A systematic literature review on hybrid energy system

Abstract

Generation of energy has to increase due to society's demand escalation. However, generation from conventional sources is one of the major reasons for greenhouse gas emission, which is a key reason for global warming and climate change issues. To mitigate the emission of greenhouse gas and to protect the environment from pollution, renewable energy sources (RESs) are the one and only effective solution till date. To reduce the fluctuation of RESs on energy generation, a RES-based hybrid system is an innocuous solution. Here, a brief discussion of hybrid systems and their opportunities are presented and reviewed the role of the different combinations of renewable energy-based hybrid systems to reduce environmental pollution, generation costs, improve efficiency, and achieve a continuous power output of the system. A discussion is made on the importance of the site selection and the importance of different kinds of storage systems for energy generation. Result of article gives a brief idea regarding different factors to design future hybrid energy system (HES).

Keywords

Hybrid energy system renewable energy sources greenhouse gas climate change storage system

Introduction

Background and significance

Global temperature is increasing rapidly due to the increasing amount of greenhouse gases in the air. Because of the increase in global temperature, glaciers and ice caps have already started melting which is the cause of the increase in sea level. The increasing sea level threatens the coastal cities and low-lying islands.¹ All these are happening due to large-scale use of fossil fuels that creates environmental contamination. From electrical or power background, the main sources of greenhouse gases emission are fossil fuel-based energy sectors as it burns fossil energy. In 2020, the emission of greenhouse gas from electricity sectors was almost 28% of total greenhouse gas emissions all over the world.² Figure 1 shows the sector-wise percentage of greenhouse gas emissions all over the worldwide in 2020. A report from the International Energy Agency (IEA) wrote that, if the policies of generating energies are remaining unchanged by 2050, emissions of CO₂ will raise up to 130% of current levels.

Figure 1.

Sector-wise percentage of greenhouse gas emissions all over the world in 2020.

Renewable energy sources (RESs) are clean energy sources which do not create severe damage to the environment.^3,4 The primary clean energy sources like solar, hydropower, and wind have less impact on the environment when they are used as the source of energy for electricity generation.⁵ In the field of energy generation, the emission of greenhouse gases can be reduced by upgrading the share of generation from clean sources.⁶ Clean energy can lessen the dependence on fossil energy.⁷ However, various types of modern clean energy technologies can be used for reliable energy generation. In concentrating solar power (CSP) technology, printable organic solar cells are one of the current solar energy technologies for generating reliable electricity. About 30 nations all over the world have more than 20% of total energies that are supplied from renewable sources. Many of the countries nowadays aimed to get 100% renewable energy in the future. Almost 47 nations all over the world have electricity of 50% that is coming from renewable energy resources. India has nearly about 42.70% wind energy and 40.40% solar energy of total installed grid renewable energy. Figure 2 shows the installed grid cooperative renewable energy capacity of India in 2021.⁸

Figure 2.

The installed grid cooperative renewable energy capacity of India in 2021.

The application of renewable sources of energy in the field of power generation is increasing.⁹ But due to some drawbacks, renewable energy systems are unable to reach guarantee reliability.¹⁰ Energy generations from RES like solar, wind, and hydro are clean¹¹ but these energy sources are variable in nature due to the seasonal variation. Because of their alternate nature characteristics, it is quite impossible to get continuous generation of energy from these sources. Direct integration of them into the power grid may make the power generation unstable.¹² Hence, this problem needs to reduce to get continuous and reliable energy generation. Two or more energy sources-based hybrid energy system (HES) can overcome such problems and it can provide a continuous generation of energy.¹³ However, for a continuous energy supply from power plant, system needs proficient management of energy. Thus, storage is required for them. The energy storage system (ESS) plays a very important role in fulfilling energy demand.¹⁴ Different types of ESS are battery storage, supercapacitor, hydrogen storage, pumped hydro energy storage (PHES), etc..¹⁵ Among them, the battery storage system is a related choice for small-to-medium size plants and the pumped storage system is appropriate for large size hydroelectric plants. Moreover, a combination of battery and supercapacitor is the frequently used as hybrid ESS.^16,17

Problem definition

Therefore, considering all the previous circumstances mentioned above, this section presents a detailed discussion about research problem and suggesting some possible solutions in Table 1.

Table 1.

Problem and possible solution.

S. No.	Problem	Possible solution
1.	What are the troubles associated with the power sectors?	Power sector faces fuels unsecure concern, allegation for environment pollution, economic oscillation, aging of power plants, backdated grid facilities, etc.
2.	What is the need for renewable energy sources (RESs) in power sectors?	To reduce greenhouse gas emission from the power sectors, to get clean electricity, to solve insecurities of fuel, to modernize the power sectors, renewable resources play a great role. Moreover, it can save environment as well as economy.
3.	What are the challenges associated with RESs?	Most importantly, RESs are fluctuating in nature. It is not possible to predict their continuity of supply.
4.	What is the need of hybrid energy system (HES)?	Combination of two or more RESs with non-renewable sources can stand against fluctuation problem and it can fulfill the load demand.
5.	What are the factors required for designing efficient HES?	For efficient operation of HES, first of all, selection of location is most important. To get continuous and cheap power supply, storage system and economic view is necessary. Moreover, it is necessary to keep in mind that greenhouse gas emission of HES should be low.

Literature survey

To decrease greenhouse gas emissions and to keep economic profit, renewable resource-based hybrid power system is the best choice. Though, to maintain uninterrupted energy supply to the consumers, a grid-connected or off-grid hybrid power system required an appropriate energy storage opportunity.¹⁸ However, the implementation of the power plant in hilly areas and remote areas is a challenging task. Here, some important research and review articles are highlighted which focused on hybrid power systems.

A study has been made by Baruah et al.¹⁹ for the techno-economic possibility of an independent hybrid plant to give electricity in the East District of Sikkim, India. Here, to choose the best one among 31 possible combinations of various renewable resources, analytical hierarchy process is taken. The result indicates that photovoltaic (PV) wind biogas syngas hydrokinetic battery-based hybrid system is the best choice for this location.

Ranjbaran et al.¹¹ have given a systematic analysis and review of different phases of floating PV (FPV) systems and a comparison is made between the FPV system and ground-mounted PV system. Here, different interconnected topologies of FPV are taken for finding the best output. It is found in the result that total cross-tied FPV-based system is more efficient, and has the ability to reduce water evaporation and carbon dioxide.

Li et al.²⁰ have discussed about configuration, mechanism, characteristics, and upgraded status of hybrid geothermal and solar power plants. Moreover, a new method is proposed here to rank the hybrid solar-geothermal power plant. For the best performance, the article suggested to go with supercritical organic Rankine cycle (ORC)-based hybrid system among the subcritical ORC, single flash, double flash, and Kalina cycles.

