Conventional Energy Resources Research Articles

Techno-Economic Potential of Wind-Based Green Hydrogen Production in Djibouti: Literature Review and Case Studies

Disputed supply chains, inappropriate weather and low investment, followed by the Russian invasion of Ukraine, has led to a phenomenal energy crisis, especially in the Horn of Africa. Accordingly, proposing eco-friendly and sustainable solutions to diversify the access of electricity in the Republic of Djibouti, which has no conventional energy resources and is completely energy-dependent on its neighboring countries, has become a must. Therefore, the implementation of sustainable renewable and energy storage systems is nationally prioritized. This paper deals, for the first time, with the exploitation of such an affordable and carbon-free resource to produce hydrogen from wind energy in the rural areas of Nagad and Bara Wein in Djibouti. The production of hydrogen and the relevant CO2 emission reduction using different De Wind D6, Vestas and Nordex wind turbines are displayed while using Alkaline and Proton Exchange Membrane (PEM) electrolyzers. The Bara Wein and Nagad sites had a monthly wind speed above 7 m/s. From the results, the Nordex turbine accompanied with the alkaline electrolyzer provides the most affordable electricity production, approximately 0.0032 $/kWh for both sites; this cost is about one per hundred the actual imported hydroelectric energy price. Through the ecological analysis, the Nordex turbine is the most suitable wind turbine, with a CO2 emission reduction of 363.58 tons for Bara Wein compared to 228.76 tons for Nagad. While integrating the initial cost of wind turbine implementation in the capital investment, the mass and the levelized cost of the produced green hydrogen are estimated as (29.68 tons and 11.48 $/kg) for Bara Wein with corresponding values of (18.68 tons and 18.25 $/kg) for Nagad.

International experience in the use of alternative energy sources (within the European Union)

The relevance of the chosen subject is due to the problem of the lack of conventional energy resources in the global and Ukrainian energy sectors. This problem is caused by a combination of external factors (outdated technologies, lack of oil, coal, and gas reserves) and internal factors, such as Russia’s military aggression against Ukraine, and its manipulative policy towards other countries, which encourages the European community to look for other options to ensure energy security. This gave a new urgency to the issue of activating the development of alternative energy. The purpose of the study is to analyse international experience in the use of alternative (renewable) energy and formulate conceptual methods and approaches to solving global energy problems. A combination of general scientific methods was used, primarily dialectical, analytical, concrete-sociological, and from special legal methods – comparative legal. The results obtained indicate that the use of alternative energy sources in the European Union countries will continue to develop in the future. Based on data from Regulatory Indicators for Sustainable Energy, it is confirmed that Denmark, Germany, and the Republic of Poland are currently the leaders in the use of renewable energy sources in the EU countries. The study analyses the successful experience of these countries in the use of renewable energy sources. It is concluded that there is a dynamic in the development of alternative energy sources in European countries, but in order for alternative energy sources to fully compete with conventional energy sources, it is necessary to maintain and regulate incentives for increasing the use of renewable energy sources at the national level. The practical value of the study lies in the fact that its results can serve as recommendations for increasing the share of alternative energy sources in Ukraine

Environmental Impact Assessment of Autonomous Transportation Systems

The transportation industry has led efforts to fight climate change and reduce air pollution. Autonomous electric vehicles (A-EVs) that use artificial intelligence, next-generation batteries, etc., are predicted to replace conventional internal combustion engine vehicles (ICEVs) and electric vehicles (EVs) in the coming years. In this study, we performed a life cycle assessment to analyze A-EVs and compare their impacts with those from EV and ICEV systems. The scope of the analysis consists of the manufacturing and use phases, and a functional unit of 150,000 miles·passenger was chosen for the assessment. Our results on the impacts from the manufacturing phase of the analyzed systems show that the A-EV systems have higher impacts than other transportation systems in the majority of the impacts categories analyzed (e.g., global warming potential, ozone depletion, human toxicity-cancer) and, on average, EV systems were found to be the slightly more environmentally friendly than ICEV systems. The high impacts in A-EV are due to additional components such as cameras, sonar, and radar. In comparing the impacts from the use phase, we also analyzed the impact of automation and found that the use phase impacts of A-EVs outperform EV and ICEV in many aspects, including global warming potential, acidification, and smog formation. To interpret the results better, we also investigated the impacts of electricity grids on the use phase impact of alternative transportation options for three representative countries with different combinations of renewable and conventional primary energy resources such as hydroelectric, nuclear, and coal. The results revealed that A-EVs used in regions that have hydropower-based electric mix become the most environmentally friendly transportation option than others.

