Enhancing Energy Access in Rural Indonesia: A Holistic Assessment of a 1 kW Portable Power Generator Based on Proton-Exchange Membrane Fuel Cells (PEMFCs)

Abstract

Hydrogen energy is a promising alternative to traditional fossil fuels, offering a clean and sustainable solution to address the challenges of climate change and environmental degradation. Fuel cells provide direct and environmentally friendly conversion of chemical energy from a fuel source into electrical energy, emitting only water vapor when utilizing hydrogen from renewable sources. This study delves into the design of a portable proton-exchange membrane fuel cell (PEMFC) device tailored for household use in rural areas. The research focuses on achieving a minimum peak power of 1000 W and a voltage of 220 VAC at 50 Hz for the fuel cell. Employing theoretical calculations derived from existing formulas and literature reviews, various fuel cell components are meticulously assessed, including real power, voltage drop, performance under current load, and pressure drop on the bipolar plate. Additionally, the study encompasses the selection of auxiliary components like converters, inverters, fans, and others. The resultant fuel cell design showcases a device capable of generating a peak power of 1132.32 W with an efficiency rating of 48.66%. Identifying suitable auxiliary components further contributes to developing a practical and efficient portable power solution for rural households.

1. Introduction

Renewable energy has emerged as a pivotal solution to address the growing global demand for electrical power while mitigating the environmental impacts of traditional fossil fuel-based energy sources [1,2,3]. Unlike finite and environmentally taxing resources such as coal or oil, renewable energy derives from naturally replenishing sources, including sunlight, wind, water, biomass, and geothermal heat [4]. Harnessing these resources to generate electricity has become a cornerstone in transitioning towards a more sustainable and environmentally friendly energy landscape. Solar photovoltaic panels convert sunlight into electricity, wind turbines harness the wind’s kinetic energy, hydropower systems utilize flowing water, biomass uses the energy from plants and plant-derived materials, and geothermal plants tap into the Earth’s internal heat. Embracing renewable energy diversifies the energy mix and contributes to reducing greenhouse gas emissions [5,6], combating climate change [7], and fostering energy independence [8]. As advancements in technology and infrastructure continue to drive down costs [9] and improve efficiency [10], the widespread adoption of renewable energy promises to create a sustainable clean energy development [11], more resilient [12], and equitable energy future [13].

Hydrogen energy is a promising alternative to traditional fossil fuels, offering a clean and sustainable solution to address the challenges of climate change and environmental degradation [14,15,16]. Unlike conventional fossil fuels, hydrogen combustion produces only water vapor as a byproduct, making it a zero-emission energy carrier when generated from renewable sources [17]. The versatility of hydrogen lies in its potential applications, ranging from fueling vehicles and power generation to industrial processes [18,19,20]. When produced through electrolysis using renewable energy sources like wind or solar power, green hydrogen becomes an eco-friendly option, minimizing the carbon footprint associated with energy production [21,22]. Additionally, hydrogen’s energy density and storability make it a viable candidate for overcoming intermittency issues in renewable energy systems, acting as an energy carrier and storage medium [23,24,25]. As research and technological advancements progress, hydrogen’s role in the global energy transition is expected to grow, contributing to a more sustainable and resilient energy landscape [26,27,28]. However, challenges such as production costs [29], infrastructure development [30], and efficient storage methods [31] must be addressed to unlock the potential of hydrogen as a clean alternative to traditional fossil fuels.

Hydrogen fuel cells represent a cutting-edge technology with the potential to revolutionize the way we generate power for various applications. At its fundamental principles, a hydrogen fuel cell converts chemical energy directly into electrical energy through an electrochemical reaction between hydrogen and oxygen, producing electricity, water, and heat as byproducts [32,33,34]. This process is remarkably efficient and emits only water vapor, making it an environmentally friendly alternative to traditional combustion-based power systems. Hydrogen fuel cells are particularly promising for transportation, as they can power electric vehicles and emit water as exhaust [35,36]. Beyond transportation, fuel cells find applications in stationary power generation for residential [37], commercial [38], and industrial use [39]. The scalability and versatility of hydrogen fuel cells position them as a critical player in the transition to a sustainable energy future, offering a clean and efficient energy solution that can help reduce greenhouse gas emissions and dependence on fossil fuels [40].

Fuel cell technology encompasses various types, each with distinct features and applications. Alkaline fuel cells (AFCs) operate with an alkaline electrolyte, typically potassium hydroxide, offering efficiency and reliability [41]. AFCs have found applications in space missions and niche industrial uses [42]. On the other hand, solid oxide fuel cells (SOFCs) function at high temperatures and are adaptable to various fuels [28], including hydrogen and natural gas [43]. Known for their high efficiency and low emissions, SOFCs are employed in stationary power generation [44] and combined heat and power systems [45]. Proton-exchange membrane (PEM) fuel cells utilize a polymer electrolyte membrane, making them suitable for applications requiring quick start-up and variable power output, such as automotive and portable electronic devices [46,47]. Each type of fuel cell technology addresses specific needs and contributes to the evolving landscape of clean and sustainable energy solutions, driving innovation in diverse sectors.

One notable advantage is their ability to operate at lower temperatures, facilitating quick start-up times, which is crucial for meeting the unpredictable energy demands of rural settings [48]. The fuel cells are compact, lightweight, and have high power density, making them ideal for various portable electronic devices, camping equipment, and backup power systems. Operating at lower temperatures further enhances their suitability for portable applications, ensuring a quick response to changing energy needs. PEM fuel cells utilize hydrogen as a fuel source, which can be supplied from easily transportable cartridges or tanks. As a result, these fuel cells reduce reliance on traditional batteries and fossil fuel-powered generators, offering a cleaner and more sustainable power source for individuals on the move or in remote locations. Their scalability and efficiency make PEM fuel cells a promising option for addressing the growing demand for portable power in a world increasingly reliant on mobile and off-grid devices.

PEMFCs offer high electrical efficiency and zero emissions, with potential socio-economic benefits such as job creation and environmental improvement. However, in order to contextualize the use of PEMFC technology, it is essential to consider region-specific factors like the energy mix, renewable resources, and infrastructure challenges [1]. Reference [2] provides an example of PEMFC technology applied in an eco-neighborhood, demonstrating its feasibility when integrated with local housing and energy systems. This kind of localized analysis is crucial for understanding how PEMFC can contribute to regional energy policies and economic development. Additionally, comparing the environmental performance of PEMFC with other fuel cell technologies for the Brazilian context could further justify its selection by highlighting PEMFC’s potential to reduce environmental impacts when combined with renewable energy resources [3].

Proton-exchange membrane (PEM) fuel cells hold significant promise for addressing the energy needs of rural areas. Their versatility and efficiency make them well-suited for decentralized power generation in off-grid or remote locations. PEM fuel cells can provide a reliable source of electricity for rural communities, offering a clean energy solution with minimal environmental impact. The modular nature of PEM technology allows for scalability, enabling systems to be tailored to the specific energy requirements of different communities. Moreover, locally sourced hydrogen can power PEM fuel cells, promoting energy independence and economic development in rural areas. As research and development efforts continue to optimize PEM fuel cell performance and reduce costs, the technology holds great potential to contribute to sustainable electrification and improve the quality of life in rural communities worldwide.

