Renewable Energy Efficiency Research Articles

Climate-adaptive battery solutions for renewable microgrids: A case study in Indian coastal and inland regions

The utilization of renewable energy has the potential to alleviate global warming, reduce carbon emissions in the environment, and offer sustainable energy solutions to remote regions. Presently, 13 % of the worldwide population resides in isolated inland and coastal areas where electricity remains inaccessible. Consequently, implementing microgrids powered by renewable energy sources becomes essential to enhance electricity accessibility in these remote locations. This study aims to identify efficient and cost-effective renewable energy technologies suitable for deployment inland and coastal areas. The techno-economic feasibility of renewable energy systems is being evaluated in two distinct locations: Yadavole (inland) and Uppada (coastal) villages in the Indian state of Andhra Pradesh. The energy analysis encompasses various sources, including photovoltaic, diesel generators, wind turbines, flywheels, and batteries (Li-ion and lead-acid). The HOMER software conducts all necessary modeling and simulations for economic analysis and optimal system sizing. According to the simulation results, the most viable microgrid configurations for the inland region, Yadavole, are photovoltaic/diesel and generator/Li-ion. In contrast, for the coastal region, Uppada, photovoltaic/diesel, and generator/lead-acid configurations prove to be the most promising configurations. Moreover, a MATLAB model of the proposed system is created to analyze energy quality. Given the superior performance of Li-ion batteries in elevated temperatures typically found inland, this study recommends a diversified range of battery solutions. Specifically, Li-ion batteries are recommended for inland areas, while lead-acid batteries are recommended for coastal regions. This approach aims to efficiently store renewable power by the specific climatic conditions of each area. It is crucial to systematically analyze region-specific renewable energy technologies to provide valuable insight to stakeholders involved in investment and energy policy decisions.

Decarbonizing the US Energy System

Recent rapid and unexpected cost reductions in decarbonization technologies have accelerated the cost-effective decarbonization of the US economy, with greenhouse gas (GHG) emissions falling by 20% from 2005 to 2020. The literature on US economy-wide decarbonization focuses on maximizing long-term GHG emissions reduction strategies that rely mostly on renewable energy expansion, electrification, and efficiency improvements to achieve net-zero GHG emissions by 2050. While these studies provide a valuable foundation, further research is needed to properly support decarbonization policy development and implementation. In this review, we identify key decarbonization analysis gaps and opportunities, including issues related to cross-sectoral linkages, spatial and temporal granularity, consumer behavior, emerging technologies, equity and environmental justice, and political economy. We conclude by discussing the implications of these analysis gaps for US decarbonization pathways and how they relate to challenges facing major global emitters.

Performance analysis of IoT-enabled hydro-photovoltaic power systems considering electrical power mission chains

Synergistically and complementarily managing the operation of hydropower plants and other weather-dependent renewable energy generation plants (e.g., solar energy plants) provides an effective measure to improve the performance efficiency (PE) of renewable energy. However, environmental uncertainty and physical system unavailability pose challenges in assessing the PE of the power generation. This paper proposes an approach to synergistically and complementarily managing the operation of hydro-photovoltaic (HPV) power systems in IoT under uncertain environments and develops a mission chain-based PE model for quantifying the capacity of the fulfilment of a power supply mission to satisfy users’ demand for power. An importance measure-based restoration strategy is then proposed to enhance the PE of an HPV power system (PEPS). The approach is examined by taking a large-scale HPV in China in the case study. The results show that, in winters and in summers, the PEPS is higher than PE of a photovoltaic power system and a hydropower system, respectively, and the PEPS with the importance measure-based restoration strategy is higher than that under the random restoration strategy, respectively. The findings not only lay the foundation for the complementary operation of hybrid renewable energy power systems but also provide a reference for the restoration in case of power cuts.

