Investigation of Solar-Driven Hydroxy Gas Production System Performance Integrated with Photovoltaic Panels with Single-Axis Tracking System

Published online

Investigation of Solar-Driven Hydroxy Gas Production System performance Integrated with Photovoltaic Panels with Single-Axis Tracking System

Farhad Salek1, Mohammad Rahnama1, Hossein Eshqi1, Meisam Babaie2, and Mohammad Mahdi Naserian3*

1. Faculty of Mechanical and Mechatronic Engineering, Shahrood University of Technology, Shahrood, Iran. 2. School of Computing, Science and Engineering, University of Salford, Manchester, UK. 3. Department of Mechanical Engineering, Faculty of Montazeri, Khorasan Razavi Branch, Technical and Vocational University, Mashhad, Iran.

Receive Date 26 April 2021; Revised 08 May 2021; Accepted Date 13 May 2021 *Corresponding author: [email protected] (M.M. Naserian)

Abstract In this work, a solar-driven alkaline electrolyzer producer of hydroxy gas is proposed, which is integrated with photovoltaic panels with a single-axis north-south solar tracking system. The main novelty of this work is providing a transient analysis of integration of an alkaline electrolyzer to the PV panels equipped with a solar tracking system. Furthermore, the transient model of the alkaline electrolyzer is employed in order to calculate its operating temperature, hydroxy production rate, and the other operational parameters at various hours of the day. The electrolyzer and the PV panels with a tracking system are modelled by the EES software. It is assumed that the system is installed in the city of Shahrood, and therefore, the geographical data for this city is used for a seasonal analysis. The effective areas of the electrolyzer electrodes and the PV panels are also assumed to be fixed at 0.25 m2 and 50 m2, respectively, in this work. Based on the results obtained, employment of the solar tracking system results in a significant increment of the PV panel power absorption rate, resulting in a power increment up to 4.2 kW in the summer. On the other hand, the transient analysis of the proposed alkaline electrolyzer shows that the maximum operating temperature reaches 80 oC at around 12 AM in the summer, causing achievement of a maximum electrical current peak in the summer. Therefore, an efficient cooling system should be employed in the summer for the decrement of the alkaline electrolyzer temperature. The proposed system is capable of producing 7.6 m3/day, 10.4 m3/day, 7.2m3/day, and 4.1 m3/day of hydroxy gas in the spring, summer, fall, and winter, respectively.

Keywords: Alkaline electrolyzer, hydroxy gas, photovoltaic panel, solar tracker.

1. Introduction Due to the environmental concerns of fossil fuel reforming method requires significant resources of consumptions across the world, most of the natural gas, which are not accessible all around the countries are looking for alternative energy world [10-12]. Meanwhile, the water electrolysis resources [1, 2]. One of the most promising fuels method does not require consumption of fossil for the future is hydrogen gas [3, 4]. Its high fuels for production of hydrogen [13, 14]. In this flammability and vast applications have made this method, only electricity and water are required for fuel a reasonable choice to be substituted by the the generation of hydrogen [15, 16]. fossil fuels [5]. Water electrolysis [6, 7] and natural Consequently, this method is considered as one of gas reforming [8] are two major methods for the sustainable methods for the production of extracting hydrogen gas. In the reforming method, hydrogen [17]. Moreover, it can be coupled to the a catalyst is required to break the chemical bonds photovoltaic panels, which generates electricity in natural gas [9]. Carbon dioxide is a side-product from solar irradiations in order to provide a stand- of the foregoing reaction, which can be used in the alone system [18-20]. other processes or is discharged to the There are many types of electrolyzers by which environment, which will also cause contamination hydrogen can be generated using electrical power [8]. Moreover, hydrogen production using the such as alkaline electrolyzers (AELs) and proton

M.M. Naserian et al./ Renewable Energy Research and Application, Published online exchange membrane electrolyzers (PEMELs) [21- south of Algeria. In this study, different strategies 23]. AELs are the convectional type used for a for controlling the output current of photovoltaic sustainable hydrogen production in various panels and their effects on the hydrogen extraction countries [24]. PEMELs have recently achieved have been investigated. According to their reports, attention, and the researchers are working on using the REF542plus relay in the controlling unit developing it as a high performance electrolyzer of the system led to an increase in the safety and with a higher power density compared to AELs production efficiency. In another research work, [24]. However, PEMELs are too costly compared Schnuelle [30] has presented the simulation results to AELs. Therefore, PEMELs are not yet for two specific types of electrolyzers including economical to be used in different industries. AELs and PEMELs in both the wind and PV power Furthermore, the structure of AELs is simpler than input for the climate of NW Germany. He that of PEMELs (3). A comparison of the alkaline concluded that the shape of the input power signals and proton exchange membrane electrolyzers is and the coupling of the electrolyzers with the other provided in Table 1. parts of the system had a great impact on the

