Download Fuel Cells for Portable Devices

Fuel Cells for Portable Devices
Abstract
This paper provides information about fuel cell power sources for portable and/or
wireless devices designed for the Microsoft® Windows® family of operating
systems. It provides guidelines for industry designers to evaluate fuel cell
technology for inclusion in future portable and/or wireless devices.
Contents
Introduction............................................................................................................................................. 3
Basic Fuel Cell Operation .................................................................................................................. 3
Fundamental Issues in Fuel Cell Device Operation ........................................................................... 5
Useful Power Levels .................................................................................................................... 5
Efficient Power Generation ........................................................................................................... 6
Effective Power Systems.............................................................................................................. 7
Fuel Cell Technologies Applicable for Portable Devices .................................................................... 8
Proton Exchange Membrane (PEM) FC ....................................................................................... 8
Direct Methanol Fuel Cell (DMFC)................................................................................................ 8
Solid Oxide Fuel Cell (SOFC)....................................................................................................... 9
Direct Methanol Fuel Cells .................................................................................................................... 10
Detailed Discussion ......................................................................................................................... 10
Design Issues.................................................................................................................................. 10
Volume ...................................................................................................................................... 10
Heat & Temperature................................................................................................................... 10
Humidity & Pressure .................................................................................................................. 11
System Exhaust ......................................................................................................................... 11
Fuel Feed & Control ................................................................................................................... 11
Integration & Other Design Factors ................................................................................................. 11
Solid Oxide Fuel Cells .......................................................................................................................... 12
Detailed Discussion ......................................................................................................................... 12
Design Issues.................................................................................................................................. 12
Volume ...................................................................................................................................... 12
Heat & Temperature................................................................................................................... 12
Humidity & Pressure .................................................................................................................. 13
System Exhaust ......................................................................................................................... 13
Fuel Feed & Control ................................................................................................................... 13
Integration & Other Design Factors ................................................................................................. 13
Commercialization Requirements ......................................................................................................... 15
Fuel Selection & Infrastructure ........................................................................................................ 15
Industry Standards & Regulatory Approvals .................................................................................... 15
Resources and Call to Action................................................................................................................ 16
Fuel Cells for Portable Devices - 2
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Author's Disclaimer and Copyright:
Copyright 2003, Dean C. Richardson, Alberta Research Council Inc.
WinHEC Sponsors’ Disclaimer: The contents of this document have not been authored or confirmed by
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Fuel Cells for Portable Devices - 3
Introduction
This paper provides information about the application of fuel cell technology to
portable and/or wireless consumer electronics or computing devices.
Simply characterized, a fuel cell is a battery (an electrochemical device) in which
the fuel for the electrochemical reaction is provided externally.
Basic Fuel Cell Operation
First demonstrated by English barrister Sir William Grove in 1839, fuel cells operate
using the same electrochemical principles as batteries, with the notable exception
that the fuel and the oxidant are supplied externally. As long as both these
