Charles E. Chamberlin

Modeling of Proton Exchange Membrane Fuel Cell Performance with an Empirical Equation

An empirical equation [E = E{sub 0} {minus} b log i {minus} Ri {minus} m exp (in)] was shown to fit the experimental cell potential (E) vs. current density (i) data for proton exchange membrane fuel cells (PEMFCs), at several temperatures, pressures, and oxygen compositions in the cathode gas mixture. The exponential term compensates for the mass-transport regions of the E vs. i plot; i.e., the increase in slope of the pseudolinear region and the subsequent rapid fall-off of the cell potential with increasing current density. As has been previously shown, the terms E{sub 0} and b yield the electrode kinetic parameters for oxygen reduction in the PEMFC and R represents the resistance, predominantly ohmic and, to a small extent, the charge-transfer resistance of the electro-oxidation of hydrogen. The exponential term characterizes the mass-transport region of the E vs. i plot. The parameter n has more pronounced effects than the parameter m in this region. A physicochemical interpretation of these parameters is needed. The PEMFC is the most promising candidate fuel cell power source for a zero emission vehicle, because of its desirable characteristics, such as quick start capability, low operating temperature, high energy efficiency, and high power density.

Operating experience with a photovoltaic-hydrogen energy system

We report on the performance, safety, and maintenance issues of a photovoltaic (PV) power plant which uses hydrogen energy storage and fuel cell regenerative technology. The facility, located at the Humboldt State University (HSU) Telonicher Marine Laboratory, has operated intermittently since June 1991, and in August 1993 went into full-time, automatic operation. After more than 3900 hours, the system has an excellent safety and performance record with an overall electrolyzer efficiency of 76.7%, a PV efficiency of 8.1%, and a hydrogen production efficiency of 6.2%.

Comparison of PV module performance before and after 11 and 20 years of field exposure

In 1990 the Schatz Energy Research Center (SERC) installed a PV array comprised of 192 ARCO M-75 modules. Prior to installation, SERC measured the performance of each module. For the past 20 years the array has continued to operate in a cool, marine environment. The performance of each module was re-evaluated in 2001 and again last year in 2010. This paper describes the equipment and procedure used in retesting the modules, and reports module performance results. The average module maximum power production at one full sun and NOCT has progressively decreased from an initial 39.88W in 1990 to 38.13W in 2001 and to 33.43W in 2010. The average module maximum power production fell by an average of 0.4%/yr from 1990 to 2001 and by an average of 1.4%/yr from 2001 to 2010.

Effects of mismatch losses in photovoltaic arrays

Abstract Experimental and modeling results on the effects of mismatch losses in photovoltaic arrays are presented. Field tests conducted on each of the 192 modules are used to describe the variation in the properties of production run photovoltaic modules. Module specific estimates of a five-parameter module model are obtained by nonlinear regression. Mathematical models of four-module parallel string and series block photovoltaic array performance based on the five-parameter module model are developed and used to evaluate the variation in maximum output power and mismatch loss of arrays with random module orderings. Module maximum output power averaged 14% below the nameplate rating and exhibited a coefficient of variation of 2.1%. Mismatch losses were very small, never exceeding 0.53%. No differences between parallel string and series block arrays in array maximum output power were observed.

A photovoltaic/fuel cell power system for a remote telecommunications station

The Schatz Energy Research Center (SERC) in cooperation with the Yurok Tribe has designed, built, installed and operated a stand-alone power system integrating photovoltaic and proton-exchange membrane (PEM) fuel cell technologies to operate a remote radiotelephone repeater station. Located within Redwood National Park in northwestern California, USA, the station is the most critical link in the Tribes telecommunications system. Primary power for the station is provided by a conventional PV system with battery storage, but the PV system alone cannot carry the load during the winter rainy season. Whenever necessary, the fuel cell system starts automatically and provides clean, reliable, quiet power that is consistent with the National Park Services (NPS) conservation ethic. This paper describes the operation of the PV-fuel cell system for the period from November 1999 through June 2000. The fuel cell ran for 3239 hours during this period, providing reliable backup power without interruption.