Groppi et al.¹⁶ talked about the solution to unpredictability and irregularity of RESs. For such context, different storage technologies like underwater compressed air storage, hydrogen storage, battery storage, pumped hydro storage (PHS), thermal energy storage, vehicle to grid, etc., are consider here for finding the best suited one. Result shows that battery ESSs are suitable for small and medium scale power plant and PHS system are suitable for large-scale power plant, both are popular technologies for the islands.

To avoid curtailment issues of renewable resources, Khan²¹ analyzed the different maximum power point tracker (MPPT) techniques of various renewable power generation systems and the hybrid systems for getting maximum power all the time. Here, perturb and observe algorithm (P&O), particle swarm optimization, genetic algorithm, global MPPT incremental conductance, fuzzy logic, neural network, adaptive neuro-fuzzy interface system, etc. MPPT strategies are used for finding the efficient one. The result shows that artificial intelligence based on hybrid MPPT provides a better presentation.

Objective of article

The main objective of the study is to present a systematic review for analyzing the role of various renewable energy resource-based hybrid systems in the compliment process. For selecting the articles, an inclusion and exclusion process is shown here. Moreover, this article also offers an intensive survey on the importance of HES by focusing on different factors like site selection, uninterrupted power output (UPO), ESS, economic operation, greenhouse gas emission, and efficient operation of RES-based HES.

Article structure

The background and the importance of HES are shown in Introduction section. In Methodology for selection of studies section, the methodology for selecting the articles has been shown. In Importance of HES section, the importance of RES-based HES has been discussed. This section also includes various journal article studies by considering the factors like site selection, uninterrupted power output (UPO), ESS, economic operation, pollution reduction, and lastly future improvement of HES. Finally, Conclusion section concludes the article. Figure 3 shows the taxonomy of the article.

Figure 3.

Taxonomy of the article.

Methodology for selection of studies

The process for selecting studies is as follows:

Initially, select any database and put the keyword.

After recognizing different studies, separate them according to their relevant keywords, abstracts, and titles.

Ignore all the unrelated and similar studies.

Fresh articles are ready to read.

Here, a systematic literature review framework including the use of inclusion and extraction criteria is taken for structuring the article. Table 2 shows the inclusion and exclusion criteria. For this, different databases are selected like Google Scholar, ScienceDirect, Scopus, and IEEE Explore and 350 probable studies were recognized. After recognizing according to their relevant keywords, abstracts, and titles, a total of 100 studies were nominated from different databases which were scrutinized for further findings. This process is simple and there is no chance for miss out of any research studies. We used the following search string: (Renewable Energy Sources*) AND (Hybrid Energy System* OR HES) AND (“Green House Gas Emission*” OR “Climate Change*”) AND (Energy Storage*). Therefore, Figure 4 shows the year-wise number of types of studies. Figure 5 shows process for selecting the articles.

Figure 4.

Year-wise number of studies.

Figure 5.

Process of review.

Table 2.

Inclusion and exclusion criteria.

Inclusion	Exclusion
The journal articles, book chapters, and conferences included in the literature review are published with at least one of these indexing like SCI, Scopus, and Web of Science.	Those journal articles, book chapters, and conferences are not added which didn't have at least one of these indexing like SCI, Scopus, and Web of Science.
The research works included in the literature review have suitable research findings and results.	Those research works are excluded in the literature review which didn't have suitable research findings and results
The research works included in the literature review provide verifiable proof of the findings.	Those research works are excluded in the literature review which didn't provide verifiable proof of the findings.
The research works included in the literature review are already published works.	Unpublished research works are excluded in the literature review.
The references of the research works included in the literature review are pertinent and satisfactory.	Those research works are excluded in the literature review which didn't have pertinent and satisfactory references.

Importance of HES

HES configurations include chemical and electrical ESS and fuel cells which are connected through a smart grid.²² Figure 6 shows a block diagram of HES. In 2018, oil-based power plant supplied the highest energy when compared to other sources total over the world.²³ However, to fulfill the increasing electricity demand, the generation of electricity has to increase. The generation of electricity from a single source of energy may face various problems. HES can improve this system performance, reduce cost, and can be tailored as the requirements of users. The demands of HES are to reduce generation cost and to improve the system efficiency by reducing unstable power as supply are increasing day by day.⁹ However, RES-based HES can reduce environmental pollution and it can maintain the system's reliability.²⁴ Moreover, the selection of location is a very important part of the implementation of HES as it is based on the availability of renewable sources. For an example, if the selected location for hydro wind HES is not sufficient enough to supply RESs for power generation, it can reduce the plant efficiency. Moreover, the initial investment cost of a RES-based system is high but it requires less maintenance cost.¹⁹

Figure 6.

Block diagram of hybrid energy system (HES).

The opportunities for HES are as follows:

Using proper size of RES-based HES, short-term scheduling problems can be reduced and smooth output power can be achieved.

By integrating a FPV system with hydroelectric power system, the water loss due to evaporation and the required area for PV plates can be reduced.

In rural areas, energy production from locally available renewable sources can decrease the crisis of electricity.

Integration of cost-effective substitute in the HES.

By implementing storage in the HES, the power shortage problem can be mitigated. Figure 7 shows pointed factors related to HES.

Figure 7.

Pointed factors related to hybrid energy system (HES).

Site selections of HES

Renewable sources are not obtained in all the locations for efficient electricity generation. If all the sources are not available in the implementation place, then the output of hybrid system will not be efficient. Therefore, the selection of appropriate place for installing a hybrid power plant is the primary problem. For example, the wind speed of the selected location should be in the range of 12–14 km/h for running any wind turbine. But, for the generation of highest wind power, 50–60 km/h is the required wind speed. For solar power plant, a huge area is required for placing the solar plates. The water head and flow of the water should be sufficient for producing power from hydro power plant with a proper grid connection, and it should be necessary that this water level is not too much environmental hazardous.^25,26 Implementations of a hydro wind PV power plant requires speedy wind, proper solar irradiance, and sufficient hydro flow rate for efficient electricity generation. Therefore, focusing on the above factors, some of the research articles are added in this section for analyzing the importance of site selection for HES.

Based on output power complementary coefficient, a size optimization design is introduced by Tang et al.²⁷ to integrate the wind and PV plants with hydro power plant. In this model, the size and location of wind PV hydro power plant is examined. For analyzing the complementary benefits of power output of hydro-wind-PV plant, a case study has been done in Yalong River basin, China. The stretches area of Yalong River basin is from 26° 32′ N to 34° 20′ N to 96° 52′ E to 102° 48′ E. This area is chosen in such way that maximum rated output can be extracted from all the sources.

