
==== Front
Data Brief
Data Brief
Data in Brief
2352-3409
Elsevier

S2352-3409(24)00731-5
10.1016/j.dib.2024.110765
110765
Data Article
Data from steady-state simulation and economic evaluation in the power to methane context for synthetic natural gas production and power generation
Rengifo Camilo b
Novoa Maria Paula a
Cobo Martha a
Figueredo Manuel manuel.figueredo@unisabana.edu.co
a⁎
a Energy, Materials and Environment Laboratory, Faculty of Engineering, Universidad de La Sabana, Campus Universitario Puente del Común, Km. 7 Autopista Norte, Bogotá, Colombia
b Department of Mathematics, Physics and Statistics, Universidad de La Sabana, Campus Universitario Puente del Común, Km. 7 Autopista Norte, Bogotá, Colombia
⁎ Corresponding author. manuel.figueredo@unisabana.edu.co
23 7 2024
10 2024
23 7 2024
56 11076511 7 2024
15 7 2024
© 2024 The Authors
2024
https://creativecommons.org/licenses/by-nc/4.0/ This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).
The data presented in this article is generated by a steady-state simulation for performing a techno-economic assessment for comparing three electrolysis technologies in the PtM context. The data is focused on two aspects. First, the description of the steady-state simulation of six PtM systems modeled using Aspen Custom Modeler (ACM) and Aspen Plus (AP). Second, an economic assessment is carried out for each of the mentioned PtM systems to compare the feasibility, the profitability and performance of these systems on a larger scale to produce synthetic natural gas, power generation and carbon utilization given in the main research article. Three electrolysis technologies (namely Alkaline Electrolysis - AE, Proton Exchange Membrane Electrolysis - PEME and Solid Oxide Electrolysis - SOE) were modeled having in mind two methane applications: a combined cycle for power generation and the syngas generation. In addition, on each PtM system is carried out an economic evaluation by calculating fixed capital investment (FCI) and manufacturing costs (MC).

Keywords

Alkaline electrolysis
Proton exchange membrane electrolysis
Solid oxide electrolysis cell
Aspen custom modeler
==== Body
pmcSpecifications TableSubject	Chemical Engineering: Process Chemistry and Technology	
Specific subject area	Chemical Process Simulation	
Data format	Raw and processed	
Type of data	Table and Figure	
Data collection	Primary data concerning specification design of the PtM systems was obtained from the literature review, Aspen Custom Modeler and Aspen Plus simulations. Data for the techno-economic evaluation was obtained from literature review and calculations using methods which are describe along this document.	
Data source location	Institution: Universidad de La Sabana
City/Town/Region: Chía, Cundinamarca
Country: Colombia	
Data accessibility	Raw data
Repository name: Simulation data for the comparison of electrolysis technologies in the context of Power-2-Gas
Data identification number: https://doi.org/10.17632/2jv2wfycfx.1
Access to simulations: https://doi.org/10.5281/zenodo.12724084
Direct URL to data: https://data.mendeley.com/datasets/2jv2wfycfx/1	
Related research article	M.P Novoa, C. Rengifo, M. Figueredo, M. Cobo. (2024) Techno-economic assessment of the Synthetic Natural Gas production using different electrolysis technologies and product applications. Submitted to International Journal of Hydrogen Energy.
DOI: https://doi.org/10.1016/j.ijhydene.2024.06.354	

1 Value of the Data

• The data shown in this article provides suitable operating conditions, specifications, and techno-economic comparison for six different Power to Methane (PtM) systems using three electrolysis technologies for gas and power generation. This data supports the assessment for PtM systems depicted in the main research article.

• The data shown in this document could be used by anyone who wants to simulate and compare three electrolysis technologies which feed a methanation reactor for synthetic natural gas production and energy generation.

• There are custom models for the three electrolyzer technologies that can be used as a foundation for more rigorous models for further analysis of the coupling of methanation reactors with electrolysis technologies.

2 Data Description

The data contains the following structure:• ELECTROLYSIS_ACM: These are the electrolysis models implemented in Aspen Custom Modeler (ACM). This folder is composed of the following subfolders:○ AEC: Contains the simulation file (AEC_UNIT.acmf) for the Alkaline Electrolysis technology.

○ PEM: Contains the simulation file (PEM_UNIT.acmf) for the Proton Exchange Membrane Electrolysis technology.

○ SOEC: Contains the simulation file (SOEC_UNIT.acmf) for the Solid Oxide Electrolysis technology.