Food waste hydrochar: An alternate clean fuel for steel industry

The growing global demand for steel and its significant environmental and economic consequences highlight the need for sustainable, eco-friendly fuel alternatives. The energy-intensive steel production process generates substantial greenhouse gas emissions, aggravating climate change and environmental degradation. Utilizing food waste-derived fuels presents a promising alternative to traditional fossil fuels. Converting food waste into valuable energy resources not only tackles waste disposal issues but also reduces carbon emissions and the industry's reliance on finite energy sources, promoting circular economy principles and sustainable development. The current study aims to build knowledge of hydrochar potential from the food waste as a clean fuel for the steel industry replacing the conventional non-renewable energy resources. The benefits and limitations of utilizing hydrochar as a fuel, including reducing greenhouse gas emissions and promoting a circular economy is comprehensively presented. In addition, the study analyzes the equipment and technology requirements for producing and post-treating hydrochar and the potential applications in the steel industry. The key stakeholders and their contribution towards promoting the adoption and implementation of hydrochar as a fuel is proposed. The paper further discusses the challenges and limitations of such conversion technology, including the costs, the energy efficiency, the compatibility with the existing infrastructure, and the regulatory considerations. Finally, the study presents the recommendations for future research and development, investment opportunities, and action to promote the adoption and implementation of hydrochar as a clean fuel for the steel industry. Overall, this study conclusively provides insights into the potential of food waste hydrochar as a sustainable and cost-effective fuel and highlights the importance of collaboration and engagement of stakeholders in realizing this potential for the steel industry.

Modeling of Hybrid Renewable Energy System

Abstract: Wind power generation (VAWT) and solar power (PV) generation are combined to make a Modeling Of hybrid Renewable Energy Systems. A On Grid and 24v, 100Ah lead-acid battery is used to store solar power and charging is controlled by a charger circuit which has been discussed here. Power output of this hybrid system is depends on wind flow and power generated by solar cells. Today, the world is progressing at quit fast rate with the use of conventional source of energy. Now a day’s electricity is most needed facility for the human being. All the conventional energy resources are depleting day by day and having disadvantages of using them are environmental pollution created by its use. So we have to shift from conventional to non-conventional energy resources. Many types of clean and renewable energy sources can be used in production of electrical energy. In this project the combination of two energy resources is takes place i.e. wind and solar energy. This process reviles the sustainable energy resources without damaging the nature. We can give uninterrupted power by using hybrid energy system. Basically this system involves the integration of two energy system that will give continuous power. Solar panels are used for converting solar energy into electricity and wind turbines are used for converting wind energy into electricity. This electrical power can utilize for various purpose. Generation of electricity will be takes place at affordable cost. This project deals with the generation of electricity by using two sources combine which leads to generate electricity with affordable cost without damaging the nature balance.

About this title - Straits and Seaways: Controls, Processes and Implications in Modern and Ancient Systems

Straits and seaways are the key features that connect oceans, seas and lakes. They regulate water, sediment and biota exchanges, and influence local and global climate. A good understanding of the dynamic evolution of straits and seaways is therefore fundamental to accurately reconstruct the palaeogeography, tectonics, palaeoecology and stratigraphy of interconnected basins, the climate dynamics of Earth's past as well as to exploit both conventional and renewable energy resources. This volume provides a comprehensive collection of articles dealing with both ancient and modern case studies, bringing together different but complementary disciplines, such as marine geology, process sedimentology and stratigraphy. With the contents encompassing the evolution, geomorphology, stratigraphy, sedimentology, oceanography and palaeogeography of straits and seaways, and their influence on climate, the book will be of interest to Earth scientists working in many fields.

