeconomic elements to explain why international tourism is behaving so slowly. Cross-sectional dependence and heterogeneous order of integration are shown by the post-estimation test. To estimate the long and short-run impacts of independent factors with the rate of ECM, this study used the CS-ARDL approach. According to the estimated results, improvements in GDP have a long-term negative influence on foreign travel to the economies of the BIMSTEC region. According to the findings, to promote international tourism, these nations must increase the approach to cleaner energy and better rules, environmental impact, and green technologies. The primary cause of unsustainable tourist development in the region is the fossil fuel energy use and the adverse ecological effects of TOR.