Odou et al.²⁸ highlighted the energy shortage in rural areas of Africa, especially in Benin, and the aim is to reduce this problem. The techno-economic feasibility of renewable is analyzed for sustainable remote electrification in Benin. To obtain the most economical, reliable benefit of hybrid system, location of the plant plays an important rule. The location of Fouay village is at 11.3° N and 3.17° E, which is 273 m above from sea level. Therefore, grid connection is quite complex for this location but a stand-alone system with storage facility is helpful for this locality. Result of the analysis shows that PV diesel generator (DG) battery-based HES is the ideal optimal scheme. It reduces the cost of battery Energy Storage System by reducing its requirement about 70% and it will decrease the emission of CO2 about 97% as compare to conventional DG.

The optimum design and techno-economic evaluation of renewable HES in the remote location of Korkadu, India is highlighted by Murugaperumal et al.²⁹ For the electrification of Korkadu village, a feasible configuration of HES was obtained by utilizing the resources which are available in the village. The per day average speed of wind and annual solar radiation are, respectively, 3.81 m/s and 5.37 kWh/m2/day for this location. Population of cattle is almost 150 in the village and availability of dung is 80 kg/day. Therefore, as the sources are sufficient, the result shows that PV/wind/biogen-based HES is the best HES solution for this village. Moreover, this HES helps to minimize the energy storage losses.

Nandi et al.³⁰ find a proper location in Middle East where average annual solar radiation is 6.15 kWh/m2/day, wind speed is 5.60 m/second, and the average annual temperature is 23.25°C. Therefore, all the sources for making HES are enough to get better outcome. Total solar energy generated from their proposed HES is 41.04, 48,455 kWh/year, and wind energy generation is 1,59,3,22,890 kWh/year which are 20.5% and 79.4% of the total energy, respectively. The total amount of production of renewable energy per year is 2,000,771,345 kWh and the levelized worth of energy is 0.00417 $/kWh and the overall net present worth is $106,890,700. Therefore, all these results indicate the location that they have chosen is the perfect one for HES.

A techno-economic analysis of two different hybrid systems was done in Bandar Dayyer where the wind speed is about 3.17 m/s and solar radiation is about 5.96 h./day; so the area is suitable for the implementation of a hybrid power plant.³¹ This location of the city is from 27°50′24′′ N to 51°56′16′′ E which is about 12 m above the sea level. Therefore, Bandar Dayyer is a suitable place for the implementation of HES.

An off-grid renewable energy-based HES with two energy storage options is proposed and analyzed using the data of the selected location of Algeria for efficient operation.⁶ In Table 3, summary of studies based on site selection of HES is shown. Figure 8 shows the percentage of articles studied for site selection of HES.

Figure 8.

Percentage of articles studied for site selection of hybrid energy system (HES).

Table 3.

Review on site selection of hybrid energy system (HES).

Author	Contribution	Study area	Limitations
Tang et al.²⁷	A hydro wind PV power plant's optimal size and complementary operation has proposed to provide the grid a reliable and sufficient power supply by reducing fluctuation problem.	Yalong River basin, China	Complex and multi-objective issues which consider economic profit and complementarily are not focused here.
Odou et al.²⁸	The techno-economic feasibility of HES has analyzed for sustainable rural area electrification in Benin to reduce energy shortage problem and CO₂ emission.	Fouay village, Africa	If solar energy will not available, generation cost of diesel generator will be higher.
Murugaperumal et al.²⁹	The optimum design has demonstrates and techno-economic assessment of HES has been done to minimize power shortage problem and pollution.	Korkadu, India	Power generation from biogas can be the cause of pollution if other sources are not available.
Nandi et. al.³⁰	Optimized and simulate an HES for reducing energy generation problem and to decrease the carbon emission.	Egypt	During night, power shortage can occur if speed of wind is not enough for generation.
Kasaeian et al.³¹	A techno-economic analysis has done in two hybrid systems to reduce cost of energy system.	Bandar Dayyer, Iran	Pollution scenario of the selected area is not mention here.
Guezgouz et al.⁶	A grid disconnected PV wind PHS battery storage-based HES are designed for analyzing the possibilities of renewable resources in the selected area for fulfilling desired load demand.	Algeria	Implementation of the facility of load and production forecasting in the EMS operation can be added.

PV: photovoltaic.

UPO of HES

Global and regional vogues reveal that demand of energy will soon be counterbalanced by extensive implementation of RES. However, intermittent, random, and fluctuating characteristics of wind and solar energy complicate their direct acceptance in the power grid. Hydropower has the good adjustable capability, rapid response, and gives continuous output and hence hydropower is the most preferable option for smooth electricity generation. A discrete mathematical simulation model of the hydro solar HES is used by Jurasz and Ciapala³² to increase water retention and smoothen the power output. The installation of more water turbines in hydropower plants for greater flexibility is a good option for maintaining the hydropower capacity factor. Electricity generation from the hydropower plants is the best choice for maintaining the relation between energy production and water usage. Zhang et al.³³ developed a multi-objective mathematical model that considers the dissimilarity among the daily outputs of a HES with variable load characteristics. For describing the everyday load demand of power grid, this innovation presents a multi-segment line generalization method. The result indicates the upstream regulation and expansion of the storage capacity of the hydro reservoir which gives a better solution for power generation. To evaluate and quantify the ability of hydropower plants, historical mean data of daily runoff characteristics, an indicator of complementary guarantee rate (CGR) can be used. Wang et al.³⁴ said that for smoothing out the fluctuations of the output of wind and solar power systems, hydropower can integrated. For the coordinated operation (CO) of cascaded hydropower, to neighboring the PV and wind facilities, a double-layer model can be used. In the case study of northwestern China, where hydro wind PV cluster project shows that local complementary hydropower (LCH) short-term fluctuations are able to smooth out with less impact on the capacity factor (−0.02). Long-term fluctuation can be reduced by global complementary hydropower (GCH) which is the cause of large capacity factor reduction (−0.25). The discharging fluctuation of GCH is markedly lesser (70–75%) than that of LCH which indicates that the introduced technique is an efficient approach for eliminating the discharge fluctuation of the hydro, wind, and photovoltaic power (HWPP) system. Hence, the output fluctuations can be removed from the system if the capacity of hydropower reaches 2200 MW. From this study, it is clear that combining hydropower with solar and wind power is a promising way to de-carbonize the electric system.^32–34 Bhattacharjee et al.¹² proposed an on-grid renewable energy-based HES for getting uninterruptable power supply operation using Internet of Things (IoT) devices-based EMS. Now, Table 4 shows the summary of studies based on smooth power output of HES. Figure 9 shows the percentage of articles studied for UPO of HES.