Table 1. Alkaline and proton exchange membrane electricity utilization, net production cost, and electrolyzer characteristics [25]. hydrogen production efficiency. Furthermore, he

Alkaline PEM reported that the AEL technology with a renewable Name Unit electrolyzer electrolyzer electricity supply was more cost-effective in KOH or NOH Solid comparison with the other studied types of Electrolyte - solution polymer electrolyzers. A stand-alone solar-driven hydrogen Current density A/m2 2000-4000 10000-20000 production system has been designed and studied by Bhattacharrya et al. [31], in which the Working pressure MPa < 3.2MPa < 5MPa electrolyzers are powered by photovoltaic panels. Operating temperature oC 80-90 50-80 The PV panels without solar tracking system was Alkaline modelled mathematically, and the empirical Corrosion - No corrosion equations were used for prediction of the AEL Manufacturing cost - Low High hydrogen production rate in this study. Based on their results, it was predicted that nearly 60 kW Lifetime years 10 3-4 electrical power was required by the PV panels for production of 10 Nm3/h of hydrogen. In a another Therefore, one of the easiest ways for production study, the experimental characterization and size of pure hydrogen, is the employment of AELs [26, optimization of a photovoltaic-driven hydrogen 27]. The employment of this method for production generation system has been studied by Ferrari et al. of hydrogen in medium- and small-scales is more [32]. The results of their work indicated that the economical than the other methods [28]. Potassium hydrogen production efficiency was highly related hydroxide with concentrations of 25% to 30% is to the solar irradiation in the location where the often used in AELs as the electrolyte. One of the photovoltaic panels were installed. Using a finite- major problems of this types of electrolyzers is the time thermo-economic analysis, an optimized high corrosiveness of the electrolyte. When the economic model was developed in this research working temperature rises, the electrode life work. In a separate study conducted by Cilogullari decreases. Therefore, the working temperature of et al. [33] about coupling of photovoltaic thermal AELs should be controlled. (PVT) panels with PEMELs, it was reported that The integration of AELs, which produces pure using the PVT panels in system could result in an hydrogen with photovoltaic panels, has been increase in the hydrogen production performance studied by many researchers. Fereidooni et al. [29] as well as the photovoltaic efficiency. have studied the coupling of the hydrogen It can be seen from the literature that different production cells with the photovoltaic panels with researchers have focused on using AELs in order to a constant tilt angle. For the simulation of the produce pure hydrogen. Apart from AELs, in system, the characteristics of 20 kW photovoltaic which a semi-permeable membrane is used for the panels, which were installed in Yazd, were used. production of pure hydrogen, there is another type The energy efficiency of photovoltaic panels was of AEL that produces a mixture of hydrogen and reported as 12.32%, and the hydrogen production oxygen gas called hydroxy gas [3, 5]. This type of rate was estimated to be approximately 373 tons gas can be used in a combustion process such as in annually. Menad et al. [19] have worked on the boilers and internal combustion engines for the integration of photovoltaic panels with AELs by production of heat and mechanical power, while considering the climate of a city located in the producing lesser emissions compared to the fossil

M.M. Naserian et al./ Renewable Energy Research and Application, Published online fuels. On the other hand, the employment of PV using the EES software, and a parametric analysis panels with solar tracking systems in solar-driven is performed to obtain the integrated systes alkaline hydrogen production systems is still functional parameter variations in various seasons missing. The solar trackers are widely used for during the year. increasing the performance and rate of the solar energy absorption of photovoltaic panels [34, 35]. 2. System description There are many types of solar trackers available The proposed system consists of PV panels and such as the multi-axis and single-axis ones. The AEL components, as it can be seen in Figure 1. The single-axis north-south solar trackers are capable of electrical energy produced by the PV panels changing the tilt angle of the panel for achieving (equipped with a solar tracker) is transferred to the optimum tilt angle at which the maximum rate AELs for production of the hydroxy gas. of solar energy can be achieved by the PV panels. Furthermore, the voltage of electricity flow The main contribution of this study is the time- transferred to AELs is changed by employment of dependent thermodynamic analysis of the alkaline a DC/DC converter (Figure 1). Moreover, by electrolyzers integrated with PV panels equipped feeding water into AELs, the electrical energy with solar tracking system in order to obtain produced by the solar panels is used for water variations in the electrolyzer functional parameters electrolysis, resulting in the production of the during the hours of the day. hydrogen and oxygen gases, a mixture of which is In the current work, the integration of PV panels called hydroxy. The produced hydroxy gas can equipped with single-axis solar trackers with AEL then be transferred to the boilers or stationary producer of the hydroxy gas is studied in order to engines, leading to the improvement of their provide a stand-alone green fuel production system performance and reduction in the emission for remote areas. The AEL and PV panels with production. solar tracking system is mathematically modelled

Figure 1. A block diagram of the proposed system.

