PEM FUEL CELLS: A RELIABLE,
COST EFFECTIVE OPTION FOR OSP
BACK UP POWER APPLICATIONS
PEM Fuel Cells – The future is now!
Vito J. Coletto [email protected]
Abstract: If you are looking for an alternative OSP backup power system for your critical loads that can replace batteries & generators, with the lowest total cost of ownership, and zero emissions, PEM fuel cell technology is your solution.
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Vito J. Coletto, Director of Sales 2/22/2015
Table of Contents Background ............................................................................................................................................. 2
VRLA Battery Overview ............................................................................................................................ 2
VRLA Battery Negative Characteristics ..................................................................................................... 3
1. Temperature Sensitivity: .......................................................................................................... 3
2. Battery Cycle Life and Depth of Discharge (DoD): ..................................................................... 4
3. Capacity Loss Due to Continuous Charging/Overcharging: ........................................................ 4
4. Parasitic Self-Discharging Characteristic of VRLA Batteries: ...................................................... 4
5. Number of Charge/Discharge Cycles Leads to Sulfation: ........................................................... 4
6. Cell Tower Failures: .................................................................................................................. 5
7. Continuous Monitoring and On-Going Preventative Maintenance: ........................................... 5
8. Weight/Space Limitations: ....................................................................................................... 6
9. High 10 -15 Year Total Cost of Ownership (TCO): ...................................................................... 6
10. Battery Disposal Costs: ............................................................................................................. 6
Applications Leveraging the Positive Characteristics of VRLA Batteries .................................................... 6
Summary of Battery Technology .............................................................................................................. 7
A Brief History of Fuel Cells ...................................................................................................................... 7
Summary of Fuel Cell Technologies & Applications .................................................................................. 8
PEM Fuel Cells: An Alternative to VRLA Batteries ..................................................................................... 8
What is a PEM Fuel Cell and How Does it Work? ...................................................................................... 9
PEM Fuel Cell Installations ..................................................................................................................... 11
Total Cost of Ownership & Key Industry Attributes Favor Fuel Cells ....................................................... 12
Flexible Fueling Options for Deployed PEM Fuel Cell Sites Nationally ..................................................... 14
Summary ............................................................................................................................................... 15
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Vito J. Coletto, Director of Sales 2/22/2015
Background Although the national utility grid is overall considered reliable, localized conditions and equipment
failures or natural events cause unanticipated outages ranging from minutes to several days. There have
been two major grid failures that were unanticipated just in the last ten years. Most VRLA batteries are
inadequate for the runtime required to meet these extended outages. Table 1 below outlines causes of
large blackouts affecting major population centers. Equipment Failure is the leading cause, followed by
Wind/Rain natural weather events.
VRLA Battery Overview Valve Regulated Lead Acid (VRLA) “deep discharge” batteries have been providing DC back-up power for
Outside Plant (OSP) critical load applications for decades. Among the largest market segments for OSP
applications where VRLA batteries are used extensively for back-up power are Wireless carrier BTS radio
equipment at cell/tower sites nationally and globally; Wireline Remote Terminals - remote Central
Offices (CO) - “Plain Old Telephone Service” (POTS); Cable TV (CATV) distributed power node OSP
cabinets; and traffic signal backup OSP cabinets. Without exception, the most commonly used batteries
for these applications are 12 volt, VRLA type batteries because of their initial cost to power ratio. A
series string of multiple 12 volt batteries will provide the correct DC voltage, typically +24VDC or -
48VDC, and paralleling strings will provide the appropriate amount of current to meet the system load
runtime requirements.
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Vito J. Coletto, Director of Sales 2/22/2015
VRLA batteries were introduced into the marketplace in the 1980’s, as an alternative Flooded Lead Acid
batteries and to address some of their negative characteristics. Manufacturers initially proclaimed that
the long life of the flooded design (approx. 20 years+ if expertly maintained) could be replicated with
the newer technology – VRLA batteries. However, after decades of experience with these batteries,
there are some well documented issues that the industry has come to acknowledge and accept as status
quo.
For several years both end-users and Industry professionals have been asking for another reliable DC
power option that could effectively address the negative characteristics of VRLA batteries, while
complimenting the positive characteristics, in a cost effective manner. Certain critical OSP back-up
power applications within the Wireless and Wireline spectrum that exacerbate the negative
characteristics of VRLA batteries can be effectively addressed with an alternative technology, specifically
Proton Exchange Membrane (PEM) fuel cells, as this paper will document and lay out. To make the case
for fuel cells as a viable alternative, let’s look at the negative characteristics of VRLA batteries that have
been well known and documented.