Bio-Electrochemical Fuel CELL: A Review Study on Electricity Generation Using Bio-Waste

This era is all about energy, humans cannot survive without energy. Conventional energy resources are not enough to fulfill the needs of energy that’s why it is necessary to find alternate energy resources that will be efficient and environment friendly. Microbial Fuel Cell (MFC) is one of the reasonably low costs and is considered as environment friendly It degrades the harmful substance during production of electricity.This technology helps out for the producing of electricity by using the microbes. The generation of electricity is the new form of non-renewable energy by treating of the waste water from different types of effluent. The purpose of this technology is to produce the electricity that is environment friendly and sustainable. This review is also the part of research which is also to make a comparison of different MFC feeds which have unique chemical composition and are rich of various biological species and designing. This report also contains the discussion of MFC principle, necessary components, bacteria that are responsible for electricity production. This MFC contain the different batch type of reactor and in each reactor anode and cathode are dipped for time to check the response of flow of electron. Electrodes are used for drawing the comparison data of the MFC and giving new direction for the researchers. Salt bridge or membrane is connected between the reactor for the flow of proton to the cathode side and oxygen is supplied in the cathode compartment.

Energy Hub Planning and Operation Optimization by Applying Demand Side Management Using GAMS

Energy hub planning and optimization considering various constraints is an emerging domain of research due to the scarcity of conventional energy resources. Strategic integration of multi-energy sources is a dominant region of research as it provides better efficiency and cost savings. Various uncertainties due to the changing electric, heating, and cooling load demand are increasing the complexity of the system. The paper investigates the effectiveness of Demand Side Management (DSM) programs by analyzing the operation of domestic Energy Hub. The paper proposes two stages for optimal energy hub planning and operation optimization and GAMS mathematical modeling is used to deduce the results. The paper provides the analysis of a two-stage optimization model using the approach of modeling uncertainties and constraints. The process of energy hub designing has been carried out by the help of PSO algorithm by considering continuous capacities of various components of energy hub. The research regarding optimal energy hub operation is modelled in GAMS and the approach of mixed-integer non-linear programming (MINLP) has been used to evaluate the results. The framework provides the energy hub model and also provided the verification of model effectiveness and efficiency.

Unlocking the potential of solar electric vehicles for post-COVID recovery and growth in the transport sector in Ghana

The increasing effect of climate change as a result of CO2 emissions emanating from utilization of conventional energy resources is driving national and regional policies towards global energy transformation in all sectors, including the transportation sub-sector. Internal combustion engine vehicles (ICEV), which use fossil fuel are the main contributors of CO2 emissions in the transport sub-sector. Grid-powered battery electric vehicles (BEV) and solar electric vehicles (SEV) have the potential to reduce emissions in the transportation sub-sector and are therefore being promoted in regions where solar radiation levels are appreciable. Sub-Saharan Africa (SSA) is one of the regions that receives significant radiation levels compared to other parts of the world, however, countries in the sub-region are yet to tap into the enormous benefits of SEV. In this study, comparative lifecycle analysis has been conducted on the total cost of ownership (TCO) of Hyundai Ioniq (BEV), Sono Sion (SEV) and Toyota Corolla (ICEV) for commercial transport operations in SSA, with a case study in Ghana. Research was conducted on 100 drivers of 5-seater petrol/diesel light commercial vehicles (LCV) in the city of Accra and Kumasi. Data were taken on their driving profiles, average travel distance, fuel cost and maintenance cost. Their choices between ICEV, BEV and SEV were also ascertained. Our study revealed that 70% of LCV travel up to 300 km and below, daily. The total cost of ownership for LCV at an average annual travel distance of 60,000 km were 0.21 US$/km, 0.17 US$/km, 0.15 US$/km and 0.14 US$/km for Used-ICEV, New-ICEV, BEV and SEV for 20-year analysis period, respectively. The total cost savings with BEV and SEV usage are at least 28% and 34%, respectively, compared to traditional diesel or gasoline ICEVs. Payback periods for SEV and BEV compared to ICEV are 3.5 years and 4.5 years, respectively. Our study has revealed that there is potential emission savings of 70% and 75% for BEV and SEV, respectively, compared to ICEV. Finally, this study highlights that utilization of SEVs and BEVs for light vehicle commercial transportation in SSA can potentially lead to post-COVID recovery and growth in the sub-region, amidst increasing diesel and petrol prices for ICEVs.