Figure 9.

Percentage of articles studied for uninterrupted power output (UPO) of hybrid energy system (HES).

Table 4.

Review on uninterrupted power output (UPO) of hybrid energy system (HES).

Author	Contribution	Study area	Limitations
Jurasz and Ciapala³²	A discrete mathematical simulation model of the hydro solar HES is presented to increase water retention and smoothen the power output.	Southern Poland	The model is not suitable for hydropower operation in large river.
Zhang et al.³³	To sizing of a large-scale hydro PV HES, to cut down the dissimilarity among the daily outputs method of the HES and setting up characteristics of the load procedure, a multi-objective mathematical model has been induced.	Qinghai Province, northwestern China	During night of dry season power shortage may occur.
Wang et al.³⁴	For coordinated operation of a cascaded hydropower, a double-layer model is proposed for smoothing out the fluctuations of output of wind, solar power systems and to reduce carbon emission.	Northwestern China	The distinct constrains of hydropower operation during wet and dry season are not considered here.
Bhattacharjee et al.¹²	An on-grid solar wind HES with battery swapping charging station for electric vehicle is constructed and incorporated into Internet of Things (IoT) devices-based EMS for efficient operation.	Meghalaya, India	Integration of biomass generator or energy back-up system for improving the uninterrupted power operation.

PV: photovoltaic.

ESS of HES

Various categories of RES are the initial choice of several countries. The random natures of RESs are unreliable. To make a reliable and continuous energy supply for fulfilling the growing load demand; ESS in the plant plays an important role.³⁵ Lithium-ion batteries, supercapacitors, and flywheel, Redox flow batteries, and PHS are the common types of ESS.³⁶ Salameh et al.³⁷ has done the examination on performance of ESS like battery, supercapacitor in a combined PV/FC/DG HES and the results shows that the performance of the hybrid system (based on levelized cost of energy (LCOE) and GHG) is good with the supercapacitor storage system. A combination of supercapacitor and battery storage system through an appropriate control method can balance the active power, control the frequency of system, voltage dynamics, and improve the output feature of the HES under a different situation like load fluctuation, variable wind speed, etc.³⁸ Li-ion and lead–acid (LA) batteries can improve the performance of a HES with less net present cost (NPC) and COE.³⁹ Berbaoui et al.⁴⁰ use a combination of DG/PV/battery HES to reduce the cost and carbon emission. The PHES system is one of the most suitable storage systems to improve the penetration level of renewable sources in any power plant. PHES is an option of a pollution-free storage system and the construction of a PHSE system is suitable where water is available at an enormous amount.⁴¹ Due to water scarcity in the dry season, the generation is reduced or stopped in many plants. Hence, the PHS system plays a vital role in the reduction of the power shortage problem and improves the generation efficiency of a power plant. Bhattacharjee et al.⁴² reduce the energy generation cost and improve efficiency by reducing the power generation problem of a hydropower plant during the dry season in a PV-pumped hydro storage system. A reliability assessment is done by Rathore and Patidar⁴³ using analytical method and Monte Carlo simulation (MCS) of a PV wind PHES system and compared the result with the system based on PV wind battery which shows that PHES is much economical and environment friendly and it is emerging as a green energy source all over the world. The short-term scheduling problem is highlighted by Xia et al.⁴⁴ which occurs due to the variable nature of wind energy and complex confinement of hydropower. During incorporation of the PHES system, wind power fluctuations can be managed and short-term scheduling problems are solved. Also, the use of the PHS system in a power plant can improve the economic conditions. Mousavi et al.⁴⁵ designed a PV-PHES based microgrid that will provide a cost-effective solution as compared to PV battery system. The PV-PHS model is well efficient for controlling the power of pumps and flow rate of the turbine at daytime with various tariff of energy and generation of power. During both the time of peak hours and off-peak hours, PHES is able to minimize the cost of electricity. Use of PHS-based hybrid system gives a lower levelized cost for which energy generation cost can be reduced.⁴⁶ Grid-connected hybrid wind pumped hydro storage system is designed for providing continuous power supply to the consumers.¹ Now, Table 5 shows the summary of studies based on HES with ESS. Figure 10 shows the percentage of articles studied for ESS of HES.

Figure 10.

Percentage of articles studied for energy storage system (ESS) of hybrid energy system (HES).

Table 5.

Review on energy storage system (ESS) of hybrid energy storage (HES).

Author	Contribution	Study area	Limitations
Bocklisch et al.³⁶	A summary of hybrid ESS and a short discussion of coupling architecture of ESS, elementary idea of energy management and a principle method of power flow decomposition are discussed here.	Chemnitz University of Technology, Germany	Future up gradation by eco-friendly way is not mentioned.
Salameh et al. ³⁷	Performance of a PV/FC/DG HES with battery or supercapacitor storage has been presented here.	Khorfakkhan City, Sharjah, United Arab Emirates	Improper external storage support for insufficient solar energy.
Shayeghi et al.³⁸	An islanded operation has been done for wind diesel HES with a hybrid ESS of battery and supercapacitor.	-	Diesel generator has to use more time when wind speed is not enough.
Ramesh et al. 2020³⁹	The outcome of cycle charging joined dispatch plans and load following has been studied on LA and Li-ion batteries with PV/hydro/battery and PV/wind/hydro/diesel battery/generator by hybrid optimization model for electric renewable.	Chikmagalur District, Karnataka, India	Li-ion battery is brittle and needs a safety circuit for secure operation.
Berbaoui et al.⁴⁰	To reduce cost and CO₂ emission, virus colony search (VCS) algorithm-based HES has been proposed for optimizing the size and placement of HES with the combination of DG/PV/battery system.	Fort-LotfiTindouf (South of Algeria)	More use of diesel generators means more emission of CO₂.
Rathore et al.⁴³	A probabilistic upper reservoir multi-state model MSM_UR (upper reservoir multistate storage model) of PHES has been exhibited to incorporate real situations by applying the analytical method to identify the benefits about PHES.	Kandla, India	Detailed cost analysis of storage unit is not added here.
Xu et al⁴⁷	A voltage source converter control method is used to designing solar-wind-hydro HES.	China	Cost of operation is not mentioned here.
Bhattacharjee et al.⁴²	A PV-pumped hydro storage system is introduced for reducing the power supply problem during dry season.	Tripura, India	Power shortage may occur due to lack of storage.
Xia et al.⁴⁴	Unit commitment model of wind thermal hydroelectric system (WTHS)-based HES is designed for reducing short-term scheduling problem.	Southwest China	Economic operation can hamper because of the uncertain budgets and various level of wind penetration.
Mousavi et al⁴⁵	To get a cost-effective solution than PV battery system and to reduce the cost of electricity, PV PHES microgrid has developed.	-	Here only one renewable source is added and real time management of PHES, electricity pricing are not discussed elaborately.
Gupta et al.⁴⁶	A HES has been presented to evaluate the levelized costs of renewable and storage technologies (LCOHS). Capacity credit for different mood of supply at different three (utility, bulk and residential) types of scale is evaluated to get a cost effective solution.	Switzerland	The assumed day-ahead forecasting of renewable energy supply and demand of electricity can't be realized in real-life situation.
Das et al.¹	A model of grid-connected wind-pumped hydro HES is designed for effective fulfillment of load demand. Pumped hydro storage system is the most crucial component of this HES.	Roseires Dam, Sudan	As wind power supply is fluctuating and therefore it is better to integrate solar power generation into the HES.