VRLA Battery Negative Characteristics 1. Temperature Sensitivity: Tens of thousands of OSP cabinets utilize batteries for critical,
uninterruptible DC backup power. Most of these cabinets are non-temperature controlled. The
graph in Figure 2 below illustrates how battery life is affected by temperature rise above the
optimum 77 degrees F:
Based on the equation Actual life = Derate factor x Design Life, a VRLA battery with a design life of
10 years, operating at 85 degrees F, per the graph, will have an actual life of 6.9 years (6.9 = 69% of
10).
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Vito J. Coletto, Director of Sales 2/22/2015
2. Battery Cycle Life and Depth of Discharge (DoD): For deep discharge VBRLA batteries used
in most OSP applications, the graph below illustrates how battery cycle life is reduced with high
percentage Depth of Discharge (DoD) or deep discharge cycles. The graph also shows how
increasing the operating temperature of the battery leads to an increase in the battery aging rate.
3. Capacity Loss Due to Continuous Charging/Overcharging: Because VRLA batteries are the
emergency power source to critical wireless/wireline telecom equipment, they must be always
maintained at full charge. This is accomplished by continuous charging, at a constant voltage,
known as float charging. Continuous charging of deep discharge VRLA batteries at operating
temperatures above 77 degrees F, will result in increased float current at constant voltage which
could lead to overcharging. It has been shown that the capacity of a typical VRLA battery will
decline and eventually the battery will fail due to grid corrosion of the positive plate and drying out
of the battery electrolyte – directly related to excess float current.
4. Parasitic Self-Discharging Characteristic of VRLA Batteries: Because of this characteristic,
VRLA batteries need constant float charging (via the grid), which will result in reduced life due to
corrosion of the positive plate and increased internal battery temperature due to the charging
function. This phenomenon of parasitic self-discharging could occur for low duty cycle stationary
backup power applications, where grid power is stable and reliable, and outages are rare or only last
for seconds or a few minutes.
5. Number of Charge/Discharge Cycles Leads to Sulfation: During normal battery use, small
sulfate crystals form, but these are normal and are not harmful to the battery. During prolonged
charge deprivation (i.e. a Partial State of Charge or (PSOC) application), however, the amorphous
lead sulfate converts to a stable crystalline that deposits on the negative plate of the battery. This
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Vito J. Coletto, Director of Sales 2/22/2015
leads to the development of large crystals, which reduces the battery’s active material and
conductivity. For newer batteries, the lead sulfate is dissolved during the subsequent charging
cycle, however, as the battery ages, the lead sulfate grows into larger crystals that are very difficult
to dissolve, & the resultant problem of sulfation.
o Sulfation also lowers charge acceptance.
o Sulfation also causes longer recharge cycles. Sulfation charging will take longer because of
elevated internal resistance as the sulfate crystal deposits grow larger, which could lead to
premature battery failure.
o See picture below (magnified) showing how the larger lead sulfate crystal form as the
battery discharge/charge cycles increase over time.
6. Cell Tower Failures: Approximately 62 percent of cell tower failures are power related and 80
percent of those are due to battery problems (Source: Battery Power Magazine). A photograph of a
cell tower OSP cabinet that was burned down by a battery fire is shown in the Figure below.
7. Continuous Monitoring and On-Going Preventative Maintenance: Monitoring is required
on a continuous basis to anticipate issues and constantly monitor battery health. This results in
increased annual operating costs, but it is an essential function utilized throughout the industry.
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Vito J. Coletto, Director of Sales 2/22/2015
8. Weight/Space Limitations: As extended runtime requirements are becoming more common
place (8 hours runtime or greater being specified), this results in more batteries/battery strings and
increased weight, along with taking up valuable real estate when placed next to the OSP cabinet
equipment they are intended to power. This limitation applies to ground level deployments where
real estate is at a premium and could result in increased lease space costs. The weight/space
limitation also applies to rooftop deployments, where the extra weight for extended runtime
requirements could result in increased structural support to carry the additional load, driving up
project costs. Available rooftop space is normally at a premium, and battery runtimes of more than
8 hours would not be a practical solution. Many densely populated cities like NYC and SF deploy
rooftop cell towers because of limited space ground level. This is especially true in very densely
populated cities in Asia like Tokyo, Japan. With small cell deployments on rooftops also becoming
more common and on the rise nationally and globally, this limitation on VRLA batteries begs for an
alternative back-up power technology.
