Energy Storage

Reliable and affordable energy storage – equipment that stores power and distributes energy on demand when and where it is needed most – will be extremely important to enable large-scale deployment of renewable resources. In addition to grid-scale storage applications, we are also exploring the use of energy storage for specific customer applications.

AEP's Electric Transmission Texas’ 4-MW NAS® sodium-sulfur battery system located in Presidio, Texas.

Distributed energy storage can have application in several areas:

  • Frequency regulation - Batteries have the ability to rapidly respond to frequency regulation signals on the grid. Regional transmission organizations are recognizing the need for greater amounts of frequency regulation due to the integration of distributed resources.
  • Firming of renewables - Wind and solar often do not generate energy when and where it is needed most. Deploying batteries to charge using excess wind/solar energy can allow for better use and management of variable renewable energy sources.
  • Peak shaving - Batteries can provide power during peak demand times to limit customer demand and alleviate strain on the power grid.
  • Reliability improvements - Batteries can provide back-up power in case of an outage. For example, a total of three2-MW NaS (sodium sulfur) batteries were deployed in Appalachian Power, Ohio Power and Indiana Michigan Power in 2008. Each battery is capable of providing islanding (backup power) for over seven hours when loss of power from the substation occurs.
  • Power quality - Batteries are capable of conditioning the flow of power so it can be used by sensitive electronic equipment.

In many cases, batteries can provide peak power and thus delay the need for building transmission or distribution lines or electrical substations located near peak loads. They can also help to smooth the variability of renewables. In addition, batteries are a relatively quick-fix solution that can be relocated if they are needed elsewhere on the system.

AEP is an industry leader in deployment of batteries to support the power grid

Year DeployedProjectBenefits to Grid Achieved
2002First U.S. demonstration of sodium sulfur (NaS) battery in the United States at AEPTested the combined power quality and peak shaving capabilities of the NaS battery
20061 MW / 7.2 MWh NaS batteryAllowed deferral of capital investment in distribution system in Charleston, WV
2009Three 2 MW/14.4 MWh NaS batteriesProvided peak load shaving and demonstrated increased reliability by providing back-up power in Milton, WV, Churubusco, IN, and Bluffton, Ohio.
20104 MW/ 24 MWh NaS batteryTransmission capital deferral while providing back-up power to the town of Presidio, Texas

The biggest barrier to wider deployment has been cost, which has significantly decreased since AEP initially piloted community energy storage as part of the gridSMART® demonstration project in Ohio.

We recognize the need to continue exploring a variety of options and possibilities for delivering electricity to our customers, including further development of energy storage technology. That’s one of the reasons we invested $5 million in Greensmith Energy Management Systems, LLC. Greensmith’s main focus is maximizing the efficiency of battery storage. We believe that our investment will help further advance energy storage technologies and support deployment of innovative energy infrastructure solutions that will benefit our customers.