Wide area monitoring system operations in modern power grids: A median regression function-based state estimation approach towards cyber attacks

Modern power grid is a generation mix of conventional generation facilities and variable renewable energy resources (VRES). The complexity of such a power grid with generation mix has routed the utilization of infrastructures involving phasor measurement units (PMUs). This is to have access to real-time grid information. However, the traffic of digital information and communication is potentially vulnerable to data-injection and cyber attacks. To address this issue, a median regression function (MRF)-based state estimation is presented in this paper. The algorithm was stationed at each monitoring node using interacting multiple model (IMM)-based fusion architecture. An exogenous variable-driven representation of the state is considered for the system. A mapping function-based initial regression analysis is made to depict the margins of state estimate in the presence of data-injection. A median regression function is built on top of it while generating and evaluating the residuals. The tests were conducted on a revisited New England 39-Bus system with large scale photovoltaic (PV) power plant. The system was affected with multiple system disturbances and severe data-injection attacks. The results show the effectiveness of the proposed MRF method against the mainstream and regression methods. The proposed scheme can accurately estimate the states and evaluate the contaminated measurements while improving the situation awareness of wide area monitoring systems (WAMS) operations in modern power grids

SOGI-FLL-WDCRC Filter for Seamless Control of Microgrid for Optimal Coordination of Conventional and Renewable Energy Resources

An efficient control strategy is presented in this paper to obtain seamless synchronization and improved power quality (PQ) for an AC microgrid feeding highly distorted and unpredictable loads. This paper proposes an improved second-order generalized integrator-frequency locked loop with DC-offset rejection capacity (SOGI-FLL-WDCRC) filter in an AC microgrid to mitigate the grid pollution and the PQ issues caused by the nonlinear loads. The SOGI-FLL-WDCRC filter accurately estimates the positive sequence components (PSCs), phase angle and frequency from the abnormal grid voltages. Thereby, high-quality grid currents and seamless synchronization are realized even at abnormal grid voltages. Moreover, it accurately extracts the fundamental active weight component of the nonlinear load currents, even during dynamic conditions. This results in the generation of accurate reference source currents, thus allowing efficient functioning of the voltage source converter (VSC) and delivering high-quality power to the system by mitigating the load's harmonics, reactive power and unbalanced components. The proposed control is designed in MATLAB/Simulink platform and its performance is studied. A 3.2kW solar PV array integrated to a 220V (line), 50Hz three-phase utility grid/DEG set is designed and developed as a laboratory prototype to validate the simulated responses. Furthermore, the effectiveness of the proposed control is verified and compared with conventional controls using dSPACE-1202 MicroLabBox on a laboratory test bed. The results obtained from the simulation software and laboratory test bed confirm the effectiveness of the proposed control in estimating the accurate PSCs of grid voltages and oscillations free weight components with higher convergence and better stability under abnormal grid and load conditions.

Optimal designing of PV-diesel generator-based system using HOMER software

Coal, petroleum, natural gas, and other fossil fuels are examples of conventional energy resources. They are not supplied at the pace at which they are spent, which implies that once used, they are not regenerated again, and generation takes millions of years. Because of rising load and demand, it has become necessary to transition from conventional to renewable energy supplies. Development of sustainable electricity systems is also a critical prerequisite for the country's financial prosperity. This article investigates the feasibility of PV and diesel generator-based system that is appropriate for the Akhnoor town in Jammu district of Jammu and Kashmir in India using HOMER Software.According to the optimization results the ideal solution is to use components having NPC of $16,157. PV arrays used are of 1.98 kW and 1.40 kW generator is required for the proposed system. The proposed system has the levelized COE of $0.4280 and an OC of $493.72. Out of 880 solutions simulated, 680 were feasible. The proposed system consists of Silicon Nanoparticles Enhance Solar Cells due to its high efficiency.

Regret-based multi-objective optimization of carbon capture facility in CHP-based microgrid with carbon dioxide cycling

Nowadays it is estimated that the Earth's temperature is above the standard level compared to pre-industrial time. The main reason for this issue is the burning of conventional energy resources namely oil, gas, and coal which speeds up global warming. In this concern, a CHP-based multi-energy microgrid is studied in this paper which involves heating, cooling, and electricity carriers to supply the energy demands. The proposed system is a multi-objective problem with operation cost management and emission cost reduction. In order to develop the environmental and economic aspects, a power-to-gas (P2G) technology as an environmentally friendly system is taken into account to curb CO2 emissions and achieve a sustainable function. The presence of the P2G system can minimize the emission level and improve the ability to take advantage of Notwithstanding this, the uncertain parameters originate from the thermal, electrical, and cooling loads, electricity price, and the renewable generations impose inflexibility and financial threats to the system function. In this regard, a scenario-based risk assessment approach, p-robust optimization, is applied to handle these uncertainties. The uncertainty analysis is carried out in With-p-robust, No-p-robust, With-P2G, and No–P2G models to appraise the components' performance. Results showed 11% of the operation cost increment to achieve a zero-level risk. Also, 55% of the emission cost is minimized in the presence of the P2G facility, which enhances the efficiency of the system.