9. High 10 -15 Year Total Cost of Ownership (TCO): This results from recurring capital costs to
replace VRLA batteries due to theft (new batteries, shipping costs, installation costs) and replacing
existing batteries every 3 to 5 years for non-environmentally controlled OSP cabinets, and 5 to 7
years for environmentally controlled OSP cabinets. Couple this with continuous monitoring costs
and PM costs noted earlier, VRLA batteries are not an optimum choice for critical OSP back-up
power applications, and will result in a high 10 -15 year TCO.
Battery theft is a growing concern, and telecom providers have seen a spike in battery thefts over
the past few years, given our current economic situation with rampart high unemployment. On a
national scale, this is costing the telecom industry millions of dollars in battery replacement and
increased security costs.
10. Battery Disposal Costs: These are sometimes known as “non-tangible” costs, but they are in fact
real and measurable directly contributing to the high Total Cost of Ownership of VRLA batteries over
a ten to 15 year span. These costs include a certified recycler, documentation, and transportation.
Applications Leveraging the Positive Characteristics of VRLA Batteries VRLA batteries have performed satisfactorily in some OSP applications, as follows:
VRLA batteries housed in an environmentally controlled equipment shelter, OSP cabinet, or
underground Controlled Environment Vault (CEV) maintained at or near 77 degrees F. However, this
results in increased up front capital costs and operating costs to maintain and power these HVAC
systems.
VRLA battery backup for low duty cycle, standby applications (minimum discharge/charge cycles) due to
a generally reliable national utility grid in many locations across the country. This can result in a reduced
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Vito J. Coletto, Director of Sales 2/22/2015
sulfation rate, due to a lower amount of discharge/charge cycles, which should have a positive overall
effect on battery cycle life and performance.
For those applications where only a minimum or 2 to 4 hours of runtime is required, VRLA batteries are
most cost effective, and require minimal footprint for these short runtime applications. However, these
OSPs (telecom & broadband CATV) that house just 2 to 4 hours of runtime do not meet the FCC
mandate of a minimum of 8 hours runtime in the event of an outage. If the FCC mandate is ever fully
enforced, PEM fuel cells will be a logical choice as an alternative technology because it will be shown
that they become more cost effective for extended runtime applications (8 hours or more).
These above applications do no preclude the use of PEM fuel cells. For all of the applications noted
above, fuel cells can also be deployed as a viable option, it is the end-user customer’s choice, weighing
everything in the balance, from technology choices, reliability, and financial value proposition.
Summary of Battery Technology VRLA batteries have been the primary choice for OSP backup power applications for decades and have
performed well some scenarios, as noted above. While battery technology has improved over the years
to address some of the negative characteristics described in the paper, most of these technology
improvements are costly and not field proven: New higher price Lead-Carbon battery technology as
compared to the legacy Lead-Acid batteries, for example. Newer battery technologies have also
resulted in additional negative characteristics, like the increased likelihood of battery fires, shown to be
a real technology challenge with certain expensive Lithium-Ion battery chemistries.
A Brief History of Fuel Cells The origin of fuel cells can be traced as far back as 1776, when the 13 American Colonies declared their
independence from Mother England! A renowned scientist at that time, Henry Cavendish, discovered
that water is not an element, but rather a compound formed when hydrogen reacts with oxygen.
Decades later in 1839, Dr. Christian F. Schönbein hypothesized that this reaction also generated an
electrical current--a hypothesis that Sir William Robert Grove confirmed in 1839 when he experimented
and assembled what he described as a “gas voltaic battery” – what is now known as the first “fuel cell.”
See above figure for his drawing of this experiment. Because of his work in advancing the hypothesis,
Sir William Robert Grove, a Welsh lawyer turned scientist has given the esteemed title: “The Father of
Fuel Cells.” The production of an electric current is by means of an electro-chemical reaction between
hydrogen and oxygen, not the combustion of fossil fuels.
What is today known as a “fuel cell” (a term first coined nearly thirty years after Sir William Grove’s
experiment in 1889, by Charles Langer and Ludwig Mond, to describe their efforts using coal gas) has
now been under development for nearly two centuries.