Mitigating economic losses and prospects for the development of the energy sector in the Republic of Kosovo

The purpose of the study was to analyse the current economic problems in the energy sector of Kosovo and to develop effective strategies to overcome them, in particular ways to minimise losses and increase the stability of the energy system, as well as to study opportunities for ensuring the country’s long-term development and energy security. The main focus was on the economic impact of implementing international energy standards, particularly European ones, within Kosovo’s national policy and development strategy. The analysis emphasised the financial benefits and challenges associated with aligning the country’s energy sector with EU directives, especially those related to renewable energy sources and energy efficiency. Key areas of the study included the economic potential of enhancing energy security, promoting renewable energy development, and reducing reliance on fossil fuels. Additionally, the study evaluated the economic implications of these reforms on Kosovo’s energy market and overall economic growth trajectory. The study also included an economic analysis that assessed possible economic losses associated with the transition to renewable energy sources. Risks were considered, including job losses in traditional energy sectors such as coal and the significant financial costs required to upgrade infrastructure. However, the study found that the long-term benefits of a green energy transition, including increased energy security, reduced dependence on energy imports and improved environmental conditions, outweigh the short-term economic costs. The results showed that although the economic transition is accompanied by significant financial costs, the long-term benefits, such as increased energy security and reduced emissions, are substantial. The study highlights the importance of further reforms and investments to ensure the sustainable development of Kosovo’s energy sector, as well as the country’s integration into the European energy environment

Investigating bubble-induced overpotential, current non-uniformity, and bubble distribution in flow-based water electrolyzers: A numerical study

The transition towards a sustainable energy landscape necessitates efficient and scalable technologies for renewable energy storage. Water electrolysis, a process that converts electrical energy into chemical energy stored in hydrogen, holds immense potential for integration with intermittent renewable sources. However, the performance and efficiency of water electrolyzers are impeded by the complex multiphase flow dynamics involving bubble nucleation, growth, and transport within the electrochemical cell. This study employs state-of-the-art three-dimensional multiphase flow simulations to unravel the intricate interplay between bubbles and the electrochemical processes in a parallel-electrodes flow-based electrolyzer (PE-FBE). By accurately capturing bubble-electrolyte interfaces, the simulations quantify the detrimental effects of bubbles on overpotentials, current density distribution, and bubble distribution. Crucially, the impact of critical parameters, including flow rate, bubble nucleation size, surfactant addition, and applied current, on these performance metrics is systematically investigated. The findings reveal strategies to mitigate bubble-induced losses, enhance current uniformity, and improve hydrogen purity, paving the way for optimized electrolyzer designs and efficient renewable energy storage.

Linkages between environmental sustainability, disaggregated emission, renewable energy, and energy efficiency: An evidence from BRI countries.

This paper examines the long-term and short-run causative relationship among environmental sustainability, energy efficiency, renewable energy and carbon emissions from all over sources (coal, oil and fossil fuels) and sector wise division (heat and power, transportation, residential, manufacturing and other sectors. The empirical evidence presented in this study is derived from a balanced panel dataset spanning the annual periods from 2000 to 2021. The dataset specifically focuses on a selection of BRI Countries. The Kao test demonstrates the presence of cointegration across variables such as carbon dioxide emissions, environmental suitability, energy efficiency and renewable energy. The Panel Pooled Mean Group-Autoregressive Distributed Lag (PMG-ARDL) model indicates a statistically significant positive association between the environmental sustainability and disaggregated CO2 emissions over a long-term period. The study found a positive relationship between disaggregated CO2 emissions and environmental sustainability and energy efficiency, with renewable energy sources reducing emissions. It suggests a need for a structural transition from an energy-intensive economy to a decarbonized one, with sectors like heat and power positively impacting sustainability. Implementing measures to reduce emissions is crucial for tackling climate change.

Energy Transition Agenda in Tanzania Within the Auspice of Sub-Saharan Africa: A Review of the Power Sector

The energy transition is on the high agenda in the global space to allow the international communities to meet the global objectives of lowering anthropogenic emissions that cause global warming. The international community is guided by the scientific evidence of increasing climate change impacts and is working under the auspice of the Paris Agreement, which aims to limit GHG emissions. As one of the significant contributors to GHG emissions, energy will play a critical role by shifting from dependence on fossil-based sources to renewables and using technologies to decarbonize the sources. Energy transition in the power sector is primarily associated with shifting towards directing investments in renewable energy. Sub-Saharan Africa (SSA) is still a niche market in the power sector with substantial suppressed demand, and where only about half of its population still does not have access to electricity. The region also strives to power its economic activities to support economic growth. The region is endowed with renewables and fossil fuels to support its economic transformation. Investment in renewable energy entails high capital costs, which makes it hard for the countries in the region with financial constraints to afford it. Renewables also have some limitations in supplying baseloads and are inherent to issues of dispatchability. Countries in SSA have been approaching the energy transition agenda with care to address local needs while supporting international climate change concerns. The energy transition agenda in countries like Tanzania considers multidimensional factors when investing in the power sector, primarily fostering universal access to electricity for its population, attaining security of supply, and accelerating industrial development. This paper reviews what the transition entails in the context of sources and technologies that will support the sustainable transition; it discusses renewable energy and energy efficiency. It also touches upon the role of fossil fuels in the energy transition agenda. The paper also reviews the policies and politics around the energy transition landscape, looking at the global context and its effects in the developing world, notably the sub-Saharan Africa region. The review concludes by analyzing different potential factors that contribute to decision-making on energy transition policies using the system thinking theory, looking at how various factors are interlinked.