feedstocks are supplied, in theory the fuel cell can operate indefinitely, in marked
contrast to batteries, which need replacement or re-charging when their energy
potential is exhausted.
One useful estimate of potential can be estimated by comparing the energy density
of typical battery materials with the energy density of potential liquid fuels such as
Methanol. Note that a typical Li-ion battery may yield 200 Watt-hours/liter (Wh/L)
whereas Methanol yields 4700 Wh/L. Care must be exercised in gross comparisons
of this like, though, as Methanol needs to be combined in aqueous solutions to act
as fuel, reducing it’s fuel density, and since efficiency calculations also need to be
treated carefully. Still, there are substantial potential benefits in applying fuel cells in
this area
Figure 1, below, illustrates the basic concept for a generic low-temperature fuel cell:
e-
eLoad
Air, Or Other
Oxidant
Fuel
Oxidation
H2 -> 2H+ + 2e-
Anode
Electrolyte
Cathode
Reduction
4e- + O2 -> O2-
H+ Proton Flow
Products
Overall Reaction
2H2 +O2 -> 2H2O + 4e-
Products
Figure 1 - Basic Fuel Cell
Figure 1 illustrates an acid-electrolyte single-cell fuel cell. A fuel feed, rich in
hydrogen, is supplied to the anode, where it is ionized, freeing electrons to flow
through the external circuit while Hydrogen ions (H+), also called protons, flow
through the acidic electrolyte. The anode reaction generates energy, and satisfies
mass balance requirements by exhausting products that may include un-ionized
hydrogen and other trace compounds from the fuel feed.
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The electrolyte provides proton conductivity to support charge flow through to the
cathode, but it also provides a barrier to electron flow, ensuring electron flow passes
through the external circuit and load.
At the cathode, the oxygen provided by the air or oxidant feed reacts with electrons
in-bound from the external circuit and H+ protons coming through the electrolyte to
form water. The water is expelled, along with any other compounds in the oxidant
feed stream out through the cathode exhaust.
An alternative form of fuel cell device is the ceramic fuel cell. These devices operate
in a similar fashion to that previously described, in that the process is an
electrochemical combination of fuel and oxidant across an electrolyte, but all the
materials are solid-state and operate at a much higher temperature. Often, an
oxygen ion conductor replaces the proton conductor across the electrolyte as well.
Note several fundamental considerations about fuel cells of either type: First, there
is an activation energy threshold that must be crossed in order for the
electrochemical reaction to commence and continue. Crossing this threshold can be
aided with the use of catalysts and also by increasing system temperature. Catalyst
utilization, in turn, can be aided by high surface area on electrodes.
Second, note that a plot of current through the load vs. voltage across the load
yields a slightly non-linear relationship between these variables, and power maxima
that also vary with cell output. This is illustrated with the following data, taken from
an ARC SOFC cell test.
Figure 2 Actual SOFC Cell Test Data (Courtesy of ARC)
This behavior (irreversible voltage drops) can stem from several causes, including
activation losses (described earlier), fuel crossover (passing through electrolyte),
ohmic or resistive losses, and concentration losses (due to local concentration
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gradients at the surface of the electrodes). Handling these parasitic losses, and
other factors related to system performance, are described in the next section.
Fundamental Issues in Fuel Cell Device Operation
Basic fuel cell theory, as discussed above, is well known. However, translating the
theory to practical devices raises a host of engineering issues.
Useful Power Levels
In order to achieve useful power levels, individual cells must be designed, then
combined into “stacks”. Individual cells can be designed in planar or tubular layouts,
with planar designs being the most popular. Planar configurations, as illustrated in
Figure 3 (an example from a ceramic fuel cell), are applicable in both ceramic and
non-ceramic fuel cell systems. They are often referred to as bipolar configurations,
since bipolar plates (along with Membrane Electrode Assemblies-- MEAs) are key
elements in such devices.
Figure 3 Planar Device Configuration
A representation of the Ballard system, for low temperature devices, follows below:
Figure 4 Bipolar Flow Plates (After Ballard Power Systems)
Tubular configurations have their genesis in ceramic fuel cells used in very large
stationary power systems, originally pioneered by Westinghouse (Now Siemens-
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Westinghouse). Figure 5 below illustrates the Westinghouse configuration.
Currently, only ceramic fuel cell systems utilize this configuration. Siemens
Westinghouse continues to produce large stationary power systems using this
architecture, and ARC has extended the configuration into small-form-factor devices
potentially suitable for portable electronic devices. Most other system developers
have opted for planar configurations.
Figure 5 Tubular Device Configuration (After Siemens Westinghouse)
Fuel cell stacks combine individual cells in series or parallel configurations to
achieve useful levels of current and voltage. This is carried out using important
components called “interconnects”. Note that examples are illustrated in both
Figures 3 and 4. Interconnects, in turn, route current that has been collected using
“current collectors”, another important engineering challenge for practical devices.