• PROCESS_SIMULATION: It contains the compiled electrolyzer models as well as the flowsheets built in Aspen Plus V 12.0. This folder is composed of the following subfolders:○ ACM_Models: It contains the compiled models ready to be imported into Aspen Plus. Their format is. atmlxz (Aspen Exported Custom Model). One can find the AlgebraicAEC.atmlz, PEMRev.atmlz, and SOEC_alg.atmlz. Their source code can be found in the ELECTROLYSIS_ACM folder.

○ AEC_GT: This folder contains the flowsheet definition for the coupled AE-Methanation process for Gas Production. The main file is named AEC_GasTreatment.apw

○ AEC_PC: This folder contains the flowsheet definition for the coupled AE-Methanation process for power generation. The main file is named AEC_PowerCycle.apw

○ PEM_GT: This folder contains the flowsheet definition for the coupled PEME-Methanation process for gas production. The main file is named PEM_GasTreatment.apw

○ PEM_PC: This folder contains the flowsheet definition for the coupled PEME-Methanation process for power generation. The main file is named PEM_PowerCycle.apw

○ SOEC_GT: This folder contains the flowsheet definition for the coupled SOEC-Methanation process for gas production. The main file is named SOEC_GasTreatment.apw

○ SOEC_PC: This folder contains the flowsheet definition for the coupled SOEC-Methanation process for power generation. The main file is named SOEC_PowerCycle.apw

3 Experimental Design, Materials and Methods

Nomenclature			
A	Area [m2]	τ	Tortuosity [-]	
а	Water activity [-]			
Ck	Experimental parameter related to gas purity	Subscripts and superscripts	
D	Diffusion coefficient [m2·s−1]	act	Activation	
dk	Experimental parameter related to ohmic resistance	an	Anode	
dm	Membrane dry density [g·cm−3]	ca	Cathode	
Ea	Activation energy [KJ·mol−1]	cat	Catalyst	
Ec	Electrical conductivity activation energy [eV]	cell	Electrolysis cell	
Ee	Irradiance [W·m−2]	conc	Concentration	
Ek	Experimental parameter related to gas purity	diff	Diffusion	
F	Faraday constant (960,485.33 C·mol−1)	drag	Electro-osmotic drag	
fk	Experimental parameter related to Faraday efficiency	e	Electrolyte	
ΔH	Adsorption enthalpy [KJ·mol−1]	eff	Effective	
I	Current [A]	exp	experimental	
i	Current density [A·m−2]	g	Gas	
iL	Limiting current density [A·m−2]	i	Component	
i0	Exchange current density [A·m−2]	in	Inlet	
K	Adsorption constant [bar−0.5]	j	Electrode	
KB	Boltzmann constant (1.3806·10−23 J·K−1)	k	Constant number for experimental parameters	
Keq	Equilibrium constant [bar−2]	Kn	Knudsen	
K0	Adsorption constant pre-exponential factor [bar−2]	LSM	Lanthanum strontium manganite	
k	Catalytic reaction kinetic factor [mol·bar−1·s−1·gcat−1]	m	Membrane	
k0	Kinetic pre-exponential factor [mol·bar−1·s−1·gcat−1]	mix	Mixture	
M	Molecular mass [kg·kmol−1]	Ner	Nernst	
m˙	Mass flowrate [kg·h−1]	NiYSZ	Yttrium and nickel stabilized zirconium	
N	Number of units	ohm	Ohmic	
n	Sample size	PV	Photovoltaic module	
N˙	Molar flowrate [mol·s−1]	R	Released	
nd	Electro-osmotic drag coefficient [-]	ref	Reference	
P	Pressure [bar]	rxn	Reaction	
p	Partial pressure [bar]	sat	Saturation	
p0	Partial pressure at ambient pressure [bar]	SG	Syngas	
Q	Heat rate [GJ·h−1]	stack	Electrolysis unit	
R	Ideal gas constant (8.314472 J·K−1·mol−1)	T	Total	
rk	Experimental parameter related to ohmic resistance	th	Experimental data in the -th position	
s	Overvoltage coefficient [V]	YSZ	Yttrium stabilized zirconium	
T	Temperature [K]	Acronyms	
tk	Experimental parameter overvoltage coefficient [V]	AE	Alkaline Electrolysis	
tsun	Hours of son per day [h]	ACM	Aspen Custom Modeler	
V	Voltage / Overpotential [V]	AP	Aspen Plus	
v	Reaction rate [mol·s−1·gcat−1]	DC	Direct Costs	
W	Electrical power [W]	EC	Equipment Costs	
z	Number of electrons transferred per ion (2)	FCI	Fixed Capital Investment	
		GI	Gross income	
Greek Letters	HHV	Higher Heating Value	
α	Change transfer coefficient [-]	HTO	Hydrogen to Oxygen	
δ	Thickness [m]	IC	Indirect Costs	
ε	Electrode porosity [-]	LHV	Lower Heating Value	
η	Efficiency [-]	MC	Manufacturing (or production) Costs	
ηf	Faraday efficiency [-]	PtM	Power to Methane	
∅p	Pore diameter [m]	PFD	Process Flow Diagram	
λ	Moisture content [-]	PEME	Proton Exchange Membrane Electrolysis	
ρ	Resistivity [cm·S−1]	RSME	Root Mean Square Deviation Error	
σ	Conductivity [S·cm−1]	SOE	Solid Oxide Electrolysis	
σ0	Conductivity pre-exponential factor [S·cm−1]	TE	Total Earnings	