DG: diesel generator; ESS: energy storage system; LV: lead–acid; PV: photovoltaic.

Economical operations of HES

Depending on the non-renewable energy sources, the upliftment of the economy would increase the prices of electricity, and the overall development of economy will be difficult in the future. Using of RES can cut down the cost of energy generation and it can provide successful development of the economy. The intermittent nature of solar and wind like RESs may be the cause of various challenges for the reliable and economical generation of electricity. Power load dispatcher faces difficulty in developing the plan for power generation of the day. Hence, to maintain economy, secure and reliable operations by applying effective policies for reducing the intermittent nature of RES are required. To overcome these challenges, Sun et al.⁴⁸ suggested an ideal combined scheme of operation for PSH and hybrid PV wind complementary energy generation system which is internally connected with a voltage source converter-based multi-terminal high-voltage DC (HVDC) system and reduced revenue loss using unit commitment solution. Using this combined operation scheme (COS), dispatch cost is stabilized in a thermal hydro wind PV system. Yin et al.⁴⁹ showed that a thermal hydro wind PV system's operational cost is less when the correlation between wind PV generations is strong. It also is observed that for an intermediate base case transmit solution with a lesser cost; the proposed stochastic model is an appropriate solution under uncertainties. There, the total life cycle cost of any HES should be at a minimum level so that the system will economical and reliable. Zhang et al.⁵⁰ want to reduce total life cycle cost and to increase the system reliability by optimum sizing of stand-alone wind solar HES using chaotic search-harmony search-simulated annealing (CS-HS-SA) coefficient heuristic approach. However, if the configuration of a hybrid power plant is not optimal, then it will be difficult to get a reliable supply of power. Hence, to achieve low cost of energy from HES and a reliable supply of energy, the configuration of the plant should be optimal. Rao optimization technique is an ideal metaphor-less technique that can be applied for solving the optimization issue of a HES and it helps to find an optimal configuration of a HES for any particular area. The optimal configuration will give the best optimal cost of energy and loss of power supply probability (LPSP).⁵¹ To make a reliable and constant electricity supply in remote locations, Xu et al.⁵² proposed a stand-alone HES that is based on RES. It is observed that the use of the PV wind HSPSI HES can reduce the LCOE by 32.8% and 45.0%, respectively, than the PV HSPSI and wind HSPSI HES in Xiaojin, Sichuan, China. Trade-off analysis among the two objectives is done based on Pareto optimality theory by means of multi-objective particle swarm optimization (MOPSO). If the consumption of fuel can be reduced in any fossil fuel power plant by increasing the use of RES, the cost of generation can be cut down. In a hybrid PV/diesel/PHS system, during normal and high radiation periods, the need for a DG is low for which cost is reduced.⁵³ On the other hand, for better economic performance, grid frequency should be maintained. PHS operation is be considered to reduce the effect of imbalanced cost because of the mismatch between actual and predicted wind power.⁵⁴ Whereas the combined benefits by CO of the pumped storage power system (PSPS) and FPV system can be achieved using a hybrid integrated floating photovoltaic-pumped storage power system (IFPV-PSPS). The FPV system helps to reduce water evaporation loss and land requirement of a solar PV system. This technology also helps to get a bugget friendly and profitable generation of clean energy.⁵⁵ Profit in the economy of HWPGS is higher through coordinated scheduling than their differentiated operations.⁵⁶ Voting-based HES is another example of economic HES which have the facility to include consumer preferences in the energy management operation cost-effectively.¹⁴ Therefore, it can be said that HES based on RES can reduce the cost of energy generation. In Table 6, the summaries of reviews based on economical generation of electricity using RES-based HES are shown. Figure 11 shows the percentage of articles studied for economic operation of HES.

Figure 11.

Percentage of articles studied for economic operation of hybrid energy system (HES).

Table 6.

Review on economical operation of hybrid energy system (HES).

Author	Contribution	Study area	Limitations
Sun et al.⁴⁸	An optimal joint operation idea has proposed for PSH and hybrid wind PV complementary energy production system.	-	In the optimal COS process, operating reserves of PV and wind plants are not included.
Yin et al.⁴⁹	A day-ahead stochastic coordinated scheme is proposed here for scheduling the electric power system with intermittent renewable generation and thermal hydro units. The introduced model can give a proper base case solution under uncertainties with lesser dispatch cost	-	System operating cost fluctuates due to different wind-PV generation penetration.
Zang et al.⁵⁰	Spatial plan is introduced for wind speed, solar insolation and air temperature forecasting by an artificial neural network (ANN) to reduce total life cycle cost and improve reliability.	Khorasan, Iran	During night, solar will not available, at that time, if load demand will high and storage will not enough, there is no other alternative way of energy generation to fulfill the demand.
Sultan et al.⁵¹	An ideal metaphor-less technique named Rao optimization technique has proposed to resolve the optimization problem of HES comprising of wind turbine, solar PV, and hydroelectric pumped storage (HOPS) system.	Ataka area, Egypt	Use of sea water for power generation maybe the cause of corrosion of the materials.
Xu et al.⁵²	A PV wind hydropower plant with pumped storage has designed and investigates to make a reliable and continuous supply of electricity in remote locations.	Xiaojin, Sichuan, China	Data related to operating and maintenance cost is absent. Several factors which impacts on PV output like, humidity, atmospheric pressure are neglected here.
Makhdoomi et al.⁵³	An optimal operation for a HES with the combination of photovoltaic, diesel generator, and PHS is presented in this article for attaining minimum consumption of fuel and reducing cost	Adrar, South Algeria	If both PV and water are not sufficient, the generation of energy from diesel generator may costlier.
Li et al.⁵⁶	A day-ahead coordinated scheduling method for hydro and wind power generation system (HWPGS) using two-part price and power flow constraints has been proposed to reduce the effect on power generation because of the uncertain nature of RES.	Western China	The supply of power for external grid will be reduced because of the separation of the wind farm or hydropower stations, which may hamper economic benefits.
Dawn et al.⁵⁴	A two-stage efficient approach has been proposed to maintain the grid frequency with maximum system profit and revenue of hybrid wind-pumped storage hydro solar thermal power plant.	-	Loss of water from the storage reservoir may occur due to evaporation.
Liu et al.⁵⁵	A model of hybrid integrated floating photovoltaic-pumped storage power system (IFPV-PSPS) is presented here to get the combined benefits by coordinated operation (CO) of the pumped storage power system (PSPS) and floating photovoltaic (FPV) system.	China	The efficiency of the power generation of PV modules on the water is less than that PV module on land.
Bhattacharjee et al.¹⁴	A hybrid voting-based renewable energy system is constructed to satisfy the required energy demand by considering cost, pollution, and consumer choice factors.	Odisha, India	To reduce emissions from biomass power plant, energy storage system can be integrated into the HES.