This study aims to assess the design process using several calculations of a 1 kW portable power generator employing proton-exchange membrane (PEM) fuel cell technology. The focus is on evaluating the potential of such a system to address the energy access challenges in rural areas of Indonesia. The portable nature of the power generator makes it a practical and versatile solution for off-grid and remote locations where reliable access to electricity is often limited. By leveraging PEM fuel cell technology, known for its efficiency, quick start-up times, and minimal environmental impact, this study aims to explore the feasibility of deploying such systems in Indonesia’s diverse and challenging rural landscapes.

2. Materials and Methods

This article provides several design processes to determine the proposed product in the proton-exchange membrane fuel cell (PEMFC) stack design used as the portable power generator. Basic conceptual design and several performance calculations are generated in this article, which led to the further process of detailed engineering design. This research develops a portable 1 kW PEMFC system specifically designed to address the challenges of energy access in rural Indonesia. One of the primary contributions of this project is its focus on delivering a sustainable, off-grid power solution for remote and underserved areas where grid extension is often difficult or economically unfeasible. This portable fuel cell system supports PLN’s (Indonesia’s state electricity company) efforts to electrify rural regions by providing a reliable and sustainable energy source that can be easily deployed in areas lacking conventional infrastructure. Another significant contribution is the system’s compact and portable design. With a power capacity of 1 kW, the design balances portability and the ability to meet household energy needs (lighting) in rural settings. The lightweight and easy-to-carry nature of the system makes it practical for deployment in remote locations where transportation and installation of traditional power solutions can be challenging. This portability aspect is critical for reaching the most isolated communities in Indonesia, where infrastructure limitations make conventional electrification difficult.

Moreover, the system’s simplicity and reliability were central to the design. The decision to use a low-complexity, air-cooled thermal management system ensures that the PEMFC operates efficiently without resource-intensive cooling methods. By relying on forced air cooling, the system avoids the additional complexity and maintenance requirements of liquid cooling systems, which are unsuitable for rural environments with limited technical support. This design choice makes the system reliable and easy to maintain, ensuring long-term functionality in remote areas. The design provides a scalable solution for rural electrification. While the current focus is on a 1 kW PEMFC system, the design principles can be adapted to create higher-power versions for larger applications. This scalability makes the system versatile, enabling it to be adjusted to different power needs in various rural electrification contexts across Indonesia.

The first stage is the design concept, where the overarching principles and objectives of the fuel cell system are defined. As discussed in the introduction, the judgement of the PEM fuel cell as the chosen fuel cell technology will be discussed comprehensively in this study stage. This stage also involves several basic judgments, such as the basic architecture and outlining of the intended applications and performance requirements. Conceptual sketches and initial design parameters are developed during this phase to guide the subsequent stages. Our calculations are proposed in this stage using the governing equations specified in this section, including the fundamental electrochemical reactions, ideal voltage, and performance losses such as activation, ohmic, and concentration losses. These calculations lay the groundwork for assessing the efficiency and performance of the PEMFC system.

The second stage is data specification, which comprehensively analyses the specific data and parameters needed for the design. This includes the required power output, efficiency targets, operating conditions, material selection, and environmental or regulatory constraints. The collection and specification of accurate data are crucial for informing the design process and ensuring that the fuel cell system meets performance expectations and aligns with technical and regulatory standards. At this stage, key parameters such as fuel flow rates, power output, and reactant flow rates are carefully analyzed to ensure the system’s operational effectiveness.

The third and final stage is engineering design, where the detailed design of the fuel cell system is carried out based on the established concept and specified data. This involves creating detailed engineering drawings and assessing the system’s mechanical and electrical integration. However, this engineering design stage is not provided in this article, which is later discussed in another article.

By systematically progressing through these three stages—design concept, data specification, and engineering design—engineers can ensure a thorough and informed approach to developing a fuel cell system that meets the desired performance goals and applications. This structured process is essential for successful and efficient fuel cell design, ensuring the fuel cell’s real-world applicability and long-term sustainability, particularly in portable power applications.

2.1. Electrochemical Reactions

In a PEM fuel cell, the critical electrochemical reactions occur at the anode and cathode, separated by a polymer electrolyte membrane. The most common fuel for PEM fuel cells is hydrogen gas (H₂). The hydrogen molecules split through electrolysis into protons (H⁺) and electrons (e⁻). This reaction is represented in Equation (1). The protons (H⁺) move through the electrolyte to the cathode, creating an electrical current. Simultaneously, on the cathode side, oxygen (O₂) is introduced. Hydrogen is oxidized, meaning it loses electrons (e⁻) that flow through an external circuit, creating an electrical current. The protons (H⁺) pass through the polymer electrolyte membrane towards the cathode.

At the cathode, the protons (H⁺) arriving from the anode combine with electrons (e⁻) travelling through the external circuit. This reaction results in water formation (H₂O), as shown in Equation (2). This reaction represents the reduction process, where oxygen is reduced by gaining electrons. The overall reaction makes PEM fuel cells an environmentally friendly and sustainable technology for electricity generation, particularly in applications such as portable power generators.

2H₂ → 4H⁺ + 4e⁻

(1)

O₂ + 4H⁺ + 4e⁻ → 2H₂O

(2)

2.2. Ideal Fuel Cell Voltage

A fuel cell’s open circuit voltage (OCV) is a crucial parameter that reflects the thermodynamic efficiency of the cell under no load conditions, meaning when no current is drawn from the cell. The OCV is determined by the Gibbs free energy ($\Delta G$) change in the electrochemical reactions occurring within the fuel cell. Gibbs free energy, denoted as G, is a thermodynamic potential that measures the maximum reversible work a system can perform at constant temperature and pressure. It is named after American physicist Josiah Willard Gibbs, who significantly contributed to thermodynamics. The Gibbs free energy is vital in chemical and physical processes as it helps determine the spontaneity of a reaction and provides insights into the system’s capacity to perform work. The ideal voltage of a PEM fuel cell is derived from the Gibbs free energy change ($\Delta G$), which represents the maximum amount of reversible work that the fuel cell can perform. Gibbs free energy ($\Delta G$) is affected by the operating temperature (T), enthalpy difference (${\Delta H}_T$), and entropy difference (${\Delta S}_T$), as shown by Equation (3).

$$\Delta G={\Delta H}_T-T{\Delta S}_T$$

(3)

The voltage (E) generated by Gibbs free energy (ΔG) in a fuel cell is significantly influenced by the operating temperature of the cell. This is because enthalpy (H) and entropy (S) are temperature-dependent thermodynamic properties. In standard conditions (298.15 K temperature and 1 atm pressure), the enthalpy and entropy of the system can be determined. However, when operating at different temperatures, the change in enthalpy (ΔH) and entropy (ΔS) can be calculated using the combined polynomial heat capacity function. The integrated polynomial function of heat capacity estimates the enthalpy and entropy differences at various temperatures, as shown in Equations (4) and (5). This function incorporates the temperature dependence of heat capacity and allows for estimating enthalpy and entropy changes over a range of temperatures. Understanding how these thermodynamic parameters change with temperature is essential for optimizing the performance and efficiency of fuel cells at different operational conditions. This knowledge aids in designing fuel cell systems that can function effectively across a spectrum of temperatures, contributing to enhanced energy conversion and overall efficiency.

$${\Delta H}_T=h_{298.15}+{\int }_{298.15}^T{C}_{p}dT$$

(4)

$${\Delta S}_T=s_{298.15}+{\int }_{298.15}^T{\displaystyle \frac{C_p}{T}}dT$$

(5)

The voltage (E) generated by a fuel cell as a function of temperature is calculated by combining the equations that describe the relationship between enthalpy change (ΔH), entropy change (ΔS), temperature (T), the number of electrons transferred in the cell reaction (n), and Faraday’s constant (F = 96,485 C/mol) as shown in Equation (6).

