Renewable Energy Sources System Research Articles

Capacity optimization allocation method for off-grid RES-H2 microgrid system considering the load-follow-source mechanism

Based on the uncertainty of the output of renewable energy such as wind and photovoltaic (PV), a capacity optimization allocation method considering the load-follow-source mechanism is proposed to solve the shortages of traditional methods, which is low in utilization rate of energy and low in economy. Firstly, considering the fluctuations of renewable energy sources (RES) and the operating characteristics of the electrolyzer, this paper proposes a capacity optimization method for off-grid hydrogen(H2) production system of renewable energy sources considering the load-follow-source operation mechanism. Then, combined with this mechanism, a capacity optimization allocation model is established, the objectives contain minimizing the levelized cost of hydrogen (LCOH), minimizing the capacity of energy storage, and optimizing the efficiency of power supply. Finally, an adaptive non-dominated sorting differential evolution algorithm (ANSDE) with external archiving is proposed to solve the established model. The calculation results show that the load-follow-source mechanism is effective for improving the economy of the system, and the proposed algorithm is high in efficiency and good in convergence comparing with traditional algorithms.

An Effective Control Approach of Hybrid Energy Storage System Based on FLC/Grey Wolf Optimisation

In the modern era, the integration of renewable energy sources (RES) has bolstered the autonomy of urban energy infrastructures, reducing reliance on distant sources and grids. Batteries serve as a vital bridge between power supply and fluctuating load demands within RES systems. However, the unpredictable nature of RES behavior and varying load requirements often subject batteries to repeated deep cycles and irregular charging patterns. These cycles diminish the battery’s lifespan and escalate replacement costs. This study presents an innovative control strategy for a Solar-Wind model featuring a Battery-Supercapacitor Hybrid Energy Storage System. The objective is to prolong the battery’s operational lifespan by mitigating intermittent strain and high current demands. In contrast to conventional methods, the proposed control approach incorporates a Low-Pass Filter (LPF) and a Fuzzy Logic Controller (FLC). Firstly, the LPF minimizes the oscillations in battery consumption. Simultaneously, the FLC optimizes the high current demand on the battery while vigilantly monitoring the supercapacitor’s charge levels. Moreover, Grey Wolf Optimization (GWO) is employed to fine-tune the FLC’s membership functions, ensuring optimal peak current attenuation in batteries. The effectiveness of the proposed model is benchmarked against standard control techniques, namely Rule- Based Controller and Filtration-Based Controller. Comparative analysis reveals that the proposed method substantially reduces peak current and high power requirements of the battery. Consequently, this enhances the utilization of the supercapacitor, significantly augmenting the battery’s operational life. The results demonstrate a remarkable improvement over conventional systems, emphasizing the potential of this approach in optimizing energy storage systems for sustainable, long-term performance.

The effect of photovoltaic system operating parameters on exergy efficiency

Solar energy is a unique source of renewable energy due to its availability and the unlimited quantity. It has long attracted the attention of scientists who are conducting theoretical and experimental research into its use. Solar energy plays an increasingly important role in the context of energy conservation. With the rising cost of conventional energy sources and limited access to natural resources, interest in the use of renewable energy sources is increasing. In this context, environmental protection is another factor favoring the development of technologies based on renewable energy sources. With economic development, the significance of new environmentally friendly technologies is increasing. One of the most popular ways for the average household to utilize renewable energy sources is by installing photovoltaic panels. Such an installation allows the use of solar energy to generate electricity, which contributes to reducing energy costs and protecting the environment. The article presents the results of an analysis of the exergy efficiency of prosumer photovoltaic systems found in the area of northern Poland. The analysis presented was based on actual operating parameters over a certain time interval. A key aspect is the analysis of exergy, which is not distributed in renewable energy sources (RES) systems.