3. Mathematical modelling calculate the amount of hourly solar irradiation on a tilted plane, the following equations are used [36, 3.1. PV panels 38]: This system comprises some sub-systems Io=Ion cos 휃 (2) including photovoltaic panels with a north- south solar tracker. The total receiving irradiation for a cos 휃 = sin 휙 sin 훿 cos 훽 - cos 휙 sin 훿 sin 훽 + (3 horizontal plane outside the atmosphere can be cos 휙 cos 훿 cos 훽 cos 휔 + 푐표푠 훿 푠푖푛 훽 푠푖푛 훿 푠푖푛 휔 ) calculated by [36, 37]: β expresses the plane tilt angle. Furthermore, the 43200 360푛 plane azimuth angle (훾) was considered to be equal 퐼 = 퐺 (1 + 0.033푐표푠 ) × 표푛 휋 푠푐 365 to zero in this work. In order to calculate the total [푐표푠 휙 푐표푠 훿 (푠푖푛 휔2 − 푠푖푛 휔1) + (1) irradiation on a titled plane, the following 휋(휔 − 휔 ) 2 1 푠푖푛 휙 푠푖푛 훿] expression is used [36]: 180 1 + cos 훽 1 − cos 훽 IT=Ibrb + Id + Iρ (4) where 휔1 and 휔2 are the beginning and the end of 2 g 2 time interval and are equal to 1 h in the In the foregoing equation, Ib and Id are the beam calculations. In addition, 휙 and 훿 are the latitude and diffused solar irradiations, respectively. In and axial tilt of the panel, respectively. In order to addition, rb is the ratio of solar irradiation on the

M.M. Naserian et al./ Renewable Energy Research and Application, Published online tilted plane horizontal plane. For estimation of the ∆퐺 푉 = (11) incident angle of the panel with north-south solar 푟푒푣 푧퐹 tracking system during the day, the following where z and F are the number of electrons equation is used [36]: transferred in a reaction (=2 for hydrogen) and 2 2 COS 휃푇 =푠푖푛 훿 + 푐표푠 훿푐표푠휔 (5) Faraday constant (=96485 C/mol), respectively. In addition, the thermo-neutral cell voltage that and the panel tilt angle should be fixed at: affects the total energy demand for splitting of (6) 훽푇=|휙 − 훿| water is calculated by [41, 42]:

∆퐺 Therefore, the solar azimuth angle in this work was 푉 = (12) 푟푒푣 푧퐹 calculated from the following equations [36]:

∘ The I-V curve form as the function of temperature 0 푖푓 |훾푠| < 90 훾푇 = { ∘ (7) for alkaline electrolyzers is obtained using the 180 푖푓 |훾푠| ≥ 90 equation below: As the efficiency of the photovoltaic panels depends on its cell’s temperature, the following 푉푐푒푙푙 = 푉푟푒푣 + 푉푎푐푡 + 푉표ℎ푚 (13) 푡 푡 equation is used in order to calculate the 푡 + 2 + 3 1 푇 푇2 temperature of the panel surface in this work [39]: 푉푎푐푡 = 푠 푙표푔 ( 퐼 + 1) (14) 퐴 푇푁푂퐶푇 − 20 퐼푇 푇푃푉=푇푎푚푏 + ( )( ) (8) 푟 + 푟 푇 800 3600 푉 = 1 2 퐼 (15) 표ℎ푚 퐴 where Tamb and TNOCT are the ambient temperature and normal working temperature, respectively. where 푉푎푐푡 and 푉표ℎ푚 are the activation and ohmic o Moreover, TNOCT equals to 44 C, as presented in the voltages that are in relation with the activation literature [39]. After calculation of the temperature losses and ohmic losses of the cell, respectively. of the panel surface, the panel efficiency can be The I and A parameters are the electrical current obtained by employment of an equation provided applied to the cell and the electrode area (=0.25 m2 below [39, 40]: in this work), respectively. The Faraday efficiency is obtained using the following equation: 휂푃푉=휂푟푒푓(1 − 훽푟푒푓(푇푃푉-푇푟푒푓)) (9) 퐼 2 ( ) where 휂푟푒푓, 훽푟푒푓, and 푇푟푒푓 are considered as 12%, 퐴 o 휂 = 푓 (16) 0.0045, and 25 C, respectively, in this work [39, 퐹 퐼 2 2 푓 + ( ) 40]. 1 퐴

