Phosphoric Acid Fuel Cell Research Articles

Long-Term Performance of Pt-Decorated Carbon Nanotube Cathodes in Phosphoric Acid Fuel Cells

We report the electrochemical properties and performance of Pt-decorated carbon nanotube (Pt-CNT) catalysts for long-term operation in phosphoric acid fuel cells (PAFCs). Electrochemical measurements of Pt-CNT catalysts including cyclic voltammetry, rotating ring disk electrode voltammetry, and electrochemical impedance spectroscopy were conducted to evaluate the catalyzed oxygen reduction reaction (ORR). Furthermore, we tested the long-term performance of the Pt-CNT catalysts in 2′′ × 2′′ PAFC cathodes operating at 190 °C in 85% H3PO4 for extended periods (up to 240 days). Lifetime studies show that electrodes containing the Pt-CNT catalysts were approximately 20 times more stable than conventional Pt-C catalyst materials, even with a substantially thinner catalyst layer. This finding of the enhanced Pt-CNT catalyst stability bodes well for possible personal electronics or automotive applications, where catalyst longevity is an essential requirement.

Novel Catalysts for Oxygen Reduction Reaction in Phosphoric Acid Fuel Cell

not Available.

Towards Mediation of Phosphate Anion Poisoning to Anodic Pt/C Catalyst by alloying Pt with Ni in Phosphoric Acid Fuel Cell

not Available.

Basic Electrochemical Thermodynamic Studies of Fuel Cells Using MALT2

There are at least four basic fuel cell thermodynamic features: maximum intrinsic thermal efficiency (electrical efficiency), reversible potential, and two new ones—intrinsic cooling requirement and intrinsic exergetic efficiency. A basic electrochemical thermodynamic analysis of fuel cells using MALT reveals that it is probably for thermodynamic reasons that cooling strategies other than excess oxidant, such as water cooling, have generally been adopted for lower temperature fuel cells such as polymer electrolyte fuel cell (PEFC) and phosphoric acid fuel cell (PAFC). One can mathematically demonstrate that for a simple hybrid system, any fuel cell, any operating temperature, and any pressure, the maximum reversible work is equal to the free energy of reaction at the standard state. This study gives information of new opportunity fuels having increasing importance is all future energy scenarios. The results of this analysis show that ammonia and direct methanol give greater maximum intrinsic thermal efficiency than hydrogen oxidation. From these simple studies alone, one would conclude that the great payoff in terms of theoretical efficiency potential for research is direct carbon fuel cell (DCFT), PEFC, and direct oxidation of methane, intermediate temperature solid oxide fuel cell (SOFC), and simple fuel cell turbine hybrids.

Optimal option of distributed generation technologies for various commercial buildings

With the development of distributed generation (DG) technologies and the implementation of policies to encourage their applications, building combined heat and power (BCHP) is expected to play a greater role in the commercial buildings in the future. BCHP is a promising efficiency improvement and carbon mitigation strategy, but careful selection of technology and operation mode is required to achieve a reasonable system performance according to energy consumption characteristics of buildings and technical features of equipments. This paper analyzed energy consumption characteristics of four typical commercial buildings in Japan and simulated the energy system performances of four mostly widely adopted DG technologies under different operation mode conditions for the four buildings studied. Various scenarios were evaluated and compared regarding energy utilization efficiency, energy saving and environmental effects, as well as economic efficiency. Results show that the hotels and hospitals are more attractive for BCHP because of their stable thermal load demands and a favorable heat-to-power ratio, which is the most compatible match with available DG technologies. Furthermore, some DG technologies are more suitable for a certain type of building than others because of their technical features more matching with the building’s energy consumption characteristics, as well as the user’s motivation of selecting BCHP. In Japan, during selecting DG technologies, the prior order is gas turbines (GT), gas engines (GE), diesel engines (DE) and phosphoric acid fuel cells (PAFC) for the hotels, PAFC, GE and GT, DE for the hospitals, PAFC, DE, GE and GT for the stores, as well as DE, PAFC, GE and GT for the offices.