Improved scheme based on memory voltage for transformer differential protection considering the effects of PLL

AbstractThe phase‐locked loop (PLL) is a critical control module applied in the control system of renewable energy sources (RESs) to synchronize with the grid voltage. When a fault occurs, the dynamic response process of the PLL will generate a phase locking error, resulting in a mass of harmonic components in the fault current of the PV inverter, which further poses challenges to transformer differential protection. To address the challenges posed by the phase locking error in practical engineering applications, this paper proposes an improved scheme that uses a digital computer algorithm to record and store the pre‐fault voltage and introduces the limiting coefficient. Firstly, the memory voltage is used to eliminate the phase locking error of the PLL, thereby mitigating harmonic distortion in the fault current of the RESs and ensuring the reliability of the transformer differential protection. In addition, the limiting coefficient is introduced to eliminate the effect of the increased amplitude of the fault current caused by the memory voltage. The voltage reference value of the inverter is multiplied by an appropriate limiting coefficient k and then output to the physical system. Finally, the effectiveness of the proposed scheme is verified by MATLAB/Simulink simulation.

Study of Renewable Potential of the Republic of Armenia for Implementation of Hybrid Autonomous Power Supply System Using Solar Photovoltaic Modules

Introduction. Solar energy is one of the leading renewable energy industries. Solar photovoltaic modules are most widely used to create hybrid autonomous electrification systems, since photovoltaics are not limited to specific limitations and can be applied almost everywhere.Aim. To determine the potential of meteorological and geographical features of the Republic of Armenia for the implementation of autonomous hybrid renewable energy sources systems (AHRESS) using solar photovoltaics (PV). To simulate operating conditions for various AHRESS configurations providing electric power to a cellular communication base station.Materials and methods. Climatic, geographical, social and economic features of the region of the Republic of Armenia are investigated. Regions are evaluated based on the key factors of AHRESS implementation potential and compared with studies performed by the Effergy-Irsolav. The simulations and technical and economic analysis were performed using the HOMER Pro software in Ttsovinar region.Results. The most efficient configuration is found to be B1, with an energy cost of 0.322 $/kW·h. The parameters of winning system: PV array with capacity of 4.5 kW, 12V battery with 100 A·h capacity, diesel generator with 3 kW capacity. The main efficiency criterion is the low economic costs for the implementation and operation of this AHRESS configuration. Ten additional variants of AHRESS were modeled in order to optimize the component base of the configuration.Conclusion. It was found that, depending on the consumer load, solar photovoltaic converters are limited and can only perform as supporting source of electricity. The use of the existing consumption load profile in the form of BSSS made it possible to cover the widest possible range of configurations of the component base, which indicates the high accuracy of the simulated results and, as a result, the technical and economic relevance of the study.

An approach to disparage the blindness of backup protection in grid connected renewable energy sources system by inducing artificial fault current

The renewable energy sources based distributed generation is increasingly penetrating into conventional distribution network . Aside from the technical and economical benefits, distributed generation may incapacitate the sensitivity of backup protection devices , which may face partial blindness in grid-connected, even full blindness in islanded mode of operation and during high impedance faults. This paper proposes a novel stratagem to completely plummet the blindness of backup relay by inducing the artificial fault current. A blindness severity index is developed to induce artificial fault current in a controlled manner according to blindness severity. Two methods are proposed. First, the OCR vulnerable to blindness is provided with an auxiliary current transformer, whose output is tuned in conjunction with blindness severity index and merged with main current transformer’s output to modulate its secondary current responsible for sensitivity. Second, the microprocessor based relay is used and the time current characteristics is modified by augmenting a new variable named as artificial fault current factor to scale the fault current. As, the current is increased by the TCC modification and no external equipment is added here, so named as AFC. To assure that the AFC is induced only in fault event and to prevent mal-functioning of OCR during normal operation, a simple logic is designed using AND gates to fend off trip signal to circuit breaker. The proposed protection scheme is evaluated on typical distribution feeder in Tianjin, China and IEEE-34 standard test benchmark and results show that the blindness of backup PDs is dwindled in a proficient manner.