The electrical voltage at the output of DC-DC and the total hydrogen and oxygen produced by the converter equals to 52 V, and the electrical proposed electrolyzer can be defined as: efficiency of the converter is assumed to be up to 푛 퐼 98%. The fill factor for the proposed PV panel 푛̇ = 2푛̇ = 휂 푐 (17) 퐻2 푂2 퐹 푧퐹 equals to 0.69 when the PV cell temperature o reaches 40 C [40]. The 푛푐 parameter in the above equation is the number of cells in the electrolyzer, which equals to 3.2. Alkaline electrolyzer 21 cells in this work. In order to calculate the heat For simulation of the alkaline electrolyzer, the transfer between the electrolyzer and ambient, the following assumptions were made in this work [41, quasi-state thermal model is provided as:

42]: ∆푡 푇 = 푇 + (푄̇ − 푄̇ − 푄̇ ) (18)  Oxygen and hydrogen are ideal gases; 𝑖 퐶 푔푒푛 푙표푠푠 푐표표푙  Water is a compressible liquid; 푡 푄̇ = 휂 (푉 − 푉 ) (19)  The liquid and gas phases are not mixed. 푔푒푛 푐 푐푒푙푙 푡푛 1 푄̇ = (푇 − 푇 ) (20) The variations in the Gibbs free energy can be 푙표푠푠 푅 푎 expressed as [41]: 푡 푄̇푐표표푙 = 퐶푐푤(푇푐푤,𝑖 − 푇푐푤,표) (21) ∆퐺 = ∆퐻 − 푇∆푆 (10) where 푇, 푇 , ∆푡, 퐶 , 푄̇ , 푄̇ , and 푄̇ are the where ∆퐻 and ∆푆 are the enthalpy and entropy 𝑖 푡 푔푒푛 푙표푠푠 푐표표푙 cell temperature, initial cell temperature, time changes during the water splitting process, interval, overall thermal capacity of the respectively. The reversible cell voltage that electrolyzer, total heat generated in the indicates how much electrical energy is required electrolyzer, total heat loss to the environment, and for splitting of water is provided as [41, 42]:

M.M. Naserian et al./ Renewable Energy Research and Application, Published online total heat transferred to the cooling water, 1 respectively. The overall thermal resistance was 0.95

calculated by defining the cooling pattern for the

y 0.9

electrolyzer for a number of different days [41]: Ct c

n e

o −1 o −1 i c 0.85 = 625 kJ C and Rt = 0:167 C W (equal to 휏 = i

푡 f f

e o

29 h). The equation used for determination of time Reference T=40 C y

a 0.8

Reference T=60oC d constant (휏푡) can be expressed as [41]: a o r Reference T=80 C a 0.75 o

F Model T=40 C 휏푡 = 퐶푡푅푡 (22) Model T=60oC o 0.7 Model T=80 C Furthermore, the constant parameters used in the mentioned equations are provided in Table 2 [41, 0.65 0 50 100 150 200 250 300 350 400 42]. Current density [A/m2]

Table 2. Constant parameters used in the alkaline Figure 3. Faraday efficiency for different cell electrolyzer model [41, 42]. temperatures in various current densities in the proposed model and reference. Parameter Unit Value 2 r1 Ω m 8.05e-5 2 o r2 Ω m / C -2.5e-7 5. Result and Discussion s V 0.185 The climate conditions of the city of Shahrood 2 t1 A m 1.002 were considered as the input parameters of the 2 o t2 m C/A 8.424 model. The variation in the average temperature of 2 o 2 t3 m C /A 247.3 this city is provided in Figure 4. Furthermore, the geographic latitude of this city (being equal to In order to calculate the f1 and f2 parameters, the o values of which depend on temperature, the 36.4 ) was used as the input of the model for calculation of the solar irradiation. The total area of following equations are utilized [41, 42]: 2 the installed PV panels was considered to be 50 m 2 푓1 = 50 + 2.5푇 + (5.082퐸 − 19)푇 (23) in this work. The dates employed as the indicators 2 푓2 = 1 − (2.5퐸 − 4)푇 − (5.346퐸 − 21)푇 (24) of the weathers of the spring, summer, fall, and winter seasons based on the Iranian climate are 4. Validation presented in Table 3.

