Fuel cells can be divided into five major categories named after the electrolyte used in each. This series of new mixed electrolytes, composed of phosphoric acid pa and diethylmethylammonium trifluoromethanesulfonate dematfo, was designed as nonhumidified it. Development of the fp100i phosphoric acid fuel cell 142 issue. Fuel cells produce electricity by combining hydrogen and oxygen. Characterization of gas flow configurations for phosphoric. The mechanism of 2phenylbenzoxazole formation from benzoic acid and oaminophenol in polyphosphoric acid ppa is studied by nmr spectroscopy and chemical analysis. Phosphoric acid fuel cells fuel cells wiley online library. Developed in the mid1960s and fieldtested since the 1970s, they have improved significantly in stability, performance, and cost. Metaphosphoric acid definition is a glassy solid acid hpo3 or hpo3n formed by heating orthophosphoric acid. Dept of energy, more than 270 phosphoric acid fuel cells were deployed in stationary applications in both the united states and abroad. Robert remick at the national renewable energy laboratory nrel, and the pafc analysis was performed by douglas wheeler of djw technology, llc. They were the first fuel cells to be commercialized. The phosphoric acid fuel cell uses a liquid phosphoric acid electrolyte in a silicone carbide matrix to carry hydrogen ions from the anode to the cathode. This presentation does not contain any proprietary, confidential, or otherwise restricted information.
Two others, alkaline fuel cell afc and carbonate fuel cell mcfc have basic electrolytes that rely on. It uses an external reformer to separate hydrogen from a hydrocarbon. Fuel cells do not need to be periodically recharged like batteries, but instead continue to produce electricity as long as a fuel source is provided. What links here related changes upload file special pages permanent link. Mechanical strength measurements show, however, that a high acid doping. Phosphoric acid doped polybenzimidazole membranes springerlink. At the core of each fuel cell is a special material called the electrolyte, which allows the production of electricity though efficient electrochemical processes rather than typical fuel combustion. This system is already commercially available, with operational installations in buildings, hotels, hospitals and electric utilities. Fuel cell handbook seventh edition national energy technology. Dynamic modeling a of phosphoric acid fuel cell pafc and. Table 51 evolution of cell component technology for phosphoric acid fuel cells 54. Current fuel cells either rely on ultrapure hydrogen as a fuel and operate at low temperatures for vehicles technologies, or run on natural gas, but operate only at high temperatures for gridscale applications. It will produce electricity and heat as long as fuel.
A fuel cell is composed of an anode, a cathode, and an electrolyte membrane. The major challenge facing the 21st century is the problem of global warming, and energy problems are themselves environmental. An introduction to fuel cells and hydrogen technology by brian cook, heliocentris vancouver, canada whereas the 19th century was the century of the steam engine and the 20th century was the century of the internal combustion engine, it is likely that the 21st century will be the century of the fuel cell. Fuel cells are provided with nitrogen equipment because, for safety reasons when the system is stopped, the flammable gas inside piping and devices must be replaced with nitrogen gas. Frumkin institute of physical chemistry and electrochemistry, russian academy of sciences, moscow, russia. The use of hydrogen as fuel is very contradictory and controversial, we present a summary of the advantages and disadvantages of fuel cells known to date. How to build the simplest fuel cell ever the green. The electrolyte is contained in a teflonbonded, silicon carbide matrix. It has important features in the vertical direction. The calculated values were compared with the real values obtained from a matrix made by rolling and tape casting.
This acid finds use in the manufacture of fertilizers, waxes, soaps and detergents. Phosphoric acid fuel cells pafc are a type of fuel cell that uses liquid phosphoric acid as an. Ganley howard university department of chemical engineering washington, dc. In phosphoric acid fuel cells pafcs, pure hydrogen serves as fuel, and liquid phosphoric acid h 3po 4, an inorganic acid, is used as electrolyte that can conduct proton in the system. The overall system consists of an air cylinder, a hydrogen cylinder, one galvanostat, two syringe pumps, a vaporizer, a phosphoric acid fuel cell pafc electrochem fc2502ma, and a fuel cell test station. Development of novel anodic and cathodic materials applied. The fuel cell he made used similar materials to todays phosphoric acid fuel cell. Fuel flexibility solid electrolyte suitable for chp hybrid gas turbine cycle high temperature corrosion and.
