Recent reports from international energy agencies indicate that more than a billion of the population in the world is deprived of basic electricity provisions, confined mainly to the remote communities of developing nations. Microgrids are promoted as a potential technology for electricity provisions to off-grid rural communities, but have failed to reach their value proposition in the context of rural electrification access. In view of the rampant rural electrification issues, the objective of this paper is to furnish an understanding of, and advance the knowledge into, methods to facilitate the design and development of microgrid systems for remote communities in developing countries. The methodology involves an integrative review process of an annotated bibliography to summarise past empirical or theoretical literature. As such, this research is based on evaluation attributes, and identifies the challenges and barriers for remote microgrids through an analysis of 19 case studies. Th... [more]

Detecting and determining which systems or subsystems of a wind turbine have more failures is essential to improve their design, which will reduce the costs of generating wind power. Two of the most critical failures, the generator and gearbox, are analyzed and characterized with four metrics. This failure analysis usually begins with the identification of the turbine’s condition, a process normally performed by an expert examining the wind turbine’s service history. This is a time-consuming task, as a human expert has to examine each service entry. To automate this process, a new methodology is presented here, which is based on a set of steps to preprocess and decompose the service history to find relevant words and sentences that discriminate an unhealthy wind turbine period from a healthy one. This is achieved by means of two classifiers fed with the matrix of terms from the decomposed document of the training wind turbines. The classifiers can extract essential words and determine... [more]

The current fossil fuel reserves are not sufficient to meet the increasing demand and very soon will become exhausted. Pollution, global warming, and inflated oil prices have led the quest for renewable energy sources. Algal biofuels represent a potential source of renewable energy. Algae, as the third generation feedstock, are suitable for biodiesel and bioethanol production due to their quick growth, excellent biomass yield, and high lipid and carbohydrate contents. With their huge potential, algae are expected to surpass the first and second generation feedstocks. Only a few thousand algal species have been investigated as possible biofuel sources, and none of them was ideal. This review summarizes the current status of algal biofuels, important steps of algal biofuel production, and the major commercial production challenges.

In South Korea, renewable energy policy is mainly focused on electricity and tends to neglect renewable heat (RH). However, for the purpose of reducing greenhouse gas emissions, the heating sector must sharply switch from its use of conventional fuels to renewable sources. The South Korean Government is considering an RH incentive (RHI) program with financial and policy support schemes and is thus demanding information about residential consumers’ acceptance of the RHI program to expand the use of RH. Therefore, this study looked into residential consumers’ acceptance of the introduction of the RHI program by applying contingent valuation (CV). For this purpose, a CV survey of 600 interviewees was conducted using a dichotomous choice question format that asked a respondent if she/he is willing to pay a given amount. Furthermore, among the various dichotomous choice question formats, the one-and-one-half-bounded format, which is considered desirable in terms of efficiency as well as con... [more]

Distributed generators (DGs) based on renewable energy systems such as wind turbines, solar panels, and storage systems, are key in transforming the current electric grid into a green and sustainable network. These DGs are called inverter-interfaced systems because they are integrated into the grid through power converters. However, inverter-interfaced systems lack inertia, deteriorating the stability of the grid as frequency and voltage oscillations emerge. Additionally, when DGs are connected to the grid, its robustness against unbalanced conditions must to be ensured. This paper presents a robust control scheme for power regulation in DGs, which includes inertia and operates under unbalanced conditions. The proposed scheme integrates a robust control algorithm to ensured power regulation, despite unbalanced voltages. The control algorithm is an artificial hydrocarbon network controller, which is a chemically-inspired technique, based on carbon networks, that provides stability, robu... [more]

To improve the reactor efficiency, this study investigated the influence of temperature on the biological hydrogen methanation (BHM) in trickle-bed reactors (TBR). Rising temperatures increase the metabolic activity of methanogenic microorganisms, thus leading to higher reactor specific methane formation rates (MFR). In order to quantify the potential for improved performance, experiments with four different operating temperatures ranging from 40 to 55 °C were carried out. Methane content increased from 88.29 ± 2.12 vol % at 40 °C to 94.99 ± 0.81 vol % at 55 °C with a stable biological process. Furthermore, a reactor specific methane formation rate (MFR) of up to 8.85 ± 0.45 m³ m−3 d−1 was achieved. It could be shown that the microorganisms were able to adapt to higher temperatures within hours. The tests showed that TBR performance with regard to BHM can be significantly increased by increasing the operating temperature.