EFFICIENCY OF USING RENEWABLE ENERGY SOURCES FOR AN AUTONOMOUS HEAT SUPPLY SYSTEM

Projects for the integrated use of renewable energy sources were considered. The efficiency of using renewable energy sources in autonomous heat supply systems with minimal use of third-party energy sources and reducing the specific cost of hourly heat supply was assessed. A new software and information complex for modeling autonomous heat supply systems with minimal use of third-party energy sources was developed. With the help of the developed software and information complex, the optimized operating modes of the autonomous heat supply system were modeled and numerical estimates of the efficiency of using renewable energy sources in the system were obtained.

Energy management based on a fuzzy controller of a photovoltaic/fuel cell/Li-ion battery/supercapacitor for unpredictable, fluctuating, high-dynamic three-phase AC load

Introduction. Nowadays, environmental pollution becomes an urgent issue that undoubtedly influences the health of humans and other creatures living in the world. The growth of hydrogen energy increased 97.3 % and was forecast to remain the world’s largest source of green energy. It can be seen that hydrogen is one of the essential elements in the energy structure as well as has great potential to be widely used in the 21st century. Purpose. This paper aims to propose an energy management strategy based a fuzzy logic control, which includes a hybrid renewable energy sources system dedicated to the power supply of a three-phase AC variable load (unpredictable high dynamic). Photovoltaic (PV), fuel cell (FC), Li-ion battery, and supercapacitor (SC) are the four sources that make up the renewable hybrid power system; all these sources are coupled in the DC-link bus. Unlike usual the SC was connected to the DC-link bus directly in this research work in order to ensure the dominant advantage which is a speedy response during load fast change and loads transient. Novelty. The power sources (PV/FC/Battery/SC) are coordinated based on their dynamics in order to keep the DC voltage around its reference. Among the main goals achieved by the fuzzy control strategy in this work are to reduce hydrogen consumption and increase battery lifetime. Methods. This is done by controlling the FC current and by state of charge (SOC) of the battery and SC. To verify the fuzzy control strategy, the simulation was carried out with the same system and compared with the management flowchart strategy. The results obtained confirmed that the hydrogen consumption decreased to 26.5 g and the SOC for the battery was around 62.2-65 and this proves the desired goal.

Innovative hybridization of the two-archive and PROMETHEE-II triple-objective and multi-criterion decision making for optimum configuration of the hybrid renewable energy system

Photovoltaic (PV) and Wind turbine (WT) systems are the most promising options for rural energy delivery. In the literature, numerous studies have simply considered only on economic efficiency, while maximizing dependability by a constant value for the given demand load. Moreover, a single set Pareto optimal front (PF) has been attained for the multi-objective optimization problem. Furthermore, the primary challenge of various the off-grid multiple renewable energy sources is excessive energy loss, resulting over/under sizing and a highly total cost for the system. Therefore, this paper presents a unique improved bi-archive approach to develop the diversity and convergence independently in order to find four optimum sets of PF solutions. In addition, a new integration based on best worst method (BWM) and preference ranking organization for enrichment evaluations (PROMETHEE II) method along with group decision making (GDM) mechanism are addressed to sort and rank the optimal sets PF solutions with full consistency ratios of the three experts opinions and high degree of stability in ranking configurations. The theoretical results based on actual hourly meteorological data in Malaysia and South Africa indicated that the suggested improved two-archive-BWM- PROMETHEE II-GDM method is not only able to construct a uniform set of Pareto optimal solutions with fast convergence and high diversity, but can also rank and select the most desired design for the PV/WT/Battery system. The optimum configurations of the two cases studies are composed of a single WT, 105 PV modules, and 69 batteries storages at zero LLP, 60185 ($) of LLC, and 13548018 (KWh) of Pdump for Malaysia case study, meanwhile it composes of 16 WTs, 80 PV modules, and 69 batteries storage at zero of LLP, 66073 ($) of LCC, and 31371 (KWh) of Pdump. The proposed standalone hybrid renewable energy sources system is verified and assessed in a comparison with existing hybrid methods in terms of increasing the reliability, lowering overall cost, and reducing wasted energy.