However, fuel cell technology did not find its first practical uses until the mid to late 1950s, when it
began to be employed for mobile applications that would eventually range from space missions to
public transportation. UTC Power, which was founded in 1959, won the sole-source contract to design
and manufacture fuel cells to NASA. All NASA Apollo & Space Shuttle missions through 2012 included
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Vito J. Coletto, Director of Sales 2/22/2015
two 85kW & 125kW fuel cell modules respectively that provided the astronauts critical power and
drinking water. Although heat is a byproduct of the electro-chemical reaction, the heat for the
astronauts was provided by a different system, not the waste heat from the fuel cells. Can you think of
a more mission critical application for fuel cells then supplying the power and water to help bring
these US astronauts to and from the moon and earth’s orbit safely?
Summary of Fuel Cell Technologies & Applications
In recent years, fuel cells have seen widespread implementation in the USA & and around the world, in
stationary prime power electric only, and combined heat and power (CHP) applications. PEM fuel cell
technology is commercially proven with thousands of deployments, millions of reliable operational
hours, and subjected to wide temperature swings in OSP back-up power applications. PEM fuel cells
have augmented or replaced VRLA batteries systems and totally replaced the diesel generator function
for extended runtime needs.
PEM Fuel Cells: An Alternative to VRLA Batteries Proton Electrolyte Membrane (PEM) fuel cells, like batteries, provide DC electricity without combustion
through an electro-chemical reaction. However, this is where the similarities end. Unlike a battery, the
fuel cell does not need constant recharging to maintain its output voltage. As long as there is a supply of
hydrogen fuel, the fuel cell will produce unlimited runtime with zero emissions at the point of use, which
makes this option excellent for extended utility outages as a replacement for VRLA batteries and diesel
generators.
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Vito J. Coletto, Director of Sales 2/22/2015
What is a PEM Fuel Cell and How Does it Work? A PEM fuel cell produces DC power as a result of a chemical reaction between hydrogen gas and oxygen
from the air, in the presence of a catalyst – without any combustion. See drawing below which
describes each step of the process.
Notes:
Hydrogen is mixed (not burned) with air. This combination, in the presence of a catalyst
converts the hydrogen and oxygen (from the ambient air) to DC electricity and water – with
zero emissions at the point of use, which can support customer sustainability objectives.
Low temperature, fast start times, making the PEM fuel cell ideal for critical CATV back-up
power applications, like distributed/centralized power nodes, wireless telecom, wire line
Remote Terminals (RT) / Central Offices (CO), and traffic signal OSP applications.
No moving parts in cell stack, making for simple and low cost annual preventative maintenance.
PEM fuel cells are modular and scalable from 100W to 100kW to meet the power needs of most back-up
power applications in the four largest OSP market segments mentioned earlier. These compact, solid
state designs address the weight/space limitations of batteries when runtimes of 8 hours or more are
specified.
Also known in the industry as
“Proton Exchange Membrane”
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Vito J. Coletto, Director of Sales 2/22/2015
To illustrate the compact footprint of fuel cell technology, see the picture below for a 10kW OSP
application with 8 hours of fuel storage on-site. These cabinets can be installed next to each other,
minimizing footprint required (see page 11 for example installations):
The Transient Power Module (TPM) or bridge battery is required to provide the 30 seconds of
uninterruptible power to the critical OSP loads while the fuel cell starts. Note that some PEM fuel cell
designs could take 30 minutes or longer to start, which requires a larger bridge battery system, making
them less desirable. If there are existing batteries at a particular OSP installation site they can be used
for short duration outages (seconds to a few minutes), then the TPM is not required. The point is that
an end-user can choose to completely remove all existing system VRLA batteries from a site, and their
associated maintenance costs/recurring capital replacement costs, and replace them with the PEM fuel
cell + small TPM.
For a typical telecom OSP application, the PEM fuel cells DC output connects directly to the system DC,
just like the battery strings, as illustrated below:
PEM Fuel
Cell
Engine
ul
Two 5kW
Fuel Cell
Engines
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Vito J. Coletto, Director of Sales 2/22/2015
Referring to the above diagram, the PEM fuel cell will monitor the DC bus, and upon utility power failure
or rectifier failure, the DC bus voltage will start to decrease. For a typical wireless telecom -48VDC
application, when the DC bus voltage drops from say -54VDC to -52VDC, with thresholds selectable in
0.1VDC increments, the fuel cell with start and power the load for the duration of the outage. When the
utility power returns, the fuel cell monitors and senses the return of the utility, waits until stable, then
returns to a standby mode, waiting for the next outage.
