Review of the marine energy environment-a combination of traditional, bibliometric and PESTEL analysis

Marine renewable energy is regarded as a nascent renewable energy resource that is less utilized due to a number of challenges in the sector. This paper focused on using both traditional and bibliometric analysis approaches to review the marine energy industry. It also assessed the various opportunities and challenges in the sector beyond technological challenges using PESTEL analysis. The results from the study identified the availability of renewable energy targets, international and national greenhouse gas (GHG) emissions reduction targets, job creation, skill transfer from offshore industries, renewable support, and low GHG emissions as the major opportunities for the sector. The challenges in the sector include the lack of commonality in device designs, high initial capital costs, lack of appropriate legal and regulatory frameworks, lack of funding, fragmentations in regulatory institutions, bad macro-economic indicators in some countries, environmental challenges, the survivability of the various technologies in the harsh oceanic environment, and strong competition from other renewable energy sources. The outcome of the bibliometric analysis spanning from 2013 to 2023 shows that tidal power is the focus of research in the field, and most studies are either focused on ways to improve its efficiency in terms of technology or on the identification of resource potentials for the siting of the various marine renewable power systems. Recommendations such as strong cooperation between the government and private sector, increased public education, collaboration with existing players in the marine sector, and increased research and development, among others, were proposed for the development of the sector.

Prioritizing Non-Carbon Dioxide Removal Mitigation Strategies Could Reduce the Negative Impacts Associated with Large-Scale Reliance on Negative Emissions

Carbon dioxide removal (CDR) is necessary for reaching net zero emissions, with studies showing potential deployment at multi-GtCO2 scale by 2050. However, excessive reliance on future CDR entails serious risks, including delayed emissions cuts, lock-in of fossil infrastructure, and threats to sustainability from increased resource competition. This study highlights an alternative pathway─prioritizing near-term non-CDR mitigation and minimizing CDR dependence. We impose a 1 GtCO2 limit on global novel CDR deployment by 2050, forcing aggressive early emissions reductions compared to 8-22 GtCO2 in higher CDR scenarios. Our results reveal that this low CDR pathway significantly decreases fossil fuel use, greenhouse gas (GHG) emissions, and air pollutants compared to higher CDR pathways. Driving rapid energy transitions eases pressures on land (including food cropland), water, and fertilizer resources required for energy and negative emissions. However, these sustainability gains come with higher mitigation costs from greater near-term low/zero-carbon technology deployment for decarbonization. Overall, this work provides strong evidence for maximizing non-CDR strategies such as renewables, electrification, carbon neutral/negative fuels, and efficiency now rather than betting on uncertain future CDR scaling. Ambitious near-term mitigation in this decade is essential to prevent lock-in and offer the best chance of successful deep decarbonization. Our constrained CDR scenario offers a robust pathway to achieving net zero emissions with limited sustainability impacts.

Transportation in Africa under Paris Agreement 2 °C goal-a review of electric vehicle potentials, cleaner alternative fuels for the sector, challenges, and opportunities

Currently, internal combustion engines and fossil fuels are the major powertrains and fuels for the transportation sector, despite their enormous emissions. This study reviews the status of electric vehicles (EVs) in Africa, the potential barriers that affect their large-scale adoption, and the continent's potential to produce cleaner alternative fuels for transportation and find the strengths, weaknesses, opportunities, and threats (SWOT) to produce alternative fuels in Africa. First, the review looked at challenges confronting the adoption of EVs in Africa, some of which include high upfront costs, poor grid systems, frequent blackouts, inadequate infrastructure (roads and charging systems), and the dominance of used conventional vehicles. The various cleaner alternative fuels, i.e., hydrogen, biogas, ethanol, methanol, ammonia, biodiesel, and vegetable oils, and their potential on the African continent were also reviewed. The last section of the study employed the SWOT analytical tool to assess the strengths, weaknesses, opportunities, and threats in the alternative fuel industry in Africa. Factors such as competition from existing technologies, inadequate funding, feeble linkages between research and production, unsustainable policies for the sector, cultural constraints and lack of awareness, volatile financial systems, and low levels of foreign direct investment are some of the identified threats that could affect the development of alternative fuels in Africa. Similarly, factors such as the continuous decline in the cost of renewable energy technologies and heightened awareness of the adverse effects of GHG on the environment were identified as opportunities for the development of alternative fuels for the transport sector.