Technical-Economic Evaluation of Residential Wind and Photovoltaic Systems with Self-Consumption and Storage Systems in Portugal

At present, a worldwide paradigm shift has become apparent, with more and more consumers consuming the energy generated by renewable energy sources (RES) systems, such as wind or photovoltaic (PV) energy, sometimes benefiting from appropriate incentives by individual governments. Consequently, it is necessary to carry out technical–economic assessments to understand the evolution of the viability of RES investments. Within the framework of an intelligent network control environment, the smart grid (SG) concept is associated with this model, and is an important tool in the management of energy distribution networks. This article aims to make a further contribution to this issue by analyzing the economic feasibility of investing in residential consumers, considering different RES configurations. Scenarios covered in this study include: “inject all on the low voltage network/consume all on the low voltage network”, self-consumption, net-metering, and storage systems. The economic study results in this article show that self-consumption with and without the injection of excess electricity into the grid is quite attractive. The bi-hourly tariff was found to be more profitable than other tariffs. Variable tariffs (bi or tri-hourly) are more profitable than fixed tariffs. It is also concluded that investment in storage systems is not yet an economically viable solution due to the high price of energy storage.

Ideal parameter distribution in renewable integrated rapid charging electric vehicle station

ABSTRACT In this paper, we provide extensive modeling of fast-charging electric vehicle stations (FCEVS) allied to a grid integrated renewable energy sources (RES like hydro and solar) system considering an electric vehicle (EV) demand characteristics, state of charge (SOC), battery ratings, arrival, and departure time. This aids in maximizing the revenue and lowering the grid energy utilization. Investigations are carried with a novel meta-heuristic technique known as the emperor penguin optimization (EPO) algorithm, which is utilized to optimize the FCEVS parameters and maximize net present value (NPV). The investigations wih EPO has shown significant improvent of 1% with particle swarm optimization (PSO) and 1.25% with crow search algorithm (CSA). Also, studies are carried using a probabilistic demand distribution based on EV behaviors considering a sequential Monte-Carlo approach with hourly intervals. The acquired economic deliberations with EPO algorithm are compared with PSO, CSA, and EPO extracts maximum revenue. Simulations with FCEVS fed by grid, RES, and hybrid grid-RES reveal that FCEVS fed by hybrid grid-RES extracts the highest NPV. Further, 78.09% increase in NPV is observed with RES feeds the Grid over Grid feeds FCEVS alone, 25.23% hike of NPV is observed with both RES and battery storage system (BSS) over RES system, 10.56% increase with considering EVs arrival time and 2.3% increase with considering flow of EVs. Further, simulations with detailed modeling of FCEVS enhance NPV values over the hybrid grid-RES system.

Modified FOPID Controller for Frequency Regulation of a Hybrid Interconnected System of Conventional and Renewable Energy Sources

In this article, a fractional-order proportional-integral-differential (FOPID) controller and its modified structure, called a MFOPID controller, are presented. To guarantee optimal system performance, the gains of the proposed FOPID and MFOPID controllers are well-tuned, employing the Jellyfish Search Optimizer (JSO), a novel and highly effective bioinspired metaheuristic approach. The proposed controllers are assessed in a hybrid system with two domains, where each domain contains a hybrid of conventional (gas, reheat, and hydro) and renewable generation sources (solar and wind). For a more realistic analysis, the presented system model includes practical limitations with nonlinear characteristics, such as governor dead zone/band (GDZ/GDB), boiler dynamics, generation rate limitation/constraint (GRL/GRC), system uncertainties, communication time delay (CTD), and load changes. The suggested methodology outperforms some newly developed heuristic techniques, including fitness-dependent optimizer (FDO), sine-cosine algorithm (SCA), and firefly algorithm (FA), for the interconnected power system (PS) of two regions with multiple generating units. Furthermore, the proposed MFOPID controller is compared with JSO-tuned PID/FOPID and PI controllers to ascertain its superiority. The results signify that the presented control method and its parametric optimization significantly outperforms the other control strategies with respect to minimum undershoot and peak overshoot, settling times, and ITSE in the system’s dynamic response. The sensitivity analysis outcomes imply that the proposed JSO-MFOPID control method is very reliable and can effectively stabilize the load frequency and interconnection line in a multi-area network with interconnected PS.