In all cases, the potentials of the anode and cathode in the fuel outlet area shifted to positive directions. Capable of running on a variety of fuels, including hydrogen, natural gas, and biogas, fuel cells can provide clean power for applications ranging from less than a watt to multiple megawatts. Hjuler nkt research center, dk2605 brndby, denmark c. The electrode material is carbon coated with a platinum catalyst. The various components that are part of pafc stack and the working principles behind the pafc are. They are quite resistant to poisoning by carbon monoxide but tend to have lower efficiency than other fuel cell types in producing electricity. Department of energy, morgantown energy technology center, microform represents a specific, individual, material embodiment of a distinct intellectual. The phosphoric acid fuel cell the phosphoric acid fuel cell pafc takes its name from the acid that serves as its electrolyte. Phosphoric acid fuel cells employ porous carbon electrodes containing a platinum catalyst and liquid phosphoric acid, which is stored in a teflonbonded silicon carbide matrix as an electrolyte. The electrolyte, which can be solid, liquid, or specialized polymer, is the heart of the fuel cell and what makes it work.
Abstractthis paper presents the dynamics of a phosphoric acid fuel cell pafc and its associated power electronics. Phosphoric acid, h3po4, is a solid at room temperature but melts at 42 c. Medium temperature phosphoric acid and high temperature solid oxide and molten. A fuel cell is an electrochemical cell that converts the chemical energy of a fuel often. Orthophosphoric acid is a very polar molecule which makes it highly soluble in water. For example, it can convert a hydrocarbon fuel like propane gas into electricity without combustion. Hydrogen economy ammonia fuel cell systems jason c. Phosphoric acid fuel cell pafc anodes accelerate the hydrogen oxidation reaction rate in phosphoric acid. Phosphoric acid fuel cells an overview sciencedirect. During operation, hydrogen starvation may cause reverse polarization and. The cell performance and polarization distribution in the horizontal plane of a phosphoric acid fuel cell pafc were studied for thirteen different types of gas flow. The anode in a fuel cell is always negatively charged and the cathode is always positively charged when energy is being created this is reversed if the fuel is being run in reverse.
The alkaline fuel cell afc, polymericelectrolytemembrane fuel cell pemfc and phosphoric acid fuel cell pafc stacks essentially require. Fuel cell resource guide for the development of the fuel cell. Collecting the history of phosphoric acid fuel cells. A polymer electrolyte membrane fuel cell operational at temperatures around. Pdf performance enhancement of phosphoric acid fuel cell. The second type of normal temperature fuel cell, referred to as an alkaline fuel cell, is similar in many ways to a battery. Commercially available fuel cell products warranty find more information and manufacturer product name application. Phosphoric acid fuel cell pafc the phosphoric acid fuel cell has a separator with phosphoric acid as the electrolyte. The number of units built exceeds any other fuel cell technology, with over 85 mw of.
This dissertation summarizes the authors research effort to identify and synthesize novel electrocatalysts for application in proton exchange membrane fuel cells pemfcs, direct alcohol acid and alkaline fuel cells dafcs and phosphoric acid fuel cells pafcs. Limiting current of oxygen reduction on gasdiffusion. Pafc is considered the first generation of modern fuel cell. These are considered as the most advanced fuel cells after alkaline fuel cells. Advantages and disadvantages of fuel cells lorecentral. Fuel cell systems convert chemical energy in fuels into electrical energy. Metaphosphoric acid definition of metaphosphoric acid by. The five types resulted from the knowledge that heat accelerates chemical reaction rates and thus the electrical current. Mass transport characteristics were determined using chronoamperometry to. Phosphoric acid fuel cell 1 phosphoric acid fuel cell.
Electrolyte additives for phosphoric acid fuel cells. A conventional combustionbased power plant typically generates electricity at efficiencies of 33 to 35 percent, while fuel cell systems can generate electricity at. Since publication of the first edition of fuel cell systems explained, three compelling drivers have supported the continuing development of fuel cell technology. Advantages using impure hydrogen as fuel and 85 of the steam can be used for cogeneration.