One-quarter of the world’s population lives without access to electricity. Unfortunately, the generation technology most commonly employed to advance rural electrification, diesel generation, carries considerable commercial and ecological risks. One approach used to address both the cost and pollution of diesel generation is renewable energy (RE) integration. However, to successfully integrate RE, both the stochastic nature of the RE resource and the operating characteristics of diesel generation require careful consideration. Typically, diesel generation is configured to run heavily loaded, achieving peak efficiencies within 70⁻80% of rated capacity. Diesel generation is also commonly sized to peak demand. These characteristics serve to constrain the possible RE penetration. While energy storage can relieve the constraint, this adds cost and complexity to the system. This paper identifies an alternative approach, redefining the low load capability of diesel generation. Low load diesel... [more]

In the industrial food supply chain, cold storage is one of the most important processes where there is a huge but still unused potential for employing renewable energy technologies. This paper analyses how the integration of rooftop photovoltaics affects the design and performance of refrigerated automated warehouses, which are becoming the preferred choice for frozen food storage facilities. The problem is modelled and solved by means of Constraint Programming. Results for the reference case in north-eastern Italy show that photovoltaic installation can lead to both yearly total cost and energy savings. Simulations highlight how design and performance of the refrigerated automated warehouse strictly depend on supply chain decision variables. PV integration offers supply chain managers more opportunities to act on the storage temperature and the incoming product temperatures strictly related to upstream and downstream stages of the whole cold chain. Attention should be paid to system... [more]

Deployment of photovoltaic (PV) systems has recently been encouraged for large-scale and small-scale businesses in order to meet the global green energy targets. However, one of the most significant hurdles that limits the spread of PV applications is the dust accumulated on the PV panels’ surfaces, especially in desert regions. Numerous studies sought the use of cameras, sensors, power datasets, and other detection elements to detect the dust on PV panels; however, these methods pose more maintenance, accuracy, and economic challenges. Therefore, this paper proposes an intelligent system to detect the dust level on the PV panels to optimally operate the attached dust cleaning units (DCUs). Unlike previous strategies, this study utilizes the expanded knowledge and collected data for solar irradiation and PV-generated power, along with the forecasted ambient temperature. An expert artificial intelligence (AI) computational system, adopted with the MATLAB platform, is utilized for a high... [more]

Hydrogen is one of the prospective clean energies that could potentially address two pressing areas of global concern, namely energy crises and environmental issues. Nowadays, fossil-based technologies are widely used to produce hydrogen and release higher greenhouse gas emissions during the process. Decarbonizing the planet has been one of the major goals in the recent decades. To achieve this goal, it is necessary to find clean, sustainable, and reliable hydrogen production technologies with low costs and zero emissions. Therefore, this study aims to analyse the hydrogen generation from solar and wind energy sources and observe broad prospects with hybrid renewable energy sources in producing green hydrogen. The study mainly focuses on the critical assessment of solar, wind, and hybrid-powered electrolysis technologies in producing hydrogen. Furthermore, the key challenges and opportunities associated with commercial-scale deployment are addressed. Finally, the potential applications... [more]

Earth−air heat exchanger (EAHE) systems are used to pre-heat or pre-cool air before entering into a building using shallow geothermal energy. Assessment of EAHE systems is important to quantify the profitability of these systems. For this purpose, an EAHE system built at ICUBE at the University of Strasbourg in the northeast of France was studied using energy and exergy analyses for a typical heating period (between 25 February and 3 March). Energy analysis was used to determine the heat gained by the air in the system during the studied period and to determine the Coefficient Of Performance (COP) of the system. Additionally, exergy analysis, which considered temperature, pressure, humidity, and the variation in the control volume boundary temperature, was realized to determine inefficiencies in the system by determining the exergy destroyed in each component of the system and evaluating its exergetic efficiency. Results showed that the heat energy gained using the system was around 63... [more]

Hydrogen is regarded as a flexible energy carrier with multiple applications across several sectors. For instance, it can be used in industrial processes, transports, heating, and electrical power generation. Green hydrogen, produced from renewable sources, can have a crucial role in the pathway towards global decarbonization. However, the success of green hydrogen production ultimately depends on its economic sustainability. In this context, this work evaluates the economic performance of a hydrogen power plant participating in the electricity market and supplying multiple hydrogen consumers. The analysis includes technical and economical details of the main components of the hydrogen power plant. Its operation is simulated using six different scenarios, which admit the production of either grey or green hydrogen. The scenarios used for the analysis include data from the Iberian electricity market for the Portuguese hub. An important conclusion is that the combination of multiple serv... [more]

This study investigates the moderating effect of financial development on the renewable energy−CO2 emissions nexus in OECD countries. We find that both composite financial development and banking sector development have an inverted U-shaped impact on CO2 emissions, while stock market development has a U-shaped impact on CO2 emissions. Further, an increase in renewable energy will reduce CO2 emissions, and this reducing impact is affected by different levels of financial development. When promoting financial development, policymakers should pay more attention to its role in enhancing renewable energy, which is related to emissions reduction.