$$E=-{\displaystyle \frac{{\Delta H}_T-T{\Delta S}_T}{nF}}$$

(6)

To incorporate the effect of operating pressure on the ideal voltage of a fuel cell, the governing equation is modified by including pressure-dependent terms. The second term on the right side of the equation accounts for the impact of operating pressure on the cell potential. The logarithmic term adjusts as pressure increases to reflect this change, providing a more accurate representation of the cell’s behavior under varying pressure conditions. By applying Equation (7), which accounts for the impact of temperature and pressure on the ideal voltage of a fuel cell, researchers and engineers can gain a comprehensive understanding of the system’s performance across a range of operating conditions. This information is crucial for optimizing fuel cell designs and ensuring efficient energy conversion in real-world applications.

$$E=-{\displaystyle \frac{{\Delta H}_T-T{\Delta S}_T}{nF}}-{\displaystyle \frac{RT}{2F}}\ln \left({\displaystyle \frac{\left(P_{H_{2}O}\right)}{\left(P_{H_2}\right){\left(P_{O_2}\right)}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}}}\right)$$

(7)

The intrinsic efficiency (ε_i) is a metric used to quantify the fundamental efficiency of a chemical reaction in a fuel cell. It precisely measures the ratio of the reversible free energy that can be converted into electrical energy (ΔG) to the internal energy of the reactants (ΔH). This ratio provides insights into the inherent efficiency of the chemical reaction itself, excluding losses or inefficiencies external to the reaction, such as those related to heat dissipation or system losses. Mathematically, the intrinsic efficiency can be expressed as shown in Equation (8).

$${\epsilon }_i={\displaystyle \frac{\Delta G}{\Delta H}}$$

(8)

The numerator, ΔG, represents the reaction’s reversible energy that can be converted into electrical energy. This is the maximum practical work that can be obtained from the reaction under ideal conditions. The denominator, ΔH, represents the reactants’ internal energy, indicating the system’s total heat content. A higher intrinsic efficiency shows a more thermodynamically favorable reaction, meaning a more significant fraction of the internal energy of the reactants can be converted into useful electrical energy. However, it is important to note that achieving high intrinsic efficiency does not guarantee high overall efficiency in a real-world fuel cell system, as additional factors such as activation losses, ohmic losses, and mass transport losses contribute to overall system efficiency. In summary, intrinsic efficiency is a valuable metric for understanding the inherent efficiency of the chemical reaction within a fuel cell, providing a fundamental perspective on the thermodynamic potential for converting chemical energy into electrical energy.

2.3. Voltage Kinetic Losses

In practical fuel cell operation, electricity production involves various losses associated with the kinetics of electron transfer and other factors. Three main types of losses occur in fuel cells, collectively affecting the overall performance and efficiency. Activation losses (${\Delta V}_{act}$) occur at the electrochemical interfaces of the fuel cell, specifically at the anode and cathode. These losses are related to the activation energy required to initiate the electrochemical reactions. The activation energy barrier must be overcome for the reaction to proceed, and the extent of these losses is influenced by factors such as the nature of the catalyst, surface properties, and the kinetics of the chemical reactions. Activation losses increase with overpotential, the difference between the actual and thermodynamically ideal potential required for the reaction. Internal resistance losses (${\Delta V}_{ohm}$), also known as ohmic losses or resistance losses, are related to the resistance encountered by the flow of ions through the electrolyte and the electrical resistance in the electrodes and interconnects. These losses are influenced by the conductivity of the materials used in the fuel cell. Internal resistance losses contribute to voltage drops within the cell, reducing efficiency and increasing heat generation. Concentration losses (${\Delta V}_{conc}$), also referred to as mass transport losses, arise from limitations in transporting reactants (such as hydrogen and oxygen) to the electrodes and removing reaction products. Concentration polarization occurs when a gradient in reactant or product concentrations near the electrode surfaces reduces reaction rates and cell performance. Effective mass transport is crucial for maintaining uniform reactant/product concentrations throughout the cell. The total losses in a fuel cell, which impact the overall efficiency and voltage output, can be expressed as Equation (9). Several losses are derived from the Butler–Volmer equation, which determines the reacting current from the voltage difference.

$$E_{sel}=E_0-{\Delta V}_{act}-{\Delta V}_{ohm}-{\Delta V}_{conc}$$

(9)

The fuel cell reaction experiences a voltage drop due to the activation energy required by the cell, as shown in Equation (10). Activation loss results in a sharp initial drop in the circuit with increased cell current. This activation loss (${\Delta V}_{act}$) is affected by the exchange current density ($j_0$), current density ($j$) and charge transfer coefficient (${\alpha }_c$).

$${\Delta V}_{act}={\displaystyle \frac{RT}{{\alpha }_{c}F}}\log \left(j_0\right)-{\displaystyle \frac{RT}{{\alpha }_{c}F}}\log \left(j\right)$$

(10)

The internal ionization resistance in the fuel cell’s MEA (membrane electrode assembly) is shown in Equation (11). Ionization resistance is typically represented by the area-specific resistance (Ri), which eliminates the dependence on the active area of the fuel cell. This internal resistance loss (${\Delta V}_{ohm}$) is affected by current density ($j$) and area-specific resistance (Ri).

$${\Delta V}_{ohm}=j\times R_i$$

(11)

This loss is caused by the decreased ability of the fuel cell to maintain reactant concentration due to the high current drawn from the fuel cell, shown in Equation (12). This concentration losses (${\Delta V}_{conc}$) is affected by the current density upper limit ($j_L$) and current density ($j$).

$${\Delta V}_{conc}={\displaystyle \frac{RT}{nF}}\mathit{ln}\left({\displaystyle \frac{j_L}{j_L-j}}\right)$$

(12)

2.4. Fuel Cell Power Produced

Once the voltage of a fuel cell has been calculated, the power that the fuel cell stack can produce can be determined. The power output is directly related to the voltage and the current flowing through the stack. Multiple individual cells are connected in series to form a fuel cell stack. When cells are connected in series, the voltage across each cell adds up, resulting in a higher stack voltage. The fuel cell stack’s power (P) can be calculated using the Equation (13). The stack voltage is the total voltage across all the cells connected in series within the stack. Since the cells are stacked in series, the voltage of each cell adds up, resulting in a higher overall stack voltage. This is beneficial for achieving higher power output from the fuel cell stack. The number of cells in the stack directly influences the stack voltage. As more cells are added to the stack, the voltage increases proportionally. This serial connection of cells allows for the convenient scaling of voltage to meet the power requirements of specific applications. This series of cell connections is a crucial aspect of designing fuel cell stacks to meet the desired power output for various applications.

$$P_{fc}={(N}_{stack}\times E_{sel})\times i$$

(13)

The energy conversion efficiency in a fuel cell system is a critical parameter that reflects how effectively chemical energy stored in reactants is converted into electrical energy. Various losses within the fuel cell influence the efficiency of the electrochemical processes. The system’s overall efficiency can be determined by combining the intrinsic efficiency with the losses, as shown in Equation (14).

$${\epsilon }_i\times {\epsilon }_e={\displaystyle \frac{\Delta G}{\Delta H}}\times {\displaystyle \frac{E}{E_0}}$$

(14)