3.1 PtM steady-state simulation

The principal streams and operating units are named in Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6. The central operating units are the methanation reactor (MR-1), the combustion reactor (CR-1), the absorption column (AC-1), the recovery column (RC-1), and the electrolysis set (ES-1). CR-1 appears in the power cycle application, and AC-1 and RC-1 appear in the gas treatment application. The rest of the operating units share the same layout conventions listed in Table 1Fig. 1 Layout for AE-based PtM system with a combined cycle.

Fig. 1

Fig. 2 Layout for AE-based PtM system with a gas treatment stage.

Fig. 2

Fig. 3 Layout for PEME-based PtM system with a combined cycle.

Fig. 3

Fig. 4 Layout for PEME-based PtM system with a gas treatment stage.

Fig. 4

Fig. 5 Layout for SOE-based PtM system with a combined cycle.

Fig. 5

Fig. 6 Layout for SOE-based PtM system with a gas treatment stage.

Fig. 6

Table 1 PtM systems PFD layout conventions.

Table 1Operating unit	Figure layout	Operating unit	Figure layout	
Compressor	Image, table 1	Turbine	Image, table 1	
Pump	Image, table 1	Valve	Image, table 1	
Heat Exchanger	Image, table 1	Stream	Figure layout	
Heat Exchanger integrated	Image, table 1	Material input	Image, table 1	
Drum / Phase separator	Image, table 1	Material intermediate	Image, table 1	
Membrane separator	Image, table 1	Material output	Image, table 1	
Mixer	Image, table 1	Power input	Image, table 1	
Gas Mixer	Image, table 1	Power output	Image, table 1	
Splitter	Image, table 1			

3.2 General layouts for PtM systems

The AE-based PtM system layout for power generation is shown in Fig. 1. This arrangement feeds water to the electrolysis set (60 electrolysis units of 12 cells each) as a 25–35 % KOH solution. Cathode and anode streams pass through drums to separate the main gas from the water that did not react, some water is purged, and some water is recycled into the system. The methanation reaction product is fed to a drum to separate the methane and gases from the produced water (recycled into the system) and this gas enters a combined cycle with air and anode oxygen generating combustion gas that passes through a gas turbine for power generation. This layout is analogue to the AE-based system with gas treatment, however, instead of entering a combustion reactor, the methanation product is fed to a water removal process using triethylene glycol as the solvent. This arrangement is shown in Fig. 2.

Fig. 3, Fig. 4 show the PEME-based PtM system layout with a power cycle and with gas treatment, respectively. They share the same configuration as the AE-based one and keeps the same energy integration arrangement since electrolysis operation temperature is comparable between both technologies. In the case of SOE-based systems, the main differences from the previous systems are the absence of water in the anode outlet due to its operating principle and the electrolysis operating temperature. A heat exchanger before the electrolysis set is required since electrolysis voltage is insufficient to bring the water inlet to the operating temperature. For the power cycle case, shown in Fig. 5, the heat exchange between the combustion gases and the steam cycle water is kept and the required heat for the water inlet to the electrolysis set is reduced by harnessing the heat from the hot fluid, methanation product, and H2/CO2 mixture streams. In the case of gas treatment, a different heat integration scheme was used obtaining the layout shown in Fig. 6.

3.3 Catalytic methanation

The operating temperature and pressure of the reactor are initially set at 400 K and 5 bar with a stoichiometric feed of 4 for H2/CO2 according to the recommendation of Ortiz-Laverde, [12]. The reactor parameters, such as diameter, length, and the number of tubes, are calculated from the reaction kinetics and design equations for Packed Bed Reactors (PBR). Ethylene glycol is selected as the thermal fluid and 550 K as its outlet temperature [12]. The thermal fluid flow is adjusted through a 3.7 ratio between the ethylene glycol mass flow and the CO2 mass flow of the process stream. The CO2 fed to the rector is considered pure for practical purposes with a temperature around 15.4–17 °C and carbon capture by pressure swing absorption representative [16]. For this model resolution, a high-order discretization method (4th order upwind biased finite differencing – UBFD4) is used, as well as a considerable number of discretization points (432), considering the sudden process stream temperature changes.