A state‐of‐the‐art review on geothermal energy exploration in Morocco: Current status and prospects

AbstractIn the last few decades, addressing the global challenge of implementation of strategies for renewable energy and energy efficiency has become crucial. Morocco, since 2009, has made a steadfast commitment to sustainability, with a particular focus on advancing the development of renewable energy resources. A comprehensive strategy has been formulated, centering on utilizing the country's energy potential to drive progress in this vital sector. Morocco is considered a country with abundant thermal water, indicating deep reservoirs with significant hydrothermal potential. Geothermal zones were selected based on the abundance of hot springs where water temperatures were high and geothermal gradients were significant. The abundance and importance of hot springs, combined with recent volcanism and ongoing non‐tectonic activity linked to alpine orogeny, strongly suggest that these regions are promising reservoirs for geothermal energy. This great potential also extends to neighboring countries. In northeast and south Morocco, the temperature of thermal water ranges from 26 to 54°C. This study serves as an inclusive review of the geothermal potentialities in Morocco.

Impact of Exposed Crystal Facets on Oxygen Reduction Reaction Activity in Zeolitic Imidazole Frameworks

Oxygen reduction reactions (ORR) are critical reactions for efficient sustainable and renewable energy storage. However, the limitation of ORR is a slow kinetic reaction due to the multi-step transfer mechanism of electrons. Therefore, electrocatalysts with high ORR activity and stability are needed to overcome the reaction limitations. Zeolitic imidazole framework-67 (ZIF-67) has attracted attention in electrochemical applications due to its multiple redox-active sites and high stability in alkali conditions. The Co-doped porous carbon catalysts derived from ZIF-67 have the potential to be used as ORR catalysts with high performance, while pure phase ZIF-67 electrocatalyst for ORR is rarely studied. The work studies the importance of crystal facets on ORR reactivity. The results show that ZIF-67 nanocube exhibits excellent ORR activity with lower half wave-potential and faster kinetics process compared to its bulk structure. It is proposed that ZIF-67 nanocube provides improvement of selectivity for the four-electron pathway, which is a favorable process with higher reaction efficiency. The density functional theory (DFT) calculations suggest unsaturated Co2+ active sites with enriched (100) facets in the cubic crystal. Therefore, the fast diffusion of oxygen molecules to active sites and strong interaction with intermediate are observed in a cubic structure. The correspondence between experiment and calculation offers enhancement of ORR activity and selectivity from control-specific growth of (100) facet with cubic shape. The work introduces a new strategy for designing highly efficient ORR electrocatalysts with facet-controlled, allowing further study in other electrochemical reactions.

Study of a Novel Updraft Tower Power Plant Combined with Wind and Solar Energy

This study presents a novel solar updraft tower power plant (SUTPP) system, which has been designed to achieve the simultaneous utilization of solar and wind energy resources in desert regions, in response to the pressing demand for sustainable and efficient renewable energy solutions. The aim of this research was to develop an integrated system that is capable of harnessing and converting these abundant energy sources into electrical power, thereby enhancing the renewable energy portfolio in arid environments. The methodology of this study involved the design and construction of a prototype SUTPP, comprising a 53 m high tower, a 6170 m2 collector, five horizontal-axis wind turbines, and a thermal energy storage layer made up of pebbles and sand. The experimental setup was meticulously detailed, and experiments were conducted to collect data on the system’s performance under various environmental conditions. Subsequently, three-dimensional numerical simulations were performed to explore the effects of ambient wind speed and solar radiation on the output power of the SUTPP. The results indicate that the output power of the system increases with the increase in ambient wind speed and solar radiation. The impact of solar irradiation on output power was observed to diminish as ambient wind speeds increased. Notably, as the inlet wind speed rose from 4 m/s to 12 m/s, the output power showed a substantial increase of 727%. The numerical simulations revealed that ambient wind speed has a more pronounced effect on power output compared to solar radiation. Furthermore, it was found that the influence of solar radiation is significant at low wind speeds, with its impact decreasing as wind speed increases. This research provides essential guidance for the design and engineering of highly efficient solar thermal energy utilization projects, representing a significant advancement in the field of renewable energy technology deployment in desert environments.