This challenge exists because fuel cell current is generated over the entire surface
of electrodes, and low-resistance methods of acquiring this current are required.
Efficient Power Generation
Fuel cells have demonstrated potential for high efficiency. Realizing this potential
requires scientific and engineering work to minimize the sources of loss outlined
earlier: Activation losses, fuel crossover, ohmic losses, and concentration losses.
Activation Losses
Minimizing activation losses is usually done by using catalysts to lower the
activation energy required for the reaction to proceed. However, low-temperature
fuel cell catalysts are often expensive Platinum Group Metals (PGM) such as
Platinum and Ruthenium, so merely adding more PGM materials is not the solution.
Research is focused on finding new materials that will catalyze these reactions.
Much engineering work goes into minimizing catalyst utilization without reducing
activity by decreasing catalyst and catalyst-support particle size, thereby increasing
surface area for a given nominal electrode size.
Fuel Crossover
Minimizing parasitic loss due to fuel crossover takes different directions depending
on whether one considers low-temperature fuel cells or ceramic fuel cells. In
ceramic fuel cells, fuel crossover is minimized using dense electrolytes. Many lowWinHEC 2003
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temperature fuel cells incorporate membranes into their designs to reduce fuel
crossover. Fuel crossover improvements in these systems stem from developing
more selective membranes while minimizing increases in electrical resistance.
Finally, another approach to minimizing fuel crossover is to use a flowing liquid
electrolyte which captures the fuel before it can reach the air electrode, though this
comes at the cost of reducing fuel available for use in the reaction, unless it can be
returned to the fuel stream entering the anode.
Ohmic Losses
Ohmic losses stem from resistance stack up in the device as elements are added.
This resistance comes from the electrolyte, both electrodes, and all current
collectors. For example, adding an additional membrane into a low-temperature
system also introduces a small system resistance. Ohmic losses can best be
addressed through innovation in material selection, current collection, interconnects,
and in system design.
Concentration Losses
Concentration losses, also referred to as mass transport losses, arise due to a
concentration gradient in reactants adjacent to the electrode face. Good design
practice here moves fuel and oxidants through flowfield patterns (e.g.: serpentine
layout) that maximize reactant contact with the electrode face.
In the realm of low-temperature fuel cells, much of the effort required to minimize
losses and maximize efficiency can be consolidated in the design of Membrane
Electrode Assemblies (MEAs). MEA design is an area of significant innovation, both
in terms of efforts to improve performance and also to reduce cost.
Effective Power Systems
If one assumes that useful and efficient power levels can be achieved with fuel
cells, the next step is to consider truly effective power systems incorporating these
devices. This requires several other considerations.
Other Systems: The “Balance of Plant” (BOP)
Fuel cells operate on hydrogen, but hydrogen presents problems in terms of
availability, transportation and storage. Other fuel feed stocks are used to
“transport” hydrogen, but then the fuel needs to be extracted, using a “fuel reformer”
to extract hydrogen. Hence, a reformer constitutes a significant portion of the BOP
for a fuel cell device, often constituting 30% or more of system cost and mass, and
requiring significant energy from the device, lowering total system efficiency.
In addition, as mentioned earlier, fuel cell voltages and currents are variable, and
need conditioning to support operation. For portable devices, this will typically mean
DC-DC conversion to levels appropriate for the device. Power conditioning
constitutes another important element in fuel cell BOP.
Finally, other elements are also required, including fuel and oxidant storage and
distribution components, pumps, sensors, and a control system to tie all the pieces
together. This constitutes the last block of components necessary for a complete
device BOP.
Dynamic Operation
Effective power systems need to be designed and matched against their load.
Starting up and shutting down fuel cells raise particular issues, particularly for
ceramic systems. For all devices, operating temperatures need to be achieved, fuel
and oxidant flows need to be started appropriately, and steady state operation
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achieved. As loads vary dynamically, a fuel cell system needs to respond with some
target latency. Achieving startup and the target latency may require additional
components in the BOP. For example, a small auxiliary battery may be used to aid
startup or to supplement fuel cell power for short-duration spikes in the load.
Finally, there are several aggregate measures of system performance that can be
useful in evaluating fuel cell systems:
Name
Definition
Notes
System Efficiency (%)
(Fuel Energy in/ Electrical
Energy out) X 100%
Overall system metric,
including BOP
Fuel Utilization (%)
Percentage fuel consumed in
fuel cell based on fuel
supplied
Volumetric Power Density VPD (Watts/Litre)
Total system power/ Total
system volume
Specific energy density
(Watt-hr/kg)
Total energy capability/ Mass
Table 1 – System Measures
Fuel Cell Technologies Applicable for Portable Devices
There are many different fuel cell technologies, but most are only applicable to large
stationary applications, often exceeding 250kW of generating capacity, and