PV: photovoltaic; RES: renewable energy source.

Greenhouse gas emission by RES-based HES

The generation of energy from fossil fuel is the reason of pollution in environment because, when fossil fuel burns, it releases CO₂ in the environment that results in increasing atmospheric temperature.⁵⁷ Power generation sectors released NO₂, SO₂, and other gases which are the main cause of acid rain. Almost 2.7 billion people all over the world are living their lives without a less polluted cooking facility and 1.2 billion people are living their lives with no electricity. Hence, RES may be the source of electricity production in the future with less effect on nature. The combination of two or more RES will give a more reliable supply of power. Nag et al.⁵⁸ proposed a solar wind hydrokinetic bioenergy type HES to get an efficient supply of energy with low cost and less pollution. However, the demand for energy is increasing gradually and the storage of fossil fuel is reducing.⁵⁹ Hence, it is necessary to find alternative ways of energy generation. Kirmani et al.⁶⁰ introduced a HES with solar wind and coal energy to reduce the rate of environmental pollution and also to find an alternative solution of energy production. Using of RES can reduces the use of fossil fuel and hence reduces carbon emission. A grid-connected HES with a PV and wind reduces the emission of carbon by about 110329.56 kg from Ennore, Chennai, India. In Bijie, Guizhou, China, the emission of carbon from a Chinese coal combusted electricity generation is reduced by about 17389.25 kg using an optimized hydro wind thermal complementary HES.⁶¹ The emission of CO₂ is reducing nearly by about 1696*104 t/year in the northwest power grid by applying the wind energy in the grid using the hydro wind compensating principle. Wang et al.⁶² also wanted to enhance the power quality and to maintain optimal scheduling by applying the peak regulation capacity of hydropower system. Moreover, it is necessary to get rid of the curtailment problem and achieve a reliable supply of power. To reduce wind power curtailment problems and reduce carbon emission, Ding et al.⁶³ proposed a hybrid solar wind power plant. The rate of CO₂ emission is minimized by about 15,470 t/year than coal-fired power plants in an 80 MW hybrid system of Zhangbei, China. In the rural areas of Ethiopia, 99% of houses and 70% of industries used biomass and local energy sources like diesel; coal to fulfill their energy demand. Gebrehiwot et al.⁶⁴ examined the electrifying capability of Golbo II village of Ethiopia by a HES and showed that HES with PV array, wind energy, battery storage, and a DG is the best option in which almost 80% electricity is generated from solar PV. It indicates in the reduction in generation cost as well as the emission of CO₂ is by about 37.3 tons. Panda et al.⁶⁵ analyzed different combinations of HES for finding the best solution to reduce pollution. In India, 57% of electricity is produced from coal energy. To reduce the burden on the national power grid because of the urban lifestyle and development of industries, Maqbool et al.⁶⁶ aimed to fulfill the demand for electricity in most of the rural areas of India by an optimal PV biomass grid microgrid. This RES-based micro-grid can reduce the CO₂ emission from 454.24 tons to 250.19 tons (around 55%) in Wanigam Pattan village, Baramulla District, and Jammu and Kashmir. An off-grid PV diesel HES in South Khhorasan, Iran can achieve a fuel saving of about 8948 l than a stand-alone diesel power plant. The CO₂ emission is reduced by 59.6% than diesel power plant using improved harmony search, simulated annealing, and a geographic information system (IHS-SA-GIS) algorithm.⁶⁷ Implementation of 100% RES-based system can reduce carbon emission as well as energy cost⁶⁸ Three configurations of HES have been designed to get the most efficient and less pollution-generating configuration.⁵ Hence, RES utilization makes the energy generation process pollution-free, economical, and efficient. Table 7 shows the summary of studies based on pollution reduction by the RES-based HES. Figure 12 shows the percentage of articles studied for pollution reduction by the RES-based HES.

Figure 12.

Percentage of articles studied for pollution reduction by the renewable energy source (RES)-based hybrid energy system (HES).

Table 7.

Review on pollution reduction by the renewable energy source (RES)-based hybrid energy system (HES).

Author	Contribution	Study area	Limitations
Nag et al.⁵⁸	A solar wind hydrokinetic bioenergy type HES has introduced to increase system efficiency with less cost	Jharkhand, India	CO₂ emission may increase due to the use of high-cost biodiesel.
Kirmani et al.⁶⁰	A HES with solar wind and coal has been developed to reduce carbon emission from the environment.	Ramapuram, Chennai, India	Using of three different hybrid system can complex the calculation process.
Xu et al.⁶¹	An optimized hydro wind thermal complementary hybrid system is introduced to reduce emission of carbon and to maintain the reliability of electricity generation.	Bijie, Guizhou, China	Interactions of downstream and upstream of hydropower plants have not considered.
Wang et al.⁶²	To enhance the quality of wind power, hydro wind grid hybrid compensating principle is used.	Northwest power grid of China	Their simplifications are different from real operating process.
Ding et al.⁶³	A hybrid solar wind power plant has proposed to reduce wind power curtailment problem.	Zhangbei, China	The integration of heater is not good option.
Gebrehiwot et al. ⁶⁴	They examined the electrifying capability of Golbo II village of Ethiopia, multiple electric renewable models are used.	Golbo II village of Ethiopia	Diesel generate is not suitable from environmental view.
Panda, et al.⁶⁵	A techno-economic scenario and multi-objective optimization of several HES wind thermal (WT), hydro thermal wind (HTW), and hydro thermal wind solar (HTWS) has presented in this work.	-	Issues related to power transmission constraints, dynamic stability improvement and optimal size for energy generation has not discussed.
Maqbool et al.⁶⁶	Distributed energy generation can be used to fulfill the energy demand in the rural areas and to reduce the burden on the national grid.	India	Replacement of the plant may cause economic impairment because the proposed system is location-based.
Cai et al.⁶⁷	An appropriate sizing and location for PV diesel HES is selected based on economic, technical, reliable, environmental and social criteria.	South Khhorasan, Iran	From the simulation result it is observed that with the increase in interest rate, cost of optimized hybrid scheme will increase.
Dawood et al.⁶⁸	To develop 100% RES-based system, a robust energy storage for stabilizing the intermittent and variable RES is proposed here.	-	At night or cloudy weather, generation from solar energy will hamper.
Bhattacharjee et al.⁵	Three configurations of HESs are analyzed, and compared here to find out the most efficient configuration with less pollution.	Thanjavur, Tamil Nadu, India	Energy storage system can be integrated with the best configuration of HES for effective operation.