Achieving carbon neutrality in an emerging oil-producing country: Renewable energy transition and international trade flows in Ghana

Over the past decade, climate variabilities have emerged as shaping the dynamics of international trade. The adverse externalities posed by climate change require a corresponding improvement in the production of food, trade and the adoption of abundant renewable energy resources. Our study focused on evaluating the impact of renewable energy transition on international trade flows in Ghana. We employed the dynamics ARDL simulation model to analyse our results using data from various institutions. We found that energy transition using both low carbon energy and renewable energy in electricity generation by 1% and 5% significantly increases the balance of trade to the 4th year after which energy transition decreases the balance of trade to the 9th year. After the 9th year, energy transition by both percentages increases the trade balance of Ghana. We observe that the energy transition by 5% has a higher impact than the energy transition by 1%. Additionally, it is observed that using the share of renewable energy in electricity generation has a decreasing rate relative to the first four years. Drafting renewable energy plans such as allocation of funds, supportive policy frameworks and incentives such as green financing, subsidies, and tax incentives can enhance and develop renewable energy infrastructure to increase renewable energy efficiency and reliability for international trade.

Performance linkage in renewable energy supply chain: A comparative analysis with coal power and the entire industry

Establishing an efficient renewable energy supply chain is crucial for mitigating climate change, contingent upon policy influence and market complementarity. Accordingly, this study 1) Draws on the characteristics of “market mechanism” and “price regulation” within China's renewable energy industry to compare the supply chain with the entire industry and the coal power industry, laying the groundwork for an analytical framework to assess performance linkage. 2) Examines the role of markets and policies in moderating performance linkage within the renewable energy supply chain based on cash flow inflow and final commodity pricing. Empirical findings indicate that: 1) China's renewable energy supply chain exhibits weaker market circulation mechanisms than the overall industry, but it has not yet shown zero-sum game characteristics akin to the coal power supply chain. 2) Cash flow inflow and final commodity pricing are identified as pivotal factors enabling China's renewable energy industry to circumvent zero-sum games while still lacking a robust positive cycle. This research aids policymakers in dynamically assessing market-based circulation levels within the renewable energy supply chain and facilitates quantifying price regulation and market funding roles in updating industrial policies.

Energy efficiency and environmental regulations for mitigating carbon emissions in Chinese Provinces

Taking into account the contributions of economic performance (GDP), urbanization (URB), industrial structure (IND), and renewable energy consumption (REC), this paper examines the impact of green technology innovation (GTE), energy efficiency (EF), and environmental regulation (ER) on CO2 emissions in Chinese provinces from 2010 to 2020. Using the GMM method for the initial estimation, the MMQR as 2nd generation test for robustness and innovative panel causality presented by the JKS test, we have found: 1) a one percent boom in GDP is linked with a 0.08% upward push in CO2 emissions throughout 30 provinces in China. 2) the renewable energy and energy efficiency data seems to effectively decrease CO2 emissions, with a more pronounced impact observed at the upper quantile. 3) The environmental policy is limited across all quantiles. The study examines novel implications regarding sustainable development and carbon neutrality objectives.

Energy efficiency, economic growth, and natural resource rent: A trilemma analysis of environmental sustainability in Africa

