By: Eoin Connolly, Director, Project Management, Plug Power Inc.
Although the wireless industry has certainly felt the crunch — especially since the recent northeast power failure — anyone who deals with outside plant (OSP) backup power knows the challenge.
Unprecedented consumer demand for new products and services, such as DSL and wireless broadband, is placing ever-higher demands on networks, while reliability and availability requirements remain deep into the nines. In the utility sector, transmission and distribution substation back-up are essential to the successful and speedy recovery of the grid after an outage.
These trends have utilities and their subcontractors, OEMs providing industrial uninterruptible power supply systems (UPS), and providers of telecom and broadband power applications — all of whom are customers for UPS and OSP fuel cells — scrambling to upgrade and optimize plant infrastructure, adding backup power, amid severe competitive cost constraints.
If that isn’t enough to worry about, the fact is that the old solutions are no longer always adequate. As traditional backup power technologies, like valve-regulated lead-acid batteries, fall short in the field, customers with particularly demanding power quality requirements are turning toward alternatives. The challenge is to find solutions that satisfy multiple requirements of reliability, flexibility and durability — at a cost that makes sense for the industry.
Out with the Old
In the secure confines of the central switching office, traditional technologies have long provided highly reliable power. Flooded lead-acid batteries typically achieve useful life spans of 20 years. Maintenance techniques for these and other widely used sources, such as engine-generator sets, are proven and easily implemented. Onsite personnel can monitor loads, equipment condition and provisioning requirements. Not withstanding the footprint and installation/replacement challenges, there is limited rationale for deploying new technology in such a critical environment — until OSP expansion.
As customers deploy digital and fiber-network electronics and corresponding backup power sources in remote outdoor environments, traditional solutions come up short. Valve-regulated lead-acid batteries, sensitive to temperature, are proving to be short-lived, too heavy for many practical outdoor applications — on rooftops for example — and too laden with environmental issues. Engine-generator sets are maintenance-dependant, produce combustion emissions and make noise. With nearly half a million wireline and wireless sites scattered across the U.S. landscape, preventative maintenance is an escalating expense.
In recent years, researchers have made advances in adapting traditional technologies to the OSP environment. Even so, alternative technologies may take the upper hand in the race to serve power quality sensitive customers in the new distributed landscape.
New Batteries Emerge
Several alternative batteries have generated extensive discussion throughout the industry. Notable among these is the lithium-ion battery. Lithium-ion batteries have expected lifetimes of more than 10 years in extreme environments. They also offer substantial weight and space savings over both traditional lead-acid and nickel-cadmium storage systems. Other benefits include no ventilation requirements, better cycling characteristics, and more flexibility of form factor, all of which fulfill many OSP requirements.
Unfortunately, those distinct advantages come with significant disadvantages. Chief among them is cost: currently at 8-10 times the expense of valve-regulated lead-acid batteries, lithium-ion batteries require a higher initial capital outlay than many customers are prepared to make. As with other innovations, cost will come down as the technology matures — but customers are under pressure to come up with solutions now.
Equally troubling is the uncertain path of innovation and cost reduction that lithium-ion batteries will take. Most high-current research has focused on automotive rather than stationary applications, particularly hybrid and electric vehicles, where the potential sales volume may accelerate development. However, issues with load response and the need for intelligent systems to charge and maintain them remain.
Another option — stationary fuel cells — circumvents battery technology. In the proton-exchange membrane (PEM) fuel cell, fuel atoms (hydrogen) are divided into protons and electrons. The electrons travel around the membrane, generating DC power. The protons pass through, combining with oxygen to produce heat and water with no combustion emissions.
Such a process makes fuel cells particularly adaptable to the OSP environment even as they carry the strengths of the new batteries. Plug Power’s new GenCore line of backup fuel cell systems is designed for reliable operation from – 40 F to 115 F. Preventative maintenance is anticipated only every three years. The system provides immediate and, as necessary, extended response to power interruptions. The lightweight and small footprint make it suitable for rooftop locations. The clean process produces zero emissions and little noise.
PEM fuel cells, moreover, have addressed many of the limitations of battery technology. Initial unit cost runs roughly half to one-third that of lithium batteries. While still more expensive than valve-regulated lead-acid batteries, fuel cells carry a lower life cycle cost, with lower maintenance needs and longer life.
The technology has drawn widespread support within key federal and state agencies, from the Department of Defense to the National Institute for Standards and Technology. Just as important, companies like Plug Power have been designing fuel cells specifically for stationary applications.
Several challenges remain to be worked out. Chief among them is the logistics of fuel supply (such as the refilling of tanks via drop-off fueling) and the corresponding concerns surrounding the siting of hydrogen. Plug Power and other companies have already undertaken field projects with customers to resolve these issues.
What Happens from Here?
All these technologies will continue to undergo development, driving down costs while expanding features. Researchers hope to turn the lithium battery into a significant commercial product within five years. Fuel cells are already in the field providing insights into application-specific needs and system design. Clearly, the potential is great for near term reliable service for customers and lower cost for the companies that serve them.
About the Author:
Eoin Connolly, Director, Product Management, is responsible for developing and executing Plug Power product and channel strategy. Previously, Connolly spent 12 years with GE, most recently with GE Plastics executing programs that improved profitability and quality of services. At GE Power Systems, Connolly led a team of project managers responsible for global power plant upgrade projects.