E108 TRI-GENERATION SYSTEMS BASED ON HIGHTEMPERATURE FUEL CELLS(Distributed Energy System-2)

The trigeneration (or trigen) is a simultaneous generation of electricity, heat and cooling. It is a technology derived from the known combined heat and power generation (CHP). This combination allows to decrease the fuel consumption as compared to separated generation, which stands for an increased energy conversion efficiency. The fuel cells are devices, which generate electricity in electrochemical processes. Currently the experiments with implementing various types of fuel cells continue around the world. The high-temperature fuel cells, like SOFC or MCFC, can be used both for generating electric power, and for trigeneration. Their distinctive feature is the flue gas of relatively high temperature, which allows to recover the heat both for the district heating water and chilled water production. The paper presents structures and key parameters of the fuel cell-based trigeneration systems. The presented solutions involve two types of chillers: absorption chillers (working on ammonia-water mixture) and vapour-compression chillers (with R-22 as the working agent). Of many types of fuel cells three were named as most appropriate for the needs of trigeneration: PAFC (Phosphoric Acid Fuel Cell), MCFC (Molten Carbonate Fuel Cell) and SOFC (Solid Oxide Fuel Cell)-these generate the flue gas of sufficiently high temperatures, 〜200℃, 〜650℃ and 800...1000℃ respectively. Main parameters of chillers were also presented and their comparative analysis was carried out.

燃料電池の原理と特徴

Fundamentals of fuel cells including polymer electrolyte fuel cell (PEFC), phosphoric acid fuel cell (PAFC), alkaline fuel cell (AFC), molten carbonate fuel cell (MCFC) and solid oxide fuel cell (SOFC), are presented. Three types of overpotential, activation overpotential, ohmic overpotential and concentration overpotential, are described. Polarization curves in PEFC and SOFC are also presented for better understanding of dominant factors that determine overall cell performance.

りん酸形燃料電池の現状と今後の展望

りん酸形燃料電池の現状と今後の展望

The Corrosion of a Stainless Steel in High Temperature Phosphoric Acid

The experiments described in this article were designed to evaluate 904L stainless steel as a candidate for replacing carbon composite in a phosphoric acid fuel cell (PAFC) bipolar plate application. We investigated the 904L steel in phosphoric acid purged with air or hydrogen gas at 170° C. Dynamic polarization showed that the steel experienced passivation with high currents. A depth profile obtained using X-ray photoelectron spectroscopy indicated that the surface film of 904L consists of an outer layer rich in Fe-oxide and an inner layer rich in Cr-oxide. After polarization, the Fe-oxide layer was selectively dissolved and Cr-oxide dominated the passive film. The Cr-oxide layer also experienced corrosion, but at a much lower rate. After 3 hours of polarization, the Fe-oxide was almost totally depleted, and phosphorus was incorporated into the passive film, changing its chemical composition. We concluded that 904L steel is an excellent candidate for use in PAFC applications.

Development of a novel computational tool for optimizing the operation of fuel cells systems: Application for phosphoric acid fuel cells

Fuel cells offer a significant and promising clean technology for portable, automotive and stationary applications and, thus, optimization of their performance is of particular interest. In this study, a novel optimization tool is developed that realistically describes and optimizes the performance of fuel cell systems. First, a 3D steady-state detailed model is produced based on computational fluid dynamics (CFD) techniques. Simulated results obtained from the CFD model are used in a second step, to generate a database that contains the fuel and oxidant volumetric rates and utilizations and the corresponding cell voltages. In the third step mathematical relationships are developed between the input and output variables, using the database that has been generated in the previous step. In particular, the linear regression methodology and the radial basis function (RBF) neural network architecture are utilized for producing the input–output “meta-models”. Several statistical tests are used to validate the proposed models. Finally, a multi-objective hierarchical Non-Linear Programming (NLP) problem is formulated that takes into account the constraints and limitations of the system. The multi-objective hierarchical approach is built upon two steps: first, the fuel volumetric rate is minimized, recognizing the fact that our first concern is to reduce consumption of the expensive fuel. In the second step, optimization is performed with respect to the oxidant volumetric rate. The proposed method is illustrated through its application for phosphoric acid fuel cell (PAFC) systems.