Bus powered by phosphoric acid fuel cell battery propulsion system. Fc type pafc phosphoric acid fuel cell rated output power ac105 kw at generating point output voltage ac 400v, 3phase and 3wire output frequency 50 hz electrical efficiency 42 % lhv at generating point. Fuel cell today is the leading source of information and analysis covering the global market for fuel cells. Molten carbonate fuel cells can reach efficiencies approaching 60%, considerably higher than the 3742% efficiencies of a phosphoric acid fuel cell plant. The phosphoric acid fuel cell pafc is the most developed of the common competing types of technology that operate at temperatures above about 200 c. The advantages of fuel cells a fuel cell can convert more than 90% of the energy contained in a fuel into electrical energy and heat. This chapter addresses some system design issues common to all high. One of the important character of pafc is stability that makes it an important fuel cell type for stationary apps. Fuel cells fuel cells are the most energy efficient devices for extracting power from fuels. At 90% utilization of fuel, the potential shift and the cell voltage changed significantly from one type to another. A fuel cell is an energy conversion device that converts chemical energy into electrical energy. Safcell solid acid fuel cells convert fuel into electricity. The fuel cell therefore is not limited by the carnot ef.
Ppt phosphoric acid fuel cell powerpoint presentation. Molten carbonate fuel cells promise high efficiency and can be powered by coalbased fuels such as carbon monoxide instead of hydrogen gas. Improved efficiency is another reason mcfcs offer significant cost reductions over phosphoric acid fuel cells. Phosphoric acid fuel cells pafc phosphoric acid fuel cells were the first fuel cells to become commercially viable. Performance enhancement of phosphoric acid fuel cell by using phosphosilicate gel based electrolyte. What links here related changes upload file special pages permanent link page. There are over 50 mw of demonstrators, worldwide, that have been tested. Safcell is developing solid acid fuel cells safcs that operate at 250 c and will be nearly free of precious metal catalysts. But the corrosion problem restricts the choice of construction materials especially for the electrodes and the catalysts. Phosphoric acid fuel cells pafc currently represent one of the fuel cell technologies that have been demonstrated in many countries around the world and for many applications.
Such operating conditions are characterized especially by a low co 2. A schematic diagram of the direct nhexadecane fueled phosphoric acid fuel cell pafc system is shown in figure 2. Think of a fuel cell like a battery in that it provides continuous dc electricity from a chemical reaction. The present study reports a new series of electrolytes for nonhumidified intermediate temperature fuel cells itfcs. Over 10 million scientific documents at your fingertips. Fuel cells are mainly classified by the characteristics affecting their performance like the type of catalysts, electrolyte used, the fuel required and temperaturerange 1, 2. Development of phosphoric acid fuel cell stack of a varying fuel gas flow rate. Phosphoric acid fuel cells pafc uses liquid form of phosphoric acid. Most of the plants are in the 50 to 200 kw capacity range, but large plants of 1 mw and 5 mw have been built. Mass transport characteristics of cathodes in a phosphoric. Modelling of an electrolyte matrix for a phosphoric acid fuel. Pafcs can be purchased, complete with a warranty, maintenance and spare parts service. Used in hospitals, nursing homes and for all commercial purposes. Mechanism of polyphosphoric acid and phosphorus pentoxide.
Acid electrolyte cells are more tolerant to co2 and allow the use of normal air and nonpure hydrogen. A fuel cell works by passing hydrogen through the anode of a fuel cell and oxygen through the cathode. While fuel cells require significant power conditioning equipment in the form of direct current to alternating current conversion, power from fuel cell systems is clean, exhibiting none of the signal disturbances observed from grid sources. Introduction as we enter the 21st century, it is more urgent than ever to respond to energy and environmental issues, not only within japan, but on a global scale. Acid absorbency, bubble pressure and current density as a function of porosity and poresize distribution were calculated. Pafc systems use primarily pt as catalyst both for hydrogen and oxygen electrodes. The simulation is done using matlabsimulink and its power system blockset psb. Department of energy doe chartered the phosphoric acid fuel cell pafc bus program to demostrate the feasibility of fuel cells in heavyduty transportation systems.
They are being used overseas in hospitals, nursing homes, hotels, offices and schools. The anode materials must be stable at high operating temperature in phosphoric acid. Serious interest in the fuel cell as a practical generator did not begin until the 1960s, when the u. The purecell system is a stationary phosphoric acid fuel cell designed, manufactured and marketed by doosan fuel cell america formerly clearedge powerutc power of south windsor, connecticut. Pafc were developed around time alkaline fuel cells were developed in the 1960s. Orthophosphoric acid an overview sciencedirect topics. Up to three 3 reserve medis fuel cells have been approved for.