3.4 Combined cycle

The combined cycle for power generation integrated into the process couples a gas turbine power plant, including an air compressor, a combustion chamber, and a gas turbine, with a non-ideal Rankine steam cycle containing a heat exchanger, a pump, a condenser, and a steam turbine. The catalytic (hexaaluminate) combustion reactor of the power cycle is a reference point in methane combustion simulation for methanation reaction products, although it is suitable for gas turbines and high operating temperatures. Therefore, combustion is simulated in a stoichiometric reactor from the AP model palette with 100 % methane conversion at operating conditions of 1533 K and 14 bar. Additionally, 10 to 20% excess air is specified for good methane combustion performance as suggested by the Environmental Protection Agency, see [5]. The other units in the cycle operate under the conditions reported by Ong'iro et al. in [11].

3.5 Gas treatment

Methanation product gas treatment for water removal consists of a first flash to remove most of the water in the stream. This flash operates at 338 K and 5 bar, see [17]. The product gas is brought to the operating conditions of an absorption tower, where it is fed through bottoms, and it enters in contact with a triethylene glycol (TEG) stream. The TEG stream containing the water removed from the product gas is taken to a distillation tower to recover the solvent and re-enter it into the process with fresh feed. Tower parameters such as stages number, reflux, height, and spacing are calculated from the equilibrium of each component system extracted from Aspen Plus simulation and design heuristics for absorption and distillation towers (Table 2, Table 3).Table 2 Streams involved in PtM systems PFD layout.

Table 2Figure	Stream	
Image, table 2	Cathode outlet stream / Hydrogen	
Image, table 2	Waste gas	
Image, table 2	Anode outlet stream / Oxygen	
Image, table 2	Water (mainly)	
Image, table 2	Steam	
Image, table 2	Heat exchange fluid (hot oil)	
Image, table 2	Carbon dioxide captured	
Image, table 2	Methanation product / SNG	
Image, table 2	Combustion gas	
Image, table 2	Potassium hydroxide (KOH)	
Image, table 2	Methanation feed	
Image, table 2	Triethylene glycol (TEG)	
Image, table 2	Triethylene glycol and water	
Image, table 2	Air	

Table 3 Color convention in the PtM systems PFD layout.

Table 3Color	Area	
Image, table 3	Water feed and recycle	
Image, table 3	Electrolysis	
Image, table 3	Methanation	
Image, table 3	Power cycle	
Image, table 3	SNG drying with TEG	

3.6 Other units

All other units involved in the system are simulated from predefined models in Aspen Plus. For AE and PEME-based systems, the phase separators are simulated as flash units at the same operating pressure as the electrolysis units and 333 K for water condensation. The SOE-based system uses a separation membrane simulated as an isothermal and isobaric splitter. Most pressure changers are simulated with an isentropic efficiency of 0.92 and mechanical efficiency of 0.99, except for the gas turbine in which a polytropic model is used, [11].

3.7 Economic evaluation model

The evaluation and economic analysis of the plant arrangements defined for each electrolysis technology follow the structure proposed by Peters et al. in [14] for fixed capital investment and manufacturing costs. The basis for these estimations consists of the equipment and raw materials costs, calculated from the Activated Economic Analysis tool integrated into the Aspen Plus simulation, the Aspen Energy Analyzer simulations or cost approximations according to its capacities and typical exponents index. Production costs and gross income are calculated for the year of 1500 operation hours and an average of 10.05 kW of electrical power is supplied to each electrolysis unit in each arrangement.

3.8 Computational and simulation aspects

The solver used to solve the electrolysis models corresponds to a standard non-linear mode for testing the model's functionality with the mixed Newton method, residual convergence criterion, a maximum of 100 iterations, and tolerance of 1·10−5, as suggested by the ACM help. For the catalytic reactor, a high-order discretization method (4th order upwind biased finite differencing – UBFD4) is used, as well as a considerable number of discretization points (432), considering the sudden process stream temperature changes. The Peng-Robinson thermodynamic model is selected as it is considered appropriate for methanation, see [12], and power cycles, along with UNIQUAC for the gas treatment units.

