Fuel Cell-Based MEMS Power Source

2008 ◽  
Author(s):  
Saeed Moghaddam ◽  
Eakkachai Pengwang ◽  
Kevin Lin ◽  
Rich Masel ◽  
Mark Shannon
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Hydrogen Generation ◽  
Control Mechanism ◽  
Membrane Electrode Assembly ◽  
High Energy ◽  
High Energy Density ◽  
Membrane Electrode ◽  
Mems Devices ◽  
Power Sources

The increasing demand for high energy density power sources driven by advancements in portable electronics and MEMS devices has generated significant interest in development of micro fuel cells. One of the major challenges in development of hydrogen micro fuel cells is the fabrication and integration of auxiliary systems for generation and delivery of fuel to the membrane electrode assembly (MEA). In this paper, we report the development of a millimeter-scale (3×3×1 mm3) micro fuel cell with on-board fuel and control system. Hydrogen is generated in the device through reaction between water and a metal hydride. The device incorporates a new control mechanism for hydrogen generation that occupies only 50 nL volume (less than 0.5% of the total device volume). More importantly, the control mechanism is self-regulating and does not consume any power, enabling the micro fuel cell to operate passively, similar to a battery.

Bipolar Plates for PEMFCs

2014 ◽  
Vol 11 (4) ◽  
Author(s):  
C. A. C. Sequeira ◽  
L. Amaral
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Manufacturing Process ◽  
High Energy ◽  
Proton Exchange ◽  
High Energy Density ◽  
Bipolar Plates ◽  
Promising Alternative ◽  
Power Sources ◽  
Fuel Cell Stack

Proton exchange membrane fuel cells (PEMFCs) have many advantages among the various types of fuel cells, such as high energy density, low temperature operation, near-zero pollution, and quick starting. Thereby, PEMFCs have been considered as the most promising alternative power sources in the transportation and stationary fields. Among the components of PEMFCs, the bipolar plates are the most representative regarding cost and volume, however, they have relevant functions on the fuel cell stack. There are about 500 bipolar plates in a PEMFC for a typical passenger car and, thus, the commercialization of the fuel cell technology becomes quite challenging. Important key aspects for a successful fuel cell stack are the design and the manufacturing process of the bipolar plate. For efficient mass production, the cycle time of the process is even more important than the material costs. It is, therefore, very important that the used material is appropriate for a fast manufacturing process. Recent developments are overcoming these issues, leading to improvements on the overall fuel cell performance and durability.

Microfluidic Fuel Cells as Microscale Power Sources and Analytical Platforms

2009 ◽  
Author(s):  
Fikile R. Brushett ◽  
Adam S. Hollinger ◽  
Larry J. Markoski ◽  
Paul J. A. Kenis
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Energy Density ◽  
Laminar Flow ◽  
High Energy ◽  
Electrochemical Analysis ◽  
High Energy Density ◽  
Liquid Fuels ◽  
Power Sources ◽  
Microscale Transport

A continuously growing need for high energy density miniaturized power sources for portable electronic applications has spurred the development of a variety of microscale fuel cells. For portable applications, membrane-based fuel cells using small organic fuels (i.e., methanol, formic acid) are among the most promising configurations as they benefit from the high energy density and easy storage of the liquid fuels. Unfortunately, the performance of these fuel cells is often hindered by membrane-related issues such as water management (i.e., electrode dry-out / flooding) and fuel crossover. Furthermore, high costs of, for example, catalysts and membranes as well as durability concerns still hinder commercialization efforts. To address these challenges we have developed membraneless laminar flow-based fuel cells (LFFCs), which exploit microscale transport phenomena (laminar flow) to compartmentalize streams within a single microchannel. The properties of various fuel and media flexible LFFCs will be presented and novel strategies for improving fuel utilization and power density will be discussed. Furthermore, the performance of a scaled-out 14-channel LFFC prototype is presented. We have also developed a microfluidic fuel cell as a powerful analytical platform to investigate and optimize the complex processes that govern the performance of catalysts and electrodes in an operating fuel cell. This platform bridges the gap between a conventional 3-electrode electrochemical cell and a fuel cell, as it allows for standard electrochemical analysis (e.g., CV, CA, EIS) as well as fuel cell analysis (e.g., IV curves).