Intended for distributed generation and micro combined heat and power applications, it is considered a good match for commercial and industrial buildings such as hotels, hospitals, data. Development of the fp100i phosphoric acid fuel cell. Types of fuel cells department of chemical engineering. The choice of electrolyte material also governs the operating temperature of the fuel cell. A study of the effect of electrode parameters on the mass transport characteristics of cathodes used for oxygen reduction in a phosphoric acid loaded polybenzimidazole membrane fuel cell is reported. Stationary fuel cell power plants based upon phosphoric acid fuel cell pafc technology have been under development at united technologies corporation utc since the 1970s.
Fuel cell development trends and future prospects 1. Marine applications for fuel cell technology part 4 of 6. Introduction fuel cells, which use phosphoric acid solution as the electrolyte, are called phosphoric acid fuel cells pafcs. Molten carbonate fuel cells, when coupled with a turbine, can reach efficiencies approaching 65%, considerably higher than the 37%42% efficiencies of a phosphoric acid fuel cell plant. The fuel has to be hydrogen and if other fuels are used then they must first be converted into hydrogen. The phosphoric acid fuel cell pafc is equivalent in structure to the proton exchange membrane fuel cell pemfc, but it has liquid phosphoric acid as the electrolyte. Phosphoric acid fuel cells pafc are a type of fuel cell that uses liquid phosphoric acid as an electrolyte. Improved efficiency is another reason mcfcs offer significant cost reductions over phosphoric acid fuel cells pafcs.
Colorless and odorless, it is soluble in water, diethyl ether, and ethyl alcohol. Molten carbonate and phosphoric acid stationary fuel cells. Sep 23, 20 pafc were the first fuel cells to cross commercial threshold in the electric power industry. In fact, many of these fuel cells are batteries with the capability of replacing the fuel usually a metal in this case to make them act more like fuel cells than batteries. Phosphoric acid fuel cell technology phosphoric acid fuel cells pafc operate at temperatures around 150 to 200 c about 300 to 400 degrees f. Outline of phosphoric acid fuel cell pafc package by. Some of these cells were disassembled and investigat.
Electrocatalysis enables modification of rates of electrochemical reactions to achieve maximum selectivity, yield and efficiency. Progress and accomplishments in hydrogen and fuel cells pdf. Phosphoric acid, or h3po4, is a chemical with a widespread variety of applications in both industry and food processing. Pyrophosphoric acid, also known as diphosphoric acid, is the inorganic compound with the formula h 4 p 2 o 7 or, more descriptively, ho 2 po 2 o. Electric utility distributed generation high efficiency. The ratio of mixed anhydride to free carboxylic acid increases dramatically as the p2o5 content of ppa increases, but this. Such characteristics have made the pafc a good candidate for early stationary applications. A fuel cell is a device that converts the chemical energy of a fuel hydrogen, natural gas, methanol, etc. The item manual of phosphoric acid fuel cell stack threedimensional model and computer program, chengyi lu and kalil a. The operating temperature is around 180c, where h 3po 4 in aqueous solution dissociates into ions as 62. The modeling of the power conditioning system for phosphoric acid fuel cell is discussed here. Phosphoric acid fuel cells, using acid as the electrolyte and fuelled by hydrogen gas, are the most commercially developed type of fuel cell.
Phosphoric acid fuel cell an overview sciencedirect topics. Department of energy fossil energy office of coal utilization and extraction. It operates at 150190c and pressure ranging from ambient to 5 atm. Figure 51 principles of operation of phosphoric acid fuel cell courtesy of utc. Unlike a battery however, a fuel cell does not run down or require recharging. Electrolyte additives for phosphoric acid fuel cells xiao gang materials science group, chemistry department a, the technical university of denmark, dk2800 lyngby, denmark h. The first fuel cell was built in 1839 by sir william grove, a lawyer and gentleman scientist. Phosphoric acid fuel cells are a type of fuel cell that uses liquid phosphoric acid as an electrolyte. An overview of fuel cells currently under development.
Orthophosphoric acid is a nontoxic, rather weak triprotic acid. Safcell fuel cells produce energy electrochemically without. Of the hydrogenoxygen fuel cell systems the most mature is the phosphoric acid fuel cell pafc. Phosphoric acid fuel cells pafcs consist of an anode and a cathode made of a finely dispersed platinum catalyst on carbon and a silicon carbide structure that holds the phosphoric acid electrolyte. Description of phosphoric acid fuel cell systems fuel cell systems are composed of three basic. A simple model of an electrolyte matrix for use in a phosphoric acid fuel cell pafc has been proposed.
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