Cost Of Fuel Cells Research Articles

Developments in fuel cell technologies in the transport sector

The demand for clean power source which can be used to run the various types of vehicles on the road is increasing on a daily basis due to the fact that high emissions released from internal combustion engine play a significant role in air pollution and climate change. Fuel cell devices, particularly Proton Exchange Membrane (PEM) type, are strong candidates to replace the internal combustion engines in the transport industry.The PEMFC technology still has many challenges including high cost, low durability and hydrogen storage problems which limit the wide-world commercialization of this technology. In this paper, the fuel cell cost, durability and performances challenges which are associated with using of fuel cell technology for transport applications are detailed and reviewed. Recent developments that deal with the proposed challenges are reported. Furthermore, problems of hydrogen infrastructure and hydrogen storage in the fuel cell vehicle are discussed.

(Invited) Elucidating PEMFC Voltage Loss Contributions Via Mathematical Modeling and Differential Cell Testing

Proton-exchange-membrane fuel cells (PEMFC) have been greatly advanced towards commercially viable hydrogen-powered fuel cell systems for automotive application in recent years. Lower fuel cell costs have been achieved by reducing the loading of Pt catalyst in the electrodes. Unfortunately lower catalyst loadings accompany higher losses in cell voltage. To quantify various voltage loss terms and thus identify the opportunity for improvement, mathematical models with parameters extracted from experiments are commonly employed. A differential cell operates at high stoichiometry flow with minimal pressure drop down the channel, making it amenable to treatment by a one-dimensional model across the cell. Hence the experiments are conducted on it to extract model parameters. The cell performance can be described by: Ecell = Erev - iRΩ - ηHOR - |ηORR| - i(RH+,a + RH+,c) - ηtx,O2 (1) where Ecell is the cell voltage; Erev is the reversible cell voltage, i is the current density; RΩ is the sum of the Ohmic resistances of proton conduction through the membrane and of electron conduction (commonly referred to as high frequency resistance or HFR); ηHOR and ηORR are the charge transfer overpotentials for the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR), respectively; RH+ is the effective resistance to proton conduction in an electrode with subscripts a and c denoting anode and cathode, respectively; and lastly, ηtx,O2 is the oxygen transport loss which consists of two parts: one results from oxygen transport through gas phase, and the other is associated with the oxygen transport resistance local to the Pt surface, namely ηtx,O2 = ηtx,O2 (gas) + ηtx,O2 (Pt-local) (2) Differential cell tests with an active area of 5 cm2 were designed to study the effects of Pt location and Pt dispersion in cathode electrodes. Membrane electrode assemblies (MEAs) with different carbon supports and various Pt loadings were fabricated and tested. In particular, Pt/HSC (high-surface-area-carbon) and Pt/Vulcan® catalysts are tested to discern the impact of Pt particles embedded in a carbon particle. Electrochemical performance of the electrodes were characterized with electrochemical active area, mass activity and polarization curves. Additionally, protonic resistance of the catalyst layer and oxygen transport resistances were calculated with impedance and limiting current techniques.An electrochemical model coupled with transport across the cell was developed to interpret the differential cell data. The novelty of the model is to consider the Pt utilization for the Pt particles inside the carbon support without ionomer coverage based on catalyst morphology. The oxygen transport resistance local to Pt surface, that is hypothesized to originate from ionomer-Pt interaction, is evaluated by model-data comparison. The model parameters perceived to be critical for accurate cell performance prediction and the voltage loss terms are examined by sensitivity analysis. Research needs for characterizing catalyst morphology and electrode structure will be discussed.

Achieving High-Power PEM Fuel Cell Performance with an Ultralow-Pt-Content Core–Shell Catalyst

The high-power performance of proton exchange membrane fuel cells (PEMFC) decreases as the Pt loading or Pt surface area decreases due to oxygen transport constraints. This has limited the Pt reduction of a fuel cell below the current ∼0.2 mgPt/cm2MEA. In this paper, the performance of a Pt-monolayer core–shell catalyst (PtML/Pd/C) was studied with a particular focus on high-current-density operation. Although conventional Pt/C electrodes with low Pt loading showed a substantial voltage falloff at high current densities, PtML/Pd/C showed superior performance due to its greater Pt surface area. We show that Pt loading can be reduced to a level as low as 0.025 mgPt/cm2 without noticeable transport-related losses. This suggests considerable potential for further fuel cell cost reduction. The performance and microscopic properties of the catalyst were also studied after accelerated stability tests. The degradation mechanism and pathways for future development are also discussed.

Measurement of a new parameter representing the gas transport properties of the catalyst layers of polymer electrolyte fuel cells.

