Throughout the last two centuries, the use of dirty energy sources, namely coal, oil, and gas, has been instrumental in fostering economic growth and industrial advancement. Nevertheless, this model has made a considerable contribution to climate change and various environmental predicaments, prompting mounting apprehensions regarding its sustainability. The increasing worldwide attention towards mitigating carbon emissions and the shift towards sustainable energy sources have resulted in substantial funding for renewable energy technologies such as solar, wind, hydro, and geothermal. The emergence of clean energy has been identified as a pivotal sector that propels economic growth in numerous countries. The WilderHill Clean Energy Index was instituted in 2004 with the aim of overseeing the advancement of the clean energy industry. The present index monitors the progress of open-source enterprises that are engaged in the creation and manufacturing of sustainable energy solutions, including but not limited to solar panels, wind turbines, and biofuels. The index is widely acknowledged as the main benchmark for evaluating the clean energy industry and has emerged as a crucial instrument for investors seeking to allocate resources to this fast-growing domain. The scope includes entities of varying magnitudes, ranging from nascent startups to expansive multinational corporations, and includes a wide range of clean energy technologies and services. Notwithstanding certain challenges, such as uncertainties in the political and regulatory spheres and the intermittent nature of certain renewable energy sources, the clean energy industry is persistently growing, powered by decreasing expenses and increasing market interest. The WilderHill Clean Energy Index has exhibited substantial progress over the last ten years, as evidenced by its impressive gains. The adoption of sustainable energy sources is of the utmost importance in addressing the effects of climate change and establishing a viable path toward sustainability ^[1][2][3].

Additionally, in recent years, a number of additional indexes pertaining to clean energy have surfaced. The financial markets for clean energy have provided investors with the chance to synchronize their financial objectives with climate goals. Amidst the global focus on mitigating climate risks and transitioning towards a carbon-resistant economy, investors have shown considerable interest in clean energy investments. This trend is observed as policymakers worldwide prioritize the reduction of carbon emissions ^[4][5].

Presently, the clean energy sector is among the fastest-expanding segments of the energy industry. According to recent statistical data, the clean energy industry demonstrated a yearly growth rate of 5% during the period of 2009 to 2019, in contrast to the annual growth rate of 1.7% observed in the non-renewable energy sector. Consequently, a significant amount of capital is being reallocated from traditional energy sources towards clean energy. An instance of noteworthy growth can be observed in the clean energy sector’s global investments, which increased from USD 120.1 billion to USD 363.3 billion during the period from 2009 to 2019. Despite the COVID-19 pandemic, there was a 2% rise in investments in clean energy. The surge in demand for environmentally friendly energy sources has resulted in heightened attention from market players toward clean energy stock investments (Bloomberg New Energy Finance, 2019).

Although the clean energy sector has experienced remarkable expansion, conventional fossil fuels continue to dominate as the primary source of energy on a global scale. Furthermore, clean energy sources are frequently regarded as substitutes for polluting energy sources, thereby implying that the advancement and endurance of the clean energy industry are inextricably linked to conventional energy markets. Furthermore, the notion of decarbonization is experiencing increasing momentum on a global scale, particularly in the wake of the Paris climate accord of 2015 and the 26th Conference of the Parties (COP26). Efforts have been made by regulatory bodies, corporations, financial institutions, and investors to substitute dirty energy with clean energy alternatives. According to a number of experts, it is widely believed that the attainment of the desired progress at COP26 hinges significantly on the investment in clean energy ^[6][7][8].