3.9 Mathematical models used in the simulation

A. Alkaline electrolysis (AE) model

For the AE, Table A.1 shows a semi-empirical algebraic model proposed and studied in [17,18]. Eq. (A.1) describes the polarization curve for the cell voltage as a sum of the reversible voltage and overpotentials (activation and ohmic overpotentials) associated with the electrolysis technology. The reversible voltage follows Eq. (A.2) proposed by Spiegel in [20] as a function of cell temperature. Gas purity is expressed as the hydrogen to oxygen fraction (HTO fraction), which refers to the molar fraction of hydrogen that comes from the anode together with oxygen (Eq. A.3-A.10). The mass balances respond to Faraday's law for electrolysis, according to Eq. (A.5). Regarding the energy balance, the electrolysis unit power input is defined as a function of current, cell voltage, and number of cells. Heat is generated within the system and released to the environment if the cell voltage is enough to drive the electrolytic reaction and have surpluses (Eq. A12-A.14). Some interest variables’ ranges for the unit are listed in Table A-2, and the experimental parameters reported by Sánchez are listed in Table A-3.B. Proton exchange membrane electrolysis model

For the PEME, an algebraic model is proposed in Table B.1, Table B.1–B.3 based on equations reported by Spiegel, Ogumerem & Pistikopoulos, and Han et al. for electrolyzers, [20,10] and [6]. The electrolytic unit model and mass balance are included, contemplating water permeation towards the cathode by electro-osmotic drag and diffusion in the membrane. The electrolytic model starts from cell voltage definition Eq. (B.1), as the sum of the Nernst voltage Eq. (B.2) (B3), and the system overpotentials: activation overpotential Eqs. (B.4), (B.5) and (B.6), ohmic overpotential Eqs. (B.7) (B.8) and concentration overpotential Eq. (B.9). The mass balance is given by calculating the molar flow of water consumed in the electrolytic reaction Eq. (B.10), the permeated water flow towards the cathode by electro-osmotic drag Eq. (B.11), and the flow permeated by diffusion Eqs. (B.12), (B.13) and B14. Eqs. (B.15) to (B.18) describe the molar flows distribution in the electrodes. The water vapor saturation pressure at operating temperature is given by Eq. (B.19). From the AE technology, Eqs. (A.11) and (A.12) are also integrated into the membrane model since they are general for the electrolysis process. Interest variables’ ranges for the unit are reported in Table B-2, and the involved parameters are listed in Table B-3.C. Solid oxide electrolysis cell model

For the SOE technology an algebraic model is proposed in Tables C.1—C.3 based mainly on the one reported in [2]. The system's mass balance is given by the water molar flow consumed in the electrolytic reaction according to Eq. (B-10) from PEME. The electrolytic model starts from the cell voltage definition as the sum of the Nernst voltage and the system's overpotentials. The expressions for cell voltage, Nernst equation, and activation overpotential are the same as those for the PEME model Eqs. (B.1)(B.2) and (B4) to (B6).Reversible potential is calculated using Eq (C.12) to (C.14). Eqs. (C.1) to (C.4) describe the ohmic and concentration overpotentials. Eqs. (C.5) and (C.6) give the effective diffusion coefficients, while the resistivities are calculated as the inverse of the conductivity Eq. (C.7), see [13]. The conductivities are given by expressions that depend on the electrode or electrolyte material as a function of temperature. According to the electrolysis system analyzed by AlZahrani & Dincer, the material for the cathode, anode, and electrolyte is assumed to be yttrium and nickel stabilized zirconium (NiYSZ), lanthanum strontium manganite (LSM) and yttrium stabilized zirconium (YSZ), respectively. Some material's conductivities can be adjusted to the Arrhenius equation as a function of temperature, as for LSM and YSZ Eq. (C.8). For NiYSZ a linear equation can model its conductivity as a function of temperature Eq. (C.9). Also, the ohmic overpotential can be assumed to be 10 % of the Nerst potential, which helps on convergence and numerical stability of the model. The mass balance is given by the calculation of the water molar flow consumed in the reaction Eq. (B.9), the other component flows through the anode and cathode are given according to the water electrolysis global reaction and the solid oxide electrolysis working principle Eqs. (C.10), (C.11) and (C.12). Some interest variables’ ranges for the unit are reported in Table C-2, and the parameters involved are listed in Table C-3.D. Model validation

The proposed mathematical models were validated using published experimental data available in the literature (Table C.4, Table D.1). The AE electrolysis model was tested using data from [20], obtaining a good fit reflected in a low RSME (2.42 %). The PEME model was validated with experimental data obtained from [21], also revealing a good agreement (RSME=3.37 %). Finally, the SOE model exhibited correspondence between the model and the experimental data (RSME=2.8614) obtained from [22]. Results are shown in Fig. D.1. All validation parameters are consolidated in Table D.2E. Catalytic methanation

Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetics proposed by Koschany in [7] for heterogeneous catalysis with Ni/SiO2 were employed according to Table E-1. The parameters involved in the reaction kinetics are listed in Table E-2.F. Economic evaluation

The fixed capital investment (FCI) corresponds to Eq. (F.1), defined as the sum of direct (DC) and indirect costs (IC). Equipment, installation, instrumentation and control, piping, electrical systems, building and services, service facilities, and land costs are included in direct costs. Indirect costs include engineering and supervision costs, legal expenses, construction, and contractor expenses, and working capital. Manufacturing or production costs (MC) include raw materials, operating labor, utilities, maintenance and repairs, and operating supplies, see [14]. The gross income (GI) comes from the produced fuel (electricity or natural gas) and carbon credits. The subtraction between the gross income and production costs is considered total earnings (TE) or profit, according to Eq. (F.2) (Table F.1, Table F.2, Table F.3).

Limitations

Not Applicable.

Ethics Statement

This work did not involve human subjects or laboratory animal, therefore did not meet any ethical issues.

CRediT authorship contribution statement

Camilo Rengifo: Methodology, Investigation, Formal analysis, Writing – review & editing. Maria Paula Novoa: Conceptualization, Methodology, Investigation, Formal analysis, Software, Writing – original draft. Martha Cobo: Funding acquisition, Formal analysis, Writing – review & editing. Manuel Figueredo: Project administration, Methodology, Investigation, Software, Formal analysis, Writing – review & editing.

Appendix

Table A.1 Table A.1. Alkaline electrolysis model equations.

Table A1Vcell=Vrev+(r1+d1+r2T+d2P)·i+s·log[(t1+t2T+t3T2)·i+1]	(A.1)	
Vrev=1.229−0.8460·10−03(T−Tref)	(A.2)	
ηF=[i2(f11+f12T)+i2]·(f21+f22T)	(A.3)	
fHTO=[C1+C2T+C2T2+(C4+C5T+C6T2)e(C7+C8T+C9T2i)]+[E1+E2P+E3P2+(E4+E5P+E6P2)e(E7+E8P+E9P2i)]	(A.4)	
N˙rxn=ηFIzFNcell	(A.5)	
N˙H2ca=N˙rxn·(1−fHTO)	(A.6)	
N˙O2an=N˙rxn/2	(A.7)	
N˙H2an=N˙rxn·fHTO	(A.8)	
N˙H2Oca=(N˙in−N˙rxn)/2	(A.9)	
N˙H2Oan=(N˙in−N˙rxn)/2	(A.10)	
Wstack=VcellNcellI	(A.11)	
I=iAcell	(A.12)	
Qg=NcellI(Vcell−1.482V)	(A.13)	
QR=0.1Qg	(A.14)	

Table A.2 Table A.2. Operating conditions range for the alkaline electrolysis model [[1], [2], [3]].

Table A2Variable	Value	Units	
Maximum hydrogen flow	2.5	m3·h−1	
Pressure	0–30	bar	
Temperature	40–90	°C	
Voltage	0–120	V	
Current	0–500	A	
Maximum power	1.5	MW	
Reference temperature (Tref)	2 5	°C	

Table A.3 Table A.3. Experimental parameters for the alkaline electrolysis model [1].

Table A3Parameter	Value	Units	
r1	4.4515×10−5	Ω·m2	
r2	6.8887×10−9	Ω·m2· °C−1	
d1	−3.12996×10−6	Ω·m2	
d2	4.47137×10−7	Ω·m2·bar−1	
t1	−0.01539	m2·A−1	
t2	2.00181	m2·°C·A−1	
t3	15.24178	m2·°C2·A−1	
s	0.33824	V	
f11	478,645.7	A2·m−4	
f12	−2953.15	A2·m−4·°C−1	
f21	1.03960	(–)	
f22	-0.00104	°C−1	
C1	0.09901	(–)	
C2	-0.00207	°C−1	
C3	1.3106×10−5	°C−2	
C4	−0.08483	(–)	
C5	0.00179	°C−1	
C6	-1.1339×10−5	°C−2	
C7	1481.45	A·m−2	
C8	−23.60345	A·m−2·°C−1	
C9	−0.25774	A·m−2·°C−2	
E1	3.71417	(–)	
E2	−0.93063	bar−1	
E3	0.05817	bar−2	
E4	−3.72068	(–)	
E5	0.93219	bar−1	
E6	−0.05826	bar−2	
E7	−18.38215	A·m−2	
E8	5.87316	A·m−2·bar−1	
E9	−0.46425	A·m−2·bar−2	

Table B.1 Table B.1. Proton exchange membrane electrolysis model equations.