Climate change, exacerbated by a global economic model reliant on carbon-intensive industrialization and unchecked growth, disproportionately affects vulnerable regions such as Africa. Therefore, transitioning to an ecologically sustainable development paradigm is imperative for developing countries facing climate disruptions. The current study analyzes the trilemma effect of energy efficiency, economic growth, and total natural resource rent on environmental quality in Africa from 2010 to 2018 using SMB-DEA and PMG ARDL methods. The results are as follows: first, SMB-DEA analysis found traditional and renewable energy efficiency at 89 % and 58 %, respectively, indicating infrastructure and policy deficiencies in optimizing renewables. Second, economic expansion poses significant environmental costs; energy efficiency has an insignificant ameliorating effect on efficiency; and counterintuitively, natural resource rents become less environmentally harmful over time, though remain detrimental in the short term. Third, country-specific analyses presented heterogeneous outcomes, reflecting the complexity of global climate solutions. Fourth, transforming inefficient energy-growth-emission systems onto sustainable trajectories requires 262 % CO2 emission cuts and 46.7 % increased renewables capacity to reach efficiency frontiers. Fifth, Bidirectional causal relationships exist between income, energy efficiency, emissions, and resource rents, mutually influencing one another. These findings support suggestions for upscaling green energy capacity and improving green energy efficiency.

AI-Driven Solar Energy Generation and Smart Grid Integration A Holistic Approach to Enhancing Renewable Energy Efficiency

This paper comprehensively analyzes AI-driven solar energy generation and smart grid integration, focusing on enhancing renewable energy efficiency. The study examines applying advanced artificial intelligence techniques in optimizing solar power production, forecasting, and grid management. Machine learning algorithms, including Support Vector Regression (SVR) and Artificial Neural Networks (ANN), are evaluated for effectiveness in solar irradiance prediction and PV system performance estimation. The integration of AI in smart grids is explored, highlighting its role in demand-side management, energy storage optimization, and grid stability control. A holistic approach to improving renewable energy efficiency is proposed, encompassing integrated AI frameworks for solar-plus-storage systems, multi-objective optimization techniques for energy management, and AI-enabled microgrids and virtual power plants. The paper also addresses the challenges and future trends in AI application to renewable energy systems, including scalability issues, regulatory considerations, and ethical implications. By leveraging big data analytics and advanced AI algorithms, this research demonstrates the potential for significant improvements in overall system efficiency, reliability, and sustainability of solar energy systems integrated with smart grids.

The political economy of electricity market coupling: Comparing experiences from Europe and the United States

Advancing the integration of neighbouring power markets is widely identified in the literature as a key enabler of power system efficiency, flexibility, and variable renewable energy integration. Nonetheless, the existing economic literature offers only partial explanations of why greater market integration is difficult to achieve in the real world despite its evident advantages in terms of overall welfare, supply security, and competitiveness. It is argued that power market coupling is an inherently political process involving significant institutional contestation and adaptation, and hence requires a more nuanced political analysis to be fully understood. This paper adds to the existing literature by conducting a comparative political economy analysis of electricity market coupling processes in Britain, Italy, and California, spanning from 2013 to 2021. It seeks to unpack how differences in the political economy contexts of these jurisdictions influenced the electricity market coupling process with their respective neighbouring systems. The analysis draws on 86 key policy documents, and 53 in-depth interviews with senior power system stakeholders in the three jurisdictions. Results widely align with claims in the political economy literature that market coupling outcomes do not simply reflect the most efficient solution. While all three jurisdictions have shown a commitment to enhance regional integration of short-term wholesale energy markets, there is considerable variation in policy outcomes, particularly the extent to which different segments of the market have been coupled. These differences can largely be attributed to variations in the political economy contexts of the three jurisdictions, including multi-level governance structures, diplomatic relations with neighbouring countries, and interactions with national political priorities and contexts. The main implications for the governance of electricity market coupling are discussed in the conclusion.

Analyzing nonlinear and asymmetric effects of green finance and renewable energy on energy efficiency amidst technological innovation in E7 countries

The study aims to explore the relationship between green funding, green energy, and energy efficiency in E7 countries, guided by the SDG-7 guidelines recommended by the United Nations General Assembly. Methodologically, the study employs the Nonlinear Autoregressive Distributed Lag (NARDL) and Two-Stage Least Squares (2SLS) techniques on data collected between 1988 and 2022. The rationale for this approach lies in its ability to capture both short-term and long-term dynamics in the relationship between green funding, green energy, and energy efficiency. Analysis of the data reveals varying stages of green funding growth among E7 countries, with China (1.52), Brazil (1.44), India (1.35), Indonesia (1.94), Mexico (1.73), and Russia (1.93) exhibiting different levels of progress. Russia and Turkey are identified as having the highest Gini coefficients in 2019, indicating disparities in green funding distribution within these countries. The empirical findings underscore the critical role of investment in the energy sector by both corporations and the public sector to enhance access to electricity, bolster energy security, and foster environmentally sustainable economic development. However, the study identifies insufficient investment as a fundamental obstacle hindering progress in green energy efficiency in E7 nations. Despite the potential for implementing energy efficiency measures and renewable energy sources in E7 countries, the future remains uncertain due to existing obstacles in green financing and regulatory frameworks. Consequently, the paper emphasizes the imperative of addressing these obstacles to unlock the full funding potential for energy efficiency initiatives in E7 nations.