2.5. Reactant Flow Rate

The flow rate of reactants during fuel cell operation is crucial to ensure the continuous supply of fuel and oxidants necessary for the electrochemical reactions. The reactant flow rate is typically determined by the current drawn by the electrical load connected to the fuel cell. The molar flow rate (N_x) measures the number of moles of reactant (fuel or oxidant) passing through the fuel cell per unit of time. It is directly related to the current (i) flowing through the electrical circuit. The relationship between the molar flow rate, current, and the stoichiometric coefficient of the reactant in the electrochemical reaction can be expressed using Faraday’s law of electrolysis in Equation (15). Volumetric flow rate (${\dot{V}}_x$) is a measure of the volume of gas that passes through a given cross-sectional area per unit of time, as shown in Equation (16). It is commonly expressed in units such as liters per minute (L/min) or cubic meters per second (m³/s).

$$\dot{N_x}={\displaystyle \frac{i}{nF}}\times N_{stack}$$

(15)

$${\dot{V}}_x={\displaystyle \frac{M_x}{{\rho }_x}}\times \dot{N_x}$$

(16)

3. Results and Discussion

The outcomes of this study will illuminate various critical aspects of the fuel cell system. A comprehensive analysis of fuel cell performance will be presented, encompassing key metrics such as power output, efficiency, and voltage-current characteristics. The investigation will delve into the intricacies of the required reactant flow rate, shedding light on the optimal rates of hydrogen and oxygen necessary for the fuel cell’s efficient operation. Additionally, the study will provide insights into the design and performance of the bipolar plate flow field, elucidating the configuration of channels crucial for the uniform distribution of reactants and efficient removal of byproducts. Purging strategies will also be detailed, essential for maintaining reactant purity and preventing undesired substance buildup.

Furthermore, the examination will extend to evaluating fuel cell secondary components, including end plates and current collector plates, which play pivotal roles in supporting the fuel cell stack’s structural integrity and electrical connectivity. The study will explore Balance of Plants (BOP) devices, elucidating their contribution to temperature control, humidity management, and overall system functionality. Through this comprehensive approach, the research aims to provide a nuanced understanding of the fuel cell system’s performance, design intricacies, and the role of essential components and auxiliary devices. Both processes are created as preliminary design processes, to be further examined to achieve the engineering design process.

3.1. Fuel Cell Technology Comparison and Judgement

As discussed in the introduction, the outcome of the fuel cell technology will generate electricity in rural areas. The chosen fuel cell technology was the PEM fuel cell, which has several advantages. The key points in choosing this technology will be discussed comprehensively in this section.

A comparison of several fuel cell technologies should be conceived to judge the most suitable fuel cell technology for this purpose. Several studies comparing fuel cell technology have been summarized in

Table 1. Comparison of fuel cell technologies [32].

Type of Fuel Cell	Alkaline Fuel Cell (AFC)	Phosphoric Acid Fuel Cell (PAFC)	Solid Oxide Fuel Cell (SOFC)
Operating Temperature (°C)	90––100	150–200	600–1000
Output System (kW)	10–100	50–1000	<1–3000
Electrical Efficiency (%)	60	>40	35–43
Combines Heat Power Efficiency (%)	>80	>85	<90
Application	Military, Aerospace, Distributed power generator	Distributed power generator, co-generation	High-scale power generator, co-generation
Advantages	High power density, fast start-up	High efficiency, stable electrolyte characteristic	High combined heat power efficiency
Disadvantages	Expensive catalyst, fuel impurity intolerance	Corrosive electrolyte, fuel impurity intolerance	Expensive, slow start-up, sulfur intolerance
Type of Fuel Cell	Molten carbonate fuel cell (MCFC)	Proton-exchange membrane fuel cell (PEMFC)	Direct methanol fuel cell (DMFC)
Operating Temperature (°C)	600–700	50–100	60–200
Output System (kW)	<1–1000	<1–250	<1–100
Electrical Efficiency (%)	45–47	53–58	40
Combines Heat Power Efficiency (%)	>80	70–90	80
Application	High-scale power generator, co-generation	Transportation, backup power plant, small-scale power generator	Mobile energy storage
Advantages	High efficiency, stable electrolyte characteristic	High power density, fast start-up, non-corrosive electrolyte	Impurities tolerance
Disadvantages	Expensive, slow start-up, sulfur intolerance	Expensive catalyst, impurity intolerance	Low efficiency, low power density

.

For this purpose, the fuel cell technology for the rural area should be as compact as possible. As additional information, the rural area has minimum human resources during operation. The complexity of fuel cell technology is one of the considerations during judgment. The PEM fuel cell has these advantages since it has the highest power density. In addition, the PEM fuel cell has the lowest operating temperature compared with several other fuel cell technologies. The higher operating temperature will increase the complexity of the heat management system.

Besides complexity, efficiency is also considered during specification judgment. Table 1 demonstrates that the PEM fuel cell has a competitive advantage in terms of efficiency. Efficiency refers to the amount of output work generated compared to the amount of input added to the system. In fuel cell systems, efficiency is mainly measured by dividing the system’s output by the amount of fuel (hydrogen) supplied. Higher efficiency means less fuel (hydrogen) is required to produce the same output.

3.2. Fuel Cell Performance

A crucial step in predicting the actual performance of the fuel cell involves calculating the three primary voltage losses as a function of current density. These losses encompass activation, internal resistance, and concentration losses, as shown in Figure 1. Each of these components contributes to the overall voltage losses experienced by the fuel cell during its operation. Activation losses relate to the energy required to initiate electrochemical reactions at the cell’s electrodes, internal resistance losses account for the electrical resistance within the cell components, and concentration losses reflect the impact of reactant concentration gradients on the electrochemical processes. The analysis comprehensively explains how different operating conditions influence the fuel cell’s performance by quantifying these losses as a function of current density. This predictive approach is essential for optimizing the fuel cell’s efficiency and tailoring its operational parameters to achieve desired energy conversion outcomes.

After calculating the three main voltage losses as a function of current density, the obtained results are utilized to predict the performance of a single fuel cell. The prediction is typically visualized using a polarization curve representation, as shown in Figure 2. A fuel cell’s performance is effectively characterized by this curve, which graphically illustrates the relationship between the voltage produced by the fuel cell and its corresponding current. The polarization curve comprehensively overviews the fuel cell’s behavior under different operating conditions. It helps identify the optimal operating points where the fuel cell achieves maximum efficiency and power output. Analyzing the polarization curve is fundamental in evaluating and optimizing fuel cell performance, providing critical insights for designing and fine-tuning these energy conversion systems.

The polarization curve analysis reveals a crucial parameter for the performance of a single fuel cell: the peak current that can be drawn, determined to be 57.6 Amperes. This specific value is strategically identified to avoid excessively high currents that may introduce unpredictability, considering the many factors that come into play. Operating at or below this peak current ensures a more predictable and stable performance, considering various influences such as activation losses, internal resistance, and concentration losses. As shown in

Table 2. Single-cell peak characteristic.

Power (W)	Current (A)	Voltage (V)
50.107	57.6	0.86992

, the peak characteristic obtained encapsulates the fuel cell’s optimal operating point, highlighting the balance between maximizing current draw for power output and maintaining a controlled and manageable operational environment. This information is instrumental in designing and operating the fuel cell within reliable and efficient performance limits.

Once the peak power output of a single cell is established, it becomes possible to determine the number of cells needed in a specific arrangement to achieve a target peak power output. In this case, the desired peak power is set at 1000 Watts. Given the known peak power of a single cell, a crucial parameter identified from the polarization curve analysis, the calculation reveals that 25 cells in one array would be sufficient to meet the 1000 Watts target.

However, it is recognized that the actual power available for external use may be influenced by additional components in the BOP that draw power from the fuel cell. To account for these power draws and ensure self-sustainment, the number of cells is prudently increased to 28, as shown in

Table 3. Stack peak characteristic.

Power (W)	Current (A)	Voltage (V)
1403.3	57.6	24.3578

. This adjustment considers the broader system requirements and aims to provide a sufficient power margin to accommodate the needs of both the external load and the internal components of the BOP, ensuring the fuel cell system operates reliably and sustainably. The calculated performance of the fuel cell provides valuable insights into its efficiency and behavior, revealing an intrinsic efficiency of approximately 80.3%. This metric reflects the fundamental efficiency of the chemical reactions occurring within the fuel cell, considering losses inherent to the electrochemical processes.

Analyzing the fuel cell’s polarization curve further elucidates its characteristics, as shown in Figure 3. Notably, as more current is drawn from the fuel cell, there is a corresponding decrease in the voltage it produces. This observation aligns with typical behavior seen in fuel cells, where higher current draw induces more significant losses in voltage due to factors like activation losses and internal resistance.

A notable phenomenon mentioned is the drastic voltage drop at the onset of the current draw, which is near the maximum current limit. This behavior is typical in fuel cells and is often attributed to activation losses dominating low currents and concentration losses becoming significant at high currents. Despite the continuous decline in voltage, the fuel cell’s power output increases with increasing current draw, reaching a peak before starting to decline. This characteristic power peak results from the interplay between voltage and current, emphasizing the importance of understanding the polarization curve for optimizing the fuel cell’s performance under varying operational conditions.

3.3. Required Reactant Flow Rate

Determining the required reactant flow rate in a fuel cell is influenced by two key factors: the current drawn by the fuel cell and the number of cells in the arrangement. This relationship is mathematically expressed through a governing equation that considers these variables. The calculation results highlight a significant observation: the reactant flow rate exhibits a linear relationship with the current drawn by the fuel cell. As the current drawn by the fuel cell increases, there is a proportional increase in the required reactant flow rate, as shown in Figure 4. This linear relationship suggests that the reactant demand is directly tied to the electrical output of the fuel cell. Such insights are crucial for system design and optimization, enabling a precise control mechanism for adjusting reactant flow rates with variations in electrical demand. Understanding this linear relationship aids in efficiently managing reactant resources, contributing to the overall performance and stability of the fuel cell system.

3.4. Bipolar Plate Flow Field Design

The choice of graphite plates as the material for bipolar plates in this design is motivated by several favorable characteristics. Graphite offers notable corrosion resistance properties, ensuring the durability and longevity of the bipolar plates in the fuel cell system. Additionally, graphite is lightweight, providing an advantage over stainless steel. This lighter weight contributes to overall system efficiency and reduces the load on the fuel cell stack. Furthermore, graphite exhibits higher conductivity than carbon composites, enhancing electron transfer efficiency within the bipolar plates. This conductivity is a critical factor in optimizing the overall performance of the fuel cell by minimizing electrical resistance. Comparing specific masses, graphite plates have a particular mass of 2.63 kg/kWh, while stainless steel, a common alternative, has a higher mass of 3.85 kg/kWh. This lower specific mass of graphite contributes to a lighter overall system, which benefits applications where weight considerations are essential.

Despite these advantages, graphite plates are not recyclable. However, this design does not prioritize recycling, suggesting that other factors such as performance, weight, and corrosion resistance take precedence. This decision underscores the importance of considering a holistic set of criteria and trade-offs in material selection for bipolar plates based on the specific requirements and priorities of the fuel cell system design.

The design of the bipolar plate flow field, encompassing both the cathode and anode flow fields, is a critical aspect of optimizing the performance and efficiency of a fuel cell system. The bipolar plates serve as the structural backbone of the fuel cell stack while facilitating the distribution of reactants (oxygen and hydrogen) to the electrodes and expeditious removal of reaction products. The design of these flow fields influences mass transport, pressure distribution, and overall electrochemical performance. The cathode flow field is engineered to ensure a uniform distribution of oxygen across the electrode surface. This is achieved through a well-defined network of channels in the bipolar plate that facilitates the even flow of air. The design aims to prevent concentration gradients, enhance mass transport, and maintain a steady oxygen supply to support the electrochemical reactions at the cathode. The channels’ geometry, size, and distribution pattern are crucial parameters that influence the performance of the cathode flow field.

Similarly, the anode flow field is meticulously designed to facilitate the uniform distribution of hydrogen to the anode electrode. The channels in the anode flow field are configured to optimize hydrogen distribution, prevent concentration gradients, and enhance mass transport to the anode. The anode flow field design considers factors such as pressure drop, flow uniformity, and avoidance of dead zones to maximize the utilization of the available catalyst and ensure efficient hydrogen oxidation.

3.4.1. Cathode Flow Field

The cathode flow supply method is a forced-convection open-cathode system. The air, which serves as the reactant at the cathode, is actively drawn into the system from the surrounding environment. The external mechanism, such as a fan or blower, enhances airflow over the cathode. The essential characteristic of this open-cathode system is that it does not restrict the air reactant source during the fuel cell’s operation. In other words, the fuel cell freely draws air from its surroundings without conserving or limiting the supply. This contrasts with specific closed-cathode systems where the air supply may be more controlled and conserved. The design choice of a parallel cathode flow path type is facilitated by the nature of the forced-convection open-cathode setup, as shown in Figure 5. In a parallel flow path configuration, multiple channels or paths are available for the cathode reactant to flow. In this specific context, the parallel configuration is chosen because there is no necessity to conserve the air reactant. The system can allow for a more straightforward and efficient design, providing flexibility in managing the cathode flow paths to optimize mass transport and fuel cell performance. The optimal pressure drop is determined based on the flow field size in length (l), width (w), and height (h) as illustrated in Figure 6 and detailed in

Table 4. Parallel flow field size.

w (mm)	d (mm)	w:l
1.3	1.5	1:0.7

, to give the optimal pressure drop. The pressure drop formed by the field is calculated to be 5955 Pa. This approach offers simplicity and ease of operation advantages, as the fuel cell can draw in air continuously from the environment without the need for complex conservation measures during its normal functioning.

3.4.2. Anode Flow Field

The chosen approach for achieving maximum hydrogen utilization in the fuel cell involves employing a dead-end anode flow configuration. In this configuration, the anode flow is closed except during specific activities such as draining or purging. This setup aims to enhance hydrogen utilization efficiency by allowing for a more thorough interaction of hydrogen with the anode electrode. However, specific challenges are associated with this dead-end configuration, particularly in managing pressure drops and preventing water flooding. To address these concerns, the pressure drop at the anode must be carefully controlled to ensure it accommodates the pressure required for the purging process. Purging removes inert gases and accumulated water from the anode flow path.

A serpentine flow design is chosen for the anode flow path to prevent water flooding, as shown in Figure 7. The serpentine configuration offers advantages in draining accumulated water compared to other flow path types like pin and parallel designs. The serpentine path allows for the effective removal of water through its winding channels. However, it is acknowledged that the serpentine flow design may increase the total pressure drop during the purging process. This trade-off is a consideration in the design process, where the benefits of improved water drainage must be weighed against the potential increase in pressure drop [49,50]. The selected design on the serpentine flow channel is defined in

Table 5. Serpentine anode flow field design.

w (mm)	d (mm)	Number of Channel
1	1	2

.

The design is based on several considerations, i.e., manufacturability, active area of reaction, and reaction byproduct management. For the manufacturability, the depth (d) of 1 mm is designed based on conventional manufacturing ability in Indonesia, which gives lower cost than the advanced process like etching.

3.5. Purging

Efficient purging in a fuel cell system involves carefully considering two key variables: purging frequency and duration. These parameters are crucial for maintaining optimal performance by addressing issues related to water accumulation in the anode flow. Purging frequency is defined as the time interval between successive purging events. Ideally, the purging frequency should be determined based on occurrences of hydrogen starvation resulting from water accumulation in the anode flow. The goal is to perform purging as infrequently as possible to minimize wasted hydrogen while ensuring it is completed before accumulated water negatively impacts the fuel cell’s performance. This research uses a purging frequency that occurs approximately every 600 s after the previous purging event.

Moreover, purging duration refers to when the purge valve is open during the purging process. Longer purging times have the advantage of removing all accumulated water but may lead to hydrogen wastage and reduced overall efficiency. This research uses the optimal purge valve, which should be open for 28 milliseconds to perform drainage effectively and then closed again. This duration strikes a balance, ensuring efficient water removal without unnecessary hydrogen loss. Optimizing purging in a fuel cell system involves finding the right balance between purging frequency and duration. The goal is to minimize hydrogen wastage while effectively removing accumulated water to prevent adverse effects on fuel cell performance. The purging frequency and purge valve duration achieve this delicate balance and ensure the fuel cell operates efficiently over its operational life.

However, the purging frequency and duration of PEMFC have different characteristics in each fuel cell. The best practical value of purging frequency and duration can be obtained by practical research. Furthermore, several research studies that indicate the optimum purging rate and efficiency will be researched in our research schedule.

3.6. Fuel Cell Secondary Components

Secondary components in a fuel cell system ensure the system’s structural integrity, electrical connectivity, and overall efficiency. The end plate and the current collector plate are two primary secondary components. The end plate is a structural component that encloses one side of the fuel cell stack. It provides mechanical support to the individual cells within the stack and helps maintain their alignment. Additionally, end plates contribute to sealing the fuel cell stack, preventing the leakage of reactants and reaction products. The design of end plates is critical for maintaining the uniform compression of the cell components, ensuring good electrical contact, and supporting the overall durability of the fuel cell stack. The current collector plate is an essential component responsible for collecting electrical current generated by individual cells in the stack. It is a conductive pathway, allowing electrons to flow from one cell’s electrodes to the adjacent ones. The current collector plate helps distribute the electrical load evenly across the fuel cell stack, promoting uniform current collection and reducing resistive losses. Materials with high electrical conductivity, such as graphite or metal-coated graphite, are commonly used for current collector plates to enhance their efficiency in facilitating electron transport.

3.6.1. End Plate

The choice of aluminum as the material for the end plate in a fuel cell system is based on several advantageous characteristics. The selection of materials in fuel cell components is crucial to achieving optimal performance and durability. Aluminum possesses a relatively lightweight density compared to other metals. This characteristic is vital for applications where weight is a significant consideration, such as portable power generation. Using aluminum helps reduce the overall weight of the fuel cell system, contributing to improved efficiency and portability. Aluminum is widely available in the market, making it a convenient and accessible material for manufacturing. Its availability contributes to cost-effectiveness and ease of sourcing, facilitating the production of fuel cell systems on a larger scale. Specific mass is a critical parameter in fuel cell design, representing the mass of the material per unit of energy produced (kg/kWh). Compared to other metals commonly used in hydrogen handling, such as stainless steel, aluminum exhibits a lower specific mass. This characteristic is advantageous in achieving a favorable balance between material strength and weight, enhancing the overall efficiency of the fuel cell system. The type of aluminum chosen for this design is 5052, known for its high corrosion resistance. Corrosion resistance is essential in fuel cell applications, where exposure to moisture or other corrosive elements could compromise components’ structural integrity and performance. Aluminum 5052 provides durability and longevity under varying environmental conditions. Aluminum offers ease of material engineering, particularly in thread manufacturing for fittings in the flow system. This characteristic simplifies manufacturing and creates precise and reliable connections within the fuel cell system.

3.6.2. Current Collector Plate

The design of the current collector plate in a fuel cell system is a critical consideration, considering the electrical resistance that occurs when an electric current flows through the plate. Electrical resistance in the current collector plate generates unwanted heat, and the design aims to minimize this resistance for efficient operation. The chosen material for the current collector plate is copper. Copper is selected for its relatively low electrical resistance, making it an excellent conductor of electricity. Low resistance is crucial in minimizing the heat generated during the flow of electric current through the plate. Additionally, copper is readily available in the field, contributing to the practicality and accessibility of the material for manufacturing processes. The primary goal of using copper is to exploit its low resistance, which allows for efficient current collection with minimal heat dissipation. A current collector plate with low resistance ensures that a significant portion of the electrical energy generated in the fuel cell is efficiently collected and utilized, contributing to the overall performance and efficiency of the fuel cell system. The design choice includes determining the thickness of the current collector plate to be 2 mm. This thickness is carefully selected to balance structural integrity and electrical performance. A relatively small cross-section helps manage the resistance and heat generation in the plate while maintaining the necessary mechanical strength. This design choice ensures that the current collector plate efficiently performs its role without unnecessary energy losses or excessive heat buildup.

3.7. System Design

Figure 8 illustrates the configuration and positioning of each component within the process. The diagram effectively delineates the system into two primary sections: the fuel line and the electrical line. The fuel line segment primarily comprises flow regulation and measurement devices essential for safely transporting and utilizing hydrogen. Key components within this section include the pressure regulator valve, the hand-operated valve, the hydrogen flow meter, and the solenoid purge valve. These devices collectively ensure the secure and efficient management of hydrogen flow throughout the system by regulating pressure, controlling the flow rate, and safely purging excess gas to maintain system balance and safety.

On the other hand, the electrical line section consists of a DC/DC converter, an inverter, and a load. These components play a pivotal role in ensuring that the electricity generated by the fuel cell can be efficiently converted and utilized. The DC/DC converter adjusts the voltage output to the required level. At the same time, the inverter converts direct current (DC) produced by the fuel cell into alternating current (AC), making it suitable for household or industrial use. The load represents the electrical devices or systems powered by this AC output.

Additionally, an axial fan is integrated into the system to maintain optimal operating temperatures by providing necessary cooling. This ensures the fuel cell operates efficiently and prevents overheating during prolonged operation. Together, these components contribute to a cohesive system that supports the secure handling of hydrogen fuel and effectively utilizes the generated electrical power for various applications.

Figure 9 illustrates the overall assembly of the portable PEMFC system, showcasing how key components from the flow diagram are compactly integrated into a cohesive and efficient system. The design preserves the core elements, including the fuel line, flow regulation components, electrical converters, and safety mechanisms, while ensuring a compact form factor suitable for portable applications. The fuel line in this assembly includes several critical elements to manage the flow and pressure of hydrogen gas. Regulating valves precisely control the fuel flow rate and pressure, ensuring that the fuel cell receives the correct amount of hydrogen for efficient operation. These valves play a pivotal role in maintaining the balance between fuel consumption and performance, preventing potential over-pressurization or under-supply that could negatively impact the fuel cell’s operation.

