What It Is and How It’s Revolutionizing Backup Power for Traffic Signals
A dark intersection is every agency’s nightmare. Even as you think about it, you can probably picture one or two intersections that would create serious traffic problems if they went dark for an extended period of time.
Most agencies do their very best to avoid that kind of chaos with portable generators, but these solutions have never been ideal: They fail, require extensive maintenance, cause pollution, and more.
Fortunately, there is now a better way. The hydrogen fuel cell—modernized and improved to provide reliable, sustainable and clean backup power. It’s been tested and proven in various sectors such as the military and telecommunication, in addition to other applications around the world.
What is a hydrogen fuel cell?
A hydrogen fuel cell—or PEM (proton exchange membrane) cell—is an electrochemical system that uses hydrogen and oxygen to produce clean electricity.
The hydrogen fuel cell is unfamiliar to many people today, but it is not new technology. It was originally developed in 1842 by a Welsh scientist named William Robert Grove. Early experiments on fuel cells date as far back as the 1700s.
The basics of what a fuel cell is and how it works has been around for more than a century, but it has, of course, been dramatically modernized and transformed. Today, hydrogen fuel cells
have been proven, over a wide-spread number of global deployments, in all kinds of climates. A modern fuel cell is, essentially, an unlimited battery.
How does a fuel cell work?
A fuel cell consists of a membrane between two solid plates. Hydrogen, the fuel for the cell, is fed on one side, and oxygen on the other.
The hydrogen atoms split into protons and electrons. The protons pass through the membrane, and the electrons are borrowed to produce electricity. The hydrogen atoms then come back together and bond with the oxygen, to produce water.
Thus, the fuel cell produces DC electricity with zero emissions, because there is no combustion of the hydrogen.
And it’s more than theory. Over the past 15 years, fuel cells have been implemented as power backups for telecommunications, public safety, military and security details, and more.
A number of hydrogen’s properties make it safer to handle and use than the fuels commonly used today, such as gasoline and natural gas. Hydrogen is non-toxic and because it is much lighter than air, when released, it dilutes quickly into a non-flammable concentration.
In addition, testing of hydrogen systems—tank leak tests, garage leak simulations, and hydrogen tank drop tests—show that hydrogen can be produced, stored, and dispensed safely.
Like any flammable fuel, hydrogen can combust. But hydrogen’s buoyancy, diffusivity and small molecular size make it difficult to contain and create a combustible situation.
Since hydrogen is non-toxic and non-poisonous, it will not contaminate groundwater (it’s a gas under normal atmospheric conditions), nor will a release of hydrogen contribute to atmospheric pollution as it does not create fumes.
The next-generation fuel cell
In 2001, two PhDs decided it was time to change how the world gets its power. They recognized the ever-increasing demand for electricity, and the strain that growing rural populations were putting on the grid.
They believed that the fuel cell held the answer, but at the turn of the century, fuel cells were individually hand-made, from fragile components. The designs did not lend themselves to mass production and were not commercially viable.
The world needed a more reliable fuel cell.
Use case: Hydrogen fuel cell backup power for traffic signals
Blackouts happen, usually because of bad weather and natural disasters—although equipment failure and operator error can happen as well:
When blackouts cause traffic signals to go dark, agencies are left scrambling (and spending extra resources). Police officers need to be deployed to keep traffic flowing smoothly, but accidents are likely. With long-lasting backup power, critical intersections can remain functional, helping create safe roadways.
DC generators are traditionally employed as traffic signal power backups, but these solutions are not without complications. That’s why, for more than a decade, PEM fuel cells have been gaining momentum as the go-to solution for critical backup applications.
A fuel cell can provide days of extended run time—up to five and a half days on a standard, full-operation intersection.
And with more and more agencies looking for ways to reduce their environmental impact, fuel cells—with zero emissions and a very small footprint—are ideal.