Energy in the European Green Deal: impacts and recommendations for MENA countries

Abstract The European Union (EU) presented its new and ambitious programme at the end of 2019—the European Green Deal (EGD), which should align its economy to reach the goal of climate neutrality in 2050. A vital part of the deal aims for the energy sector within the leitmotif of supplying clean, affordable and secure energy. Because energy-related Greenhouse Gas (GHG) emissions accounted in 2020 for three-quarters of all GHG emissions of the EU, the most important pillar for the EGD to succeed is the energy sector. The deal does not function within a vacuum as it will impact other countries, including those with vast conventional energy resources and close ties to the EU, like nations from the region of the Middle East and North Africa (MENA). This article assesses the deal’s impacts on MENA countries and includes recommendations concerning various aspects of low-carbon transition that could be applied. The EGD programme will be used as a reference scenario for those recommendations because of its universal character.

SCADA System for Online Electrical Engineering Education

Renewable energy sources are increasingly being integrated into small-scale production systems, so plants with multiple supply sources are becoming more common. This improvement in technology added to a greater social awareness of energy saving and resource usage, which makes flexible systems to manage these facilities necessary. Modern energy management can be more accessible to the interested public if it is located in universities, making it available to teachers and students alike. Furthermore, as it is a developing field of study, its location on campus facilitates research, maintenance, and financing. In this scenario, a SCADA system is proposed, capable of monitoring and centrally storing the values of the most important production and consumption parameters. In addition, by using this system, it is possible to control the state of the different energy sources in a centralized way, as well as their distribution in the plant where it is implemented. This study focuses on the management of a flexible, modern, and accessible solution to the advances in electrical systems because of technological development in this field, which broadens the experience of university teachers and students in their engineering careers. The systems have been put into practice in the facilities of a research and teaching laboratory at the University of Almeria, which integrates renewable and conventional energy resources.

Recent advances in biogas purifying technologies: Process design and economic considerations

Biogas is a promising renewable energy source that is produced from biowaste and can potentially replace conventional energy resources. The economic value of biogas, which is primarily comprised of CH4, CO2, and other impurities (e.g. H2S, and N2) can be increased by upgrading and purification. This study presents the techno-economic feasibility of the cryogenic biogas upgrading process (CBioUP) based on product purities, biomethane selling prices and different refrigeration systems over 25 years of lifetime. The proposed CBioUPs is comprised of compression, refrigeration, and separation sections. Compressed biogas was liquefied in two refrigeration systems (propane pre-cooled mixed refrigerants and optimized cascade technologies) followed by a distillation separation unit. CBioUP proved its flexibility in terms of the number of distillation columns to produce low-grade CH4 (≈94.58 mol%), high-grade CH4 (≈97.13 mol%), and liquid CO2 by-product. The process's robustness to varying biogas feed composition revealed higher CO2 content would necessitate additional duty and/or equipment to enhance separation efficiency, whereas a CH4 content of ≥70% generated biomethane with a purity >99.6 mol% even in a single distillation column. CBioUP demonstrated its suitability for producing different grades of CH4 with a promising net present value (NPV) of $28.3 and $30.9 billion for low/high-grade biomethane.

Techno-Economic Analysis of Renewable-Energy-Based Micro-Grids Considering Incentive Policies

Renewable-energy-based microgrids (MGs) are being advocated around the world in response to increasing energy demand, high levels of greenhouse gas (GHG) emissions, energy losses, and the depletion of conventional energy resources. However, the high investment cost of the MGs besides the low selling price of the energy to the main grid are two main challenges to realize the MGs in developing countries such as Iran. For this reason, the government should define some incentive policies to attract investor attention to MGs. This paper aims to develop a framework for the optimal planning of a renewable energy-based MG considering the incentive policies. To investigate the effect of the incentive policies on the planning formulation, three different policies are introduced in a pilot system in Iran. The minimum penetration rates of the RESs in the MG to receive the government incentive are defined as 20% and 40% in two different scenarios. The results show that the proposed incentive policies reduce the MG’s total net present cost (NPC) and the amount of carbon dioxide (CO2) emissions. The maximum NPC and CO2 reduction in comparison with the base case (with incentive policies) are 22.87% and 56.13%, respectively. The simulations are conducted using the hybrid optimization model for electric renewables (HOMER) software.

