Department of energy doe chartered the phosphoric acid fuelcell pafc bus program to demostrate the feasibility of fuel cells in heavyduty transportation systems. An overview comparison of fuel cell technologies by the fuel cell technologies office. Figure 51 principles of operation of phosphoric acid fuel cell courtesy of utc. Minh, in science and engineering of hydrogenbased energy technologies, 2019. The key to a hydrogen economy ammonia fuel cell systems. 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. Dept of energy, more than 270 phosphoric acid fuel cells were deployed in stationary applications in both the united states and abroad. The backbone of a polyphosphoric acid molecule is a chain of alternating p and o atoms. When a renewable source, such as wind or solar, is connected to the electrolyzer the input power is used to produce hydrogen. A company called fuel cell system manufacturing, llc is setting up a detroit base, and will be mass producing fuel cells by 2020, with 100 new jobs being made in the process. Marine applications for fuel cell technology part 4 of 6.
A fuel cell is an energy conversion device that converts chemical energy into electrical energy. Phosphoric acid fuel cell pafc phosphoric acid fuel cells pafc use a phosphoric acid electrolyte. Molten carbonate fuel cells, when coupled with a turbine, can reach efficiencies approaching 65%, considerably higher than the 37%42% efficiencies of a. Although, phosphoric acid fuel cell technology is now nearly commercially mature, it is mandatory to make it cost competitive with existing power technologies. A highperformance phosphoric acid fuel cell sciencedirect. Phosphoric acid fuel cells pafcs operate at 150220 c, using a 100% phosphoric acid electrolyte retained in a silicon carbide matrix. Robert remick at the national renewable energy laboratory nrel, and the pafc analysis was performed by douglas wheeler of djw technology, llc.
The fuel cell industry has today found acceptance in applications related to hospitals, universities, water. Due to the aggressive medium, only diluted acid was used some years ago. Safcell is developing solid acid fuel cells safcs that operate at 250 c and will be nearly free of precious metal catalysts. The calculated values were compared with the real values obtained from a matrix. Concentrated phosphoric acid in a silicon carbide sic teflon matrix is used as the electrolyte in this fuel cell type. Molten carbonate and phosphoric acid stationary fuel cells. It is also used as phosphorylating agent, analytical. Safcell fuel cells produce energy electrochemically without. This presentation does not contain any proprietary, confidential, or otherwise restricted information. The objective of this work was to examine fuel cells as a possible alternative to the diesel fuel engines currently used in railway locomotives, thereby decreasing air emissions from the railway transportation sector. 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.
During the doping process the membrane takes up a large amount of phosphoric acid. Phosphoric acid fuel cells pafc were the first fuel cells to be commercialized. The electrodes of a pafc cell are made from porous carbon paper to which a catalyst is applied. 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. Parkes, in reference module in materials science and materials engineering, 2016.
One of the important character of pafc is stability that makes it an important fuel cell type for stationary apps. A fuel cell is a device that silently generates electricity from hydrogen rich fuels, through a clean electrochemical reaction rather than dirty combustion. It provides an easy assembly structure to install the electrode and fill the liquid fuel. We have investigated the performance of a phosphoric acid fuel cell pafc reactor, with nhexadecane, c 16 h 34 a model compound for diesel fuel, cetane number. Its a rugged, efficient, electrical generator which operates on a wide range of fuel sources. Generally, platinum electrocatalysts are used in both anode and cathode. Think of a fuel cell like a battery in that it provides continuous dc electricity from a chemical reaction. Key companies covered in phosphoric acid fuel cells pafc. It is important to select an operating point cell voltage and related current density of a fuel cell till the system requirements are satisfied 6. There are over 50 mw of demonstrators, worldwide, that have been tested. Sep 23, 20 set up of pafc these fuel cell use liquid phosphoric acid as electrolyte contained in a silicon carbide matrix placed between electrodes. Two or more of these po 4 tetrahedra may be connected by shared singlebonded oxygens, forming linear or branched chains, cycles, or.
For example, it can convert a hydrocarbon fuel like propane gas into electricity without combustion. Pafc systems use primarily pt as catalyst both for hydrogen and oxygen electrodes. Modelling of an electrolyte matrix for a phosphoric acid. Each extra orthophosphoric unit that is condensed adds 1 extra h atom, 1 extra p atom, and 3 extra o atoms. Dynamic modeling a of phosphoric acid fuel cell pafc and.
An overview of the phosphoric acid fuel cell pafc technology is provided in this chapter. Molten carbonate fuel cell mcfc, solid oxide fuel cell sofc are explained, describing. 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 cells are electrochemical devices that generate electricity without combustion. The temperature is high enough to be used for additional power production through cogeneration of steam. Compared to the other fuel cell systems it has a lower power density and the pafc systems achieve only 37 to 42 % electrical efficiency based on the lhv of natural gas. The various components that are part of pafc stack and the working principles behind the pafc are.
