By Scott T. Egbert, Plug Power Inc.
Inevitably, utility managers rethink many aspects of their operations in the wake of major outages. Backup power for substations is no exception.
The industry is ripe for alternatives. Extreme cost pressure is compelling utilities to root out inefficiencies in every process. Skyrocketing consumer demand places a strain on substations and their backup power sources. Anything that extends runtime, lowers maintenance, delivers cost savings and expedites power restoration will be welcome in this environment. Fortunately, one intriguing alternative may be able to fulfill those requirements.
Room for Improvement
Not that a wholesale change is needed immediately; indeed, the traditional technology continues to provide reliable backup power at substations. Flooded lead-acid batteries typically achieve useful life spans of 15 to 20 years and maintenance techniques are well established. Up until recently, few questioned the rationale for deploying battery technology in the substation environment.
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Now those questions are increasing. The major outages of the past three years-first the blackout of 2003, then the Florida and Gulf hurricanes of 2004 and 2005-pointed up the general need for extended runtime beyond the capacity of traditional technologies. The quest for cost-cutting highlighted the frequent maintenance batteries require. With substations numbering in the tens of thousands, monthly, bimonthly and quarterly maintenance schedules become cost-prohibitive.
In the face of such disadvantages, it should surprise no one that utilities are looking carefully at alternative technologies to augment, or perhaps even replace, the tried-and-true battery.
An Alternative Emerges
One of those technologies-the fuel cell-has drawn considerable attention as a viable alternative. It has several advantages in its favor.
Start with cost savings. While roughly equivalent to flooded lead-acid batteries in initial price, fuel cells nonetheless carry several cost advantages. New battery installations require new, environmentally controlled spaces-and the related expenses in labor and systems-to protect the batteries from the harsh conditions of the outside plant. Even replacement batteries take up valuable space in existing structures and incur the expense of climate control. Fuel cells, with their ability to withstand even extreme environmental conditions, need no such sheltering, thus generating significant savings.
The cost advantages become even more apparent over the systems’ respective life cycles. The reason, in a word, is maintenance: The fuel cell’s three-year schedule dramatically reduces the time and cost involved in upkeep. Moreover, the clean technology of fuel cells makes maintenance a safer proposition, with none of the risks inherent in flooded lead-acid batteries (such as exposure to acid).
Plug Power’s GenCore backup power system. Click here to enlarge image
Then, there is runtime. Fuel cells for backup power have been designed to run 24 hours or more-three times as long as traditional batteries. Especially in areas with a high risk of extended outage, this longer runtime becomes essential to maintaining service. In addition, fuel cells can keep existing batteries fully charged during an outage. This not only keeps monitoring and remote systems operational, but enables the batteries to close breakers as required for automatic reconnection to the grid when power is restored.
Other advantages make the technology ideal for the outside plant. As mentioned earlier, fuel cell systems run successfully in a broad range of outdoor conditions: One particular line of backup systems is designed for reliable operation from minus 40 degrees Celsius to 46 degrees Celsius.
Also consider that fuel cells meet most zoning requirements for urban and rural installations. With minimal moving parts, they produce very little noise. In addition, they include on-board diagnostics, allowing staff to monitor and predict remaining runtime and plan support visits effectively.
Utilities can also capitalize on fuel cells as an environmentally friendly alternative. When operating on gaseous hydrogen, proton exchange membrane (PEM) fuel cells produce zero emissions; heat and clean water are the only byproducts. In addition, the recycling programs administered by several fuel cell companies eliminate disposal issues and the environmental challenges that accompany them.
Fuel cell technology has drawn widespread support within key federal and state agencies, from the Department of Defense to the National Institute for Standards and Technology. Stationary fuel cells have already logged millions of hours in the field, powering such highly sensitive applications as telecommunications and uninterruptible power supply. And the technology has been gaining certifications from such agencies as Underwriters Laboratories.
Even though challenges remain-principally in hydrogen delivery and siting-the fuel cell industry has made substantial headway toward resolving them. Partnerships with major industrial gas suppliers are optimizing the logistics of hydrogen fuel supply. Collaborations with standards groups and universities are accelerating the development of siting guidelines that facilitate the use of hydrogen while ensuring safety.
What’s Next for Substation Backup Power?
To be sure, fuel cells will continue to undergo development, driving down costs while expanding features. Current field installations are providing insights into application-specific needs and system design.
Most likely, the future of substation backup power will take the form of a mosaic. Some instances will call for replacement of batteries with fuel cells. In others, the fuel cell will augment the existing battery-not only adding more runtime on its own, but acting essentially as a battery charger, extending the life of the battery plant. In the event of an outage, a fuel cell in this configuration would generate power for two critical purposes: closing the breakers automatically during restoration of grid power, and maintaining smooth operation of monitoring and remote systems. As such, fuel cells may even allow utilities to keep less battery capacity at each substation, reducing costs further.
Regardless of the specifics, it seems certain that new solutions will make backup power safer, more efficient and more reliable. Fuel cells in particular offer hope for a win-win situation: uninterrupted service for customers-and lower costs for the utilities that serve them. â®â®
Scott Egbert is director of product marketing, GenCore Programs, for Plug Power Inc. He can be reached at email@example.com