A review contribution to emission trading schemes and low carbon growth

In this study, the researchers focus on policy instruments that employ a market-based strategy to promote emission reduction, find the key spots and recent changing aspects in the field of Eemission Trading Systems (ETS) and Low Carbon Growth, and make suggestions for future studies. Making use of the bibliometric analysis, the researchers examine a sample of 1,390 research from the ISI Web of Science database to find research activity on ETS and low carbon growth between 2005 and 2022. Also, the researchers visualized the knowledge domains in this field using software like CiteSpace and R-Biblioshiny. The research unravels the most influential published articles and authors on their citations and publications and their location and significance within the network. The researchers further examined the recent themes, identified the barriers to developing literature in this field, and made recommendations for future research. Research on ETS and low carbon growth globally lack cross-border collaborations between emerging and developed economies. The researchers concluded the study by recommending three future research directions.

Wildfires in Australia: a bibliometric analysis and a glimpse on 'Black Summer' (2019/2020) disaster

A wildfire, an unplanned fire that is mainly uncontrolled and originates in combustible vegetation in rural or urban settings, is one of the most pervasive natural catastrophes in some areas, such as Siberia, California and Australia. Many studies, such as standard reviews, have been undertaken to look into the works of literature on wildfires or forest fires and their effects on aquatic and terrestrial ecosystems. Regrettably, conventional literature reviews failed to identify the important researchers, evolving complexities, emerging research hotspots, trends and opportunities for further research on the ground of wildfire study. The present study employs bibliometric analysis to investigate this study area qualitatively and quantitatively. The Scopus database systems and Web of Science Core Collection yielded 78 qualifying papers, which were then evaluated using Biblioshiny (A bibliometrix tool of R-studio). According to the statistics, the discipline is expanding at a pace that is 13.68% faster than average. So far, three key periods of transformation have been documented: preliminary evolution (8 articles; 1999-2005), gentle evolution (14 articles; 2006-2013) and quick evolution (56 articles; 2014 to 2021). Forest Ecology and Management and Science journals have the highest number of publications, accounting for 7.70% of total wildfire-related articles published from 1999 to 2021. However, recent data indicate that investigators are shifting their focus to wildfires, with the term 'Australia' having the highest frequency (91) and 'wildfire' having the second highest (58) as the most appeared keywords. The present study will provide a foundation for future research on wildfire incidence and management by receiving information by synthesising previously published literature in Australia and around the world.

Biofuels and Nanocatalysts: Python Boosting Visualization of Similarities

Among the most relevant themes of modernity, using renewable resources to produce biofuels attracts several countries' attention, constituting a vital part of the global geopolitical chessboard since humanity's energy needs will grow faster and faster. Fortunately, advances in personal computing associated with free and open-source software production facilitate this work of prospecting and understanding complex scenarios. Thus, for the development of this work, the keywords "biofuel" and "nanocatalyst" were delivered to the Scopus database, which returned 1071 scientific articles. The titles and abstracts of these papers were saved in Research Information Systems (RIS) format and submitted to automatic analysis via the Visualization of Similarities Method implemented in VOSviewer 1.6.18 software. Then, the data extracted from the VOSviewer were processed by software written in Python, which allowed the use of the network data generated by the Visualization of Similarities Method. Thus, it was possible to establish the relationships for the pair between the nodes of all clusters classified by Link Strength Between Items or Terms (LSBI) or by year. Indeed, other associations should arouse particular interest in the readers. However, here, the option was for a numerical criterion. However, all data are freely available, and stakeholders can infer other specific connections directly. Therefore, this innovative approach allowed inferring that the most recent pairs of terms associate the need to produce biofuels from microorganisms' oils besides cerium oxide nanoparticles to improve the performance of fuel mixtures by reducing the emission of hydrocarbons (HC) and oxides of nitrogen (NOx).