The electrolyte, which can be solid, liquid, or specialized polymer, is the heart of. A simple model of an electrolyte matrix for use in a phosphoric acid fuel cell pafc has been proposed. They are quite resistant to poisoning by carbon monoxide but tend to have lower efficiency than other fuel cell types in producing electricity. The latter is normally platinum or a platinum alloy. Development of onsite phosphoric acid fuel cell units. Introduction fuel cells, which use phosphoric acid solution as the electrolyte, are called phosphoric acid fuel cells pafcs. Its derivative, sodium hexametaphosphate is used as a sequestrant and a food additive. 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. In a regenerative system a fuel cell and an electrolyzer are combined to both produce and consume stored hydrogen, and optionally oxygen.
This book provides an introduction to the hazards associated with fuel cells and. Phosphoric acid fuel cells pafc are a type of fuel cell that uses liquid phosphoric acid as an electrolyte. 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. Of the hydrogenoxygen fuel cell systems the most mature is the phosphoric acid fuel cell pafc. 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. This is at the low end of the efficiency goal for fuel cell power plants. Pafc1980 two electrodes of porousconducting material to collect charge 2. This system is already commercially available, with operational installations in buildings, hotels, hospitals and electric utilities. Will south korea lead the way with its ambitious fuel cell. We have investigated the performance of a phosphoric acid fuel cell pafc reactor, with nhexadecane, c 16 h 34 a model compound for diesel fuel, cetane.
The first fuel cell was built in 1839 by sir william grove, a lawyer and gentleman scientist. Set up of pafc these fuel cell use liquid phosphoric acid as electrolyte contained in a silicon carbide matrix placed between electrodes. The efficiency of these type of fuel cells has risen to 50% in a combined electrical and steam cycle. Molten carbonate fuel cell mcfc they operate at 600c and can use co as a fuel input on the cathode side but need hydrogen on the anode. Fuel cell systems convert chemical energy in fuels into electrical energy.
Jan 07, 2015 to achieve adequate proton conductivity for fuel cell operation more than 0. Metaphosphoric acid is used as a dehydrating agent. Phosphoric acid fuel cells pafc phosphoric acid fuel cells were the first fuel cells to become commercially viable. Some of these cells were disassembled and investigat.
It is also used as phosphorylating agent, analytical reagent and in dental cements. Improved efficiency is another reason mcfcs offer significant cost reductions over phosphoric acid fuel cells. Moltencarbonate fuel cells mcfcs are hightemperature fuel cells that operate at temperatures of 600 c and above molten carbonate fuel cells mcfcs are currently being developed for natural gas, biogas produced as a result of anaerobic digestion or biomass gasification, and coalbased power plants for electrical utility, industrial, and military applications. The number of units built exceeds any other fuel cell technology, with over 85 mw of demonstrators that have been tested, are being tested, or are being fabricated worldwide. 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. Safcell fuel cells produce energy electrochemically. Pafc were developed around time alkaline fuel cells were developed in the 1960s. Since, the cost and power density of fuel cells are linked to each other, attempts are being made to enhance the power density of phosphoric acid fuel cells. Acid absorbency, bubble pressure and current density as a function of porosity and poresize distribution were calculated. British standards can be obtained in pdf or hard copy formats from the bsi online. The electrodes are composed by dispersed platinum particles on a porous graphitic substrate 15. Materials and characterization techniques for high. The hydrogen is then stored within the system and consumed.
Phosphoric acid fuel cells pafc uses liquid form of phosphoric acid. Low temperature fuel cell advantages quick startup to operating temperature 100c wide range of cell construction materials high temperature fuel cell advantages fuel flexibility via internal fuel reforming inexpensive, base metal electrocatalysts easier heat recovery for increased efficiency intermediate temperature fuel cells. Pafcs can be purchased, complete with a warranty, maintenance and spare parts service. Phosphoric acid fuel cells an overview sciencedirect. A polymer electrolyte membrane fuel cell operational at temperatures around 150 200 c is desirable for fast electrode kinetics and high toleran. Since the fuel electrolyte is liquid, the solution is soaked in a matrix so that t it can be contained in the fuel cell. Think of a fuel cell like a battery in that it provides continuous dc. The liquid electrolyte fuel cell is equipped with a reservoir for the continuous supply of liquid fuel i. They were the first fuel cells to be commercialized. It operates at 150190c and pressure ranging from ambient to 5 atm. Development of onsite phosphoric acid fuel cell units 23 maintenance. Phosphoric acid doped polybenzimidazole membranes springerlink. To achieve adequate proton conductivity for fuel cell operation more than 0.
The phosphoric acid fuel cell pafc was the first fuel cell technology to be commercialized. Department of energy doe chartered the phosphoric acid fuel cell pafc bus program to demostrate the feasibility of fuel cells in heavyduty transportation systems. Developed in the mid1960s and fieldtested since the 1970s, they have improved significantly in stability, performance, and cost. Phosphoric acid fuel cells request pdf researchgate. The electrodes are made of carbon paper coated with a finely dispersed platinum catalyst bonded with teflon. The calculated values were compared with the real values obtained from a matrix made by rolling and tape casting. Newly developed corrosionresistant materials have made it possible to operate with concentrated acid, which.
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