providing high quality heat as well. Examples include Phosphoric Acid Fuel Cells,
Molten Carbonate Fuel Cells, or Alkaline Fuel Cells. However, most observers
would select only one or two candidate technologies applicable for portable
applications: Proton Exchange Membrane (PEM) systems and Direct Methanol Fuel
Cells (DMFC), which some consider a subset of PEM devices. This author argues
that small ceramic fuel cells can also fit portable applications, based on Solid Oxide
Fuel Cell (SOFC) technology. Each are introduced below.
Proton Exchange Membrane (PEM) FC
The PEMFC, also known as the solid polymer fuel cell, is the technology selected
by the majority of low-temperature fuel cell developers, including the largest fuel cell
company in the world, Ballard Power Systems of Vancouver, BC. It features a solid
polymer electrolyte membrane that is acidic, furnishes excess protons to support
charge transfer, while providing a physical barrier to fuel crossover and an electrical
barrier to electron flow (short circuits) through the membrane. The anode and
cathode feature PGM catalysts and are usually configured in bipolar plate
configurations. Hydrogen fuel is provided either by a separate fuel reformer or in
high-pressure tanks that store gaseous hydrogen. These devices operate at low
temperatures (typically 60-80º C) and 1 – 3 atmospheres pressure. Their low
temperature tends to support rapid on/off operation, and they can work in any
orientation. However, the membrane only electrically conducts when it is wet, so
water management of PEM systems is extremely important.
Direct Methanol Fuel Cell (DMFC)
The DMFC is often considered a subset of PEMFC system, since most DMFC
devices also use proton exchange membranes. Hence, many DMFC system
considerations (temperature, pressure, requirement for water management) are
identical to those required for PEMFC. However, on DMFC anodes the PGM
catalysts are supplemented with another PGM, Ruthenium, so methanol can be
oxidized directly at the anode. This eliminates the need for a separate fuel reformer,
or managing hydrogen fuel, and greatly simplifies DMFC systems. In addition,
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methanol is already available in industrial quantities and has a high fraction of
hydrogen relative to the total molecular weight, so it is a good candidate for practical
system fuels. Unfortunately, given the small size of the methanol molecule
(CH3OH), fuel crossover is a significant challenge for these systems. In addition, the
kinetics of the oxidation reaction are relatively slow, so DMFC performance can be
adversely affected and can degrade over time.
This author disagrees with the assertion that DMFC devices are subsets of PEMFC,
as there are some commercial entities pursuing DMFC devices that do not require a
solid polymer electrolyte membrane. Instead, they use a flowing liquid electrolyte
(acidic) that transports protons for the reaction, minimizes electron passage, but
also reduces losses due to fuel crossover. Finally, eliminating the membrane can
reduce system resistance and potentially reduce cost as well. The potential
improvements in performance, which can be significant, must be carefully balanced
against the additional complexity of managing a liquid electrolyte, however.
Solid Oxide Fuel Cell (SOFC)
The SOFC device is a class of ceramic fuel cell. It is a high-temperature solid state
device. The majority of applications are in stationary or larger-format systems
(vehicle auxiliary power units – APUs, for example) where the high temperature can
provide high-quality heat to drive a bottoming cycle, for example. However, recent
work at the ARC has opened the door to applying SOFC devices into portable
device applications as well. This allows other benefits of SOFC devices to be
brought to bear on the portable market. SOFC devices tend to be much more
efficient then other fuel cell technologies (rapid reaction kinetics related to higher
temperature). SOFC devices can internally reform some fuels to deliver hydrogen
fuel, and they can be fabricated in a variety of shapes and form factors. They also
do not require expensive PGM catalysts to operate. Water management is
simplified in SOFC devices, but the tradeoff comes in terms of a much more
complex thermal management problem for small portable devices.
DMFC and SOFC technologies will be discussed in more detail below, where for the
purposes of this discussion, DMFC will be discussed as the appropriate portabledevice realization for PEM systems.
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Direct Methanol Fuel Cells
Detailed Discussion
In DMFC devices methanol or methanol-water solutions are fed to the anode as
fuel. Air is typically fed to the cathode as the oxidant. DMFCs offer the advantage
of directly converting methanol to electric power without a reformer or fuel processor
that is typical of other low temperature fuel cell systems. They also offer the
potential of the high energy density of liquid methanol fuel relative to hydrogenbased systems. The chemical reactions occurring in the DMFC are as follows:
Anode Reaction:
CH3OH + H2O => CO2 + 6H+ + 6e-
Cathode Reaction:
3/2O2 + 6H+ + 6e- => 3H2O
Overall Reaction:
CH3OH + H2O + 3/2O2 => CO2 + 3H2O
Most DMFC systems being developed are based on the proton exchange
membrane fuel cell (PEMFC) technology originally developed for hydrogen fuel. In
order to use methanol as the fuel (rather than hydrogen) Pt-Ru catalysts are used
on the anode. A few technologies are being developed that are attempting to
replace the polymer membrane electrolyte with liquid electrolytes.
Design Issues
There are several challenges to be overcome in DMFC development:

The relatively slow anode reaction necessitates high loadings of expensive
platinum group metal catalysts.

Methanol crossover to the cathode degrades cell performance through reduced
voltage and power, cathode poisoning, reduced fuel conversion efficiency,
cathode flooding.

Carbon dioxide generation at the anode can lead to mass transfer limitations
that reduce cell performance.

Membrane-electrode assembly durability reduces the useful life of the devices
Volume
DMFC systems offer the potential for small volume and attractive form factors for
portable devices due to the high specific energy content of the fuel, low temperature
operation and the possibility to operate with essentially ambient air pressures (little
or no compression). These advantages, if realized, offer the opportunity to reduce
the size and parasitic losses of the balance of plant equipment. This advantage is
already being demonstrated with prototype battery chargers (Motorola) and laptop
battery replacement (Toshiba) devices based on PEM-DMFC technology
Heat & Temperature
The low temperature operation (typically less than 80 oC), the liquid nature of the
fuel and the amount of water circulating in the process make the thermal
management and temperature control of DMFC systems attractive for portable
device applications. The presence of water in the system necessitates design
provision for exposure to sub-zero temperature environments, however.
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Humidity & Pressure
Humidity is not as great a concern in DMFC systems as in conventional PEM
systems, for example. However, control of water flux at the air electrode (cathode)
is crucial to avoid electrode flooding.
System Exhaust
System exhaust typically consists of warm excess air, CO2 and water vapour which
should not present any particular problems or significant design considerations.
Fuel Feed & Control
Fuel (methanol) is typically fed to the anode as a dilute (usually 0.5 to 3 mole
CH3OH per litre) solution in water. The reason for this is that methanol crossover
increases with anode methanol concentration so in order to keep the crossover at
tolerable levels very dilute solutions are used. This necessitates the design of
accurate methanol injection systems and methanol sensors to maintain optimum
fuel concentration and flow rates.
Integration & Other Design Factors
A simple system schematic is found below, illustrating a number of the issues
defined above.
Figure 6 Representative DMFC Device Schematic
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Solid Oxide Fuel Cells
Detailed Discussion
The SOFC basic structure is same as the basic fuel cell outlined earlier, in that it
consists of three layers: the electrolyte, anode and cathode. In contrast to a
PEM/DMFC system, which uses a proton exchange membrane for the electrolyte,
the electrolyte in an SOFC this element is a doped metal oxide. The charge carrier
across the electrolyte is an oxygen ion conducted by oxygen vacancy migration
through the electrolyte. One of the key electrolyte materials is Yttria-Stabilized
Zirconia (YSZ) where Y3+ is a dopant and replaces Zr4+. To maintain charge
neutrality, an oxygen vacancy is created in the lattice. The mobility of the oxygen
vacancy is extremely low at room temperature and as a result oxygen ion
conductivity is low at room temperature. Therefore, a fuel cell made out of YSZ
needs a high operating temperature (800-1000C) to produce power.
PEM/DMFC devices suffer from so-called “poisoning” of the catalyst sites by the
presence of carbon monoxide, CO. One of the major advantages of SOFC over
PEM is its fuel flexibility, in that the electrode does not get poisoned by CO. In fact,
CO can even act as a fuel for SOFC devices. In addition, the SOFC device can
reform or partially reform fuel internally. Historically, SOFC devices have had low
thermal shock resistance, with the result that system start up times can be
measured in hours.
Design Issues
Volume
The Siemens-Westinghouse tubular design mentioned earlier remains the most
developed SOFC system, and has been evaluated in units generating 25kW,
100kW and 200kW. Other companies have established advanced planar designs.
Both types of stack designs produce a Volumetric Power Density (VPD) of less than
1kW of power per liter.
ARC has pioneered technology to dramatically increase power density and reduce
system size with a High Density Tubular SOFC design. One design embodiment,
dubbed Micro SOFC (µSOFC), has high potential for portable applications. The
proposed SOFC has a tube diameter 2mm and total (tube) wall thickness
250m. The thickness of the electrolyte is 5 to 15m. Intuitively, in any unit
volume one can pack a higher number of small tubes then larger tubes. In the case
of the SOFC at 2mm diameter, there is a potential increase in the VPD  10 times
relative to conventional planar SOFC devices.
Heat & Temperature
As discussed earlier, SOFC devices require higher operating temperatures to
exceed activation energy levels and encourage oxygen ion conductivity through the
electrolyte. Currently, SOFC temperatures must exceed 750ºC to operate.
Obviously, with this kind of temperature in a system, thermal management for
portable devices is a crucial system design issue. One approach to deal with this
problem is through improved materials in electrode fabrication. There is a high
potential in the near future for SOFC operating temperatures to be reduced down to
~ 600C by changing electrolyte from YSZ to cerium gadolinium oxide (CGO) or
doped LaGaO3. ARC is investigating this approach for SOFC devices. In addition,
significant material advances are occurring in the insulation area, with newgeneration aerosol-based products that offer lightweight, high thermal insulation.
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Another significant aspect of system thermal management is operating cycle. These
devices need to support near “instant-on” operation, so some form of pre-heat is
required. Advances in catalytic heating can provide flameless pre-heating for small
SOFC devices. ARC’s SOFC devices promise higher thermal shock resistance in
a package with low thermal mass, which means it can pre-heat rapidly.
Lower-temperature operation, high insulation capability, and simplified, flameless
pre-heating hold the potential to address the significant thermal management issues
involved in small SOFC devices.
Humidity & Pressure
Typically, an SOFC system will include 3% moisture in the fuel gas. This reduces
the phenomena of “coking”, in which carbon forms on the Nickel catalyst sites and
plugs pores in the electrode. This dramatically reduces performance and system
life. The addition of moisture triggers the preferential creation of carbon dioxide,
sequestering the carbon.
System Exhaust
SOFC systems exhaust H2O, CO2 and excess air.
Fuel Feed & Control
One important factor is to ensure there is very low sulfur present in the fuel
feedstock. If present, some processing may be required to remove sulfur. After this
step, liquid fuel will typically be fed through a reformer first, which will extract the
hydrogen component and feed the resulting mixture through to the stack. Often, to
take advantage of the heat inherent in the stack operation, the reformer will be
thermally integrated with the stack. Reformation may be based on steam reforming
or partial oxidation, and the output reactants will fuel the stack operation.
Integration & Other Design Factors
An example system schematic follows below:
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Figure 7 Representative SOFC Device Schematic
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Commercialization Requirements
Fuel Selection & Infrastructure
Fuel selection and infrastructure is the single most important question confronting
the entire fuel cell industry. Hydrogen generation is well known, and fuel cells can
provide an effective use for the fuel. Transportation, distribution and storage raise
significant problems. Currently, several approaches are being investigated,
including:

The use of high-pressure tanks which contain hydrogen gas;

Hydrogen stored as temporarily bonded constituents in metal hydride
compounds;

Utilizing on-board reformation from conventional liquid fuels like methanol to
generate hydrogen on demand.
However, it is safe to say that no single approach has emerged to solve this
problem.
Luckily, the challenge is less daunting for portable devices. In essence, the industry
needs a liquid-based fuel carrier to transport hydrogen. Many suppliers have
embraced methanol as the fuel of choice for this segment, citing the fact that the
material is already available in industrial quantities, and the hydrogen can be
extracted with ease. Methanol works directly in DMFC devices, but it also reforms at
a very low temperature approx. 230ºC, so it can easily be used in SOFC devices as
well.
Industry Standards & Regulatory Approvals
Even with a generally accepted fuel such as methanol available, a number of issues
remain:

Regulatory approval for transportation, particularly on aircraft

Industry-standard fuel specification for PC-grade methanol

Industry-standard fuel containers, for both distribution and point-of-use
packaging; and consumption
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Call to Action and Resources
Call to Action:

For system or device manufacturers: With many OEM fuel cell producers
announcing portable fuel cell product commercialization starting in 2004 or
2005, manufacturers need to gain familiarity with the technology, and consider
how and in what products to introduce it to their customers.
Further Reading and Research:

As with most fast-moving industries, the best source of current information will
be conference attendance, web information or conversations with potential
vendors or consultants in this area.

For a solid introduction to fuel cell technology in general, one highlyrecommended source is: Fuel Cell Systems Explained, by James Larminie and
Andrew Dicks, published by: John Wiley & Sons, in 2000.
Feedback:

To provide feedback about this article, please send e-mail to co-author Dean
Richardson, of the Alberta Research Council Inc., at: [email protected].
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