2. Studies Related to the Links between Clean and Dirty Energies

In recent years, there has been a growing interest in understanding the relationship between dirty and clean energy, especially in the context of occurrences such as the COVID-19 pandemic in 2020 and the volatility of energy markets in 2022. The identification of renewable energy sources as a critical element in tackling energy and climate change concerns has been established. The advancement of renewable energy sources is frequently constrained by the traditional prices associated with fossil fuels. Therefore, it is essential to explore the interconnections between these two energy sources in order to foster the expansion of renewable energy and accomplish sustainable energy objectives. The authors ^[9] conducted an empirical investigation into the relationship between the prices of alternative energy stocks, technology equities, oil, and interest rates. The study conducted by the authors demonstrates the impact of technology stock prices and oil prices on the price of alternative energy companies’ stocks, as evidenced by the Granger causality test. In ^[10], the authors investigated the interactive relationships between crude oil prices and the performance of alternative energy companies, revealing that from late 2006 onwards, the performance of alternative energy companies has been considerably influenced by fluctuations in oil prices. The authors ^[11][12], as well as ^[13], conducted research on the synchronization trends between oil prices, technology, financial variables, and clean energy indexes. According to ^[11], the stock prices of alternative energy companies are subject to the influence of technology companies’ stock prices, oil prices, and short-term interest rates. As noted by ^[12], there is evidence to suggest that crude oil prices are not the main driver of the stock market performance of renewable energy companies, both in the short and long term. This finding implies that there is a disconnection between the alternative energy sector and the conventional energy market. The authors in ^[13] assert that the carbon market has the power to explain the movements in the stock prices of clean energy companies, while the stock prices of clean power companies also exert an impact on the carbon market. As stated by ^[14], there exists a weak connection between oil markets and renewable energy markets, suggesting that shocks in oil prices have a limited impact on the development of the renewable energy industry. On the other hand, the author ^[8] investigated the shocks between clean energy indexes and cryptocurrencies, taking into account their respective energy consumption levels. The authors discovered that clean energy is a more reliable safe haven for “dirty” cryptocurrencies than for “clean” ones, particularly during periods of uncertainty. In a more recent study, ^[15] investigated the impact of fossil energy market shocks on clean energy stock markets during the COVID-19 pandemic. The authors discovered that the crash in crude oil prices led to significant shocks in the clean energy market. Meanwhile, the declaration of COVID-19 as a global pandemic caused an increase in the prices of natural gas and renewable energy sources following a substantial crash. In ^[16], the authors conducted an analysis of the spillovers of volatility among the renewable energy, oil, and technology stock markets spanning from 2004 to 2020. The study revealed that the oil and clean energy markets exhibit a bidirectional spillover effect, with the oil market acting as the main receiver of volatility. The authors of ^[17], conducted a study on the impact of shocks between renewable energy prices and clean energy on the stock prices of the green economy. The study analyzed data from December 2010 to July 2021 and revealed that negative shocks were more prevalent than positive shocks in the renewable and clean power generation markets. The study revealed that the prices associated with the generation of renewable energy have a significant influence, either positively or negatively, on the stock prices of markets operating within the green economy. The author ^[6] conducted a study on the co-movements between clean energy and dirty energy stocks, both before and during the COVID-19 pandemic. The study used an extensive range of dirty energy stocks, including crude oil, heating oil, diesel, gasoline, and natural gas, while clean energy stocks were represented by the S&P Global Clean Energy Index and WilderHill Clean Energy Index. The findings suggest that there are feeble shocks between the stocks of clean energy and dirty energy indexes in both the short and long term. Significantly, there exists a notable dissociation trend between the markets for clean and dirty energy. Furthermore, the results demonstrate that the clean energy market remained largely insulated from the effects of the COVID-19 pandemic in 2020, highlighting the advantages of diversifying portfolios across both clean and dirty energy markets. Several macroeconomic studies, including the work by ^[18], have examined the efforts of EU member states, specifically Poland and Lithuania, to shift towards renewable energy sources. One of the principal findings is that individuals in the nations examined have exhibited an increasing commitment to the energy transition by means of their energy-related decisions. This fact acts as a sign of heightened awareness and responsibility with regard to the use of sustainable energy sources. Moreover, the governmental efforts and initiatives implemented in the studied countries have demonstrated efficacy and suitableness in achieving the determined objectives for sustainable development. Furthermore, the results derived by the authors underscore the significance of promoting the shift toward environmentally friendly sources of energy, not solely from an ecological perspective but also from an economic standpoint. Within the European Union, the prioritization of transitioning towards a more environmentally sustainable reality is of utmost importance, given the ambitious objectives aimed at mitigating greenhouse gas emissions. The study highlights the promising advancements in Poland and Lithuania, which serve as a positive indication that the energy transition can be accomplished and viable in diverse national settings. The significance of examining the interconnections between clean and dirty energy indexes has been underscored by recent occurrences in 2020 and 2022. Recent research indicates that there is a weak linkage between these two types of energy in the short term. However, there is a possibility of significant co-movements in the long term. The interconnections between fossil energy markets and clean energy stock markets call for an in-depth understanding of the potential impact that shocks in the former may have on the latter. Lastly, understanding the relationship between clean and dirty energy actions is crucial to improving the progress of renewable energy and attaining sustainable energy objectives, particularly in light of worldwide predicaments such as climate change and pandemics.