AEP Talks ENERGYStorage

By Kathleen Davis, Senior Editor

Discussions about the smart grid pervade this industry. It’s white noise; it’s the utopia on the horizon. Details, however, must be put into place before any version of that utopia can be realized.

One of those details is energy storage, although no one knows how much is needed how soon. During an interview with POWERGRID International magazine, Emeka Okafor, American Electric Power’s program manager for energy storage systems, distribution research and technology, explained energy storage, its place in the smart grid and the latest advancements.

POWERGRID: We’ve been talking about energy storage a long time. What’s changed in the past decade or so, and what’s the newest view of energy storage?

Okafor: A lot of discussion and work has been done in the area of distributed energy storage systems. Megawatt-sized storage systems were common, but smaller-sized storage systems are being developed for electric vehicle and distributed stationary utility use. Newer technologies such as flow batteries and lithium-ion-based batteries, which are more compact in size, are being developed for these applications.

POWERGRID: How important is energy storage to the smart grid and electricity?

Okafor: Energy storage will be critical to help address certain electric grid challenges. Renewable sources of power are being deployed at a faster rate than a decade ago, partially due to state renewable portfolio standards; however, these sources of power are intermittent and energy storage can play a role in mitigating their intermittency.

The great value of storage is its ability to aggregate several benefits. In addition to enabling renewable sources of power, energy storage systems can provide relief through load leveling that enables electric utilities to defer building new or upgrading stressed infrastructure. Load leveling is the ability to store energy from the grid at night during low-usage periods and dispatch that stored energy during high-usage periods in the day. Energy storage systems can also provide backup power during outages on the electric system. There are several other benefits of energy storage systems, several of which can be aggregated by a single system to justify the cost of the system and address electric grid challenges.

POWERGRID: We hear the most about energy storage in relation to renewables. Is there an energy storage area we don’t hear much about?

Okafor: The ability to provide backup power to customers during outages on the electric system is a benefit AEP has been able to show with a megawatt-sized storage system. We plan to implement backup power with community energy storage (CES) being deployed in northeastern Columbus, Ohio.

POWERGRID: AEP’s done much with energy storage from backyard energy storage to sodium sulfur batteries. What mix of energy storage technology works best?

Okafor: There is no silver bullet on the best way to deploy energy storage systems. Site-by-site analysis will be needed to determine the best choice of an energy storage system to tackle a particular grid challenge. Easily transportable, large-scale storage systems can be used to defer utility upgrades. Small-scale backyard storage systems, like community energy storage systems, can be used to provide a higher level of reliability through limited amount of backup power to electric utility customers while still providing grid-level support through load leveling.

POWERGRID: Does return outweigh the cost of energy storage?

Okafor: It is challenging, except in very specific situations where energy storage systems justify their cost today; however, projections in the industry show steady decline in cost to where systems may justify their cost over the next several years.

POWERGRID: How important will cost be to the general acceptance of energy storage technology across the U.S. grid?

Okafor: Cost is the biggest challenge to the deployment of these systems. AEP hopes that as more electric vehicles are deployed that utilize lithium-ion batteries, the cost of these batteries will drop, as well. Electric utilities can then leverage these lower costs to deploy these batteries in energy storage systems.

POWERGRID: What’s new and exciting with energy storage at AEP?

Okafor: Community energy storage is the main focus of energy storage systems at AEP. CES are small-scale energy storage devices that utilize lithium-ion batteries. We will be deploying 80 CES units in Columbus in 2011. These systems will be able to provide backup power to customers during outages. AEP will also be able to utilize these systems to provide load leveling to our infrastructure, as well as voltage support. Although CES is the focus of our current deployment, we are constantly testing and researching other energy storage technologies at AEP’s Dolan Technology Center in Groveport, Ohio.

John Mandeville, senior engineering technologist for AEP, tests a CES battery system prototype.

POWERGRID: What are the biggest benefits to CES?

Okafor: The biggest benefits are backup power and load leveling, as we’ve already discussed. Also, because of the size of the unit, a loss of a single unit does not dramatically impact grid benefits from the other units. As with any new technology, we understand that we will learn lessons on how to improve future deployments of energy storage systems.

POWERGRID: What advice would you give other utilities?

Okafor: It is definitely a benefit to understand the value that energy storage systems can provide to tackle grid challenges, especially as the costs come down. An understanding of the application is also needed, and then the right system can be chosen to address that need.

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The Clarion Energy Content Team is made up of editors from various publications, including POWERGRID International, Power Engineering, Renewable Energy World, Hydro Review, Smart Energy International, and Power Engineering International. Contact the content lead for this publication at

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