A Proton Exchange Membrane (PEM) fuel cell—backed by a premium, maintenance-free lead acid battery—can provide an optimum solution for extended runtimes at telecom sites.

Provides sustainable, “green” solution for extended runtime in telecom apps

Virtually every business today is concerned—if not obsessed with—its carbon footprint. Many companies have already come to the conclusion that going “green” is not only good for the environment; it’s good for business as well.

The telecom industry is no exception. That’s why energy-efficient, sustainable solutions, such as hydrogen fuel cells, are becoming increasingly popular and more widely accepted by communications providers throughout the United States and abroad.

In the aftermath of Hurricane Katrina—which saw vital communications links, such as 911 services fail as the power grid went out and AC power was lost—a panel appointed by the FCC requested telecom companies to implement solutions that would provide longer emergency power runtimes for critical areas of their networks.

Lead acid batteries dominate the backup power market and provide approximately four to eight hours of reserve power at each cellular site. Diesel gas generators are also a viable alternative that allow telecom operators to achieve extended runtimes and strengthen their communications infrastructure. Interest in fuel cells for telecom applications, however, continues to grow for a number of good reasons.

Fuel Cells Are Clean & Green

A Proton Exchange Membrane (PEM) fuel cell—backed by a premium, maintenance-free lead acid battery—can provide an optimum solution for extended runtimes at telecom sites. In comparison to loud and dirty diesel generators, fuel cells provide “green” advantages and a low-impact energy solution.

Eco-friendly fuel cells do not emit pollutants; they produce only water and heat byproducts, which have no impact on the environment. Generally speaking, fuel cells have a smaller footprint and are easier and less expensive to install than generators. In addition, fuel cells are nearly maintenance free, requiring only a simple air filter change after every 500 hours of operation.

Issues usually associated with diesel generators, such as fuel spillage and spoilage, carbon emissions and noise, are never a concern with PEM fuel cell/battery hybrids. Self-contained fuel cell units have the versatility to operate indoors or outdoors, and can be safely installed in most places, including building rooftops where space is at a premium and weight restrictions are an important consideration. Pending government legislation may prohibit diesel generators from being sited on rooftops as well as restrict the amount of time the generator can run before the power source must be switched over to a backup battery.

Fuel cells use renewable, readily-available, commercial-grade hydrogen that has unlimited shelf life. Generators, on the other hand, run on diesel fuel that can only be stored for a limited period of time before it must be replaced. While fuel cells can be remotely monitored for easy and efficient upkeep, generators require trained mechanics to perform regularly scheduled maintenance to ensure reliable emergency power.

Efficient Operation & Long Service Life

A typical PEM fuel cell consists of a bi-polar plate with an anode on one side and cathode on the other side. Airflow across one side of the plate and hydrogen on the other side of the plate, coupled with the use of a membrane, facilitates proton exchange which is captured as usable electricity. Fuel cells are considered a “clean” technology because they use hydrogen and generate water.

Today’s fuel cells can operate continuously for up to 20,000-plus hours. They are even more reliable and cost effective than models produced only a few years ago. PEM fuel cells typically run from a low end of 1 kW to the high end of 20 kW, with most centered on 5 – 10 kW to meet telecom base station requirements.

Because time is needed for the fuel cell to engage in an emergency situation, and hydrogen has to be replaced, a battery is used to power the load until the situation is determined to be catastrophic. This complementary set-up can be configured to provide eight hours of runtime for batteries, 48 hours for fuel cells, or 160 hours as a combined solution.

Modern fuel cells are also modular and scalable. Users can start with a 5 kW system and add capacity to the site as the need for backup power grows. Fuel cells can be configured to fit inside a standard relay rack or installed in a cabinet that can be wall mounted or set on an exterior concrete pad.

Longer Runtime

Fuel cells combined with maintenance-free batteries can provide exceptional runtimes when batteries are discharged during the hours when the site loading is lower. This reduces the total Depth of Discharge (DOD) on the batteries and maximizes cycle life.

During the day, the fuel cell supports the site load and recharges the batteries to prepare them for discharge the following evening. This alternating pattern of fuel cell and battery use optimizes DOD and controls battery recharge.

More importantly, the fuel cell/battery combination can produce runtimes of more than 160 hours. In complete outage situations, telecom sites using fuel cells to provide emergency power can run unattended for six days, essentially operating as an off-grid system.

Less Maintenance

Maintenance on fuel cells has been dramatically reduced as a result of high-speed manufacturing processes that have improved reliability and serviceability. In fact, some designs have routine maintenance schedules programmed into their normal operation, which enables maintenance guidelines to be focused on operating intervals rather than calendar days.

Since the unit operates as a solid state device, fuel levels can be checked automatically, the system can perform self-diagnosis, and alarms can be outputted to the base station network for easy monitoring or to alert operators of problems.

In effect, all maintenance checks can be scheduled based on actual outage times or coordinated with other regular site visits. In this unique pairing of battery and fuel cell, it is critical that the battery is reliable and designed to withstand harsh operating conditions. In extreme cases, the battery will be discharged multiple times and expected to stand on open circuit for extended periods or sit on float while not in use.

Incentives To Go “Green”

In today’s political landscape dotted with stimulus programs, carbon credits and tax breaks, the incentives for companies to develop a “green” infrastructure and focus on sustainability are very attractive.

Incentives include a federal fuel cell investment tax credit, with a maximum claim of up to $3,000 per kW; a federal alternative fuel infrastructure tax credit that covers 30 percent of the cost of installing alternative fueling equipment up to $30,000; and a federal modified accelerated cost-recovery system (MACRS) that allows businesses to recover investments in certain properties through depreciation deductions.

Under the MACRS program, fuel cells are classified as a five-year property. If the property meets program requirements, the owner is entitled to deduct 50 percent of the adjusted basis of the property in the current year. An ordinary depreciation schedule would apply to the remaining 50 percent.

With the help of the federal, state and local programs, incorporating PEM fuel cell technology to extend runtimes for telecom applications can no longer be considered cost-prohibitive. 

The Positive Impact Of Fuel Cells

As the world continues to evolve and grow as a wireless society, demand for backup power on the wireless infrastructure will increase significantly. In a market historically serviced by batteries and diesel generators, an eco-friendly solutions-based fuel cell/battery combination is a welcome step in the right direction for telecom operators and the environment.

Robust, reliable, mass-produced and cost-effective fuel cells coupled with premium, maintenance-free lead acid batteries provide a low-noise, no-emissions, reduced-maintenance and cost-effective solution for extended runtime, and eliminate dependency on fossil fuel generators.

By incorporating a synergistic blend of materials and design features that provide superior performance, fuel cell/battery hybrids satisfy user requirements for long life, design flexibility, high energy density, compact configuration, and high cycling.

When it comes to emergency power solutions, sustainability is not a passing fad—it is a mandate for long-term business success.

For more information visit www.enersys.com or www.extendedruntimesolutions.com