Taxonomy of Chinas’s “Green” Economy

The article is devoted to the study of the peculiarities of the development of the energy system of modern China. The analysis of the main directions of the formation of the system of renewable energy sources in the country is carried out, the current regulatory and legal acts regulating the direction of development in the field of energy are considered. In the PRC, under the current conditions, preference is given to economic growth and ensuring energy security due to a moderate increase in generating capacity from fossil sources using modern available technologies to minimize damage from their use, while simultaneously increasing renewable energy sources (RES). One of the main reasons for increasing renewable energy in China is strategic in nature: by increasing the share of renewable sources in its energy balance for electricity consumption, China can reduce geopolitical tensions, making the country less dependent on unstable regions in terms of energy security. The energy market, dependent on fossil fuels, depends on ensuring the safety of oil and gas transportation routes, but one of the main reasons why the Chinese government is promoting renewable energy is to reduce air pollution. The NPC Environmental Protection Committee has repeatedly noted that the production and consumption of fossil fuel energy is responsible for 90% of sulfur dioxide emissions in the country and that for this reason, 7 of the 10 most polluted cities in the world are located in China. The country is working on the reconstruction and modernization of production facilities in order to reduce energy consumption and carbon emissions, technologies for carbon capture, use and storage are being developed. Currently, the country is implementing a very important transition from control over the total volume of energy consumption and the energy intensity of GDP to a new “double control” — control over the total amount of carbon emissions and the intensity of emissions.

An investigation of optimal power system designs for a net zero energy house: A case study of Kahramanmaras

This paper aims to optimize the power system design of a vineyard house in Pazarcık, Kahramanmaras. In this process, the electrical energy demand is met by the hybrid Photovoltaic-Wind-Diesel-Battery system because the vineyard house is remote from the electric network. The vineyard house is located in Karagol, southern of Pazarcık. During the summer in Karagol, many people stay in and visit the vineyard houses. However, the vineyard houses are generally unoccupied in winter. Therefore, an economical energy source is required in this process without compromising life quality. Capital costs are high and the running costs are low for stand-alone renewable sources. On the other hand, it is the opposite for stand-alone diesel power generators. This study is designed to take these circumstances into consideration. The optimal design is investigated for a hybrid system of renewable energy sources and a diesel power generator. The Homer software is used during this process. The realized design is evaluated in terms of its technical and environmental aspects. As a result of the study, 6 kW photovoltaic panels, a 1 kW wind turbine, a 1 kW diesel generator, a 2 kW converter, and an optimally sized 8-unit battery system are used to meet the electricity needs of the vineyard house. The renewable energy factor is 99.8% for a vineyard house. This value is an acceptable rate for a net zero energy house. This study shows that the hybrid system meets the house's electric energy demands and has a positive impact on the environment by reducing greenhouse gas emissions.

Optimal Design of Electric Vehicle Fast-Charging Station’s Structure Using Metaheuristic Algorithms

The fast development of electric vehicles (EVs) has resulted in several topics of research in this area, such as the development of a charging pricing strategy, charging control, location of the charging station, and the structure within the charging station. This paper proposes the optimal design of the structure of an EV fast-charging station (EVFCS) connected with a renewable energy source and battery energy storage systems (BESS) by using metaheuristic algorithms. The optimal design of this structure aims to find the number and power of chargers. Moreover, the renewable energy source and BESS can reduce the impact on the grid, so these energy sources are considered as ones of the optimally-designed structure of EVFCS in this work. Thus, it is necessary to determine the optimal sizing of the renewable energy source, BESS, and the grid power connected to EVFCS. This optimal structure can improve the profitability of the station. To solve the optimization problem, three metaheuristic algorithms, including particle swarm optimization (PSO), Salp swarm algorithm (SSA), and arithmetic optimization algorithm (AOA), are adopted. These algorithms aim to find the optimal structure which maximizes the profit of the EVFCS determined by its net present value (NPV), and the results obtained from these algorithms were compared. The results demonstrate that all considered algorithms could find the feasible solutions of the optimal design of the EVFCS structure where PSO provided the best NPV, followed by AOA and SSA.