PEM Fuel Cell Installations PEM fuel cells have been installed in thousands of locations nationally & globally, experiencing wide
temperature swings in summer & winter, overcoming the operating temperature (life and capacity)
issues of VRLA batteries. With these thousands of installations, and on-going additional deployments,
PEM fuel cells are a proven, rugged and reliable back up power solution for your critical OSP
applications. Fuel cells are no longer a science experiment or a technology just for niche applications.
Some examples of PEM fuel cell installations at wireless tower/cell sites is are shown below:
Regarding rooftop deployments, besides the weight and space limitations noted earlier for VRLA
batteries, it is difficult to nearly impossible to obtain a permit to operate a diesel or propane generator
on the roof due to potential fuel leaks, pooling on roof surface, and increasing the chances of a
secondary fire. If H2 gas leaks, rather than pool – it is lighter than liquid fossil fuels and the air, it rises at
70 ft/min away from equipment and roof, minimizing the chance of fire at the building structure.
With continued improvements in the supply chain, coupled with significant advances in fuel cell stack
manufacturing, the upfront capital costs of fuel cells, which have been the major issue in the past, have
significantly decreased in the past decade. Rebates & incentives that encourage the use of green and
sustainable technology may be available at the State level and an Investment Tax Credit (ITC) is available
from the federal level providing $3000/kW or 30% of the total project costs, whichever is less. This is a
dollar for dollar reduction in the federal income tax liability for the system owner. No such incentive is
available for battery back-up or generator back-up. This ITC incentive helps narrow the gap in up-front
capital costs between fuel cells and VRLA batteries.
Rooftop application, (L to R) BTS radio
cabinet, PEM fuel cell cabinet, H2 fuel
cabinet. Existing battery cabinet removed, in
favor of the PEM fuel cell + TPM.
Ground level application, (L to R) BTS radio
cabinet, PEM fuel cell cabinet, H2 fuel
cabinet. Existing battery cabinet removed, in
favor of the PEM fuel cell + TPM.
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Vito J. Coletto, Director of Sales 2/22/2015
PEM fuel cells, depending on the design, components used, and manufacturing techniques employed,
have a design life of greater than 10 years, much more than the real life of deep discharge VRLA
batteries, typically 3 to 4 years for most deployed OSP equipment cabinets, which are non-temperature
controlled.
Total Cost of Ownership & Key Industry Attributes Favor Fuel Cells For extended runtime requirements, a typical OSP site (wireless, wire line, CATV, and traffic signal) will
deploy 2 to 8 hours of battery backup in addition to an on-site Appleton connector/manual transfer
switch where a mobile/portable diesel generator can plug into. Some OSP sites have a permanently
installed stationary diesel or propane generator with an Automatic Transfer Switch (ATS) for extended
runtime needs. Due to the high annual operating costs of maintenance for the VRLA battery + diesel
generator combination, in addition to the recurring capital costs of replacing the batteries every three
years or so, it will be shown that PEM fuel cells will provide the lowest 10 year Total Cost of Ownership
(TCO).
As an illustration of the above statements, the graph below shows a typical, generic telecom OSP
application and compares the 10 year TCO of PEM fuel cells to batteries and generators. From review of
this graph, one cannot dispute that PEM fuel cells are an excellent cost effective alternative for your
critical OSP backup power applications and will provide comparable up-front capital costs and the
lowest overall TCO.
5kW PEM Fuel
Cell w/8 hours
runtime
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Vito J. Coletto, Director of Sales 2/22/2015
Notes:
Y axis represents capital and operating costs (OPex) in dollars; X axis represents a ten year look after
initial up front capital investment shown at time “0”. The up-front capital costs for the equipment and
installation are shown for unconditioned batteries in red, conditioned batteries in black, diesel
generator in blue, and finally the PEM fuel cell in green.
The slope of each technology line represent the on-going operating costs and the “jump” every 3 years
for the unconditioned batteries and every 5 years for the conditioned batteries represents recurring
capital costs to replace these VRLA batteries.
For the diesel generator, daily, weekly, monthly, and annual maintenance are required. These costs, as
well as up-front capital costs will be significantly higher going forward due to more stringent EPA
emissions and noise regulations. The other OPex cost element is the cost of diesel fuel + delivery for this
generic scenario.
The PEM fuel cell has no moving parts in the cell stack, and preventative maintenance is simply cleaning
or replacing an air filter once every 1000 hours or one year of operation. The only other OPex cost is the
cost of fuel + delivery, which is much lower than diesel fuel. As you can surmise, the 10 year TCO for the
fuel cell is very compelling compared to VRLA batteries and diesel generators and will provide the best
overall value to the end-user customer.
