Jean Hamelin

Performance of a stand-alone renewable energy system based on energy storage as hydrogen

Electrolytic hydrogen offers a promising alternative for long-term energy storage of renewable energy (RE). A stand-alone RE system based on energy storage as hydrogen has been developed and installed at the Hydrogen Research Institute, and successfully tested for autonomous operation with developed control system and power conditioning devices. The excess energy produced, with respect to the load requirement, has been sent to the electrolyzer for hydrogen production. When energy produced from the RE sources became insufficient, with respect to the load requirement, the stored hydrogen was fed to a fuel cell to produce electricity. The RE system components have substantially different voltage-current characteristics and they are integrated through power conditioning devices on a dc bus for autonomous operation by using a developed control system. The developed control system has been successfully tested for autonomous operation and energy management of the system. The experimental results clearly indicate that a stand-alone RE system based on hydrogen production is safe and reliable.

Dynamic behavior of a PEM fuel cell stack for stationary applications

We discuss the behavior and performance of a proton exchange membrane fuel cell stack under fast load commutations. We present experimental results for the polarization curves, energy balance sheet, and time response of the fuel cells. Although load transients are present both in the voltage and current generated, it is found that the fuel cell system response is faster than 0.15 s to load commutations. The experimental results were also compared to the Amphlett et al. and Kim et al. models, which were found to describe the data well.

Renewable energy systems based on hydrogen for remote applications

An integrated renewable energy (RE) system for powering remote communication stations and based on hydrogen is described. The system is based on the production of hydrogen by electrolysis whereby the electricity is generated by a 10 kW wind turbine (WT) and 1 kW photovoltaic (PV) array. When available, the excess power from the RE sources is used to produce and store hydrogen. When not enough energy is produced from the RE sources, the electricity is then regenerated from the stored hydrogen via a 5 kW proton exchange membrane fuel cell system. Overview results on the performances of the WT, PV, and fuel cells system are presented.

Characterization of a Ballard MK5-E Proton Exchange Membrane Fuel Cell Stack

We present the results of an experimental investigation of the energy balance of a Ballard MK5-E proton exchange membrane fuel cell (PEMFC) stack. We have investigated the transient phenomena that occur during PEMFC stack warm-up, under load switching, and when the PEMFC stack is connected to a DC/AC inverter. A simple and convenient model describing the polarization curve as a function of the temperature is presented and validated by our experimental data. We also present experimental results on the increase PEMFC stack performance as a function of the current density for different oxygen concentrations of the oxidant gas.

Analytical model for predicting the performance of photovoltaic array coupled with a wind turbine in a stand-alone renewable energy system based on hydrogen

We present the results of an analysis of the performance of a photovoltaic array that complement the power output of a wind turbine generator in a stand-alone renewable energy system based on hydrogen production for long-term energy storage. The procedure for estimating hourly solar radiation, for a clear sunny day, from the daily average solar insolation is also given. The photovoltaic array power output and its effective contribution to the load as well as to the energy storage have been determined by using the solar radiation usability concept. The excess and deficit of electrical energy produced from the renewable energy sources, with respect to the load, govern the effective energy management of the system and dictate the operation of an electrolyser and a fuel cell generator. This performance analysis is necessary to determine the effective contribution from the photovoltaic array and the wind turbine generator and their contribution to the load as well as for energy storage.

Toroidal cross capacitor for measuring the dielectric constant of gases

We describe toroidal cross capacitors built to accurately measure the dielectric constant of gases. We tested the capacitors by measuring the dielectric polarizability of helium and argon at 7 and 50 °C at pressures up to 3 MPa. For helium, the results are consistent with the ab initio calculation of the molar polarizability and are limited by the uncertainties of the capacitance measurements. For argon, the results are consistent with the best previously published measurements of the polarizability and are limited by the uncertainties of the pressure measurements. Lessons learned are provided.

Resonators for accurate dielectric measurements in conducting liquids

The compact, rugged, re-entrant radio-frequency resonator [A. R. H. Goodwin, J. B. Mehl, and M. R. Moldover, Rev Sci. Instrum. 67, 4294 (1996)] was modified for accurate measurements of the zero-frequency dielectric constant (relative electric permittivity) er of moderately conducting liquids such as impure water. The modified resonator has two modes with frequencies near 216/er MHz and 566/er MHz. The results for er at both frequencies were consistent within 0.0002er, verifying that the low-frequency limit had been attained with water samples with conductivities in the range 100–2500 μS/m. The results for water and for the insulating liquid cyclohexane were within 0.0005er of literature values. The present analysis is based on a simplified equivalent circuit that accounts for the loading of the resonator by the external instrumentation. This circuit can easily be generalized for a resonator with three or more modes. The present resonator has a thick gold plating on its interior surfaces. With the plating...

Synthesis and Characterization of Carbon Nanostructures as Catalyst Support for PEMFCs

A detailed procedure for synthesis, characterization, and possibility of carbon nanostructures (CNS) as support for catalysts in polymer electrolyte membrane fuel cells (PEMFCs) is presented. The fabrication process is two-staged ballmilling of carbon graphite in the presence of hydrogen and transition metals (Fe, Co) followed by heating of the milled carbon initially in an argon atmosphere. The milling induces amorphous forms of carbon and metal, as well as C-H bonds. During the second stage, the production of methane by catalytic reaction of the bonded carbon and hydrogen is first observed, followed by the formation of metallic nanocrystals, and, finally, the formation of carbon structures on the metallic nanocrystals at a temperature of 700°C. Subsequently, metals and carbon nanoparticles are removed from the as-prepared sample. The purified samples are platinized after surface treatment by either air or chemical oxidation. Material characterization results obtained by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, X-ray photoelectron spectrocopy, and atomic adsorption spectroscopy are presented. In addition, we also report their measured electrical conductivity, specific surface, and porosity. The real electrochemical active surface area was evaluated by cyclic voltammetry on a thin porous coated electrode.

High Performance PEM Fuel Cell with Low Platinum Loading at the Cathode Using Magnetron Sputter Deposition

Platinum cluster formations have been investigated as a way to reduce the amount of Pt at the cathode of polymer electrolyte membrane fuel cells. One, two, and three layers of Pt (0.05 mg/cm2) sputtered directly on microporous layers of gas diffusion layers with and without interfacial carbon-Nafion layers and carbon-polytetrafluoroethylene (CPTFE) layers have been used as a cathode. Comparison with experimental results had showed that the best performance was obtained with three layers of Pt sputtered on carbon-Nafion containing 34.8 wt.% of Nafion and sputtered carbon-polytetrafluoroethylene containing 16.9 wt.% of polytetrafluoroethylene. High limiting current densities (>1.1 A/cm2) have been reached with cathode Pt loading as low as 0.05 mg/cm2. SEM imagery and cyclic voltammetry characterization have been performed to consolidate this study. High Pt utilization can be showed by this method. The factor influencing Pt utilisation in the oxygen reduction reaction is intrinsically related to Pt clusters formation and helps in enhancing the PEMFC performance with low Pt loading.

Load commutation for stand alone wind and PV hydrogen energy system

The authors present a renewable energy (RE) system based on production and storage of hydrogen. The principal source of energy is a wind turbine (WT) generating a maximum power of 10 kW. The energy from the WT will be directed to the load while the remaining excess power, when available, will be used to produce and store hydrogen. They also have as secondary power source a photovoltaic (PV) away generating a maximum power of 1 kW. The hydrogen will then be restored to the stand alone site to produce electrical energy, via proton exchange membrane fuel cells (PEMFC) as a load-levelling electrical system, when not enough energy is produced from the RE sources.