The Impact of Agroecological Practices on the Biodiversity of Arthropod Fauna in Târnave Vineyard


 In viticultural ecosystems, considered energy-intensive systems, the amplification of biocoenotic imbalances with the onset of pest explosions, is a problem and also an evidence of the biodiversity’s decline. In this study the biodiversity was quantified in Târnave vineyard, in the period 2016-2018, in the experimental plots of SCDVV Blaj cultivated with the Fetească regală cultivar, for two cultivation technologies, the extensive agroecological (EA) and the intensive conventional (IC). The determined biodiversity characterization indicators were: the species richness, Simpson biodiversity index (D), Shanon biodiversity index (H) and Equity index (E). In case of the Heteroptera group EA technology doubled the number of the arthropods (11.333 ± 0.882 for EA versus 5.33 ± 1.453 for IC). The reverse effect was observed for Coleoptera were in the case of EA it was found a taxa richness of 8.667 ± 0.882 and for IC one of 15.667 ± 1.764. Considering the increase of the number of useful species from the order Heteroptera in the agroecological variant compared to the conventional variant, we consider that the implementation of the agroecological technology for a longer period (5-10 years) can be a long-term solution that will contribute to reducing the risk induced by the intensive practices, while reducing the dependence of culture on conventional energy resources.

The primary and secondary mineral resources of Montenegro and their mapping into the European data model

Primary and secondary mineral resources are of strategic importance to the EU economy. Montenegro, as a country candidate for membership in the EU, is required to follow (and later to implement) European policies, strategies as well as initiatives, including those related to mineral resources and the mining sector. The importance of providing access to mineral raw materials in the future is recognized by the EU, as well as meeting the needs of European industry, maintaining employment and ensuring further development. Considering the overall economic situation in Montenegro, it is important to encourge the mining sector and other industries based on the use of mineral resources in making a greater contribution to the development and sustainability of society as a whole and also increase the share of national GDP. The potential for discovery and utilization of primary and secondary mineral resources in Montenegro is demonstrated. The most important metallic mineral resources are bauxite, lead and zinc, while conventional energy resources include coal (oil and gas potential has yet to be proven). In addition, there are abundant non-metallic mineral raw materials - industrial minerals and construction materials. Secondary mineral resources, especially aluminous red mud (bauxite residue), are also significant and have been the subject of research in recent years. Tailings from flotation processes at operating and abandoned lead and zinc mines might also be of interest for metal recovery. Bottom and flay ash from thermal power plants, slag from steel production, as well as marlstone and limestone from the hanging wall of coal deposits may also have potential. Waste rocks could be used particularly for secondary aggregate production. A database was developed and the most important deposits of primary and secondary mineral resources in Montenegro were mapped during the RESEERVE project. Mineral data were harmonised so as to be INSPIRE compliant. In addition, some novel geochemical exploration results of secondary mineral resources are presented.

Recent developments of proton exchange membranes for PEMFC: A review

The decreasing abundance of conventional energy resources of nature, such as crude oil, natural gas, and coal, is putting forward the issues of energy shortcoming for the future. With a sentiment of this, most researchers are now directing either on non-conventional resources that already prevail or invent it. The most promising non-conventional energy resource is the hydrogen energy, which can be used in fuel cell to get electricity. Therefore, a number of researchers are putting a light on developing the most efficient and affordable fuel cell. This review is mainly focused on the developments of proton exchange membranes (PEMs) in two parts as low and high temperature PEMs for proton exchange membrane fuel cell (PEMFC) and based on that some outperformed PEMs are mentioned in the respective tables. Most of the energy and automobile industries are concentrating to apply PEMFCs for power generation and to apply in vehicles. The cost of PEMFCs is higher due to the manufacturing cost of PEM. Therefore, research works in PEMs are now in trend to reduce the cost, to improve efficiency, and to withstand particular operating conditions. In this review article, recent developments in PEM by number of researchers and the importance of it in near future have been elicited.