Taking into account factors such as unfavorable climate changes, shrinking fossil fuel resources, low energy efficiency, and the pace of population growth, the transformation towards green and renewable energy is one of the most important goals and challenges facing the world. The energy sector is the source of about 75% of global greenhouse gas emissions and energy-related emissions are reaching new record levels. For the energy transition to succeed, innovation at the level of technology, business processes and policies (local, national, and international) are necessary. Therefore, the aim of this article is to analyze the size, structure, and dynamics of research on innovations in the field of green and renewable energy in the last decade in order to identify the main topics and research trends in this field. The authors conducted a bibliometric review based on the PRISMA guidance together with visualization analysis based on the VOSviewer software. For this purpose, the Web of Scie... [more]

Despite the enormous efforts put into practice by governmental entities, most of the energy consumption worldwide proceeds from fossil fuels. In this regard, there is a clear need to advance toward the use of cleaner energies. This situation is especially critical in developing countries, where a high population, increased commercial and industrial activities, and rising greenhouse gas (GHG) emissions are major concerns. This paper focuses on reviewing the current energy map in Jordan, one of the developing countries in the Southwest Asia area. Jordan generates 2.7 million tons of municipal solid waste annually, which can cause a variety of environmental problems rather than benefit the energy industry or the country’s economy. Jordan uses biomass energy to provide just 0.1% of its overall energy needs. Presently, produced energy comprises logs, chips, bark, and sawdust is made up of around 44% wood. Jordan has a high potential for producing biomass in the future. About 96% of the biom... [more]

Energy security affects the functioning of countries politically, economically, and socially. Energy is an important factor in sustainable development efforts. Hence, countries are assessing their energy systems for compatibility with sustainable development goals by creating new concepts for energy development. Combining the concepts of energy security and sustainable energy consumption, an analysis of the differentiation of EU countries in terms of selected indicators indicated in Goal 7 of Agenda 2030 was carried out in dynamic terms. Two groups of indicators were distinguished. One group of indicators was selected to represent the changes in energy demand reported by final consumers, taking into account the use of energy obtained from renewable sources. The second group of indicators represents those relating to the security of supply of raw materials, i.e., energy dependency indicators broken down by major energy commodities and an energy productivity indicator. The analysis uses... [more]

Climate change and global warming, caused by excessive carbon emissions from transportation and other environmentally hazardous activities, are serious problems for many countries nowadays. Therefore, while some countries are not making optimal use of their resources, others are working hard to preserve a green and clean environment in order to foster long-term growth. Governments and policymakers throughout the world are finally starting to take the risks of climate change and global warming seriously. This paper extends previous literature related to environmental design practices by investigating the impacts of environmental innovation and the deployment of green energy on decreasing carbon dioxide (CO2) emissions for Saudi Arabia during the period 1990−2018. Different CO2 emission measures are incorporated in the analysis, namely per capita CO2 emissions, CO2 intensity, CO2 emissions from liquid fuel use, and CO2 emissions from heat and electricity generation. Overall, the outcomes... [more]

: Wind speed and solar radiation are two of the most well-known and widely used renewable energy sources worldwide. Coal, natural gas, and petroleum are examples of fossil fuels that are not replenished and are thus non-renewable energy sources due to their high carbon content and the methods by which they are generated. To predict energy production of renewable sources, researchers use energy forecasting techniques based on the recent advances in machine learning approaches. Numerous prediction methods have significant drawbacks, including high computational complexity and inability to generalize for various types of sources of renewable energy sources. Methodology: In this paper, we proposed a novel approach capable of generalizing the prediction accuracy for both wind speed and solar radiation forecasting data. The proposed approach is based on a new optimization algorithm and a new stacked ensemble model. The new optimization algorithm is a hybrid of Al-Biruni Earth Radius (BER) an... [more]

Global climate policy commitments are encouraging the development of EU energy policies aimed at paving the way for cleaner energy systems. This article reviews key decarbonization drivers for Italy considering higher environmental targets from recent European Union climate policies. Energy efficiency, the electrification of final consumption, the development of green fuels, increasing the share of renewable energy sources in the electric system, and carbon capture and storage are reviewed. A 2030 scenario is designed to forecast the role of decarbonization drivers in future energy systems and to compare their implementation with that in the current situation. Energy efficiency measures will reduce final energy consumption by 15.6%, as primary energy consumption will decrease by 19.8%. The electrification of final consumption is expected to increase by 6.08%. The use of green fuels is estimated to triple as innovative fuels may go to market at scale to uphold the ambitious decarbonizat... [more]