Design, Technical and Economic Optimization of Renewable Energy-Based Electric Vehicle Charging Stations in Africa: The Case of Nigeria

The transportation sector accounts for more than 70% of Nigeria’s energy consumption. This sector has been the major consumer of fossil fuels in the past 20 years. In this study, the technical and economic feasibility of an electrical vehicle (EV) charging scheme is investigated based on the availability of renewable energy (RE) sources in six sites representing diverse geographic and climatic conditions in Nigeria. The HOMER Pro® microgrid software with the grid-search and proprietary derivative-free optimization techniques is used to assess the viability of the proposed EV charging scheme. The PV/WT/battery charging station with a quantity of two WT, 174 kW of PV panels, a quantity of 380 batteries storage, and a converter of 109 kW located in Sokoto provide the best economic metrics with the lowest NPC, electricity cost, and initial costs of USD547,717, USD0.211/kWh, and USD449,134, respectively. The optimal charging scheme is able to reliably satisfy most of the EV charging demand as it presents a small percentage of the unmet load, which is the lowest when compared with the corresponding values of the other charging stations. Moreover, the optimal charging system in all six locations is able to sufficiently meet the EV charge requirement with maximum uptime. A sensitivity analysis was conducted to check the robustness of the optimum charging scheme. This sensitivity analysis reveals that the technical and economic performance indicators of the optimum charging station are sensitive to the changes in the sensitivity variables. Furthermore, the outcomes ensure that the hybrid system of RE sources and EVs can minimize carbon and other pollutant emissions. The results and findings in this study can be implemented by all relevant parties involved to accelerate the development of EVs not only in Nigeria but also in other parts of the African continent and the rest of the world.

Economic requirements and justifications for ensuring energy security of the population in Ukraine

The article considers the problem of identifying barriers and justifying the application of possible organizational and economic measures to ensure the energy security of the population of Ukraine in the short and long term based on the state policy. The article examines the economic prerequisites of small generation based on a comparison of the benefits and costs of the population. It has been found that the higher the financial support of microgeneration due to appropriate material incentives, the higher the attractiveness for investment by households. The positive impact of financial incentives depends on the level of household income, the volume of electricity consumption and the level and dynamics of electricity prices. It has been proven that technical components have a significant impact on the use of renewable energy sources in households, especially when building housing using integrated systems based on intelligent digital technologies and shaping the demand for renewable energy source systems. The paper substantiates the main directions of the state policy of promoting renewable energy sources and investigates the measures of the energy security policy. It has been outlined that the main motives for the use of renewable energy sources by Ukrainian households are: ensuring their own electricity needs, autonomy of energy supply and the possibility of receiving passive income. The dynamics of electricity consumption by consumer groups has been analyzed. The increase in the total volume of electricity supply by all sources of energy supply and a reduction in the volume of import and export of electricity have been noted. The structure analysis of electricity consumption by households due to their purposes has been carried out. It has been mentioned that the largest consumption of electricity occurs for the purpose of lighting premises and powering household appliances. The state of coverage of households with their own sources of electricity from SPPs has been studied. The significant increase in the number of households that installed SPPs and the amount of electricity generation has been noted. However, despite the positive developments, the share of households supplied with SPP energy will remain at a rather low level. Measures to ensure the energy security of the population by the state in the organizational plan have been substantiated. Keywords: energy security, electricity, level of energy consumption, renewable energy sources, household, electricity consumption, tariff, energy saving, energy market, small generation, solar power plant.