Green Packaging and Environmental Safety in Ghana’s Hospitality Industry: A Systematic Review

This study seeks to review on green packaging practices on environmental safety in Ghana’s hospitality industry. The reviewed studies adopted a cross-sectional study design. A systematic review was carried out with the aid of online research journal websites as well as other in-context articles. While conducting this study, the key words in the search query were directed towards the impact of green practices on environmental safety in Ghana. Areas noted in relation to this study was use of green practices in hotels. Therefore, there was linkage of papers pointing out the impact of green practices on environmental safety. The results revealed that, hotels fared well in environmental health but badly in eco-labeling and certification. At 34%, hotels supported sustainability. Results affect MDGs, volunteering, and environment. Hierarchical multiple regression demonstrated that hotel size, class, national hotel trade association engagement, and manager remuneration increased environmental performance. No performance improvement from global chain link. Many Ghanaian hotels provide green enhancements. Most municipal hotels affect the environment. Sustainability demands hotel personnel green management training. Based on observations and interviews, they promote resilience in solid and liquid waste management, renewable energy development, green designs, energy efficiency, water conservation, and green environmental regulatory compliance. Conclusion: The research shows that hotels are important to their communities' economies, but if we neglect their environmental impact, they may damage the ecosystem. There is a need for hotels that invest money into environmental audits or certification programs like eco-labels to get monetary recompense for their environmental efforts.

Exploring the complex interplay of green finance, business cycles, and energy development

Green finance has emerged as a contemporary mechanism to support investments in renewable energy, energy efficiency, and sustainable infrastructure projects. This study aims to provide empirical insights into the asymmetric influence of green finance and business cycle fluctuations on energy development in 60 developing countries from 2000 to 2021. Four aspects of energy development, including energy access, stability, efficiency, and production gap, are examined using panel quantile regression with additive fixed effects. The research findings demonstrate that green finance plays a significant role in fostering energy development, with varying effects across different quantiles of the distribution. Specifically, the results indicate that green finance supports energy access and stability, particularly during economic recession, low-income levels, and limited technological advancement. However, the impact of green finance on energy efficiency exhibits notable heterogeneity, contingent upon technological and periods of economic expansion. Achieving tangible improvements in energy efficiency necessitates a certain level of technological and economic development. Moreover, green finance shows a capacity to maintain an optimal level of energy production, particularly evident during economic expansion and for highly technologically developed countries. The impact of business cycle fluctuations varies across different quantile distributions of energy development indicators, predominantly exerting an inhibitory effect of economic recession. In light of these results, it is recommended that policies in developing countries be revised to enhance energy access, optimize energy production levels, and promote the cost-effectiveness of renewable energy in conjunction with green finance initiatives.

Can forests realize the carbon neutrality dream? Evidence from a global sample

The enlarge in economic activities and the urban population at the global level has brought about an increase in the demand for energy, food, and natural resources, as well as an exacerbation in global climate change concerns. In this respect, it is important to ensure the balance between global climate change and global economic activities. Therefore, a wide literature has emerged that searches for alternative solutions to improve climate change and carbon dioxide (CO2) emissions. The majority of existing studies emphasize the importance of renewable energy sources in environmental improvement efforts. Few studies highlight the importance of forestation in environmental improvement efforts, highlighting the non-linear effects of forestation. To fill this gap, this study uses panel data from 181 countries between 1990 and 2022 and evaluates the non-linear impact of economic growth, forest extent, energy efficiency, and urban growth on per capita CO2 emissions using a dynamic panel threshold and dynamic panel quantile threshold methods. Furthermore, we extend the model and conduct robustness tests examining the non-linear threshold effects of renewable and non-renewable energy consumption on per capita CO2 emissions. Our findings provide pieces of evidence that forest extents are an alternative solution to renewable energy use and energy efficiency in environmental improvement efforts.