PV: photovoltaic.

Efficient operation of HES

An efficient power supply can reduce the energy cost and make the power plant more longevity. Today's world needs a huge amount of energy to fulfill the demand of developed society.⁶⁹ But the rising seriousness related to the energy crisis and problems of environment limits the use of fossil sources of energy. Different fossil energy sources like coal, natural gas, and petroleum products create a hazardous impact on the environment. Therefore, environmental hazards should be reduced as well as the energy demand has to fulfill economically. Therefore, an alternative way of energy generation is required for the reliable and pollution-free future. But the curtailment problem hampers the development of HES and reduces the plant efficiency. A complementary CO model of hybrid hydro thermal wind photovoltaic (HTWP) plants is used to reduce the curtailment problem and to improve the efficiency of the system.⁷⁰ Improper policies and absence of appropriate planning may be the reason of energy crisis. Baloch et al.⁷¹ give a long-term, midterm, and short-term solutions to deal with power crisis, to improve efficiency, and reduce environmental pollution. Short-term solution can be done by reducing electricity theft using prepaid meters. The power plants which are not fully operational or constructed should be completed as soon as possible and power management techniques have to implemented in the power plants to reduce the power crisis problem. By implementing wind power plant, short-term problem can be reduced. By reducing the losses of electricity in transmission and distribution and using renewable energy sources for power generation can help to reduce midterm solution, improve efficiency, and reduce environmental pollution.^70,71 Ming et al.⁷² proposed different steps for the proper operation of a large hybrid hydro PV power plant to increase system efficiency and reliability. PV energy loss function is estimated using short-term simulation model which identify the correlation among PV curtailment rate and hydropower generation. By this, the proposed model can increase production of hybrid power plant and power supply reliability and decrease water shortage index (WSI). PV energy loss function incorporated by a multi-objective long-term optimized model based simulation and six rule curves of operation using multi-objective cuckoo search (MOCS) algorithm is designed by Ming et al.⁷² Long-term stochastic optimization method is used to decrease the uncertainty impact and improve efficiency. Li et al.⁷³ presented four schemes using the stochastic optimization technique in different conditions of stream flow and PV output of hybrid power plants. The long-term stochastic optimization model has two constraints, namely operational and physical constraints (which have reservoir storage, water balance, release, output power, and the power grid constraints). Three-stage method based on the Bender decomposition algorithm can enhance the computational efficiency of the scheduled model of a hybrid system that consists of solar, wind, hydro, thermal, and pumped storage system.⁷⁴ Chen et al.⁷⁵ solve the probability interval optimization (PIO) model of a hydro -wind thermal hybrid system using an evolutionary predator and prey strategy (EPPS) method and showthat PIO model is robust and effective to measure HWTS combination with the fluctuation of wind energy. Ebhota and Jen⁷⁶ highlighted that by improving the energy material, the efficiency of HRES can be improved. Use of HRES with pumped storage hydroelectric power or DG can reduce the fluctuation in supply. A day-ahead scheduling process is proposed by Liu et al.⁷⁷ for CO of the hydro wind solar HES. It was done to aid peak shaving and reduce the problem of fluctuation and to reduce the power shortage problem for which efficiency of the system will increase. Das et al.⁷⁸ proposed an on-grid HES based on wind and hydro sources with PHS to efficiently satisfy the energy requirement of consumers. Table 8 shows the summary of studies based on improvement of energy generation efficiency using HES. Figure 13 shows the percentage of articles studied for future improvement of HES.

Figure 13.

Percentage of articles studied for future improvement of hybrid energy system (HES).

Table 8.

Review on improvements of hybrid energy system (HES).

Author	Contribution	Study area	Limitations
Wang et al.⁷⁰	A complementary coordinated model of hydro thermal wind photovoltaic (HTWP)-based HES has introduced to shorten the curtailment issue of wind-solar energy.	Qinghai and Gansu Grid, China	Proposed model is not sufficient to solve curtailment problem.
Baloch et al.⁷¹	A good potential for power generation using solar and wind energy units has analyzed and represented the long-term, midterm, and short-term solution to deal with power crisis.	Pakistan	Generation of energy from coal is a long term solution that can increase the pollution.
Ming et al.⁷²	A large hydro PV HES has been proposed to adopt operating rules and different steps for the proper operation.	China's Longyangxia	If both the hydro and solar power is unavailable, power shortage will occur.
Li et al.⁷³	A long-term stochastic optimization method has proposed by considering uncertainty and weak correlation between stream flow and PV power output of the hydro photovoltaic HES.	Eastern Qinghai province, China	The outcomes of long-term complementary operations are comparatively rough.
Yiwei et al.⁷⁴	A day-ahead optimal dispatch scheme has proposed for an HES to resolve the multi-objective difficulty, maximize the economic benefit and consumption of renewable energy.	-	The existing resources are unable to meet whole load demand.
Chen et al.⁷⁵	A risk-aware probability interval optimization (PIO) method is presented for reliable operation of short-term hydro wind thermal scheduling.	-	In dry season and low wind speed situation, generation from thermal energy sources can increase the pollution.
Ebhota and Jen⁷⁶	By developing the energy materials (EMs) at community-scale HES, various sustainable improvement challenges into low-middle-income countries can be reduced.	-	DSSC solar cell has the temperature stability problem. When temperature is low, the liquid electrolyte of the cell may freeze which can be the cause of physical damage.
Liu et al.⁷⁷	A day-ahead scheduling process is introduced for coordinated operation of the hydro wind solar HES.	Southwest China	Power storage facilities are not available.
Das et al.⁷⁸	A hybrid grid-connected wind hydro HES with PHS is constructed for efficient fulfillment of load demand.	Tamil Nadu, India	PV-based system or biomass generator can be integrated with the HES for more efficient fulfillment of load demand.