Performance analysis and socio-enviro-economic feasibility study of a new hybrid energy system-based decarbonization approach for coal mine sites

The mining sector contributes to 4-7 % of global GHG emissions, of which 1 % are from scope 1 and scope 2 emissions, caused by operations such as electricity consumption used for the mining process. China heavily relies on coal for power generation, and the energy demand for coal production in the country is primarily met by fossil-based electricity. In addition, the transportation of the mined coal to various destinations within the supply chain is achieved by fossil fuel-powered transport systems. These daily activities of the Chinese coal sector further compound foreign and domestic pressure on China to limit its carbon emissions. The current study attempts to provide a solution to the situation by investigating the feasibility of adopting renewable energy sources for the process of coal mining in Northern China. The selected coal mine is one out of 643 coal mines in Shanxi Province, with a combined production capacity of ∼1 billion tonnes of coal per annum. In addition, the excess electricity generated has been designated to produce hydrogen on-site as a refueling source for hydrogen fuelled-trucks to replace diesel fuelled-trucks in transporting coal. The analysis has been completed using HOMER Pro software, and the key contributions are summarized as follows. 4 different scenarios comprising of standalone solar photovoltaic, wind turbine, and diesel generator have been designed in the current study to serve a daily load of 215 MWh and 2.4 t of electricity for coal mining and hydrogen for transport of 100 % of the mined coal by road using hydrogen fuel cell trucks, respectively. A technical, economic, environmental, and social feasibility analysis have been investigated in the present work. A grid-tied system is subsequently added to the base scenario and the results are compared against the base system in an attempt to identify the more feasible option between the two systems. Also, a sensitivity analysis has been conducted to reveal the performance of the base system amidst future uncertainties. The findings in the current work could prove beneficial to China's quest to reach carbon peak by 2030 and achieve carbon neutrality by 2060.

Research Progress, Trends, and Current State of Development on PEMFC-New Insights from a Bibliometric Analysis and Characteristics of Two Decades of Research Output

The consumption of hydrogen could increase by sixfold in 2050 compared to 2020 levels, reaching about 530 Mt. Against this backdrop, the proton exchange membrane fuel cell (PEMFC) has been a major research area in the field of energy engineering. Several reviews have been provided in the existing corpus of literature on PEMFC, but questions related to their evolutionary nuances and research hotspots remain largely unanswered. To fill this gap, the current review uses bibliometric analysis to analyze PEMFC articles indexed in the Scopus database that were published between 2000-2021. It has been revealed that the research field is growing at an annual average growth rate of 19.35%, with publications from 2016 to 2012 alone making up 46% of the total articles available since 2000. As the two most energy-consuming economies in the world, the contributions made towards the progress of PEMFC research have largely been from China and the US. From the research trend found in this investigation, it is clear that the focus of the researchers in the field has largely been to improve the performance and efficiency of PEMFC and its components, which is evident from dominating keywords or phrases such as 'oxygen reduction reaction', 'electrocatalysis', 'proton exchange membrane', 'gas diffusion layer', 'water management', 'polybenzimidazole', 'durability', and 'bipolar plate'. We anticipate that the provision of the research themes that have emerged in the PEMFC field in the last two decades from the scientific mapping technique will guide existing and prospective researchers in the field going forward.

Investigating evolutionary trends and characteristics of renewable energy research in Africa: a bibliometric analysis from 1999 to 2021

Several countries across the African continent have been challenged with energy crises for decades. A growing number of studies have identified renewable energy as a sustainable way for Africa to address its persisting energy situation while combating climate change, as the continent has in abundance some of the common renewable energy resources. Little has been reported in the body of literature to quantitatively and qualitatively map the knowledge domain of this growing research field. In the current study, we conduct a bibliometric analysis on research documents extracted from the Web of Science Core Collection to identify trends and characteristics of the knowledge domain related to renewable energy in Africa from 1999 to 2021. Using two different software (VOSviewer and ITgInsight), we report the contribution of journals, countries, institutions, and authors and their collaboration patterns. We also perform co-citation and keyword analysis to identify the intellectual base and central themes of this research field. The results from the study revealed a growing interest in Africa's renewable energy, with about 90% of the total publication from within the last decade. Renewable & Sustainable Energy Reviews was identified as the most productive as well as the most influential journal in this field. The most contributing countries in this field were South Africa, USA, and Algeria. Centre de Developpement Des Energies Renouvelables, a research institute in Algeria, emerged as the most productive and influential institution. The analysis of research hotspots under different categories revealed that "solar energy," "CO2 emissions," and "rural electrification" are the topics that have gained maximum attention over the years. Keyword evolution analysis also identified "economic growth" and "green hydrogen production" as emerging topics that will play a major role in future studies. We conclude our work by providing specific suggestions and strategies to help bridge the gap which exists in the quantity and quality of renewable energy research between Africa and the rest of the world.