Another way of illustrating the total value proposition of PEM fuels versus the legacy technologies,
please see the chart below, which list key industry attributes important to end-user customers and
where PEM fuel cells rank compared to VRLA batteries and diesel generators. As you can see, in 8 out of
11 key attributes, the PEM fuel cell is the best technology of choice and best overall value.
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Vito J. Coletto, Director of Sales 2/22/2015
Flexible Fueling Options for Deployed PEM Fuel Cell Sites Nationally Hydrogen gas (H2), the most abundantly used industrial gas nationally, is readily available in most major
cities and localities in the USA. For typical OSP applications, the H2 is stored in steel tanks or cylinders,
and enclosed in a telecom grade OSP cabinet, as shown in the picture above on page 10. Hydrogen has
an excellent safety record for more than 50 years! While hydrogen is a combustible gas, it is been shown
to be safer than traditional fossil fuels like diesel, gasoline, propane, and natural gas.
Re-fueling H2 “Fill” trucks use “Fill-In-Place” technology (FIP) today as a means of re-fueling PEM fuel
cell sites. See pictures below, as an example of FIP technology. The traditional or old method of “bottle
swapping”; having to have access inside the fuel cabinet, disconnecting empty cylinders from the fuel
manifold and connecting full cylinders to the manifold, is no longer necessary. With FIP, where available
nationally, a fill truck fitted with DOT certified hose (see below) connected to H2 large storage cylinders
on the truck, connects to a fill port located on the fuel cabinet door. The hose is simply connected to
the fill port nozzle, and in just minutes, all the cylinders are re-filled in place, with no handling of the
cylinders or access inside the cabinet required. This is a proven, simple, safe, efficient and cost effective
method of providing hydrogen refueling to installed PEM fuel cell system sites, providing “unlimited
runtime” for the end user – something that can never by achieved with VRLA batteries.
Remember, as long as there is a source of H2 fuel, the PEM fuel cell will continuously and reliably
generate the DC output power required for OSP applications, with none of the negative characteristics
or limitations of VRLA batteries itemized earlier in this paper.
For remote locations, with no easy access to H2 gas, propane, or diesel fuel, an extended runtime
solution is still viable with PEM fuel cells using a pre-mixed methanol/water solution and an integrated
steam reformer to generate H2 gas on-site. Several size sealed storage tanks are available and provide
FIP Port
with
Nozzle &
Pressure
Gauge FIP Port, with Small Access Door, Fuel Cabinet View
Fill Hose from
Fill Truck
Typical FIP Capable Fill Truck
Note: Higher storage pressure, composite cylinders
shown above; Aluminum tank, with a carbon-fiber
wrap, they store 2X the amount of H2 gas than the
standard steel cylinders, for longer runtime needs.
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Vito J. Coletto, Director of Sales 2/22/2015
runtimes is days versus hours, and is ideal for remote tower/cell sites, or RT sites, etc. Methanol/Water
reformer systems, like gaseous H2 fueled PEM fuel cell systems, are commercially proven with hundreds
of applications both nationally and globally. The picture below shows an example of an integrated fuel
cell power and H2 generator cabinet.
Summary As this paper illustrated, with unanticipated utility grid failures nationally, VRLA battery performance can
be unpredictable and affected by a wide variety of factors that have been well known for many years,
due to the design characteristics of VRLA batteries. These factors include:
o Charge level
o Ambient/Operating Temperature effects on life and capacity
o Age/Pre-mature failures
o Number of charge/discharge cycles resulting in sulfation
o Weight/space limitations and theft
o Amount of monitoring and on-going maintenance
o Disposal Costs
PEM fuel cells, on the other hand, have been shown to be a more cost effective, scalable, reliable,
extended runtime solution without any of the limitations of batteries and the high maintenance and
environmental issues associated with diesel generators. In thousands of successful installations across
the vertical markets discussed in this paper, PEM fuel cells have met or exceeded requirements and are
a commercially proven technology that should be considered by end-users as a viable alternative to
batteries for OSP back-up power systems.
If you are tired of the issues associated with legacy back up power technologies, and have not looked at
PEM fuel cells recently or at all, I hope this paper has shed new light on this clean, reliable, cost effective
alternative back up power technology, for serious consideration at existing sites where there are
planned battery or generator replacements or for new OSP sites being considered.
Sealed Methanol/Water
Storage Tank
H2 Generator
2.5kW or 5kW
Fuel Cell
Engine
Fill Port Access
for Refills
48” W x 41” D x 72” H
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