Review on challenges of direct liquid fuel cells for portable application

2015 ◽  
Vol 12 (6) ◽  
pp. 591-606 ◽  
Author(s):  
Venkateswarlu Velisala ◽  
G. Naga Srinivasulu ◽  
B. Srinivasa Reddy ◽  
K. Venkata Koteswara Rao
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Energy Density ◽  
Liquid Fuel ◽  
Electronic Devices ◽  
High Energy ◽  
Pem Fuel Cells ◽  
Green Energy ◽  
High Energy Density ◽  
Power Sources

Fuel cells technologies are the most promising green energy technologies for diverse applications. One of the fastest growing areas is the portable electronic applications where the power range is the order of 1–100 W. For most of the portable electronic devices, rechargeable battery is the major energy source. Due to limitations like limited capacity, requirement of external power for recharge have led many researchers to look for alternative power sources to power portable electronic devices. The high energy density of fuel cells makes them very attractive alternative to batteries for portable power applications. There are a variety of fuel cell technologies being considered to replace batteries in portable electronic equipment. Direct Liquid Fuel Cells (DLFCs) have attracted much attention due to their potential applications as a power source for portable electronic devices. The advantages of DLFCs over hydrogen fed PEM fuel cells include a higher theoretical energy density and efficiency, a more convenient handling of the streams, and enhanced safety. Unlike batteries, fuel cells need not be recharged, merely refueled. This paper provides an overview on challenges of DLFCs (Direct Liquid Fuel Cells), like fuel crossover, cost, durability, water management, weight and size along with approaches being investigated to solve these challenges. Portable Fuel Cell Commercialization Targets for future and producers of portable fuel cells across the globe are also discussed in this paper.

scholarly journals Electrochemical Performance Improvement of the Catalyst of the Methanol Micro-Fuel Cell Using Carbon Nanotubes

2019 ◽  
Author(s):  
Mohammad Kazemi Nasrabadi ◽  
Amir Ebrahimi-Moghadam ◽  
Mohammad Hosein Ahmadi ◽  
Ravinder Kumar ◽  
Narjes Nabipour
Keyword(s):  
Carbon Nanotubes ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Carbon Black ◽  
Oxidation Reaction ◽  
High Energy ◽  
Proton Exchange ◽  
Operating Conditions ◽  
High Energy Density ◽  
Methanol Oxidation Reaction

Due to low working temperature, high energy density and low pollution, proton exchange fuel cells have been investigated under different operating conditions in different applications. Using platinum catalysts in methanol fuel cells leads to increasing the cost of this kind of fuel cell which is considered as a barrier to the commercialism of this technology. For this reason, a lot of efforts have been made to reduce the loading of the catalyst required on different supports. In this study, carbon black (CB) and carbon nanotubes (CNT) have been used as catalyst supports of the fuel cell as well as using the double-metal combination of platinum-ruthenium (PtRu) as anode electrode catalyst and platinum (Pt) as cathode electrode catalyst. The performance of these two types of electro-catalyst in the oxidation reaction of methanol has been compared based on electrochemical tests. Results showed that the carbon nanotubes increase the performance of the micro-fuel cell by 37% at maximum power density, compared to the carbon black. Based on thee-electrode tests of chronoamperometry and voltammetry, it was found that the oxidation onset potential of methanol for CNT has been around 20% less than CB, leading to the kinetic improvement of the oxidation reaction. The current density of methanol oxidation reaction increased up to 62% in CNT sample compared to CB supported one, therefore the active electrochemical surface area of the catalyst has been increased up to 90% by using CNT compared to CB which shows the significant rise of the electrocatalytic activity in CNT supported catalyst. Moreover, the resistance of the CNT supported sample to poisonous intermediate species has been found 3% more than CB supported one. According to the chronoamperometry test results, it was concluded that the performance and sustainability of the CNT electro-catalyst show remarkable improvement compared to CB electro-catalyst in the long term.

Mg-based composites as effective materials for storage and generation of hydrogen for FC applications

2021 ◽  
pp. 53-80
Author(s):  
D. Korablev ◽  
◽  
A. Bezdorozhev ◽  
V. Yartys ◽  
J. Solonin ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Hydrogen Generation ◽  
High Energy ◽  
High Energy Density ◽  
Hydrolysis Reaction ◽  
Preparation Technique ◽  
Power Sources ◽  
Safety Issues ◽  
Renewable Power ◽  
Physical And Chemical

Today, hydrogen is considered as an ideal choice for storing and carrying energy produced by renewable power sources since it is renewable, eco-friendly and has a high energy density. However, due to the low hydrogen storage capacity, high cost and safety issues of the conventional storage methods, several challenges need to be resolved to effectively use hydrogen in mobile applications. Solid-state hydrogen storage in atomic form in hydrides is a promising method of storage for this purpose, particularly because a double amount of hydrogen can be produced via hydrolysis reaction of chemically active hydrides. Among the metal hydrides, magnesium hydride (MgH2) is considered to be one of the most attractive candidates. However, the hydrolysis reaction is rapidly hindered by the passivation layer formed on the surface of MgH2. In order to improve MgH2 hydrolysis efficiency various approaches have been applied. This paper reviews recent progress on the modifications of MgH2-based materials by adding different type of additives, including metals, oxides, hydroxides, halides and surfactants. The introduced additives possess different catalytic properties due to their intrinsic physical and chemical characteristics, and therefore can strongly influence the hydrolysis reaction of MgH2. The most promising results were obtained for various salt additives showing that the reaction rate depends mostly on the additive type rather than on concentration. The effect of preparation technique on the hydrolysis of MgH2 – MgCl2 composites was studied in detail. The obtained results indicate that efficient hydrolysis performance can be achieved by ball milling of the freshly synthesized MgH2 with 5 wt.% MgCl2 and 1 wt.% TiC–2TiB2 additives. The combination of the applied approaches exhibited a notable synergistic effect on the hydrogen generation.

Polymer electrolyte membrane fuel cell flow field designs and approaches for performance enhancement

2019 ◽  
Vol 234 (8) ◽  
pp. 1189-1214 ◽  
Author(s):  
Erman Çelik ◽  
İrfan Karagöz
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Flow Field ◽  
Polymer Electrolyte ◽  
Polymer Electrolyte Membrane ◽  
High Energy ◽  
Cell Performance ◽  
High Energy Density ◽  
Field Development ◽  
Electrolyte Membrane

Polymer electrolyte membrane fuel cells are carbon-free electrochemical energy conversion devices that are appropriate for use as a power source on vehicles and mobile devices emerging with their high energy density, lightweight structure, quick startup and lower operating temperature capabilities. However, they need more developments in the aspects of reactant distribution, less pressure drops, precisely balanced water content and heat management to achieve more reliable and higher overall cell performance. Flow field development is one of the most important fields of study to increase cell performance since it has decisive effects on performance parameters, including bipolar plate, and thus fuel cell weight. In this study, recent developments on conventional flow field designs to eliminate their weaknesses and innovative design approaches and flow field architectures are obtained from patent databases, and both numerical and experimental scientific studies. Fundamental designs that create differences are introduced, and their effects on the performance are discussed with regard to origin, objective, innovation strategy of design besides their strength and probable open development ways. As a result, significant enhancements and design strategies on flow field designs in polymer electrolyte membrane fuel cells are summarized systematically to guide prospective flow field development studies.

Evaluation of the Performance Characteristics of a Direct Methanol Fuel Cell With Multifuels

2010 ◽  
Vol 7 (4) ◽  
Author(s):  
Sujith Mohan ◽  
S. O. Bade Shrestha
Keyword(s):  
Fuel Cell ◽  
Direct Methanol Fuel Cell ◽  
Direct Methanol Fuel Cells ◽  
Operating Temperature ◽  
High Energy ◽  
High Energy Density ◽  
Power Sources ◽  
Transport Losses ◽  
Direct Methanol ◽  
Methanol Fuel Cell

Direct methanol fuel cells are one of the alternate power sources for the field of power electronics because of their high energy density. The benefits of a fuel cell toward the environment can be greatly improved if the fuel used for its application comes from renewable sources. In this study, the performance of a direct methanol fuel cell was investigated under five different methanol concentrations. The effect of methanol concentration on the cell operating temperature is studied. Impedance spectroscopy was conducted to measure the ohmic, activation, and mass transport losses for all concentrations. The cell performance was evaluated using methane and ethanol fuels and this was compared with methanol operation.

Evaluation of the Performance Characteristics of a Direct Methanol Fuel Cell With Multi Fuels

2009 ◽  
Author(s):  
Sujith Mohan ◽  
S. O. Bade Shrestha
Keyword(s):  
Fuel Cell ◽  
Direct Methanol Fuel Cell ◽  
Direct Methanol Fuel Cells ◽  
Operating Temperature ◽  
High Energy ◽  
High Energy Density ◽  
Power Sources ◽  
Transport Losses ◽  
Direct Methanol ◽  
Methanol Fuel Cell

Direct methanol fuel cells are one of the alternate power sources for the field of power electronics because of their high energy density. The benefits of a fuel cell towards the environment can be greatly improved if the fuel used for its application comes from renewable sources. In this study, the performance of a direct methanol fuel cell was investigated under five different methanol concentrations. The effect of methanol concentration on the cell operating temperature is studied. Impedance spectroscopy was conducted to measure the ohmic, activation and mass transport losses for all concentrations. The cell performance was evaluated using methane and ethanol fuels and this was compared with methanol operation.

Highly Efficient Conversion of Ammonia in Electricity by Solid Oxide Fuel Cells

2006 ◽  
Vol 3 (4) ◽  
pp. 499-502 ◽  
Author(s):  
N. J. J. Dekker ◽  
G. Rietveld
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Energy Density ◽  
High Pressures ◽  
Cell Voltage ◽  
Electrical Current ◽  
High Energy ◽  
Solid Oxide ◽  
High Energy Density ◽  
Oxide Fuel

Hydrogen is the fuel for fuel cells with the highest cell voltage. A drawback for the use of hydrogen is the low energy density storage capacity, even at high pressures. Liquid fuels such as gasoline and methanol have a high energy density but lead to the emission of the greenhouse gas CO2. Ammonia could be the ideal bridge fuel, having a high energy density at relative low pressure and no (local) CO2 emission. Ammonia as a fuel for the solid oxide fuel cell (SOFC) appears to be very attractive, as shown by cell tests with electrolyte supported cells (ESC) as well as anode supported cells (ASC) with an active area of 81cm2. The cell voltage was measured as function of the electrical current, temperature, gas composition and ammonia (NH3) flow. With NH3 as fuel, electrical cell efficiencies up to 70% (LHV) can be achieved at 0.35A∕cm2 and 60% (LHV) at 0.6A∕cm2. The cell degradation during 3000 h of operation was comparable with H2 fueled measurements. Due to the high temperature and the catalytic active Ni∕YSZ anode, NH3 cracks at the anode into H2 and N2 with a conversion of >99.996%. The high NH3 conversion is partly due to the withdrawal of H2 by the electrochemical cell reaction. The remaining NH3 will be converted in the afterburner of the system. The NOx outlet concentration of the fuel cell is low, typically <0.5ppm at temperatures below 950°C and around 4ppm at 1000°C. A SOFC system fueled with ammonia is relative simple compared with a carbon containing fuel, since no humidification of the fuel is necessary. Moreover, the endothermic ammonia cracking reaction consumes part of the heat produced by the fuel cell, by which less cathode cooling air is required compared with H2 fueled systems. Therefore, the system for a NH3 fueled SOFC will have relatively low parasitic power losses and relative small heat exchangers for preheating the cathode air flow.

scholarly journals Analysis on Geometry of Fluid Flow Manifold in Direct Methanol Fuel Cell

2020 ◽  
Vol 5 (8) ◽  
pp. 822-827
Author(s):  
Govindarasu Ramasamy ◽  
R. Kavitha ◽  
M. Nambiraj ◽  
R. Praveen Kumaar ◽  
N. N. Harish Kumar
Keyword(s):  
Carbon Dioxide ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Direct Methanol Fuel Cell ◽  
Flow Distribution ◽  
High Energy ◽  
High Energy Density ◽  
No Production ◽  
Direct Methanol ◽  
Methanol Fuel Cell

Fuel cells are the devices that convert chemical energy into electrical energy through an electrochemical reaction. Direct Methanol Fuel cell (DMFC) is a proton exchange membrane fuel cells in which methanol is used as fuel. Its high energy density makes it suitable for fuel cells. Even though carbon dioxide is produced, there is no production of sulfur or nitrogen oxides. The problems usually occurred while working with DMFC are methanol crossover, condensation of methanol, water management and carbon dioxide release. In that the uneven flow distribution, accumulation of carbon dioxide bubbles in the fuel cell are the major issues in DMFC. To prevent these issues, this work focuses on the theoretical and experimental studies on development of fuel cells with special importance to geometry of the manifold. This paper provides the optimal solution for preventing uneven flow distribution that is the usage of squoval shaped manifold which is the combination of both square and circle. Performance of DMFC with squoval shape manifold is evaluated experimentally and is compared with square shape manifold and rectangle shape manifold geometry design.

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