Marianne P. Rodgers

Membrane Degradation Mechanisms and Accelerated Durability Testing of Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cells (PEMFCs) have increasingly received worldwide attention as the technology that can lead to substantial energy savings and reductions in imported petroleum and carbon emissions. Cost, durability, performance, reliability, efficiency, and size, are some of the requirements that must be met before PEMFCs can be used commercially. The lifetime requirement for stationary applications is about 40,000 hours and for transportation applications 5,000 (cars) and 20,000 hours (buses) (1). Today, the typical operating temperature for both applications is between 60 – 80°C, but to meet the 2010 and 2015 Department of Energy targets, PEMFCs must operate at temperatures from below the freezing point to higher than 100°C (~120 °C maximum), humidity from ambient to saturated, and half-cell potentials from 0 to >1.5 V. Durability studies of proton exchange membrane fuel cells (PEMFC) show that, along with cost, the long-term stability of PEMFCs is a limiting factor in their commercialization (2-6). Degradation of PEM fuel cells is generally observed as slow, unrecoverable performance decay, followed by sudden failure. The gradual performance loss is typically associated with changes in the electrodes and the membrane. The degradation of electrodes is usually caused by catalyst degradation and carbon corrosion. Membrane chemical and mechanical degradation are related to reactant gas crossover, Pt dissolution and migration, transition metal ion contaminants, and hydroxyl radical formation, and cycling of relative humidity. The chemical decomposition of the side

Evaluation of the Durability of Polymer Electrolyte Membranes in Fuel Cells Containing Pt/C and Pt-Co/C Catalysts under Accelerated Testing

One of the main sources of degradation in fuel cells is hydroxyl radical attack of the membrane. Radicals are formed where platinum, hydrogen, and oxygen are present. Radical formation occurs at the electrodes, where reactants diffusing through the membrane can react on the Pt catalyst. Additionally, Pt ions form at the cathode, and can then migrate into the membrane and form a Pt band where there is also significant radical generation. Radical attack of the membrane leads to pinhole and crack formation, resulting in significant hydrogen crossover, large performance losses, and shortened cell life.

Automatic Generation Control Using an Energy Storage System in a Wind Park

This paper demonstrates the operation of a 1 MW/2 MWh grid-tied battery energy storage system (BESS) in a 10 MW wind R&D park for Automatic Generation Control (AGC) for 29 days. The efficiency and utilization of the BESS in the context of regulation and grid integration are examined. The response time for the BESS is as low as one second, which is faster than the current accepted practice of a conventional generator with governor control. Using PJMs performance template gives an average performance score of 93% while the storage is providing AGC. However, because the storage system only charges when there is sufficient wind energy and spent significant time in maintenance mode, the 29-day performance average is only 65%. The battery was able to carry out some mode of AGC for 64% of the test period. When energy costs and battery degradation are considered, utilizing the battery costs USD 19,000 over the 29-day period, whereas the potential income from AGC, charging only with wind power, was USD 9,037. This 29-day demonstration shows that batteries have fast response and can perform AGC, but within a wind farm AGC is unlikely to be suitable without changes in the tariff schemes.

Accelerated Durability Testing of Perfluorosulfonic Acid MEAs for PEMFCs Using Different Relative Humidities

Polymer electrolyte membrane fuel cells (PEMFCs) receive worldwide attention as the electricity-generating engine for the hydrogen economy. Cost, durability, performance, reliability, efficiency, and size, are some of the requirements that must be met before PEMFCs can be expanded commercially. The lifetime requirement for onsite, combined heat and power applications is about 40,000 hours and for transportation applications 5,000 (cars) and 20,000 hours (buses). Membrane durability is one of the most important factors limiting the lifetime of PEMFCs.

Accelerated Durability Testing of Perfluorosulfonic Acid MEAs for PEMFCs

There is a strong interest in durability studies of proton exchange membrane fuel cells (PEMFC) because, along with cost, the long-term stability of PEMFC is a limiting factor in their commercialization. Examining the characteristics of a membrane electrode assembly (MEA) over a prescribed amount of time under accelerated degradation conditions can give an indication of the degradation behavior of each MEA. Testing under low humidities and/or high temperatures or by humidity or temperature cycling are techniques that accelerate degradation.

Effect of Equivalent Weight of Phosphotungstic Acid-Incorporated Composite Membranes on the High Temperature Operation of PEM Fuel Cells

Fuel cells have shown great promise for future power sources and there has been substantial advancement in the technology of fuel cells over the past decades. For automobile application, however, there are still challenging issues related to its performance and durability. It is highly desirable to operate fuel cells at high temperature because of a number of benefits, e.g., improved reaction kinetics and carbon monoxide tolerance. Since the conventional polymer electrolytes such as Nafion are not stable at high temperatures, the development of novel membranes that are mechanically, thermally, and electrochemically stable at high temperatures while providing good conductivity under low relative humidity condition is one of the most challenging areas of research for automobile applications of fuel cells. In fact, extensive research efforts have been made to design new proton exchange materials that can overcome the limitations of conventional polymer electrolytes.

A review of manufacturing metrology for improved reliability of silicon photovoltaic modules

In this work, the use of manufacturing metrology across the supply chain to improve crystalline silicon (c-Si) photovoltaic (PV) module reliability and durability is addressed. Additionally, an overview and summary of a recent extensive literature survey of relevant measurement techniques aimed at reducing or eliminating the probability of field failures is presented. An assessment of potential gaps is also given, wherein the PV community could benefit from new research and demonstration efforts. This review is divided into three primary areas representing different parts of the c-Si PV supply chain: (1) feedstock production, crystallization and wafering; (2) cell manufacturing; and (3) module manufacturing.

Developing, implementing and testing up and down regulation to provide AGC from a 10 MW wind farm during varying wind conditions

With increasing levels of electrical energy generated by intermittent sources such as wind turbines, their participation in grid ancillary services is becoming a necessity. Typically, all generated energy from variable generators is absorbed by the electric grid and balancing is left to traditional generators. Wind turbine technology has matured to the level where a large wind generator is capable of providing ancillary services such as up- and down-active power regulation (secondary frequency regulation). The up-regulation capacity of a variable generator is constrained primarily by external factors such as the prevailing wind speed in the case of a wind turbine. This work uses the Wind Energy Institute of Canadas (WEICan) 10 MW Wind R&D Park (Type 5 generators) in Prince Edward Island, Canada, to test and evaluate a simple algorithm to provide up- and down-regulation services from a wind park. The developed algorithm uses a 10-minute averaged wind speed to estimate the available park generation potential. A fixed power curtailment is applied to provide room for up-regulation. An historical, external AGC signal is then applied to the wind parks active power set-point and the resulting park performance is evaluated. Results of the 4.5 hour test prove the technical capability of the wind farm in participating in the regulation market. A performance score of 64 % was calculated according to the PJM method, averaged across the test duration.