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Smart Storage

The intelligent grid cannot be achieved without energy storage.

Fortnightly Magazine - June 2009

batteries are, for example, trending toward a practical blend of cost, performance, and flexibility to compete in niche markets. NaS batteries offer the power and energy required for many utility power system applications—particularly backup power and grid investment deferral—at zero emissions and with plug-and-play operation that easily integrates into T&D systems.

All told, these and other applications are enhancing utility practices by adding predictability and helping to eliminate risk. Still, while the value of energy storage may be growing, the technologies’ long-term success remains yoked to further system cost reductions that will come only from greater commercial deployment. But the prospect of future high-volume sales should trigger escalating project demand and a gradual reduction in up-front costs.

Several recent commercial energy-storage deployments have potential implications for the intelligent grid’s development. Their demonstrated ability to provide enhanced grid management and end-user reliability is offering an alternative strategy to addressing a number of issues that traditionally have been solved via investment in conventional generation, transmission, or distribution assets.

Battery Systems

Several Lithium-ion (Li-ion) battery makers—including A123Systems (A123), Altair Nanotechnologies (Altairnano), and Saft—are making commercial inroads into the increasingly competitive electrical energy storage space. In particular, recent Li-ion technology vendor activity is focusing on the deployment of novel products that provide grid-stabilization services, like frequency regulation and spinning reserves, to enable greater grid penetration of variable renewable energy resources and also to introduce alternatives for conventional power plants to meet reserve requirements.

Li-ion technologies in their various chemistries are considered to be promising candidates to handle a number of utility-scale stationary storage applications (and they are also a major focus of research to serve as the batteries in electric vehicles and plug-in electric hybrid vehicles). Part of a growing legion of emerging systems that are attempting to tap the growing energy-storage market, some Li-ion battery systems are now being positioned to provide shorter-term grid ancillary services, putting them in direct competition with other technologies such as flywheels.

Historically, energy density has been a major challenge for batteries intended to support the grid. Lead-acid batteries, for example, are far too large to provide substantial transmission and distribution system backup. Furthermore, they charge slowly and require regular maintenance and replacement. Li-ion batteries, however, have the potential to solve the density problem; in addition to their high-energy density attributes, they have a high cycling capability, long calendar life, short response time, and high power charge and discharge capability.

Though cost—and its proper valuation ( i.e., using metrics that more accurately portray the costs of power delivery versus energy delivery)—remains an issue, Li-ion technology manufacturers are encouraging initial utility and system operator adoption of their systems by citing their technologies’ ability to load balance and effectively smooth the power intermittencies of variable resources such as wind and solar. Furthermore, they are justifying investment in their systems as a way to free up thermal power plant capacity reserves typically set aside for frequency regulation and synchronous reserve. The upshot: Greater plant capacity that can be dedicated to baseload electricity production, and in turn, generate higher revenues. An added benefit: