Phosphoric Acid Fuel Cell Research Articles

Thermodynamic, Economic and Regulation Strategies Analysis of a Phosphoric Acid Fuel Cell Combined Heating and Cooling

Thermodynamic, Economic and Regulation Strategies Analysis of a Phosphoric Acid Fuel Cell Combined Heating and Cooling

Optimal design and dispatch of phosphoric acid fuel cell hybrid system with direct heat recovery through coupled calculation and artificial intelligence-based optimization

A phosphoric acid fuel cell (PAFC) is the first-generation of modern fuel cells that can use waste heat in various ways. This study presents a PAFC hybrid system with direct heat recovery. Direct heat recovery uses PAFC cooling water as the working fluid for the steam turbine, simplifying the system and improving performance. The PAFC in this hybrid system acts as a power generator and evaporator. The hybrid system operates in power generation mode (mode_pg) and combined heat and power mode (mode_chp). The overall behavior of the hybrid system was analyzed using a coupled calculation method. Under mode_pg, the electric power and efficiency of the hybrid system were 37.0% and 10.5% higher, respectively, than those of a conventional system. The thermal power and CHP efficiency in mode_chp were 35.7% and 8.8%p higher, respectively, than those of a conventional system. The optimal dispatch was obtained using an artificial intelligence-based optimization framework that considered two scenarios. As a result, the optimal demand was 25.8% higher when the hybrid system with the optimal dispatch was used. In addition, the economic and environmental indices were 7.3% and 6.8% lower, respectively, than the conventional system, highlighting the feasibility and eco-friendliness of the hybrid system.

Thermodynamic and Economic Analysis of a Phosphoric Acid Fuel Cell Combined Heating Cooling and Power System

Thermodynamic and Economic Analysis of a Phosphoric Acid Fuel Cell Combined Heating Cooling and Power System

A Recent Comprehensive Review of Fuel Cells: History, Types, and Applications

This review discusses the history, fundamentals, and applications of different fuel cell technologies, including proton exchange membrane fuel cells (PEMFCs), direct methanol fuel cells, solid oxide fuel cells (SOFCs), phosphoric acid fuel cells (PAFCs), alkaline fuel cells (AFCs), and molten carbonate fuel cells (MCFCs). Recent advances in fuel cell technologies have led to potential applications in aerospace, transportation, and portable and stationary power generation due to high efficiency and low emissions. Fuel cell types are also compared based on efficiency, operating temperature, lifetime, energy/power density, and cost. It was noticed that PEMFCs have the highest mass power density, reaching 1,000 W/kg compared to less than 100 W/kg for SOFCs, which makes them suitable for portable applications such as aircraft. PEMFCs and AFCs are suitable for low‐temperature applications and are highly efficient. SOFCs and MCFCs are better for high‐temperature operations. SOFCs are robust and suitable for high‐power demands, while MCFCs are advantageous for high‐power output. Hydrogen fuel cells promise to decarbonize transportation and aviation sectors with the advantages of lower weight, compactness, and quick startup times. However, challenges remain around renewable hydrogen production/infrastructure and aircraft integration, besides hydrogen storage, water management inside fuel cells, and operational robustness under varying pressures. Generally, for all fuel cell types, more focus should be given to enhancing the stability and efficiency of fuel cell materials and reducing their cost.

Life cycle assessment shows that retrofitting coal-fired power plants with fuel cells will substantially reduce greenhouse gas emissions

Life cycle assessment shows that retrofitting coal-fired power plants with fuel cells will substantially reduce greenhouse gas emissions

Feasibility Study and Economic Analysis of a Fuel-Cell-Based CHP System for a Comprehensive Sports Center with an Indoor Swimming Pool

Unlike a general commercial building, heating for a building with an indoor swimming pool is highly energy-intensive due to the high energy demand for swimming water heating. In Korea, the conventional heating method for this kind of building is to use boilers and heat storage tanks that have high fuel costs and greenhouse gas emissions. In this study, a combined heat and power (CHP) system for such a building using the electricity and waste heat from a Phosphoric Acid Fuel Cell (PAFC) system was designed and analyzed in terms of its primary energy saving, CO2 reduction, fuel cell and CHP efficiency, and economic feasibility. The mathematical model of the thermal load evaluation was used with the 3D multi-zone building model in TRNSYS 18 software (Thermal Energy System Specialists, LLC, Madison, MI, USA) to determine the space heating demand and swimming pool heat losses. The energy efficiency of the fuel cell unit was evaluated as a function of the part-load ratio from the operating data. The fundamental components, such as the auxiliary boiler, thermal storage tank, and heat exchanger are also integrated for the simulation of the system’s operation. The result shows that the system has a high potential to improve the utilization efficiency of fuel cell energy production. Referring to the local condition of the energy market in Korea, an economic analysis was also carried out by using a specific FC-CHP capacity at 440 kW. The economic benefit is significant in comparison with a conventional heating system, especially for the full-time operating (FTO) mode. The net profit made by comparison with the conventional energy supply system is about 178,352 to 273,879 USD per year, and the payback period is expected to be 6.9 to 10.7 years under different market conditions.

Types of fuel cells and their potential directions of use

Fuel cells are not a new technology, but they are gaining in popularity and are being intensively developed. The article presents and characterizes various types of fuel cells that are currently of interest to research and development centers dealing with environmental protection issues. These include: alkaline fuel cell (AFC), phosphoric acid fuel cell (PAFC), solid oxide fuel cell (SOFC), molten carbonate fuel cell (MCFC), proton exchange membrane fuel cell (PEMFC), including direct methanol fuel cell (DMFC). The operating parameters of the previously mentioned fuel cells were compared. The principle of operation of a fuel cell was described. The growing interest in devices using hydrogen as a fuel also results from the development of Power to Gas technology (P2G). Furthermore, the article presents the potential directions of development and use of fuel cells in various fields and sectors of the economy. Fuel cells can be used in transport. The characteristic of motor vehicles fleet by fuel type in usage in the European Union was presented. The technical specification of commercially available passenger cars using fuel cells with proton exchange membrane was presented. The possibility of using fuel cells in public transport (buses, trains) was discussed. The possibilities of operation of fuel cells in combined heat and power systems (CHP) were presented. Usage of fuel cell technology in large cogeneration units and micro systems was considered. One of the presented cogeneration systems is a combination of fuel cells with a gas turbine. Another possibility of using fuel cells is energy storage systems (EES). Interesting way of using fuel cells can also be Power to Power systems, which were briefly characterized.

Basic Study on Application of Fuel Cells to Ocean Going Vessels

While IMO (International Marine Organization) regulates CO2 emissions from ocean going vessels to protect the marine environment, efforts are underway to design and develop various systems to reduce such emissions. As part of these efforts, the author carried out a simulation by applying PAFCs (phosphoric acid fuel cells) that do not release air pollution gases to the electric power system of an ocean going vessel model. At first, the author developed a vessel model in consideration of routes, speed, sailing schedules, diesel engine generator capacity and electric power consumption etc. Then the author designed the electric power system with PAFCs based on the model. Finally, the simulation designed to supply electric power from the diesel engine generator and PAFCs was carry out. From the results of the simulation, the author calculated the degree of reductions in fuel consumption and greenhouse gas emissions and concluded that the use of the PAFCs was an effective method to protect the marine environment.

Analysis of a phosphoric acid fuel cell-based multi-energy hub system for heat, power, and hydrogen generation

Natural gas (NG) is delivered to homes and businesses through a complex pipeline network that mainly consists of high-pressure main feed lines and many low-pressure local distribution lines. To date, throttling valves have been employed to reduce the NG pressure between the two types of pipeline, leading to the loss of the work potential generated by the expansion of pressurized NG in the NG supply chain. As a result, research is currently underway to replace throttling valves with turbo expander generators (TEGs) to obtain additional work power. In this study, a multi-energy hub system consisting of phosphoric acid fuel cell (PAFC) and TEG modules is proposed and analyzed using ASPEN-HYSYS® modeling and simulations. The key concept underlying the system configuration is to maximize overall system efficiency through the integration of exothermic PAFC and endothermic TEG operations. When the TEG system is combined with four 460kWe PAFC stacks, the simulation results show that roughly 1.73 MWe of power can be produced in the TEG system via the expansion of a 28,000 kg/h NG stream. However, when the PAFC stack runs under hydrogen production mode (which requires high voltage operation), an additional heating source is required to fully deliver the expansion work generated by the NG flow within the TEG system. This study clearly illustrates the beneficial features of the proposed multi-energy hub system in terms of thermal integration and overall efficiency but also reveals that the system configuration and operation need to be carefully optimized in order to advance the technology.

Thermo-economic analysis of Phosphoric Acid Fuel-Cell (PAFC) integrated with Organic Ranking Cycle (ORC)

Hydrogen produced from renewable resources has been gaining attention and its use is encouraged, as an effort of emission control. Consequently, the development of hydrogen production methods allows for fuel cell technologies to be developed in parallel. As a clean system for generating electricity, the reaction between hydrogen and oxygen occurring in a fuel cell produces only water and heat. By recovering heat release, thermal energy can be converted to mechanical work or electric power, improving performance and profitability of the system. This work studies the process integration of a 300 kW Phosphoric Acid Fuel-Cell (PAFC) and the Organic Ranking Cycle (ORC); a combined heat recovery process for generating additional electricity. A thermo-economic analysis is performed to determine the optimal working fluid with minimum payback time and net profit of PAFC/ORC integration. Among 15 working fluids examined, utilizing ammonia for ORC increased additional electricity produced by 6.64%, showing the greatest net profit, approximately 149 K€, and the payback time is reached after 3.3 years. Examined fluids with high critical temperature were water, benzene, and toluene, and obtained great efficiency improvement (about 9–11%) but they were unable to results to profit during 10 years of fuel cell lifetime.

Thermal analysis and optimization of combined cold and power system with integrated phosphoric acid fuel cell and two-stage compression–absorption refrigerator at low evaporation temperature

The thermal analysis and optimization of a proposed combined cold and power system with integrated phosphoric acid fuel cell and two-stage compression– absorption refrigerator at low evaporation temperature (CPAR) are conducted. The mathematical model of the CPAR system is established on the basis of the electrochemical model of the phosphoric acid fuel cell (PAFC) and the conservation models of the two-stage compression–absorption refrigerator (TSCR). The validation of the proposed model is conducted through partial verifications of the PAFC and the TSCR subsystems. The energy conservation is verified considering the basic design condition, and the total conductance of each component is calculated and discussed. The effects of PAFC and evaporation temperatures and compression ratio on 13 operating parameters are simulated and analyzed. Four key operating parameters are optimized on the basis of the exergy perspective. The exergy conservation is also calculated and verified considering the basic design condition. The largest exergy destruction for the PAFC subsystem is caused by the electrochemical reaction. Meanwhile, heat transfer and phase change are the main reasons for exergy destructions for the TSCR subsystem.

Electrical Resistivity of Natural Graphite/Polymer Composite based Bipolar Plates for Phosphoric Acid Fuel Cells by Addition of Carbon Black

Conductive polymer composites with high electrical and mechanical properties are in demand for bipolar plates of phosphoric acid fuel cells (PAFC). In this study, composites based on natural graphite/fluorinated ethylene propylene (FEP) and different ratios of carbon black are mixed and hot formed into bars. The overall content of natural graphite is replaced by carbon black (0.2 wt% to 3.0 wt%). It is found that the addition of carbon black reduces electrical resistivity and density. The density of composite materials added with carbon black 3.0 wt% is 2.168 g/cm3, which is 0.017 g/cm3 less than that of non-additive composites. In-plane electrical resistivity is 7.68 μΩm and through-plane electrical resistivity is 27.66 μΩm. Compared with non-additive composites, in-plane electrical resistivity decreases by 95.7 % and through-plane decreases by 95.9 %. Also, the bending strength is about 30 % improved when carbon black is added at 2.0 wt% compared to non-additive cases. The decrease of electrical resistivity of composites is estimated to stem from the carbon black, which is a conductive material located between melted FEP and acts a path for electrons; the increasing mechanical properties are estimated to result from carbon black filling up pores in the composites.

Optimal thermo-economic design of a PAFC-ORC combined power system

Phosphoric acid fuel cells (PAFCs) are appropriate for applications that require high-quality power because of their high reliability. We propose a system that combines an 11 MW PAFC and an organic Rankine cycle (ORC). The ORC recovers waste heat from the PAFC and produces power. The performance and economics of the system were simulated with changes in the working parameters of the PAFC and ORC to find economically optimal design conditions. The optimal working conditions with the best economic performance were found between the operating conditions with the maximum power and the maximum efficiency. The best design conditions were predicted for various ORC working fluids: the power was between 14.63 and 15.51 MW, and the efficiency was between 40.35 and 42.75 %. The maximum improvements of the power and efficiency over the stand-alone PAFC system were 41.77 % and 47.18 %, and the estimated payback period was around 5.50 years.

Phosphate tolerance of nitrogen-coordinated-iron-carbon (FeNC) catalysts for oxygen reduction reaction: A size-related hindrance effect

The greatest challenges facing the large – scale commercialization of the intermediate temperature phosphoric acid fuel cell (PAFC) technology are: (i) the high cost of Pt catalyst that is required to overcome the slow kinetics of oxygen reduction reaction (ORR) on the PAFC cathode, and (ii) deactivation of the Pt catalyst by exposure to the phosphoric acid electrolyte. Inexpensive carbon-based materials, particularly iron-nitrogen-coordinated carbon supported catalysts (FeNC), are promising cathodes for PAFCs. The higher ORR activation energy and phosphate poisoning resistance of FeNC present a clear advantage over the Pt-based commercial catalysts that are easily susceptible to deactivation after exposure to phosphate anions. While the immunity of FeNC catalysts to phosphate anion poisoning has been reported previously, this work explores the counter-intuitive and conditional nature of this poisoning resistance based on the properties of the carbon support used in the preparation of the FeNC catalyst. A combination of electrochemical measurements with characterization experiments performed using X-ray photoelectron spectroscopy, infrared spectroscopy and in-situ X-ray absorption spectroscopy is used to explore the phenomenon of phosphate poisoning on FeNC catalysts synthesized from two different carbon supports. Results from these studies reveal a “size-related hindrance effect” wherein the ORR active Fe centers in FeNC remain inaccessible to larger anions such as phosphate when the Fe sites are present deeper inside the pores of a carbon support with high porosity. However, FeNC catalyst is poisoned by phosphate anions when synthesized using a carbon support with low porosity. This work helps gain insights into the nature of active sites in FeNC catalysts that will be useful in designing precious-metal free ORR catalysts for intermediate temperature fuel cell technologies.

Thermodynamic analysis of fuel cell combined cooling heating and power system integrated with solar reforming of natural gas

Hybrid natural gas combined cooling, heating, and power (CCHP) systems integrated with solar technologies offer the efficient use of distributed energy resources for reducing the use of fossil fuels and greenhouse gas emissions. This paper proposes a novel CCHP system, using the phosphoric acid fuel cell (PAFC) as the prime mover, integrated with the natural gas reforming with solar energy assistance. Their respective thermodynamic models are constructed for simulation of the system thermodynamic performance. The simulation results demonstrate that the energy efficiencies of the hybrid system with solar energy assistance are 55.12% for the heater mode and 66.77% for the chiller mode, while the exergy efficiencies are 32.87% and 31.59%, respectively. Similarly, when solar energy is not available, its energy efficiencies are 59.24% and 69.18%, while its exergy efficiencies are 40.09% and 39.01%, respectively. In the PAFC–CCHP hybrid system, the exergy efficiencies are key components in the overall efficiency, and the efficiencies with and without solar energy are 29.34% and 36.95%, respectively. Solar energy and exergy share is employed to analyze the solar energy contribution, and they are 36.1% and 35.6%, respectively. Meanwhile, the parametric analysis is also carried out to evaluate the effects of key parameters on the performance. The results show that increasing the reforming temperature, influenced by solar energy, improves the natural gas conversion and boosts the hydrogen concentration of the syngas fed into the PAFC, which increases the overall exergy efficiency. However, the effect of the reforming temperature is reduced when the reforming temperature is higher than 1073.15 K.

Investigation of a new hybrid fuel cell–ThermoElectric generator–absorption chiller system for combined power and cooling

Abstract In this work, a new hybrid system for combined power and cooling applications is developed and investigated. The novelty of this research originates from two major achievements. First, the use of detailed analytical model for double-effect AC with fuel cell. Second, using two heat recovery systems (TEG and AC) to utilize the waste heat from a fuel cell. The system consists of a phosphoric acid fuel cell (PAFC), ThermoElectric generator (TEG), and an absorption chiller (AC). The internal heat generation in PAFC is utilized using TEG to achieve additional electricity production, while the exhaust heat by PAFC is utilized to run an AC to produce cooling power. The results show that the maximum useful power (electricity and cooling) obtained from this hybrid system is 11% greater than the maximum electrical power generated by the standalone PAFC. The maximum efficiency of this hybrid system is 7% greater than the maximum standalone PAFC efficiency, but the improvement can reach 10% when optimizing the system operating conditions. The sensitivity analysis study demonstrates that decreasing the operating temperature, increasing the fuel pressure, and decreasing the ambient temperature could enhance the overall hybrid system performance. Additionally, we found that a better performance is achieved when the heat utilized by TEG is minimized and majority of the useful heat is used in the AC.

Energy and exergy analyses of a novel hybrid system consisting of a phosphoric acid fuel cell and a triple-effect compression–absorption refrigerator with [mmim]DMP/CH3OH as working fluid

Energy and exergy analyses were conducted on a proposed hybrid system consisting of a phosphoric acid fuel cell (PAFC) and a triple-effect compression–absorption refrigerator with [mmim]DMP/CH3OH as working fluid (HFCAR). The HFCAR system was modeled and simulated based on the current density model of PAFC, isentropic efficiency model of assisted compressor, and mass and energy conservation model of the compression–absorption refrigerator. For the basic design condition, the detailed operating parameters of each status point, energy conservation, temperature difference, and total thermal conductance of each component were simulated and discussed. For the variable conditions, the effects of electrical current density, PAFC temperature, and compression ratios on 16 key operating parameters were simulated and analyzed. A critical electrical current density was proposed. Under condition of critical current density, HFCAR system works as a cooling system with the largest cooling capacity. The variation characteristics of the critical electrical current density were studied. The exergy losses of each component were simulated and analyzed. The PAFC efficiency and heat transfer characteristic of certain components should be optimized to improve the thermal performance of the HFCAR system.

Waste Heat Recovery of Phosphoric Acid Fuel Cell Based on Thermoelectric Generator

Waste Heat Recovery of Phosphoric Acid Fuel Cell Based on Thermoelectric Generator

High-performance and low-leakage phosphoric acid fuel cell with synergic composite membrane stacking of micro glass microfiber and nano PTFE

A novel composite membrane consisting glass microfiber (GMF) and polytetrafluoroethylene (PTFE) nanoporous film is applied to phosphoric acid fuel cell (PAFC) for performance enhancement and reducing electrolyte leakage. With 93% high porosity, the GMF can fully load phosphoric acid to maintain high proton conductivity. However, the large opening of the GMF membrane cannot effectively prevent the leakage of phosphoric acid. Therefore, in this study, a 25 μm thick PTFE thin film with pore size 50–400 nm is employed to cover the surface of GMF for preventing phosphoric acid leakage. This composite proton exchange membrane possesses both thermal and chemical stability at the working temperature of phosphoric acid fuel cell, while providing high proton conductivity. The proton conductivity of the composite membrane (0.71 S/cm at 150 °C) is much higher than those of reported phosphoric acid porous membranes (∼10−2 S/cm at 150 °C). The fuel cell using the composite membrane with Pt/C catalyst exhibits excellent performance with peak power density of 614 mW/cm2 and current density of 1761 mA/cm2 at 140 °C under pure H2 and O2 supply, while proton conductivity is maintained 2.6 times higher than that of the pure GMF membrane due to the less phosphoric acid leakage by using PTFE film.

Stochastic multi-objective economic-environmental energy and reserve scheduling of microgrids considering battery energy storage system

Due to environmental concerns and ever-increasing fuel costs, governments offer incentives for clean and sustainable energy production from Distributed Generations (DGs) such as Wind Turbine (WT) and Photovoltaic (PV) generators. Optimal operation of Microgrids (MGs) and management of demand side are necessary to increase the efficiency and reliability of distribution networks. In this paper, the stochastic operation scheduling of a MG consisting of non-dispatchable resources including WT and PV and dispatchable resources including Phosphoric Acid Fuel Cell (PAFC), Micro-gas Turbine (MT), and electrical storage as Battery Energy Storage System (BESS) is investigated to minimize operation cost and emissions. The problem is solved by combination of Differential Evolutionary (DE) and Modified PSO (MPSO) algorithms considering Incentive-based (IB) Demand Response (DR) program and generation reserve scheduling. A stochastic model is also proposed for energy management in MGs in the grid-connected operating mode by taking into account the uncertainty of WT and PV generations and forecasted electric demands. A scenario tree is used to generate scenarios and then, representative scenarios are selected by a scenario reduction technique based on DE. The proposed method is applied on a typical MG and simulation results illustrate its efficiency in comparison to other techniques.