In order to validate the AEL model presented in the Table 3. Dates that are indicators of various season last section, the results obtained were compared climates in Iran [36]. with the references [41, 42]. The comparison of cell Season Date voltage and faraday efficiency for different cell Spring 20th of March temperatures in various current densities in the Summer 21st of June proposed model and reference are presented in Fall 22nd of September st Figures 2 and 3, respectively. As it could be seen in Winter 21 of December these figures, the same results were obtained in the 30 proposed AEL model, compared to the reference 25

values, which confirmed that the model was ]

o [

reliable. e

r 20 u

2.5 t

r e

p 15

2.4

2.3 g 10

]

a r

[ e

v e 2.2

g A 5

t l Reference T=40oC

v 2.1 o

l Reference T=60 C l o 0 e Reference T=80 C Spring Summer Fall Winter C 2 Model T=40oC Model T=60oC Figure 4. Average ambient temperature of the city of o 1.9 Model T=80 C Shahrood in various seasons.

1.8 0 50 100 150 200 250 300 350 400 Figure 5 shows the percentage of the extra power Current density [A/m2] absorbed by the PV panels using the single-axis Figure 2. Cell voltage for different cell temperatures in solar tracker in different seasons. As it could be various current densities in the proposed model and seen, the PV panel power generation rate increased references [41, 42]. by approximately 0.25%, 17%, 0.65%, and 2.3% in

M.M. Naserian et al./ Renewable Energy Research and Application, Published online the spring, summer, fall, and winter, respectively. resulting in more power production by the PV The rate of electrical power generated by the PV panels in the summer compared to the other panels in different hours of the day during the year seasons (see Figure 6). is presented in Figure 6. Based on the results 0.135 presented in this figure, the maximum peak power produced by PVs in the summer equals to 4.2 kW. 0.13

Furthermore, the minimum and maximum hours of y c

n 0.125 e

sunlight belong to the winter and summer, i

f f

respectively, as it can be seen in this figure. e

0.12

l e

20 n

a p 0.115

]

V Spring P

[ Summer

e 0.11

g 15 Fall

t Winter

e 0.105 c 6 8 10 12 14 16 18

r e Hours of day p

t 10

e FIGURE 7. PV PANEL EFFICIENCY IN VARIOUS HOURS OF

m THE DAY IN DIFFERENT SEASONS.

5 The PV panel output electrical current in various

r e hours of the day is shown in Figure 8 for different

P seasons. In fact, the electrical current at the output 0 of the DC-DC converter was used in this figure. As Spring Summer Fall Winter it could be seen, the maximum electrical current Figure 5. Solar power absorption increment percentage in various seasons by employment of a single-axis solar peak reached 80 A in the summer, and then it tracker. decreased to approximately 74 A and 68 A in the spring and fall, respectively. In addition, it x 103 decreased up to 50 A in the winter. The variation in 5 the electrical current input of the electrolyzer Spring affects its cell operating temperature, as it can be ] Summer

W seen in Figure 9. As the maximum peak current was [ 4 Fall

o Winter reached in the summer, the maximum temperature

r of the electrolyzer operating temperature cell is

e 3 achieved in this season, which equals to almost 80

g o

e C. The peak cell temperature in the fall is higher

o than that in the spring because the ambient

r 2

a temperature in the fall is higher than spring,

S resulting in achieving a higher initial cell temperature in the fall. 1 6 8 10 12 14 16 18 The range of hourly ohmic voltage changes for Hours of day each electrolyzer cell in various seasons is

FIGURE 6. SOLAR POWER GENERATED BY THE PV PANELS indicated in Figure 10. The increment of ohmic IN DIFFERENT HOURS OF THE DAY IN VARIOUS SEASONS. resistance of the cell results in an increase in its temperature, leading to the generation of more The variation in the efficiency of the PV panels in waste heat and reduction of faraday efficiency. The different hours of the day is shown in Figure 7. As ohmic voltage is also called the ohmic over-voltage it could be clearly seen in this figure, the maximum of the cell. As it can be seen in Figure 10, the ohmic efficiency of the PV panels was achieved in the voltage of each cell in the summer and spring winter, which was between 12.5% and 13%, while reaches its maximum amount, which equals to the efficiency of the PV panels in the spring was 0.021V, and its peak decreased to 0.019 and 0.015 around 12.25%. Moreover, the PV panel efficiency in the fall and winter, respectively. in the summer and fall was predicted to be between Figure 11 presents the hydroxy gas production rate 10.75% and 12% in different hours of the day. of the system and the electrolyzer average Faraday While the efficiency of PV in the summer was the efficiency for various seasons of the year. The rate lowest due to increment of its cell temperature, the of hydroxy production rate is 7.6 m3/day, 9.4 proportion of the solar energy absorbed in the m3/day, 10.4 m3/day, and 4.1 m3/day in the spring, summer was still more than the other seasons, summer, fall, and winter in the city of Shahrood,