PV: photovoltaic.

Discussion

After doing the literature surveys of different countries, we have found that China has maximum number of studies on HES and it has the highest installed grid-connected renewable energy capacity. Figure 14 shows installed grid cooperative renewable energy capacity of G20 countries. Moreover, in this section, we provide practical and theoretical implications of HES with their future research scope as per the findings of our literature survey.

Figure 14.

Installed grid cooperative renewable energy capacity of G20 countries.⁷⁹

Practical and theoretical implications

Implication shows the reasonable relation between the condition of research and the result of it. Simply, it is the combination of finding research problem and the area for applying. Theoretical implication shows the interesting areas form previous theories. More or less, theoretical implication gives an idea about the research gap from past theories for future work. Practical implication designates the direction how to get the result of analysis practically. It explains real-world relation of the outcome.⁸⁰

Limitation

The major important limitations for designing HES are as follows:

To maintain and maximize economic profit by reducing operational cost, trading cost and generation cost

To use efficient and cost-effective ESS that can help to maintain uninterrupted power supply using RESs.

To reduce the forecasting error of RESs for planning different policies and management techniques.

To select optimal location for installing HES is a challenging task as it helps to efficiently utilize RESs.

To reduce the curtailment problem of HES for improving its overall efficiency.

Present scenario of research

In the present scenario, the researchers are developing open-source robust modeling tools for simulating and optimizing HES. For example, hybrid optimization and performance platform (HOPP) is a software tool which helps in sizing, analyzing, designing, and setting topologies of HES.

To find out the optimal location for HES, the researchers are creating high-resolution maps regarding different renewable resources using National Databases.

The researchers are making partnerships with industries for improving the measurements and observations of renewable resources.

The researchers are tracking classical patterns in technology and economic expenses for analysing future innovation opportunities.

The researchers are designing and validating updated control technologies for maximizing energy generation from renewable resources with ESS at hybrid circumstances.

Further research scope

Interconnections between eectric vehicle with HES can store energy sustainably. It can eliminate uncertainty issue of charging station.

HES are combined with green batteries like liquefied air, redox batteries for environment-friendly storage system.

One platform is necessary that can provide all data regarding availability of renewable energy resources for the selected location.

Efficient energy management techniques should be developed to minimize operational cost and improve economic for HES.

Attachment of carbon tower and filters are necessary for reducing emission from pollution-generating power plants.

Advance algorithm should be developed for predicting future data of renewable energy resources without any errors.

Conclusion

Generation of electricity from conventional sources emits huge amount of pollutant in the environment, hence by integration of suitable RES in the existing plants can reduce the pollution rate. The generation of power from RES is pollution-free and its refueling is cost free. Due to the advantageous characteristics of RES, the sources get valuable remark in today's generation field. The main disadvantage of RES is high variability that can be overcome by combining two or more RESs for energy production. This article presents a comprehensive literature survey on RES-based HES by focusing on environmental aspects, economical operation, site selection, reliable generation, and also storage system. This review demonstrates that:

The electricity generation by RES in remote areas can help to reduce electricity problem, transmission cost and loss, etc., if RES are sufficiently available. An appropriate location for an HES will help to give an efficient output by properly utilizing all available RES of that location.

ESS is very much important for the betterment of power supply by HES in rural areas. As the electricity generation from RES are fluctuating and heavily depends on weather condition, storage is the most important node.

Generation cost is much lower as RES are abundantly available in nature. Therefore no fuel cost is required during the operational mode of RES-based HES.

The generation of energy from renewable sources is less polluting. Thus, for green energy generation, the RES-based HES are the future of the earth. Moreover, using of FPV system can reduce evaporation, which means loss of water hydro PV-based HES.

China has the maximum number of studies on HES and the second position is occupied by India, as per this survey.

Therefore, this study opens various future research directions based on various techniques of voltage and frequency control of power generation by which the efficiency of the power plants can be improved; by reducing forecasting error, cost of energy generation can be reduced, which can include in a new direction of open research; during power generation from seawater, the use of corrosion-resistant material is beneficial for a better output; attachment of carbon tower and filters into the HES to reduce emission of GHGs; integration of electric vehicle with HES can eliminate uncertainty of power supply; improvement in the life cycle efficiency of ESS. Truly, RES-based HES can improve system reliability, efficiency, and it can give the clean green earth to the mankind.

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Uttara Das

Uttara Das received her Diploma degree in Electrical Engineering from Dhalai District Polytechnic, Ambassa, Tripura, India in 2015. She received her BE degree in Electrical Engineering from Techno India Agartala, Agartala, Tripura, India in 2018. She has completed her M-Tech in Electrical Engineering from Tripura University, Tripura, India in 2020. Currently, she is pursuing PhD in Electrical Engineering from Tripura University, Tripura, India. Her research interest includes renewable energy resources, conventional energy, hybrid energy system, environment and environment related issues, life cycle of different power plants.

Champa Nandi received her BE degree in Electrical Engineering from Tripura University, Tripura, India in 2004 and M-Tech in Electrical Engineering from Tripura University, Tripura, India in 2008. From 2008 to 2010, she served as a Lecturer at the Department of Electrical Engineering in NIT Agartala. She received her PhD from NIT Agartala on May 2016. She is serving from 2010 to till date as an Assistant Professor for the Department of Electrical Engineering Tripura University, Tripura, India. Her research interest includes renewable based hybrid energy, microgrid protection.

Sarbani Mandal received her BE degree in Electrical Engineering from Tripura Institute of Technology, Narsingarh, Tripura, India. She is completed her M-Tech in Electrical Engineering from Tripura University, Tripura, India. Her research interests include voltage stability improvement in power system, hydro power plant, wind power plant, solar power plant, different renewable energy sources, environmental pollution and global warming, power factor improvement, economic benefits of hybrid renewable energy sources, and environmental impacts of conventional energy sources.

Somudeep Bhattacharjee presently doing the job of guest faculty in Electrical Engineering Department at Tripura University. Moreover, he is pursuing PhD in Electrical Engineering from Tripura University, Tripura, India. He have completed his M-Tech from the Department of Electrical Engineering, Tripura University. He done his BE project in 'Chaos masking communication'. He done his M-Tech project on the topic of intelligent controller design for the energy management of hybrid power plant. His research areas interest include electric vehicle, hybrid energy system and solar panel.

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