Open-source project feasibility tools for supporting development of the green ammonia value chain

Ammonia plays a vital role in feeding the world through fertilizer production, as well as having other industrial uses. However, current ammonia production processes rely heavily on fossil fuels, mostly natural gas, to generate hydrogen as a feedstock. There is an urgent need to re-design and decarbonise the production process to reduce greenhouse emissions and avoid dependence on volatile gas markets and a depleting resource base. Renewable energy driven electrolysis to generate hydrogen provides a viable pathway for producing carbon-free or green ammonia. However, a key challenge associated with producing green ammonia is managing low cost but highly variable wind and solar renewable energy generation for hydrogen electrolysis while maintaining reliable operation of the less flexible ammonia synthesis unit. To date, green ammonia production has only been demonstrated at pilot scale, and optimising plant configurations and scaling up production facilities is an urgent task. Existing feasibility studies have demonstrated the ability to model and cost green ammonia production pathways that can overcome the technical and economic challenges. However, these existing approaches are context specific, demonstrating the ability to model and cost green ammonia production for defined locations, with set configurations. In this paper we present a modelling framework that consolidates the array of configurations previously studied into a single framework that can be tailored to the location of interest. Our open-source green ammonia modelling and costing tool dynamically simulates the integration of renewable energy with a wide range of balancing power and storage options to meet the flexible demands of the green ammonia production process at hourly time resolution over a year or more. Unlike existing models, the open-source implementation of our tool allows it to be used by a potentially wide range of stakeholders to explore their own projects and help guide the upscaling of green ammonia as a pathway for decarbonisation. Using Gladstone in Australia as a case study, a 1 million tonne per annum (MMTPA) green ammonia plant is modelled and costed using price assumptions for major equipment in 2030 provided by the Australian Energy Market Operator (AEMO). Using a hybrid (solar PV and wind) renewable energy source and Battery Energy Storage System as balancing technology, we estimate a levelized cost of ammonia (LCOA) between 0.69 and 0.92 USD kgNH3-1. While greater than historical ammonia production costs from natural gas, falling renewables costs and emission reduction imperatives suggest a major future role for green ammonia.

Designing a hybrid renewable energy source system to feed the wireless access network

Today, our society mainly relies on the energy generated by burning fossil fuels, which provides a reliable supply at an affordable price. However, this energy is not renewable and will eventually be depleted in the future. To address sustainability issues, we need to take action in all layers of our society, including our wireless access networks, which are still large power consumers. A possible solution in this field is the integration of RESs (Renewable Energy Sources) for the network supply. Nevertheless, since the production of these RESs is characterized by randomness, which is strictly dependent on the weather conditions, the network service may be compromised because of lack of energy for its supply. In this paper, we investigate the network’s power performance i.e., how much power should be bought from the traditional electricity grid, when using either solar, wind, and geothermal energy or a combination of these three to feed the network (this is here called a multiple RES system). Furthermore, we propose a novel algorithm optimizing the (multiple) RES system accounting for the related CAPEX (Capital Expenditures) and OPEX (Operational Expenditures) costs. Our study shows that geothermal energy is the most reliable one, but also extremely expensive to invest in. Wind energy is the most appropriate choice – even for summer – since it is a rather cheap RES to invest in. The optimized multiple RES system performs the best as only between 0.4% and 11% (depending on the season) of the power required by the network should be bought from the traditional electricity grid.

Interfacing Standalone Loads With Renewable Energy Source and Hybrid Energy Storage System Using a Dual Active Bridge Based Multi-Port Converter

Batteries used for providing backup power in renewable energy sources (RES) fed standalone power systems often suffer from a limited lifetime because of high charging and discharging currents arising from sudden changes in load and/or generation. To prevent this, supercapacitors (SCs) are used to supply the high-frequency (HF) power surges. In this article, a new way of interfacing hybrid energy storage systems (HESSs) (Battery + SC) with RES and loads by employing a current fed dual active bridge (DAB) converter based multi-port converter (MPC) is proposed. The proposed approach enables the MPC to regulate the load voltage while tracking the maximum power point (MPP) of the RES and protecting the battery from transients arising from variations in load and/or renewable generation. The SC is used for tracking MPP so that the transient changes in RES generation do not cause a sudden rise/fall in the battery current. The employed MPC structure is designed in such a way that most of the power processing takes place in one stage only resulting in lower losses. The number of switches is reduced by merging the power conversion stages, which helps in keeping the cost low. Experimental results on a laboratory prototype under various static and dynamic conditions are presented.