Table B1Vcell=Vnernst+Vact+Vohm+Vconc	(B.1)	
Vner=Vrev+RTzFln(pH2pO20.5pH2O)	(B.2)	
Vrev=1.229−0.8460·10−03(T−Tref)	(B.3)	
Vactca=RTαcaFarcsinh(i2ica0)=RTαcaFln(i2ica0+1+(i2ica0)2)	(B.4)	
Vactan=RTαanFarcsinh(i2ian0)=RTαanFln(i2ian0+1+(i2ian0)2)	(B.5)	
Vact=Vactca+Vactan	(B.6)	
Vohm=δmiσm	(B.7)	
σm=(0.005139λm−0.00326)e[1268(1303−1T)]	(B.8)	
Vconc=RTzFln(iLiL−i)	(B.9)	
(continued on next page)	

Table B.1 Table B.1. (continued)

Table B1N˙H2Orxn=I·NcellzF	(B.10)	
N˙H2Odrag=I·nd·NcellzF	(B.11)	
N˙H2Odiff=NcellDH2OmAcelldmδmMm(λan−λca)	(B.12)	
λj=0.043+17.81аj−39.85аj2+36аj3	(B.13)	
аj=pH2OjPH2Osat	(B.14)	
N˙H2ca=N˙H2Orxn	(B.15)	
N˙O2an=N˙H2Orxn/2	(B.16)	
N˙H2Oca=N˙H2Odrag+N˙H2Odiff	(B.17)	
N˙H2Oan=N˙H2Oin−N˙H2Odrag−N˙H2Odiff−N˙H2Orxn	(B.18)	
log(PH2Osat)=7.94917−(1657.462T+227.02)	(B.19)	

Table B.2 Table B.2. Operating conditions range for the proton exchange membrane electrolysis model.

Table B2Variable	Value	Units	References	
Cell's area	50–400	cm2	[[4], [5], [6], [7], [8]]	
Cells number	4–20	(–)	
Current density	0.5–1.6	A·cm−2	
Pressure	0–35	bar	
Temperature	313–355	K	
Maximum power	4.7–5.6	kW	

Table B.3 Table B.3. Parameters used in the proton exchange membrane electrolysis model.

Table B3Parameter	Value	Units	References	
δm	0.015	cm2	[9]	
dm	1.92	g·cm−3	(Satterfield et al., 2006)	
Mm	1100	kg·kmol−1		
ian0	1.381·10−5	A·cm−2		
ica0	4.640·10−3	A·cm−2		
αan	2.0	(–)		
αca	0.5	(–)		
λm	22	(–)		
nd	0.27	(–)		
DH2Om	1.28 0·10−10	m2·s−1		
iL	2.0	A·cm−2		

Table C.1 Table C.1. Solid oxide electrolysis model equations.

Table C1Vohm=i(ρanδan+ρcaδca+ρeδe)	(C.1)	
Vconcca=RTzFln[1+(iRTδca2FDH2effpH20)1−(iRTδca2FDH2OeffpH2O0)]	(C.2)	
Vconcan=RTzFln{[1+(iRTδan4FDO2effpO20)]0.5}	(C.3)	
Vconc=Vconcca+Vconcan	(C.4)	
Dieff=ετDiKn	(C.5)	
DiKn=∅p38RTπMi	(C.6)	
ρj=1σj	(C.7)	
σjT=σj0e(−EcjkBT)	(C.8)	
N˙H2ca=N˙H2Orxn	(C.9)	
N˙H2ca=N˙H2Orxn	(C.10)	
N˙O2an=N˙H2Orxn/2	(C.11)	
N˙H2Oca=N˙H2Oin−N˙H2Orxn	(C.12)	
Vrev=ΔGzF	(C.13)	
ΔG=ΔH−TcellΔS	(C.14)	
ΔH=HH2+12H02−HH2O	(C.15)	
ΔS=SH2+12S02−SH2O	(C.16)	
Hi(Tcell)=aiTcell+45biTcell5/4+23cjTcell3/2+47diTcell7/4	(C.17)	
Si(Tcell)=ailn(Tcell)+4biTcell14+2cjTcell12+43diTcell34−Rln(P)	(C.18)	

Table C.2 Table C.2. Operating conditions range for the solid oxide electrolysis model.

Table C2Variable	Value	Units	References	
Cell's area	25–400	cm2	[[13], [14], [15], [16]]	
Current density	1000–25,000	A·cm−2	
Pressure	0–15	Bar	
Temperature	500–1000	°C	

Table C.3 Table C.3 Parameters used in the solid oxide electrolysis model.