In addition to the regulating valves, the system features a flow meter, which continuously monitors the hydrogen feed. Real-time hydrogen flow monitoring is essential for ensuring that the fuel cell operates at peak efficiency and provides accurate data on fuel consumption, enabling the operator to manage fuel resources effectively in real-world conditions. The system is equipped with a purging valve on the anode side of the fuel cell. This component is responsible for the critical function of purging inert gases and excess water that may accumulate during the electrochemical reactions inside the fuel cell. Inert gases like nitrogen and water can reduce the fuel cell’s efficiency if allowed to build up, and the purging valve helps maintain a clean, reactive environment in the anode. Proper purging ensures that the hydrogen reacts efficiently within the cell, improving the fuel cell’s performance and longevity.

The cooling system, consisting of axial fans, is another critical component of this assembly. These fans ensure the fuel cell stack operates within the optimal temperature range by preventing overheating. Adequate cooling is vital for maintaining the chemical stability of the membrane and other internal components, directly impacting the system’s durability and operational efficiency. In terms of electrical management, the system incorporates a DC/DC converter and inverter, essential for conditioning the power output from the fuel cell. The DC/DC converter regulates the voltage level from the fuel cell to match the load requirements. At the same time, the inverter converts the direct current (DC) generated by the fuel cell into alternating current (AC), which is necessary for powering standard electrical appliances and devices.

Finally, the assembly also integrates several safety features, including pressure regulators, sensors, and feedback systems that monitor the overall status of the fuel cell. These components work together to ensure the fuel cell operates within safe parameters, automatically adjusting flow rates or initiating purging when necessary. In summary, the assembly in Figure 9 brings together a well-organized arrangement of critical components, including fuel regulation devices, cooling systems, power conditioning units, and safety mechanisms. Each element works in unison to create a portable, efficient, and safe fuel cell system designed to meet the energy needs of remote or off-grid environments. This comprehensive integration ensures the system can deliver reliable power while maintaining high operational standards, durability, and ease of use in real-world applications.

3.8. Water Management System

The water management system is a critical design element in PEMFCs. Proper water management is essential for the efficient operation of the PEMFC, as it ensures the membrane’s hydration level is optimal for proton conduction, directly impacting overall performance. The hydration of the PEMFC membrane is closely related to the surrounding humidity, which plays a role in the membrane’s ability to conduct protons effectively. Insufficient hydration can lead to higher resistances within the membrane, reducing efficiency, while excessive water can cause flooding, leading to performance degradation.

One commonly used method for membrane hydration in PEMFCs is the self-humidification technique. In this approach, the membrane utilizes the water produced as a byproduct of the electrochemical reaction to keep itself hydrated. This method works well under high-power loads, where the water production is sufficient to maintain adequate hydration levels. However, this type of self-humidification becomes less effective under low-power conditions, where the water production rate is reduced. As a result, at lower current densities, the membrane may not receive enough water to remain hydrated solely through self-humidification. External water injection into the fuel supply line becomes necessary to ensure consistent membrane hydration. This method, while effective, introduces additional complexities and will require further investigation in future research, as several design considerations must be addressed to optimize the water injection system for varying operating conditions.

Flooding is another significant issue associated with the water management system in PEMFCs. Under high-load conditions, the water production rate can exceed the membrane’s hydration needs, accumulating excess water. This excess water can block the flow of reactants, such as hydrogen and oxygen, which are essential for the fuel cell’s operation. When the reactants are obstructed, the overall power output of the PEMFC drops, resulting in a lower power density. This phenomenon, known as flooding, poses a considerable challenge to the consistent performance of the fuel cell. The flooding phenomena are also related to the bipolar design, explained in Section 3.4.1 and Section 3.4.2. The technique to address flooding is the anode purging method, where excess water is expelled from the system through the anode side. Another approach is liquid separation, which involves physically removing the excess water to prevent blockages. The anode purging method is part of this model’s simple design and judgment. However, the time and period of anode purging are critical aspects of the design model.

3.9. Thermal Management System

The thermal management methods primarily used in PEMFCs are air-cooled and liquid-cooled models. The air-cooled model is often utilized in lower-power PEMFC systems. In this configuration, the air supply serves a dual purpose: it provides the necessary oxygen for the electrochemical reaction and simultaneously aids in cooling the fuel cell. The design leverages the natural air flow to dissipate heat generated during operation, making it a straightforward and cost-effective solution for systems with lower power demands. This approach is particularly advantageous in applications with a preference for simplicity and minimal additional infrastructure.

On the other hand, the liquid-cooled model is employed in higher-power PEMFC systems, where more significant thermal management is required due to the increased heat generation. This system uses a separate cooling circuit, with a coolant—typically a water-glycol mixture—circulated through channels or passages within the fuel cell stack. This method allows for more efficient and precise temperature control by directly transferring heat away from critical components. The liquid-cooled model is essential for high-power applications, such as larger stationary power systems or advanced automotive applications, where maintaining optimal operating temperatures is vital for performance and reliability. Both thermal management methods are designed to ensure that the PEMFC operates within its optimal temperature range, enhancing efficiency and extending the lifespan of the fuel cell components. The choice between air-cooled and liquid-cooled systems depends on the specific power requirements and operational conditions of the PEMFC application.

In the current design model, the thermal management system employs forced airflow, the exact mechanism for supplying air to the cathode side of the PEMFC. This design choice was carefully made based on several factors, primarily focusing on the power output of the PEMFC, which is approximately 1000 watts. Given this relatively low power output, it was determined that a more complex cooling system, such as a liquid-cooled thermal management system, would be unnecessary and overcomplicate the design.

The forced air-cooling method is a more suitable solution for this power range, as it can efficiently dissipate the heat generated during the fuel cell’s operation without adding significant weight, cost, or complexity to the system. Forced air cooling systems are more straightforward to design and implement, and they can be easily integrated into the existing air supply infrastructure used for the cathode, minimizing the need for additional components. This dual-purpose approach—using the same airflow for cooling and oxygen supply—streamlines the overall design, making it more compact and efficient.

In contrast, a liquid-cooled thermal management system, though highly effective for high-power fuel cells or systems with greater heat loads, would be excessive for a PEMFC producing only 1000 watts. Liquid cooling systems involve pumps, heat exchangers, and additional plumbing, increasing the system’s weight, cost, and complexity without providing proportional benefits. Moreover, maintaining and servicing a liquid cooling system requires more effort and resources, which would not be justified for a fuel cell of this power capacity. Therefore, the design team concluded that forced air cooling offers a more balanced solution, providing adequate thermal management while keeping the system lightweight and cost-effective.

Additionally, this decision aligns with optimizing the PEMFC system for smaller-scale applications where simplicity, reliability, and ease of operation are prioritized. By avoiding using an overdesigned liquid cooling system, the overall efficiency of the fuel cell can be maximized without unnecessary trade-offs. Future design iterations could consider alternative cooling methods if the power output increases, but for the current model, forced air cooling is deemed the most practical and efficient solution.

3.10. Balance of Plants (BOP) Devices

In a fuel cell system, the BOP encompasses various auxiliary components and devices essential for the overall operation and control of the system. Two crucial BOP devices are converters and inverters, along with self-sustainable components, which play distinct roles in managing electrical power within the system. A converter in a fuel cell system is responsible for converting the direct current (DC) generated by the fuel cell stack into alternating current (AC). This conversion is crucial for compatibility with AC-based electrical systems, as many applications and power grids utilize AC power. The converter ensures that the electrical output from the fuel cell stack is suitable for use in various devices and applications that require AC power. Conversely, an inverter performs the opposite function. It converts AC power from the grid or an external source into DC power. This functionality is necessary when external power sources, such as the electrical grid, need to supplement or support the fuel cell system. The inverter ensures that the external AC power is converted into DC power compatible with the fuel cell stack.