The optimization of the catalyst layers is necessary for obtaining a better fuel cell performance and reducing fuel cell cost. Although the ionomer coverage of the Pt catalyst is said to be a key parameter in this regard, the proportion of Pt either directly or indirectly covered by the ionomer is thought to be an important parameter with regard to gas transport (indirectly covered Pt: its gas transport paths are completely blocked by the ionomer even if it does not directly cover Pt). In this study, a new technique has been developed for evaluating the proportion of Pt covered indirectly or directly by the ionomer, which is defined as the "capped proportion", based on the carbon monoxide (CO) adsorption properties at different temperatures. The validity of the method was thoroughly examined by identifying the CO adsorption properties of the components of the catalyst layers. The capped proportion and oxygen transport resistance in the catalyst layers showed a good correlation, indicating that the capped proportion is a dominant factor of oxygen transport resistance. This technique thus enables the evaluation of the dominant factor of the gas transport properties of the catalyst layers. The method has another significant advantage in that it does not require a membrane electrode assembly, let alone electrochemical measurement, which should be helpful for catalyst layer optimization.

Highly Active and Durable Extended Surface Oxygen Reduction Electrocatalysts

The amount of platinum (Pt) in the catalyst layer accounts for a significant portion of fuel cell cost and limits the commercial deployment of proton exchange membrane fuel cells.[1] Extended surface nanomaterials have been developed as electrocatalysts in the oxygen reduction reaction for use in fuel cells. Extended surfaces offer key advantages to nanoparticles, including an order of magnitude higher specific activity, long range conductivity, and long term durability, but are traditionally limited by low surface area.[2] Catalyst development has included a variety of approaches, but recently has focused on galvanic displacement. Spontaneous galvanic displacement occurs when a less noble metal template contacts a more noble metal cation and combines aspects of corrosion and electrodeposition. Catalysts formed by spontaneous galvanic displacement are ideally situated, being able to take advantage of the specific activities generally associated with the catalyst type while significantly improving upon the surface area.[3] Recent developments in Pt-nickel (Ni) nanowires have produced materials with surface areas in excess of 90 m2 gPt ‒1.[4] Post-synthesis processing has been used to alloy the Pt-rich and Ni-rich zones, improving activity for oxygen reduction. Exposure to a variety of acid types and concentrations has been used to remove increasing amounts of Ni, creating nanostructures with high Pt surface areas and an array of compositions. Oxidative treatments have also been used to improve catalyst durability in rotating disk electrode (RDE) accelerated stress tests (30,000 potential cycles, 0.6‒1.0 V). By optimizing these techniques, extended surface electrocatalysts have been created with oxygen reduction mass activities 7 times greater than Pt nanoparticles and 5 times greater than the U.S. Department of Energy membrane electrode assembly (MEA) target in RDE half-cells. In accelerated stress tests, these materials lose less than 3% activity and less than 0.5% of their mass due to electrochemical dissolution. Remaining barriers, including synthesis scalability and MEA fabrication, are being addressed. Recent improvements in MEA performance suggest that the promise of extended surface catalysts in half-cells can be realized in the device. [1] D. Papageorgopoulos, in: U.S. Department of Energy (Ed.), http://www.hydrogen.energy.gov/pdfs/review14/fc000_papageorgopoulos_2014_o.pdf, 2014. [2] M. Debe, in: U.S. Department of Energy (Ed.), http://www.hydrogen.energy.gov/pdfs/review09/fc_17_debe.pdf, 2009. [3] S.M. Alia, Y.S. Yan, B.S. Pivovar, Catalysis Science & Technology, 4 (2014) 3589-3600. [4] S.M. Alia, B.A. Larsen, S. Pylypenko, D.A. Cullen, D.R. Diercks, K.C. Neyerlin, S.S. Kocha, B.S. Pivovar, ACS Catalysis, 4 (2014) 1114-1119. Figure 1. Surface areas (x-axis) and site-specific oxygen reduction activities (y-axis) of Pt nanoparticles and Pt-Ni nanowires, as-synthesized and modified by post-synthesis processing. The US Department of Energy MEA mass activity target (440 mA mgPt ‒ 1) is included as the solid black line. Figure 1

Experimental Development of Acid-Alkaline Bipolar Membrane Electrolytes

Anion-exchange membranes (AEMs) have received attention for use in alkaline fuel cells and bipolar membrane applications [1] The bipolar membrane concept was recently demonstrated by Unlu et al. as a way to reduce fuel cell costs (i.e., Pt loading) and the overall balance of plant (BOP).[2-3] Bipolar membranes are typically comprised of an H+-conducting membrane adjacent to an OH--conducting membrane with at least one internal acid-alkaline junction. However, most AEMs studied to-date are organic and exhibit low chemical stabilities and low ionic conductivities after prolonged exposure to high pH media and temperatures greater than 60°C.[4] A number of advancements have been made to increase the ion-exchange group stability by using phenyl guanidinium-[5], imidazolium-[6] and other metal-cation exchange groups[7], among others; all of which provide potential routes to circumvent stability issues. In this study, we prepared AEM and PEM precursors which are further developed into bipolar membranes. The combination of our precursors and our electrospinning process proves useful for preparing H+- and OH--conducting membranes. In addition to the aforementioned AEM stability issues, bipolar membranes can suffer from material compatibility issues at the AEM/PEM junction. We demonstrate an approach to create bipolar membranes by, for example, co-electrospinning that allows for short- and long-range fabrication with desirable AEM/PEM interfacial binding. For example, Park et al. recently demonstrated a novel approach for creating AEM membranes by electrospinning, which we extend specifically to develop bipolar membranes.[8] As a proof of concept, we chose PEM and AEM components made primarily of Nafion and modified polysulfone or modified poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) derivatives, respectively. We present 3 different approaches for conjoining the AEM and PEM layers to create the bipolar membranes. Ex-situ ion-transport measurements are presented for bulk in-plane ionic conductivities (σ) of the isolated membranes in OH--, H+- and CO3 2—forms and are compared to the through-plane σ for the bipolar membranes. Physical characterizations such as SEM, BET, and gravimetric swelling measurements are presented for each isolated and combined membranes. For select membranes, we show polarization (i-V) curves for a single MEA operating under H2/O2. Figure 1 shows a schematic of the electrospinning process whereby a rotating roll configuration is utilized for fabricating a co-electrospun bipolar membrane with a typical SEM image shown for an AEM fiber mat. Acknowledgments: We gratefully acknowledge the fuel cell team at the U.S. Army Research Laboratory. We acknowledge the U.S. Department of the Army, AMC and RDECOM for funding and support.

(Invited) Diagnostic Methods Utilized in Accelerated Stress Testing of Polymer Electrolyte Membrane Fuel Cells

The cost and durability of Polymer Electrolyte Membrane Fuel Cells (PEMFCs) are the two major barriers to the commercialization of these systems for stationary and transportation power applications.1 The cost and durability of fuel cells are inter-related as more often than not lower cost components are less durable than their higher cost counterparts. Given the long expected life times of these fuel cell systems in the field (> 5500 hours for transportation and > 60,000 hours for stationary applications), there is a pressing need to develop Accelerated Stress Tests (ASTs).2 The ASTs should be representative of degradation in the field and are expected to provide estimates of fuel cell lifetime using short experiments. The U.S. DOE Fuel Cell Tech Team has recommended various ASTs for PEMFC components.3,4 While these ASTs are good at evaluating the relative durability of the various materials used in PEMFCs, there is little information available on acceleration factors of these ASTs for various applications. In this paper we will present various diagnostic techniques that are utilized in conjunction with these ASTs to better evaluate the durability of fuel cell components and their effect on fuel cell performance. Diagnostic techniques used to evaluate electrocatalyst durability include, performance curves, electrochemical surface area, mass activity, electrode capacitance, AC impedance, evolved CO2 from the cathode, catalyst particle size, and electrode thickness. Figure 1 illustrates the performance of PEMFCs subjected to two different support ASTs; a 1.2V hold and a 1 to 1.5 V potential cycle @ 500 mV/sec. The observed degradation rate is 150 – 200 times faster during the potential cycling compared to the potential hold. This is consistent with the 100 times faster increase in Pt particle size observed during the potential cycling experiment (Figure 2). In addition to the Pt particle size increase and associated kinetic losses, there are clear mass transport losses associated with these ASTs. This is illustrated in Figure 3 where the lower frequency mass transport resistance dramatically increases during the AST especially for carbons that corrode faster. Diagnostic techniques used to evaluate membrane durability include performance curves, hydrogen cross over, high frequency impedance, shorting resistance, fluoride emission, membrane thickness, membrane morphology and membrane mechanical strength. The importance of these diagnostic techniques in the development of a new membrane AST will be discussed.

Barriers of scaling-up fuel cells: Cost, durability and reliability

Since its creation over 170 years ago, and despite major investments and efforts by stakeholders over the last few decades to move this technology to the mainstream, today fuel cells continue to be regarded as a fledgling industry. In spite of the commitment by industry leaders, analysis shows that their actions do not address the critical questions facing this technology: Why has scaling-up of fuel cells failed so often when many researchers have stated their successes in the small scale? Why do fuel cell stacks have lower durability, reliability and robustness than their individual cells? Could investments of a hydrogen fueling infrastructure stimulate advancements in the key issues of durability, reliability and robustness and substantially reduce fuel cell costs? In this paper, we will analyze and confront these fundamental questions to improve understanding of the challenges of scaling-up technologies and identify key barriers. Then we will examine options and suggest a procedure for change to substantially improve the durability and reliability of fuel cells and reduce their costs.

On the comparison and the complementarity of batteries and fuel cells for electric driving

This paper considers different current and emerging power train technologies (ICE, BEV, HEV, FCEV and FC-RE) and provides a comparison within a techno-economic framework, especially for the architectures of range-extender power trains. The economic benefits in terms of Total Cost of Ownership (TCO) are based on forecasts for the major TCO-influencing parameters up to 2030: electric driving distances, energy (fuel, electricity, hydrogen) prices, batteries and fuel cell costs. The model takes into account functional parameters such as the battery range as well as daily trip segmentation statistics.The TCOs of all the vehicles become similar in 2030, given a 200 km battery range for BEVs. BEVs are profitable for yearly mileages of 30,000 km and over, and for higher battery ranges.The competitiveness of FCEVs is examined through the H2 target price at the pump. There is a very significant effect of the fuel cell cost on the TCO. A FCEV with a fuel cell cost of 40 €/kW will be competitive with a similar ICE car for a 1.75 €/l fuel cost and ca. 7 €/kg hydrogen cost. This depends too to a great extent on possible ICE cars' CO2 taxes. As regard the FC-RE electric car, the hydrogen target price at the pump is noticeably higher (ca 10 €/Kg). FC-RE cars TCOs are strongly affected by the FC power, the discount rate chosen and the yearly mileage. Moreover, it therefore seems reasonable to confine FC-RE battery ranges in the region of 60 km.

Modeling ion conduction and electrochemical reactions in water films on thin-film metal electrodes with application to low temperature fuel cells

Transport-regulated electrochemical reactions in thin-film platinum (Pt) electrodes for polymer electrolyte fuel cells (PEFCs) is theoretically investigated with a meso-scale modeling framework. These electrodes are of interest for their potential to reduce low temperature fuel cell costs, but the mechanisms governing their operation are not well-understood at this time. A primary question arising from experimental data is the origin of the high ion conductivity and oxygen reduction reaction (ORR) activity on ionomer-free Pt during PEFC operation when typical ORR potentials are well above commonly measured potentials of zero charge (PZC) for Pt surfaces. These ORR potentials should result in low proton conductivity and high activation losses. Herein, we address these questions with a model that considers both polymer electrolyte and water-covered portions of the Pt electrocatalysts similar to the experimental electrodes. Local electroneutrality is not assumed and the ion transport in water- and polymer electrolyte-covered regions of the Pt is modeled using the continuum Poisson- Nernst- Planck (PNP) equations including spatially-resolved domains for the compact (Stern) portions of the double layer. In addition, the model incorporates the water dissociation reaction (WDR) and both the acidic and alkaline ORR mechanisms. In water-covered regions, the ionic conductivity is highly dependent on the Pt surface charge, local pH, and transport-regulated ORR pathway. The model predicts the experimentally observed high ionic conductivity for Pt thin films in water and attributes it to high hydroxide concentration.

Electrospun Bipolar Membranes for Portable Fuel Cells

Shifting to high pH fuel cell operating environments could potentially lower the overall fuel cell costs by reducing or replacing noble metals with other electrocatalytically-active non-noble metal materials. Anion-exchange membranes (AEMs) with mobile OH- ions are one way to shift to higher pH environments, and have received attention for use in alkaline fuel cells.[1] Most AEMs studied to-date are organic and exhibit low chemical stabilities and low ionic conductivities (i.e. mobile transport ions are OH-, CO3 2- or mixed ion form) after prolonged exposure to high pH media and temperatures greater than 60°C.[2] A number of advancements have been made for increasing the ion-exchange group stability for reasonable ion-conductivities by using phenyl guanidinium-[3], imidazolium-[4] and other metal-cation exchange groups[5]. Park et al. recently demonstrated a novel approach for creating AEM membranes by electrospinning.[6] The electrospinning approach allows for short- and long-range fabrication, which is useful for proton- and/or hydroxide-transport membranes. In addition to the electrocatalyst and membrane materials concerns, fuel cells commonly employee auxiliary components to assist in balancing the water production and consumption at the anode and cathode compartments.[7] The auxiliary components cause the total fuel cell device (i.e. composed of stack and other components) to increase in size and weight. One way to reduce the logistics burden and overall balance of plant (BOP) is to design bipolar membranes that are comprised of an acid membrane component spatially separated from an alkaline membrane component. The bipolar membrane concept was recently demonstrated by Unlu et al.[8] The reduction in the BOP would therefore reduce the overall cost and size of the fuel cell device. In this study, we synthesize AEM and PEM precursors and subsequently co-electrospin these precursors into a bipolar membrane. The bipolar membrane produced may be potentially used for portable hybrid acid-alkaline fuel cells. The electrospun PEM component is primarily made of Nafion embedded in an inert matrix layer. The electrospun AEM component is comprised of a synthesized and subsequently modified polysulfone derivative embedded in an inert matrix layer. We provide physical characterizations such as TEM, SEM, BET, swelling and dimensional change measurements to understand each electrospun component at the PEM and AEM compartments. Moreover, we perform ex-situ ion-transport measurements for bulk conductivities of the isolated and combined components. Figure 1 shows a schematic of the electrospinning process whereby a rotating roll configuration with multiple high voltage power supplies is utilized for fabricating a co-electrospun bipolar membrane. An SEM image is shown for the AEM fiber mat component, which is typically placed at the cathode compartment. Acknowledgements We gratefully acknowledge the fuel cell team at the U.S. Army Research Laboratory. We acknowledge the U.S. Department of the Army and Army Materiel Command for funding and support.

Performance of Advanced Pt-Ni Alloy Catalysts in Polymer-Electrolyte Fuel Cells

The cost of a Polymer-Electrolyte Fuel Cells (PEFC) system is still the primary barrier to commercialization, although it has decreased significantly over the past decade. Platinum electrocatalysts are required due to the slow kinetics of the oxygen reduction reaction (ORR). To reduce electrocatalyst cost, platinum alloys with higher ORR mass activity are being developed.1,2 ORR activities exceeding DOE’s 2015 targets were reported by various research groups for carbon-supported Pt alloys and core-shell nanoparticles in rotating-disk electrode (RDE) tests.3,4 However, it can be challenging to achieve similarly high mass activities for these electrocatalysts in membrane-electrode assemblies (MEAs), as evidenced by in-cell performance at low current densities (kinetically-controlled) region, and it is even more challenging to achieve improved cell performance at higher current densities with these advanced alloy catalysts.5 United Technologies Research Center (UTRC) is a part of an on-going DOE-supported research project, led by Argonne National Laboratory (ANL), focused on improving the understanding, performance, and durability of advanced Pt-alloy catalysts operating in complete PEFCs. In the current study, advanced MEAs with high ORR activity Pt-Ni alloy catalysts are prepared by Johnson Matthey Fuel Cells (JMFC) and tested by UTRC in small PEFCs (12.5-cm2 active area). A variety of parameters, including: Pt-Ni catalyst composition and structure, catalyst-ink formulation, and MEA-fabrication procedures are being explored in order to develop MEAs with superior performance over the entire PEFC operating range relative to Pt-only MEAs. A comparison of Pt-only and Pt-Ni MEAs, which have similar catalyst particle size and the same carbon support and electrode composition, are shown in Figure 1. Results obtained from in-cell diagnostics will be used to explain the differences in the polarization curves, as well as project paths to future performance improvements. The impact of Pt:Ni ratio on ORR activity and cell performance will also be reported. Acknowledgements The authors gratefully acknowledge funding from the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office (Nancy Garland, Technology Development Manager) under contract number DE-AC02-06CH11357. The authors would also like to thank their DOE project colleagues at ANL and at JMFC for both their support of this work and for helpful discussions. References S. C. Ball, S. L. Hudson, B. R. C. Theobald, and D. Thompsett, ECS Transactions, 11 (1), 1267-1278 (2007).H. R. Colón-Mercado, and B. N. Popov, Journal of Power Sources, 155 (2), 253–263 (2006).N. Markovic and V. Stamenkovic, DOE Hydrogen Program 2010 Annual Report (2010).M. Shao, A. Peles, and K. Shoemaker, Nano Letters, 11 (9), 3714-3719 (2011).K.C. Neyerlin, R. Srivastava, C.F. Yu, and P. Strasser, Journal of Power Sources, 186 (2), 261-267 (2009).

Invited: Remaining Technical Challenges in R&D for Automotive PEM Fuel Cell System

It is a consensus that the cost and durability of the hydrogen PEM fuel cell system are still significant challenges to overcome before fuel cell vehicles can compete in the market [1]. The US Department of Energy (DOE) sponsored fuel cell cost study estimates the 2012 cost of automotive fuel cell systems to be $51/kW, assuming high volume production [2]. This is more expensive than the DOE target of $40/kW even though the study uses an aggressively low platinum group metal (PGM) catalyst loading assumption. This means that a reduction of PGM loading by itself may not be sufficient. The USDRIVE Fuel Cell Tech Team Roadmap indicates that increasing the area specific power density is the most effective way to reduce cost, followed by reduction of platinum (Pt) loading in the fuel cell stack [1]. To find technical solutions, it is necessary to pursue not only engineering to develop incremental improvements, but also fundamental research to improve baseline performance. The remaining fundamental research can be focused on two areas: mass transport overpotential and catalyst mass activity. It is also important to obtain these technical solutions while providing for a durable system.The oxygen reduction reaction (ORR) overpotential at the cathode is significantly greater than the overpotential of the hydrogen oxidation reaction [3, 4]. Therefore, the oxygen concentration in the cathode is vital for the performance and operational robustness. Particularly, providing high oxygen concentration at high current density operation is critically important to enhance the area specific power density. However oxygen concentration at the cathode is locally lowered by unsatisfactory water management [5-7]. Thus, mass transport overpotential at high current density is the major barrier to achieving high power density with acceptable operational robustness. Experimental investigation of mass transport has been limited by an inability to resolve water saturation-dependent properties in the gas diffusion layer. An approach of computational fluid dynamics based Thermal Lattice Boltzmann Method has been taken to represent gas/liquid transport in the cathode [8]. Ford is working with the University of South Carolina in this area. A risk of this approach is the accuracy of the mathematical modeling which will provide direction for the advanced mass transport design. To mitigate it, ex-situ material characteristics and in-situ data will be pursued to validate the modeling. A novel analytical methodology has been developed to measure oxygen partial pressure in the flow field by using oxygen sensitive fluorophore molecules [9].Enhancing the catalyst mass activity for ORR is also imperative to achieve the cost target. The most important need in catalyst research is to improve performance and durability at the same time under automotive usage conditions. One of the approaches of catalyst development looks at morphology of catalyst and its support materials. A newly developed Pt two dimensional nanometer scale network structure on amorphous niobium oxide support shows high mass activity and durability at the same time [10].The technical outlook and research approaches for remaining technical challenges of automotive PEMFCs will be discussed at the ECS meeting.

Manufacturing Readiness and Cost Impacts for PEM Stack and Balance of Plant

Balance-of-Plant (BOP) cost for PEM fuel cell systems are now equal to or exceeding the cost of PEM fuel cell stack. The fuel cell systems cost analyses funded by the Fuel Cell Technologies Office (FCTO) of the U.S. Department of Energy (DOE) confirms the near equivalency of the BOP cost to fuel cell stack cost for PEM fuel cells in the studies by Battelle[1], Lawrence Berkeley National Laboratory[2], and Strategic Analysis Inc.[3]. The cost equivalency between the BOP and the PEM fuel cell stack is observed over the full spectrum of fuel cell applications; Material Handling Equipment (MHE) fuel cell systems, stationary fuel cell systems, automotive fuel cell systems. James et al[4]evaluated PEM automotive fuel cell costs and found that at production rates of 30,000 automotive units per year or greater the BOP cost were more than the PEM fuel cell stack cost, as shown in Figure 1.Battelle[5] reports the BOP cost is 3.5X the cost of the fuel cell stack in their analysis of the cost of a PEM 10 kW fuel cells for MHE; these data are represented in Figure 2 where the balance of plant is 59% of the fuel cell system cost at production rates of 10,000 MHE fuel cell systems per year.For a PEM 100 kW hydrogen fueled stationary fuel cell systems, Wei and McKone[6]of Lawrence Berkeley National Laboratory (LBNL) reported the ratio of BOP-to-stack cost is 1.3 at production rates of 1,000 hydrogen fueled units per year. For a PEM 100 kW reformate fueled stationary power plants, the LBNL data demonstrate the ratio of BOP to fuel cell stack cost is 1.1 for a production rate of 10,000 fuel cell systems per year.LBNL evaluated smaller hydrogen fueled PEM stationary, backup power (BUP) systems and the ratio of BOP to fuel cell stack cost was 1.5 for a 10 kW system. At BUP system production levels of 50,000, the ratio of BOP-to-fuel cell stack cost increased to 2.3 in the LBNL data.A three part approach to improving BOP performance, durability and reduced cost is:Increasing awareness of BOP specifications for performance, durability and cost within the supply chain.Optimization of manufacturing processes to reduce cost of BOP componentsDevelopment of fuel cell system BOP components that meet original equipment manufacturers specifications. Increasing awareness of BOP specifications: For many years, the approach to fuel cell BOP components has been to use Off The Shelf (OTS) components developed for non-fuel cell applications. Overall, this approach has not been successful because of a lack of awareness of the OEM specifications by the BOP manufacturers. The Ohio Fuel Cell Coalition brought the OEMs and BOP manufacturers together to share specifications, discuss manufacturing capabilities, and establish acceptable cost targets. The results of these exchanges will be presented.Optimization of Manufacturing Processes for BOP Components: The FCTO has sponsored manufacturing R&D programs for the last three years. Manufacturing R&D for BOP components will be discussed and recommendations for optimization of manufacturing methods for specific BOP components presented.Development of Fuel Cell Balance-of-Plant Components: Replacement of OTS components that are mismatch for fuel cell applications will in many cases require alternative materials and specialized designs to meet the OEM durability and performance requirements. The R&D pathways to identify alternative materials and specialized designs will be discussed.

On the competitiveness of electric driving in France: Impact of driving patterns

Abstract The environmental issues in the transport sector are numerous and CO2 capture is not even plausible for vehicles at the moment. This report describes a number of different emergent power train technologies (ICE, BEV, PHEV, FCEV) before providing an inter-comparison of these technologies within a technical and economic context. The economical benefits are discussed in terms of the “Difference of Total Cost of Ownership” (DTCO) and take: electric driving distances, energy (fuel, electricity, hydrogen) prices, batteries and fuel cells costs. To simulate electric driving distances, the model uses several functional parameters such as the battery range and the ‘range anxiety’ based on the assumption of one recharge per day. The potential electric driving distances are evaluated according to the segmentation statistics of daily trips. The results show the yearly mileages, as well as the range and cost of batteries and fuel cells, together with their relative impact on the DTCO and on the competitiveness of electric vehicles. The price of electric vehicles remains high with strong dependency on the battery׳s capacity, but the benefits in terms of fuel cost savings can be considerable. The price of electricity is currently noticeably lower than petroleum-based fuels, which balances the high costs of the batteries. 50% or more of LDV yearly mileages can be electric-driven, even for limited battery ranges (ca. under 50 km). There are stakes for the battery costs (competitiveness under €215/kWh) and lifetimes, while the low battery ranges (100 km in our case) provide the best margins. As regards FCEVs, the hydrogen target price at the pump should be achievable (less than €6.5/kg) with reasonable gasoline prices (€1.7/liter at the pump) and fuel cell costs (€20/kW). CO2 taxes and ICE efficiency gains will lead to opposite impacts of the H2 target prices at the pump.

Electrochemical Studies on High Durable Carbon Supported Fuel Cell Catalysts

Fuel cell cost reduction demands improved catalyst performance and durability. Platinum (Pt) particle size, crystallite geometry, metal dispersion on carbon support, conductivity, and porosity of the catalyst layer are key features that determine the catalytic activity in fuel cell operating environment. These properties can be controlled by proper design of the catalyst synthesis process with suitable carbon support1. The fundamental properties of the carbon support can have great influence on fuel cell catalyst at low temperature PEMFC as well as high temperature PAFC systems. Pt catalysts supported on high surface area carbon supports result in smaller Pt crystallites with increased electrochemically active surface area but it results in lower durability due to carbon corrosion. The durability of Pt catalyst at cathode is considered as one of the key challenges for fuel cell system reliability. The major degradation in fuel cell performance is due to loss of electrochemical surface area of Pt catalyst due to carbon corrosion2. This phenomenon is attributed to Oswald ripening (Pt particles detached from carbon support to form larger aggregates), which contributes to the loss in fuel cell performance. In the present study we have prepared fuel cell catalysts with three high durable carbon (HDC) supports with varying surface areas and graphitization. The carbon corrosion behavior of catalysts was studied using cyclic voltammetry. With high durable carbon support, optimization of electrode structure with PTFE binder is crucial for improved performance and to mitigate carbon corrosion. The electrodes are prepared with different loadings of PTFE content and characterized by measuring electrochemical surface area and linear sweep voltammetry (Figure 1). The carbon corrosion experiments are conducted in 0.5M H2SO4 by sweeping the voltage from 0.4 to 1.0 using Ag/AgCl as reference electrode. After every 1000 cycles, electrochemical surface area is measured (Figure 2). An optimum surface area and graphitization is required to balance the performance and durability.Reference:Chunzhi He, Sanket Desai, Garth Brown, and Srinivas Bollepalli, The Electrochemical Society Interface, 41-45, Fall 2005.R. Borup, J. Meyers, B. Pivovar, Y.S. Kim, R. Mukundan, N. Garland, D. Myers, M. WilSon, F. Garzon, and D. Wood, Chem. Rev., 107, 3904 (2007)

Density Functional Theory Studies Combined with Experimental Investigations of the Oxygen Reduction Reaction on Fe- or Co-Containing Carbon Fibers

The oxygen reduction reaction (ORR) is responsible for a large potential loss for anion-exchange membrane fuel cells (AEMFCs), and researchers continue to develop non-Platinum-group-metal (non-PGM) electrocatalysts that attenuate the related kinetic losses. Moreover, it is desirable to use non-PGM electrocatalysts to mitigate fuel cell costs, and with respect to the ORR, AEMFCs provide an operating environment that allows a shift to non-PGM electrocatalysts.1,2 Many research investigations have been performed on non-PGM electrocatalysts such as M-phthalocyanines (MPc, where M = Fe, Co or Mn for example)3,4, heat-treated metal macrocycles5,6 and nitrogen-doped carbons devoid of metal nanoparticulates7. In some cases, these non-PGM electrocatalysts exhibit ORR activities comparable to Pt/C electrocatalysts. As a contribution to non-PGM electrocatalysts research efforts, we studied the ORR in 0.1N KOH at room temperature on Fe- or Co-carbon fibers derived by pyrolyzing electrospun nanofiber precursors. Electrospinning provides a facile approach for developing high-surface area carbon materials with a wide range of morphologies. However, as is the case with most heat-treated non-PGM electrocatalysts, the active site(s) for heat-treated metal-containing carbon materials are not well defined. Therefore, we combine our physical characterizations and electrochemistry findings with density functional theory (DFT) calculations and attempt to probe potential ORR pathways for Fe- or Co-N4-containing graphitic electrocatalyst clusters.We probe H2O, O2, HOOH, OOH, and OH adsorption on the Fe- and Co-containing graphitic clusters. In addition, we compare each of the adsorbate binding energies as a function of the spin and oxidation states. We also compare various DFT methods for each of the systems including M06-L, M062X and B3LYP. Lastly, we provide rotating ring disk electrode (RRDE) voltammetry, cyclic voltammetry and other physical characterizations such as XRD, XPS, TEM and SEM to better relate the electrocatalyst activity, morphology and surface chemistry to the DFT models developed. Figures 1 a-d show typical Fe- or Co-containing graphitic clusters used for the DFT calculations. Additional graphitic cluster configurations are considered and may be presented. Acknowledgements We gratefully acknowledge the fuel cell team at the U.S. Army Research Laboratory. We acknowledge the U.S. Department of the Army and Army Materiel Command for funding and support. The authors would also like to thank ARL for facilitating this opportunity through the Science, Mathematics and Research for Transformation (SMART) program.

Generation of Bio-Electricity from Ammonia Fertilizer Plant Liquid Effluent

Microbial fuel cells (MFCs) are typically designed as a two-chamber system with the bacteria in the anode chamber separated from the cathode chamber by a polymeric proton exchange membrane (PEM). Most MFCs use aqueous cathodes where water is exposed to air to provide dissolved oxygen to electrode. To increase energy output and reduce the cost of Microbial Fuel Cells, charcoal electrode (locally prepared) at the composition of 2:1 charcoal/cement ratio was used. Ammonia fertilizer plant liquid effluent was used as the substrate, while the bacteria present in the wastewater were used as the biocatalyst. The cells were operated at room temperature with pH of 6.68. The anode and cathode chambers were kept under anaerobic and aerobic conditions respectively. The cell 3 set-up with electrode area of 3.63×10 -3 m 2 was observed to have the highest power density of 134.5455mW/m 2 and current density of 181.8182mA/m 2 while cell 4 set-up with electrode area of 3.63×10 -3 m 2 was observed to have the least power density of 108.9807mW/m 2 and current density of 126.7218mA/m 2

Direct Fuel Cell DFC Durability Progress

FuelCell Energy, Inc. (FCE) is a global leader in providing ultra-clean baseload distributed generation at more than 50 locations worldwide. These plants have generated more than one billion kilowatt hours of ultra-clean power using a variety of fuels including renewable biogas, coal-bed methane, propane, and natural gas. The generator design is based on the internal reforming direct carbonate fuel cell (DFC®) concept. The key to widespread fuel cell commercial acceptance is grid competitive cost of electricity (COE). The prime contributor to the fuel cell COE is first-time and most importantly, periodic replacement costs of the fuel cell stack. As such, the focus of technology development is on reducing fuel cell cost as well as extending service. This paper reports on the progress on understanding and extending the carbonate fuel cell durability.

Hydrogen vehicles: Impacts of DOE technical targets on market acceptance and societal benefits

Hydrogen vehicles (H2V), including H2 internal combustion engine, fuel cell and fuel cell plug-in hybrid, could greatly reduce petroleum consumption and greenhouse gas (GHG) emissions in the transportation sector. The U.S. Department of Energy has adopted targets for vehicle component technologies to address key technical barriers to widespread commercialization of H2Vs. This study estimates the market acceptance of H2Vs and the resulting societal benefits and subsidy in 41 scenarios that reflect a wide range of progress in meeting these technical targets. Important results include: (1) H2Vs could reach 20–70% market shares by 2050, depending on progress in achieving the technical targets. With a basic hydrogen infrastructure (∼5% hydrogen availability), the H2V market share is estimated to be 2–8%. Fuel cell and hydrogen costs are the most important factors affecting the long-term market shares of H2Vs. (2) Meeting all technical targets on time could result in about an 80% cut in petroleum use and a 62% (or 72% with aggressive electricity de-carbonization) reduction in GHG in 2050. (3) The required hydrogen infrastructure subsidy is estimated to range from $22 to $47 billion and the vehicle subsidy from $4 to $17 billion. (4) Long-term H2V market shares, societal benefits and hydrogen subsidies appear to be highly robust against delay in one target, if all other targets are met on time. R&D diversification could provide insurance for greater societal benefits. (5) Both H2Vs and plug-in electric vehicles could exceed 50% market shares by 2050, if all targets are met on time. The overlapping technology, the fuel cell plug-in hybrid electric vehicle, appears attractive both in the short and long runs, but for different reasons.