Table C3Parameter	Value	Units	References	
δca	312.5·10−6	m		
δan	17.50·10−6	m		
δe	12.50·10−6	m		
ε	0.3	(–)		
τ	5.0	(–)		
∅p	0.5·10−6	m		
σLSM@900∘C	235	S·cm−1		
σYSZ@700∘C	0.0037	S·cm−1		
EcLSM	0.09836	eV		
EcYSZ	1.12	eV·m2·s−1	[19]	
ian0	6500	A·m−2		
ica0	2500	A·m−2		

Table C.4 Table C.4. Parameters used for Eqs (C.17) and (C.18).

Table C4Component	ai	bi	ci	di	
Water	180	−85.4	15.6	−0.858	
Hydrogen	79.5	−26.3	4.23	−0.197	
Oxygen	10.3	5.4	−0.18	0	

Table D.1 Table D.1. Model validation equations.

Table D1RMSE=∑(Vth−Vexp)2n−1	(D.1)	
MAPE=∑(Vth−Vexp)Vthn	(D.2)	

Table D.2 Table D.2. Model validation parameters.

Table D2Model	Temperature (°C)	Pressure (bar)	MAPE (%)	RSME	
AE	75	5	1.045	0.0242	
PEME	80	1	1.740	0.0337	
SOE	750	1.8	2.283	0.0286	

Fig. D.1 Model Validation using previously published data.

Fig. D.1

Table E.1 Table E.1. Catalytic methanation equations.

Table E1vR−1=k·pCO20.5pH20.5(1−pCH4pH2O2KeqpCO2pH24)(1+KOHpH2OpH20.5+KH2pH20.5+KmixpCO20.5)2	(E.1)	
k=k0e[(EaR)(1Tref−1T)]	(E.2)	
Keq=137T−3.989e(158.7RT)	(E.3)	
Ki=Ki0e[(ΔHiR)(1Tref−1T)]	(E.4)	

Table E.2 Table E.2. Catalytic methanation kinetic parameters [4].

Table E2Parameter	Value	Units	
KOH0	0.50	bar−0.5	
KH20	0.44	bar−0.5	
Kmix0	0.88	bar−0.5	
k0	3.46·10−4	mol·bar−1·s−1·gcat−1	
Ea	77.5	kJ·mol−1	
Tref	555	K	
ΔHOH	22.4	kJ·mol−1	
ΔHH2	−6.2	kJ·mol−1	
ΔHmix	−10.0	kJ·mol−1	

Table F.1 Table F.1. Fixed capital investment and total earnings.

Table F1FCI=DC+IC	(F.1)	
TE=GI−MC	(F.2)	

Table F.2 Table F.2. Direct, indirect, and production costs calculation.

Table F2Cost	Percentage	Basis	
Direct Costs			
Equipment cost (EC)	19.32	FCI	
Installation cost	42.33	EC	
Instrumentation and control	31.33	EC	
Piping	60.00	EC	
Electrical systems	20.33	EC	
Building and services	18.00	EC	
Service facilities	65.00	EC	
Land costs	5.00	EC	
Indirect Costs			
Engineering and supervision	33.00	EC	
Legal expenses	4.00	EC	
Construction and contractor's expenses	63.00	EC	
Working capital	76.00	EC	
Production Costs			
Raw materials	66.60	MC	
Operating labor	10.00	MC	
Utilities	15.00	MC	
Maintenance and repairs	7.00	MC	
Operating supplies	20.00	Maintenance	

Table F.3 Table F.3. Products prices.

Table F3Product	Price	Units	References	
Electricity	0.12	USD$/kWh	[22]	
Natural Gas	0.04	USD$/kWh	[3]	
Carbon credits (2021)	3.68	USD$/CO2 ton	[21]	
Carbon credits (minimum 2030)	50.00	USD$/CO2 ton		
Carbon credits (maximum 2030)	100.00	USD$/CO2 ton	

Data Availability

Simulation data for the comparison of electrolysis technologies in the context of Power-2-Gas (Original data) (Mendeley Data).

Acknowledgements

This project is funded by Ministry of Science, Technology, and Innovation (Minciencias, Patrimonio Autónomo del FONDO NACIONAL DE FINANCIAMIENTO PARA LA CIENCIA, LA TECNOLOGÍA Y LA INNOVACIÓN, FRANCISCO JOSÉ DE CALDAS) through the contract 441-2023 and Universidad de La Sabana through the projects ING-284-2021 and ING-208-2018. Novoa-Ramirez also acknowledges the support of Universidad de La Sabana through her research assistant position.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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