M.M. Naserian et al./ Renewable Energy Research and Application, Published online

respectively. Furthermore, the maximum average 10 98

]

] y

a Hydroxy generation

Faraday efficiency of the cells is achieved in the %

[ /

Faraday efficiency

3 y

summer, while the minimum average Faraday 8 96 c

[

i t

efficiency is achieved in the winter because of the c

r f

6 94 e

lower electrical current produced by the PV panels n

t a

in the winter compared to the summer. d r

a e

4 92 r

n a

90 e

e y

Spring g

a o

] 2 90 r 80 r Summer e

d v

[ y

t Fall H

e 70 Winter 0 88 r Spring Summer r Fall Winter

c 60

t Figure 11. Hydroxy gas generation rate and average

p Faraday efficiency of the electrolyzer in various seasons of

u 50 the year.

a 40

p 5. Conclusions

V The hydroxy gas is one of the green fuels that can P 30 be used in the transportation systems as an 20 alternative to the fossil fuels. In this work, the 6 8 10 12 14 16 18 Hours of day thermodynamic analysis of an alkaline electrolyzer producer of hydroxy gas integrated with Figure 8. PV panel output electrical current in various hours of the day in different seasons. photovoltaic panels equipped with a single-axis solar tracking system was performed. In order to 80 simulate the integrated systems, the transient

]

o mathematical model of the alkaline electrolyzer

[

e Spring

r and PV panels was developed and written in the

u t Summer a 60

r EES software. The main aim of this work was to

p Fall

m 50 provide a transient analysis of a stand-alone

Winter

g hydroxy production system for investigation of the

t 40

a variations in the system functional parameters in

o 30 various conditions during the year. It was assumed

z that the proposed solar driven hydroxy generation

l 20

r system was installed in the city of Shahrood, and

e 10 l the climate data of this city was used in the

E 0 simulations. Then the hourly changes of the 6 8 10 12 14 16 18 electrolyzer parameters in various seasons during Hours of day the year were analyzed. The main conclusions Figure 9. Electrolyzer stack operating temperature in drawn from this work can be listed as follow: various hours of the day in different seasons.  By installation of the PV panels with an area of 50 m2, up to 4.2 kW electrical power could be x 10-2 2.5 generated. In addition, the electrical current

Spring peak generated by PVs was between 50 A and Summer 80 A in various seasons during the year. 2 Fall  The proposed alkaline electrolyzer operating Winter ] o

[ temperature reached 80 C in the summer;

e o

a however, its peak temperatures were 66 C, 56

o 1.5 o o

C, and 32 C in the fall, spring, and winter,

m respectively.

O 1  The peak ohmic voltage of the electrolyzer cells reached 0.021 V in the spring and summer, and then its peak decreased to 0.019V 0.5 and 0.015V in the fall and winter, respectively. 6 8 10 12 14 16 18  The rate of the hydroxy gas generation was 7.6 Hours of day m3/day in the spring. It increased to 10.4 Figure 10. Ohmic voltage of each electrolyzer cell in 3 various hours of the day in different seasons. m /day in the summer, which was the maximum hydroxy generation rate of the

M.M. Naserian et al./ Renewable Energy Research and Application, Published online

proposed electrolyzer. After that, it decreased generator coupled with a gasoline engine. Energy to 7.2 m3/day and 4.1 m3/day in the fall and Reports. 2020;6:146-56.

winter, respectively. [4] Thanompongchart P and Tippayawong N. Experimental investigation of biogas reforming in 6. Appendix gliding arc plasma reactors. International Journal of Chemical Engineering. 2014;2014. a. Nomenclature [5] Salek F, Zamen M, Hosseini SV, and Babaie M. 2 I Solar irradiation [J/m ] Novel hybrid system of pulsed HHO generator/TEG 흎 Solar hour angle [degree] waste heat recovery for CO reduction of a gasoline 휽 Angle of incident [degree] engine. International Journal of Hydrogen Energy. 2020;45(43):23576-86. 휷 Tilt angle [degree] 흓 Geographic latitude [degree] [6] Zhao H, Nie T, Zhao H, Liu Y, Zhang J, Ye Q et al. Enhancement of Fe-C Micro-electrolysis in Water by 휹 Declination angle [degree] Magnetic Field: Mechanism, Influential Factors and 휸 Azimuth angle [degree] Application Effectiveness. Journal of Hazardous Materials. 2020:124643. V Cell voltage [V] G Gibbs free energy [7] Bos M, Kersten S, and Brilman D. Wind power to z Number of electrons methanol: Renewable methanol production using electricity, electrolysis of water and CO2 air capture. F Faraday constant Applied Energy. 2020;264:114672. T Cell operating temperature o [8] Fang H, Haibin L, and Zengli Z. Advancements in [ C] development of chemical-looping combustion: a review. I Electrical current [A] International Journal of Chemical Engineering. A Electrode area [m2] 2009;2009.