고체산화물 연료전지 시스템을 위한 kW급 마이크로채널 촉매 디젤 자열 개질기

Solid oxide fuel cell(SOFC) has a higher fuel flexibility than low temperature fuel cells, such as polymer electrolyte fuel cell(PEMFC) and phosphoric acid fuel cell(PAFC). SOFCs also use CO and CH₄ as a fuel, because SOFCs are hot enough to allow the CH₄ steam reformation(SR) reaction and water-gas shift(WGS) reaction occur within the SOFC stack itself. Diesel is a good candidate for SOFC system fuel because diesel reformate gas include a higher degree of CO and CH₄ concentration than other hydrocarbon(methane, butane, etc.) reformate gas. Selection of catalyst for autothermalr reforming of diesel was performed in this paper, and characteristics of reforming performance between packed-bed and microchannel catalyst are compared for SOFC system. The mesh-typed microchannel catalyst also investigated for diesel ATR operation for 1㎾-class SOFC system. 1㎾-class diesel microchannel ATR was continuously operated about 30 hours and its reforming efficiency was achieved nearly 55%.

IMPLICATIONS OF IMPLANT DESIGN ON JOINT STABILITY FOR PATIENTS WITH A ROTATOR CUFF TEAR

Fuel cell generators are reviewed from the viewpoint of systems, markets, emissions, and cost-reduction. Their most attractive features are likely to be their unobtrusiveness, which includes very low emissions, combined with their availability in small sizes, allowing cogeneration at the widest range of sites. Unattended operation and very high availability will result in low O&M costs. System designs require rethinking with a view to cost reduction, to make them more attractive compared with competing technologies. This is being pursued by developers. The fuel cell promises to be an important energy conversion technology, which will help to reduce carbon dioxide emissions in the next century. This review covers progress in the phosphoric acid fuel cell (PAFC), molten carbonate fuel cell (MCFC) and solid oxide fuel cell (SOFC) technologies for stationary applications. Although not exhaustive, it attempts to review the literature in a general manner from 1989, when the last overview (Ref. 6) was published. It more extensively reviews papers and presentations at symposia and conferences from 1991 to May 1995. A general review of engineering activity to August 1995 is included.

Learning for supplying as a motive to be the early adopter of a new energy technology: A study on the adoption of stationary fuel cells

Abstract By early adopting a new technology, firms may attempt to improve their production efficiency and become further involved in the supply chain of the technology. These two different advantages derived from learning a new technology are identified as motives for adopting the technology. When learning for supplying (LFS) (becoming involved in the supply chain of the new technology) highlighted in this paper is significant enough, potential adopters may still be willing to adopt the new technology, even though learning for using (LFU) (increasing current production efficiency) is not significant. This paper identifies LFS as a motive for early adopters of the new technology. Firms may adopt a new technology for the purpose of learning how to become the suppliers of the relevant parts, materials, or equipment for the new technology. By investigating the adoption decision of a new energy technology (namely, phosphoric acid fuel cells (PAFC)), our arguments are supported by both observation of early adopters’ attributes and a survey of Taiwanese firms’ willingness to adopt new technology.

Austenitic stainless steels in high temperature phosphoric acid

Austenite 316 L, 317 L, and 904 L stainless steels were investigated in 98% H 3PO 4 at 170 °C and they experienced passivation regardless of the purged gas. When polarized at 0.1 V (hydrogen) and 0.7 V (air) (phosphoric acid fuel cell (PAFC) environments), currents at the level of mA cm −2 were observed. Compared to carbon composite under identical conditions, 904 L showed lower currents while 316 L and 317 L showed much higher currents. X-ray photoelectron spectroscopy (XPS) depth profiles indicated that the surface film of the fresh steels consists of a Fe-oxide-rich outer layer and a Cr-oxide-rich inner layer. After being polarized in the PAFC environments, the Fe-oxide layer was selectively dissolved and Cr-oxide dominated the passive film. Phosphorus was incorporated into the film during the process, thus the chemical composition of the passive film differed from those formed in the polymer electrolyte membrane fuel cell (PEMFC) environments. The thicknesses of the stainless steels in the passive films in PAFC environments were estimated.

The Past, Present, and Future of Phosphoric Acid Fuel Cells Operating on Anaerobic Digester Gas

ABSTRACT With high efficiency, virtually zero emissions, and 24/7 generation capability, fuel cells represent the cleanest means of generating continuous on-site electrical power of any available technology. When fueled by the waste gases (anaerobic digester gas, ADG) from anaerobic digestion-based wastewater treatment facilities, stationary fuel cells can turn an emissions liability into a revenue-generating asset, while significantly reducing emissions of both air pollutants and greenhouse gases. ADG fuel cell applications often qualify for sizeable government incentive programs given the widespread acceptance of ADG as a renewable fuel. The PureCell™ fuel cell power system from UTC Power has accumulated more than 400,000 hours of operation on ADG at 22 installations worldwide. This article will describe the capabilities of the PureCell system operating on both natural gas and ADG, as well as the experience gained from UTC Power's fleet. Current and future product offerings will be presented with specif...

The Past, Present, and Future of Phosphoric Acid Fuel Cells Operating on Anaerobic Digester Gas

With high efficiency, virtually zero emissions, and 24/7 gen-eration capability, fuel cells represent the cleanest means of generatingcontinuous on-site electrical power of any available technology. Whenfueled by the waste gases (anaerobic digester gas, ADG) from anaero-bic digestion-based wastewater treatment facilities, stationary fuel cellscan turn an emissions liability into a revenue-generating asset, whilesignificantly reducing emissions of both air pollutants and greenhousegases. ADG fuel cell applications often qualify for sizeable governmentincentive programs given the widespread acceptance of ADG as a re-newable fuel. The PureCell™ fuel cell power system from UTC Powerhas accumulated more than 400,000 hours of operation on ADG at 22installations worldwide. This article will describe the capabilities of thePureCell system operating on both natural gas and ADG, as well as theexperience gained from UTC Power’s fleet. Current and future productofferings will be presented with speci fic emphasis on opportunities forADG applications.

Predicting the Effect of Time, Temperature and H2 Concentration on the CO Tolerance of a Phosphoric Acid Fuel Cell

not Available.

Niche Entry as a Route to Mainstream Innovation: Learning from the Phosphoric Acid Fuel Cell in Stationary Power

The paper charts the efforts to establish a successful niche position for the phosphoric acid fuel cell (PAFC) in stationary power generation, as a precursor to wider technological system and regime change. Market entry depends on matching price/performance characteristics to a niche, and improving performance through increasing returns, the most important and immediate of which are ‘learning effects’. The paper identifies five types of learning effect: (i) migrating the technology to other niches and into the mainstream; (ii) opening the way for other technologies that may have greater scope for migration; (iii) transferring learning within the pioneering company to other technologies or products; (iv) transferring experience to others in the industry; and (v) enabling users to learn. Although PAFC may be perceived as a failure in some respects, a wider perspective suggests it has made a positive and useful contribution to learning.

Polymeric materials for fuel cells: concise review of recent studies

AbstractPolymeric materials find applications in almost all types of fuel cells (FCs). For example, microstructural optimization of materials by poly(methyl methacrylate) microspheres in solid oxide fuel cells (SOFCs) or as the conductive binders for the preparation of carbon electrodes for the phosphoric acid fuel cells (PAFCs). However, these applications are only marginal and not intrinsically essential to the functioning of these types of fuel cells, and will not be discussed in this review. On the other hand, ion exchange polymers used for the preparation of the ion exchange membranes, separating anode and cathode compartment of proton exchange membrane fuel cells (PEMFCs), anion exchange membrane fuel cells (AEMFCs), and direct methanol fuel cells (DMFCs) are one of their major components, and investigations of them, conducted during the last two years, are discussed in the present review. The same is true for a few polymers used for complexation of enzymes and their attachment to electrodes of biofuel cells (BFCs). Copyright © 2007 John Wiley & Sons, Ltd.

Development of Commercialize Fuel Cells Accomplishing Enough Durability and by Reliability

The fuel cell is known as environment friendly power generation plant. Among various types of fuel cells, phosphoric acid fuel cell (PAFC) is the only one commercial. In this paper, our process for the development of the fuel cell stack that is the most important part of PAFC is shown. Regarding the reliability, we observed the rapid break of several cells in the fuel cell stack, which is consisted of the new type cells. We found new phenomenon of phosphoric acid movement in the cell. As for durability, we improved air electrode catalyst. We also improved the catalyst layer consisting of catalyst and PTFE with consideration of the zeta potential of the catalyst and PTFE. This is to mix the catalyst and PTFE well. As the result, PAFC has enough durability and reliability for practical use, and we are expanding PAFC business.