In this article, the authors present the results of research undertaken in relation to the situation regarding renewable and non-renewable energy reserves in the European Union, as well as the way in which this energy is consumed. The general view presented regarding energy resources around the world is that oil, natural gas and coal are being exhausted at an alarming rate and if we continue to exploit these oil resources at our current pace, we will see a massive depletion in energy resources over the next 41 years. The authors also focus on representing the intensity of greenhouse gas emissions from energy consumption, demonstrating that it has shown a slight decrease in the European Union. The resources and consumption of renewable and non-renewable energy were analyzed in close interdependence with these indicators under study, such as final energy consumption, renewable energy and total energy production, in order to give a correct interpretation of how these resources are used. A... [more]

Rivers in tropical climates are characterized by highly variable flows which are becoming more variable due to climate change. In tropical conditions, most hydropower plants are designed as run-of-river plants with limited water storage. The aim of this study is the selection and sizing of a hydropower plant for highly variable flows, using the Sebeya River as a case study. As is often the case, flow data was incomplete, and the study also demonstrated the use of machine learning to predict the Sebeya flow rate for 2019. Stochastic modeling was used to estimate the energy generation for multiple turbine types and the levelized cost of energy for all configurations, capturing the uncertainty in many of the input parameters. River flow varies between 1.3 m3/s and 5.5 m3/s in a year; the minimum LCOE occurs at the knee in the flow exceedance curve of river flow rate, near 1.8 m3/s. The optimal LCOE for the Sebeya river is around 0.08 $/kwh with an uncertainty of −0.011/+0.009 $/kWh. Addit... [more]

Increasing global warming is largely attributable to human activities. International strategies have already been implemented to reduce emissions to zero, thus reducing energy consumption. Given the current world situation and the rising costs of raw materials (gas and oil), it is incumbent on us to find savings solutions that can also be implemented in our own small way; there are many solutions, especially in the domestic sphere. In this paper, the focus is on building energy savings that can be achieved using modern technologies and starting with the simplest solutions. In particular, this paper shows how the conscious use of natural lighting can lead to significant electricity savings. Moreover, it describes the effect of innovative building insulation materials and the effect due to the installation of a local photovoltaic power generation system; at the end, it illustrates the new horizons that are opening with the introduction of new building control techniques. Some studies are... [more]

Energy price fluctuations pose a significant risk and uncertainty to financial investments for new developments in conventional power and freshwater cogeneration facilities. This study attempts to address the problem of making robust valuation for low-carbon energy project investments subject to multi-dimensional price risk, particularly looking at some key research questions: (a) how does the correlation structure, or independence, between the price risks affect the project value; and (b) does adding flexibility in investment enhance or worsen the project valuation, given (a). This study identified three price factors with significant fluctuations that impact conventional power generation, namely: wholesale electricity spot price, natural gas spot price, and CO2 market price. The price factors were used to construct a multidimensional risk model and evaluate investment decisions for cogeneration project expansion in the future based on a low-carbon energy mix. To this end, five cogene... [more]

Sustainable development has positioned itself as a fundamental element of a transversal nature, being linked to the energy transition. In this sense, it must be included as a mainstream objective of all actions and strategies developed at the social, academic, business, and political levels. However, to the best of our knowledge, no bibliometric work has been carried out to date to analyze the main contributions to the literature focused on the concepts of renewable energy and sustainable development. The main aim of this paper is to establish the key trends and academic contributions made in the field of renewable energies and sustainable development. For this purpose, a bibliometric and co-citation analysis has been carried out using the Bibliometrix® tool, an open-source R package. The results show that this is a field of study that has significantly increased its importance in recent years, which is illustrated using different indicators. We conclude that research trends seem to be... [more]

Recently, the concept of green building has become popular, and various renewable energy systems have been integrated into green buildings. In particular, the application range of fuel cells (FCs) has become widespread due to the various government plans regarding green hydrogen energy systems. In particular, proton exchange membrane fuel cells (PEMFCs) have proven superiority over other existing FCs. However, the uniqueness of the operating maximum power point (MPP) of PEMFCs represents a critical issue for the PEMFC control systems. The perturb and observe, incremental conductance/resistance, and fuzzy logic control (FLC) represent the most used MPP tracking (MPPT) algorithms for PEMFC systems, among which the FLC-based MPPT methods have shown improved performance compared to the other methods. Therefore, this paper presents a modified FLC-based MPPT method for PEMFC systems in green building applications. The proposed method employs the rate of change of the power with current (dP/d... [more]