풏̇ Molar flow rate [mol/s] [9] Ghorbani B, Mehrpooya M, and Sadeghzadeh M. 푾̇ Electrical power [W] Process development of a solar-assisted multi- production plant: Power, cooling, and hydrogen. ∆풕 Time interval [s] International Journal of Hydrogen Energy. 푸̇ Heat Transfer rate [W] 2020;45(55):30056-79.

[10] Riyadi BS. Culture of Abuse of Power due to b. Subscripts Conflict of Interest to Corruption for Too Long on the sc Solar constant Management form Resources of Oil and Gas in T Tracker Indonesia. International Journal of Criminology and Sociology. 2020;9:247-54. b Beam d Diffuse [11] Woollacott J. A bridge too far? The role of natural gas electricity generation in the US climate policy. amb Ambient Energy Policy. 2020;147:111867. rev Reversible [12] Ahmadi A, Jamali D, Ehyaei M, and Assad MEH. act Activation Energy, exergy, economic, and exergoenvironmental ohm Ohmic analyses of gas and air bottoming cycles for production i Initial of electricity and hydrogen with gas reformer. Journal of Cleaner Production. 2020;259:120915.

7. References [13] Ahmadi MH, Ghazvini M, Sadeghzadeh M, Alhuyi [1] Naseri A, Fazlikhani M, Sadeghzadeh M, Naeimi A, Nazari M, Kumar R, Naeimi A et al. Solar power Bidi M, and Tabatabaei SH. Thermodynamic and technology for electricity generation: A critical review. Exergy Analyses of a Novel Solar-Powered CO2 Energy Science & Engineering. 2018;6(5):340-61. Transcritical Power Cycle with Recovery of Cryogenic [14] Ahmadi MH, Banihashem SA, Ghazvini M, and LNG using Stirling Engines. Renewable Energy Sadeghzadeh M. Thermo-economic and exergy Research and Application. 2020;1(2):175-85. assessment and optimization of performance of a [2] Alayi R and Jahanbin F. Generation Management hydrogen production system by using geothermal Analysis of a Stand-alone Photovoltaic System with energy. Energy and Environment. 2018;29(8):1373-92. Battery. Renewable Energy Research and Application. [15] Rashid MM, Al Mesfer MK, Naseem H, and Danish 2020;1(2):205-9. M. Hydrogen production by water electrolysis: a review [3] Salek F, Zamen M, and Hosseini SV. Experimental of alkaline water electrolysis, PEM water electrolysis study, energy assessment, and improvement of hydroxy