Progress and Recent Trends in the Application of Nanoparticles as Low Carbon Fuel Additives—A State of the Art Review

The first part of the current review highlights the evolutionary nuances and research hotspots in the field of nanoparticles in low carbon fuels. Our findings reveal that contribution to the field is largely driven by researchers from Asia, mainly India. Of the three biofuels under review, biodiesel seems to be well studied and developed, whereas studies regarding vegetable oils and alcohols remain relatively scarce. The second part also reviews the application of nanoparticles in biodiesel/vegetable oil/alcohol-based fuels holistically, emphasizing fuel properties and engine characteristics. The current review reveals that the overall characteristics of the low carbon fuel–diesel blends improve under the influence of nanoparticles during combustion in diesel engines. The most important aspect of nanoparticles is that they act as an oxygen buffer that provides additional oxygen molecules in the combustion chamber, promoting complete combustion and lowering unburnt emissions. Moreover, the nanoparticles used for these purposes exhibit excellent catalytic behaviour as a result of their high surface area-to-volume ratio—this leads to a reduction in exhaust pollutants and ensures an efficient and complete combustion. Beyond energy-based indicators, the exergy, economic, environmental, and sustainability aspects of the blends in diesel engines are discussed. It is observed that the performance of the diesel engine fuelled with low carbon fuels according to the second law of efficiency improves under the influence of the nano-additives. Our final part shows that despite the benefits of nanoparticles, humans and animals are under serious threats from the highly toxic nature of nanoparticles.

Visualization and analysis of mapping knowledge domains for the global transition towards clean cooking: a bibliometric review of research output from 1990 to 2020

Current statistics report that 2.6 billion households across the globe rely on polluting and inefficient cooking fuels and technologies, posing death-threatening health risks to people mainly from developing countries/regions. Several studies on clean cooking have been conducted with the emergence of international organizations such as the Clean Cooking Alliance to raise awareness. In the current study, a bibliometric tool, CiteSpace, was employed to analyze the 877 documents retrieved from the SCI-EXPANDED, SSCI, and A&HCI databases on clean cooking research from 1990 to 2020. The results reveal that interest in clean cooking research took a sharp rise in the last decade, especially after 2016. The research field has become increasingly interdisciplinary but has mostly centered on environment, energy, and health. The most productive countries/regions in this field are the USA, India, England, and China. The keyword and citation analyses indicate that research in this field mostly focuses on adverse impacts of household air pollution from unclean cooking fuels and technologies on the environment and public health particularly, in developing countries/regions. Also, the drivers and barriers to the large-scale adoption of clean cooking fuels and technologies have become a topic of interest in recent years. The three most studied clean cooking fuels among various regions are LPG, biogas, and electricity. This study synthesizes global research on clean cooking and may be beneficial to other researchers in understanding current trends in this field and serve as a guide for concentrating on the most important topics.

Low-carbon alcohol fuels for decarbonizing the road transportation industry: a bibliometric analysis 2000-2021

The application of low-carbon alcohols (LCA fuels) in internal combustion engines has become one of the most important topics in road transport decarbonization. This paper aims to identify the trends and characteristics of LCA combustion research for the period 2000-2021 through bibliometric analysis. Citation analysis is used to evaluate the influence of most productive journals, countries/regions, authors, institutions, and relevant literature, while collaborative network between various authors, countries/regions, institutions, and the co-occurrences among different keywords are discussed. A dataset of 2250 publications was extracted from the Web of Science Core database and analyzed with CiteSpace and Biblioshiny. The extracted documents involve 429 journals of publications by 4782 authors from 1434 institutions across 83 countries/regions. The results reveal that the research output in this field has undergone three main stages of development, i.e., initial development (2000-2007), slow development (2008-2015), and rapid development (2016-2021). Currently, the research field is growing at an annual growth rate of 9.24%, with most of the contributions by authors and institutions originating from China. The analysis from relevant keywords and literature suggests that the core of this research field centers on the combustion, performance, and emission characteristics of LCA-fueled engines. The current study helps keep the scientific community informed of the latest paradigms in the LCA combustion research field.