The power consumption of BOP devices is an essential consideration in the overall efficiency of the fuel cell system. These devices consume electrical power during the conversion process, and minimizing power losses is crucial for optimizing the system’s efficiency. Efficient BOP devices contribute to maximizing the net electrical output of the fuel cell system. The interplay between components of these devices is carefully managed to ensure seamless integration with the electrical grid, efficient utilization of electrical power, and compatibility with the requirements of various applications. The design and selection of BOP devices are crucial for achieving a well-balanced and high-performance fuel cell system. Engineers aim to optimize these components to minimize energy losses, enhance efficiency, and provide a reliable and adequate power generation solution.

3.10.1. Converter and Inverter

In a fuel cell system, both DC/DC converters and inverters play crucial roles in converting the fuel cell’s output into usable electricity for various applications. The DC/DC converter is employed to stabilize the electricity output from the fuel cell. Fuel cells can exhibit fluctuating outputs, and the DC/DC converter is essential for ensuring a consistent and stable electrical output. Dynamic resistance control is a crucial feature of the DC/DC converter, enabling it to adapt to changes in the fuel cell’s output conditions. This control mechanism helps optimize the electrical output to meet the requirements of connected devices or systems. The inverter, in contrast, is responsible for converting the direct current (DC) output from the fuel cell or the DC/DC converter into alternating current (AC). AC is commonly used in household appliances and electrical grids. By converting the fuel cell’s DC output to AC, the inverter facilitates plug-and-play usage for various household devices, making it compatible with existing electrical systems. The DC/DC converter and the inverter introduce some efficiency loss during the conversion process, as shown in Figure 10.

Efficiency measures how effectively the devices perform their functions without unnecessary energy losses. The efficiency of these devices impacts the overall electrical output of the fuel cell system. It is important to note that the fuel cell’s output will experience a further decrease due to the efficiency losses in the converter and inverter. This decrease is a result of the energy lost during the conversion process. Engineers aim to design and select efficient converters and inverters to minimize these losses and maximize the net electrical output available for consumption.

The overall efficiency of a fuel cell system is determined by combining the efficiencies of the DC/DC converter and the inverter with the intrinsic efficiency of the fuel cell itself. The efficiency of the DC/DC converter and the inverter refers to the effectiveness of these devices in converting and managing electrical power with minimal losses. These efficiencies are typically expressed as percentages and represent the ratio of helpful output power to the input power. For example, if the DC/DC converter has an efficiency of 90%, 90% of the input power is converted into useful output power, and 10% is lost as heat.

The intrinsic efficiency of the fuel cell reflects its fundamental efficiency in converting chemical energy into electrical energy. It is based on the electrochemical processes occurring within the fuel cell and is a crucial determinant of the overall system efficiency. The overall efficiency of the fuel cell system is calculated by multiplying the efficiencies of the DC/DC converter and the inverter with the intrinsic efficiency of the fuel cell. The efficiency of the fuel cell system can vary depending on operating conditions, as shown in Figure 11 and Figure 12. During peak power demand, when the fuel cell operates at its maximum output, the overall efficiency is calculated to be around 48.664%. On the other hand, during the open circuit voltage (OCV) state, where no electrical power is drawn from the fuel cell, the efficiency is higher, measured at around 66%. The OCV state reflects the fuel cell’s ability to generate voltage without delivering power to external loads.

3.10.2. Power Consumption

Incorporating various BOP components in a fuel cell system introduces a degree of self-sustainability by redirecting a portion of the generated power to fulfil the energy needs of these auxiliary components. This self-sustaining approach ensures the proper functioning of critical BOP devices. The BOP components requiring power from the fuel cell include cathode fans, solenoid valves, hydrogen sensors, display, pressure sensor, current sensor, and voltage sensor. The cathode fans are crucial for maintaining the appropriate airflow on the cathode side of the fuel cell. These fans contribute to cooling and ensuring optimal operating conditions, enhancing the overall efficiency and performance of the fuel cell. The solenoid valve regulates the flow of reactants into the fuel cell. It controls the hydrogen or air supply, ensuring proper functioning and safety in the fuel cell system. The hydrogen sensor is a safety component that monitors the concentration of hydrogen in the system. It plays a vital role in detecting and alerting potential leaks or unsafe conditions, contributing to the overall safety of the fuel cell device. The display is a user interface providing real-time information about the fuel cell system’s status, performance, and relevant parameters. It enhances the user experience and facilitates monitoring and control. The pressure sensor measures the pressure levels within the fuel cell system. It helps maintain optimal pressure conditions, ensuring efficient operation and safety. The current sensor monitors the electrical current flowing within the system. It plays a role in assessing and optimizing the electrical performance of the fuel cell. The voltage sensor measures the electrical potential difference within the fuel cell. It aids in monitoring and regulating the electrical output to meet system requirements.

By utilizing a portion of the generated power to meet the energy demands of these BOP components, the fuel cell system achieves a degree of autonomy and self-sustainability. This design strategy contributes to the reliability and continuous operation of the fuel cell, ensuring that critical components receive the necessary power for proper functioning. The specific power requirements and specifications of each BOP component are tailored to align with the fuel cell system’s overall design and operational needs, as shown in

Table 6. BOP power consumption.

Devices	Power (W)
Axial Fan (2 Unit)	3.3
Hydrogen Valve Sensor	2.5
Solenoid Valve	6.48
Display	5
Pressure Sensor	0.32
Current Sensor	0.3
Voltage Sensor	0.3
Total	18.2

.

4. Conclusions

This study addresses the critical issue of energy access in rural Indonesia by comprehensively assessing a 1 kW portable power generator based on PEMFC. The design, rooted in a meticulous series of calculations, has successfully yielded specifications for the fuel cell system. The results indicate that the fuel cell, configured with 28 cells, achieves a peak output of 1403 W and 24.3578 VDC, translating into usable electrical power of 1133.32 W at 220 VAC and 50 Hz. The fuel cell’s efficiency at peak power is measured at 48.66%. Additionally, the study revealed non-linear relationships between the power generated and current load, emphasizing the influence of current load magnitude on voltage and power values. Notably, the fuel cell’s efficiency varies with changes in the current load, reaching 66% at the open-circuit voltage (OCV) state and recording 48.66% at peak power. This holistic assessment provides valuable insights into the design, performance characteristics, and efficiency dynamics of the PEMFC-based portable power generator, contributing to the advancement of sustainable and accessible energy solutions in rural contexts.

One exploration avenue involves optimizing the PEMFC system’s design parameters to enhance efficiency and power output further. Investigating advanced materials for fuel cell components, such as catalysts and membranes, could improve performance and durability. Additionally, integrating energy storage systems and smart grid technologies would better manage fluctuating power demands in off-grid environments. The current research focuses on the theoretical design and assessment of the portable PEMFC system, with performance metrics such as peak power, efficiency, voltage, and current being evaluated through direct analytical calculations. However, experimental validation is planned for the next phase of this research, where we will develop a physical prototype of the portable PEMFC and conduct tests under controlled conditions to validate the theoretical findings. Furthermore, future research could focus on upscaling to 5 kW, field trials, and real-world implementations of the designed portable power generator in diverse rural settings, as well as assessing its adaptability, reliability, and socio-economic impacts. This holistic approach would provide valuable insights for refining the technology and tailoring it to the specific needs of rural communities.