M.M. Naserian et al./ Renewable Energy Research and Application, Published online and high temperature water electrolysis. Int J Eng Adv [28] Dehghanimadvar M, Shirmohammadi R, Technol. 2015;4(3):2249-8958. Sadeghzadeh M, Aslani A, and Ghasempour R. Hydrogen production technologies: Attractiveness and [16] Ezzahra Chakik F, Kaddami M, and Mikou M. future perspective. International Journal of Energy Effects of operating parameters on hydrogen production Research. by electrolysis of water. international journal of hydrogen energy. 2017;42(40):25550-7. [29] Fereidooni M, Mostafaeipour A, Kalantar V, and Goudarzi H. A comprehensive evaluation of hydrogen [17] Ghazvini M, Sadeghzadeh M, Ahmadi MH, production from photovoltaic power station. Renewable Moosavi S, and Pourfayaz F. Geothermal energy use in and Sustainable Energy Reviews. 2018;82:415-23. hydrogen production: A review. International Journal of Energy Research. 2019;43(14):7823-51. [30] Schnuelle C, Wassermann T, Fuhrlaender D, and Zondervan E. Dynamic hydrogen production from PV [18] Khosravi A, Rodriguez ORS, Talebjedi B, and wind direct electricity supply–Modeling and Laukkanen T, Pabon JJG, and Assad MEH. New techno-economic assessment. International Journal of Correlations for Determination of Optimum Slope Hydrogen Energy. 2020;45(55):29938-52. Angle of Solar Collectors. 2020. [31] Bhattacharyya R, Misra A, and Sandeep K. [19] Menad CA, Gomri R, and Bouchahdane M. Data on Photovoltaic solar energy conversion for hydrogen safe hydrogen production from the solar photovoltaic production by alkaline water electrolysis: conceptual solar panel through alkaline electrolyser under Algerian design and analysis. Energy Conversion and climate. Data in brief. 2018;21:1051-60. management. 2017;133:1-13. [20] M. Sultan S, Tso CP, M. NEE. A Case Study on [32] Ferrari M, Rivarolo M, and Massardo A. Hydrogen Effect of Inclination Angle on Performance of production system from photovoltaic panels: Photovoltaic Solar Thermal Collector in Forced Fluid experimental characterization and size optimization. Mode. Renewable Energy Research and Application. Energy Conversion and Management. 2016;116:194- 2020;1(2):187-96. 202. [21] Touili S, Merrouni AA, El Hassouani Y, Amrani A- [33] Cilogulları M, Erden M, Karakilcik M, and Dincer i, and Rachidi S. Analysis of the yield and production I. Investigation of hydrogen production performance of cost of large-scale electrolytic hydrogen from different a Photovoltaic and Thermal System. international solar technologies and under several Moroccan climate journal of hydrogen energy. 2017;42(4):2547-52. zones. International Journal of Hydrogen Energy. 2020;45(51):26785-99. [34] Maatallah T, El Alimi S, and Nassrallah SB. Performance modeling and investigation of fixed, single [22] Beigzadeh M, Pourfayaz F, and Pourkiaei S. and dual-axis tracking photovoltaic panel in Monastir Modeling Heat and Power Generation for Green city, Tunisia. Renewable and Sustainable Energy Buildings based on Solid Oxide Fuel Cells and Reviews. 2011;15(8):4053-66. Renewable Fuels (Biogas). Renewable Energy Research and Application. 2020;1(1):55-63. [35] Afanasyeva S, Bogdanov D, and Breyer C. Relevance of PV with single-axis tracking for energy [23] Castrillo EDR, Santaella JRB, Assad MEH, scenarios. Solar Energy. 2018;173:173-91. Khosravi A, and Pabón JJG, editors. Modeling and validation of a comercial dry electrolytic cell for the [36] Duffie JA, Beckman WA, and Blair N. Solar production of oxyhydrogen. 2020 Advances in Science engineering of thermal processes, photovoltaics and and Engineering Technology International Conferences wind: John Wiley & Sons; 2020. (ASET): IEEE. [37] Zhang D and Allagui A. Fundamentals and [24] Ruuskanen V, Koponen J, Huoman K, Kosonen A, performance of solar photovoltaic systems. Design and Niemelä M, and Ahola J. PEM water electrolyzer model Performance Optimization of Renewable Energy for a power-hardware-in-loop simulator. International Systems: Elsevier; 2021. p. 117-29. Journal of Hydrogen Energy. 2017;42(16):10775-84. [38] Pourderogar H, Harasii H, Alayi R, Delbari SH, [25] Guo Y, Li G, Zhou J, and Liu Y, editors. Sadeghzadeh M, and Javaherbakhsh AR. Modeling and Comparison between hydrogen production by alkaline Technical Analysis of Solar Tracking System to Find water electrolysis and hydrogen production by PEM Optimal Angle for Maximum Power Generation using electrolysis. IOP Conference Series: Earth and MOPSO Algorithm. Renewable Energy Research and Environmental Science; 2019: IOP Publishing. Application. 2020;1(2):211-22.

[26] Keçebaş A, Kayfeci M,and Bayat M. [39] Olukan TA and Emziane M. A comparative Electrochemical hydrogen generation. Solar Hydrogen analysis of PV module temperature models. Energy Production: Elsevier; 2019. p. 299-317. Procedia. 2014;62(2):694-703.

[27] Navarro R, Guil R, and Fierro J. Introduction to [40] Fesharaki VJ, Dehghani M, Fesharaki JJ, and hydrogen production. Compendium of Hydrogen Tavasoli H, editors. Effect of temperature on Energy: Elsevier; 2015. p. 21-61. photovoltaic cell efficiency. Proceedings of the

M.M. Naserian et al./ Renewable Energy Research and Application, Published online

1stInternational Conference on Emerging Trends in [42] Tijani AS, Yusup NAB, Rahim AA. Mathematical Energy Conservation–ETEC, Tehran, Iran; 2011. modelling and simulation analysis of advanced alkaline [41] Ulleberg Ø. Modeling of advanced alkaline electrolyzer system for hydrogen production. Procedia electrolyzers: a system simulation approach. Technology. 2014;15:798-806. International journal of hydrogen energy. 2003;28(1):21-33.