Benefits of PEM fuel cells as traffic signal “battery” backups
The benefits of PEM fuel cells as backup power supplies for traffic signals are exciting.
- Green energy — As mentioned, the only output from a hydrogen fuel cell is warm water vapor.
- Fast start times — The low temperature/fast start time available from the fuel cell makes it ideal for critical traffic backup power.
- Minimal maintenance — The system is air-cooled and there are no moving parts, which means no oils or liquid lubricants. A standard air filter needs to be changed about once a year, or every 100 operating hours. That’s the whole PM checklist: air filter.
- Quiet — Because there are no moving parts, there’s no hum or noise.
A PEM fuel cell “battery” backup frees you from generators, the grid, pollution, and unwanted noise. It’s an ideal solution.
How the fuel cell works as a traffic signal power backup
The Fuel Cell system uses standard, industrial hydrogen bottles, widely available and often referred to as “K bottles.” Each bottle provides nine kilowatt hours of energy storage, and the standard fuel cabinet holds six bottles—for a total of 54 kilowatt hours of energy. The design is modular, though, and can be adjusted. Some cabinets, for example, are built for 12 hydrogen bottles.
The fuel cell attaches—off the ground—to the side of the fuel cabinet.
Also inside the fuel cell enclosure is the UPS module, transient power module, and a small heater fan for cold weather. The fuel takes about 30 seconds to start up from stand-by, so the transient power module is present to ensure uninterrupted power for those 30 seconds.
The hydrogen bottles can be replaced even while the system is running.
- Agency-monitored — In these situations, the agency monitors the fuel cells. When replacement bottles are needed (indicated by a “low fuel” alarm).
- Western Systems-monitored — Our team can also take over monitoring the installments, and replacing the bottles as needed.
- Disaster relief — This arrangement is ideal for installations in areas with earthquakes and fires.
The PEM fuel cell is not a one-size-fit-all solution for every intersection in every state. Some intersections don’t have or need backup power. Others have a small battery string that provides a couple hours of backup power, and that’s all they really need.
Fuel cells make the most sense as signal backup supplies for critical intersections or complex interchanges, especially where agencies need to guarantee eight or more hours and even days of runtime in any circumstance.
Generators vs. fuel cells
Traditional technology for signal backup power is portable—or, in some cases, stationary—generators.
Generators are previous-generation tech. They work, most of the time, but the reason that they’re the popular choice is not because they’re the best choice—it’s because they’re familiar. Corporate inertia dictates that organizations keep doing what they’re familiar with, so portable generators keep getting used as power backups for traffic signals.
Generators, however, run on diesel fuel and are highly pollutive. They’re also usually left chained to the signal and unattended. There’s nothing to stop someone from trying to mess with it, and either breaking it or hurting themselves in the process. Neither is there any security for the system that a bolt cutter can’t get through.
DOT engineers were surveyed about traditional traffic signal backup power options. One engineer made this comment:
“Portable generators must be used where maintaining backup power for long periods is critical—is there another option?”
Yes, there is another option.
Fuel cells produce green energy, and are safe and secure within their units. As long as hydrogen bottles are replaced, they are an eternal source of power, and the regular maintenance is trivial.
Reliable backup power for less
The initial investment for fuel cell backup power at an intersection is quickly offset by eliminating other costs:
- Avoiding deploying officers to guide traffic during an outage.
- Avoid injuries and lawsuits when accidents occur at a dark intersection.
- Eliminate the hours and budget dollars spent on maintenance and replacement of generators.
Over 10 to 15 years, PEM cell systems offer the lowest total cost of ownership. They are also safe, quiet, and environmentally friendly—all while offering more reliable and longer-lasting backup power.
Engineers and agency decision-makers have long been waiting for a better solution for traffic signal backup power, and it’s finally here.
Western Systems is here to help
Contact us if you have any questions regarding Fuel Cell Technology. Our team can help you with your back up power needs by phone, email, and online webinars as well as optional onsite field services.