Energy Storage

As we introduce more wind and solar power into our energy mix, the need to invest in energy storage grows. Energy storage helps maintain a constant flow of power when the wind isn’t blowing and at night or on cloudy days when the sun isn’t shining. Storage technology also supports local reliability for our customers and is integrated into our distribution and resource planning processes. Today, we are also testing new ways of combining storage with hydroelectric power to support the grid.

Sometimes, pairing the old with the new can result in something groundbreaking. In 2017, AEP partnered with Greensmith Energy to integrate a 4 MW energy storage system with the Buck and Byllesby hydroelectric power plants in southwest Virginia. The hybrid system combines advanced energy storage and software with hydroelectric generation to provide ancillary services to the grid; it is due to begin operation in 2018.

Once it comes online, the programmable energy storage system will serve PJM’s frequency regulation market, which helps to balance the transmission system as it moves electricity from generating stations to retail customers. The Buck and Byllesby facilities are operated by Appalachian Power and have been in operation since 1912.

The concept of energy storage is not new, but the need for reliable, cost effective solutions has never been more critical. We are exploring new ways of using energy storage to manage demand and support the interoperability of the grid, including investing in technology companies to accelerate development and deployment. Today, as the energy landscape transitions to more distributed and intermittent resources, we need the ability to store energy from such resources. Batteries are a relatively modular solution that can be mobilized and relocated if they are needed elsewhere on the system.

Distributed Energy Storage Applications

  • Reliability improvements - Batteries can provide back-up power in case of an outage. For example, a total of three 2-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 more than seven hours when loss of power from the substation occurs.
  • 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 to maintain system stability with the increased integration of variable generation resources.
  • Firming of renewables - Wind and solar often do not generate energy when and where it is needed most. Deploying batteries to combine with wind and/or 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 lower customer demand and alleviate strain on the power grid.
  • Power quality - Batteries are capable of conditioning the flow of power so it can be used to protect sensitive electronic equipment.

AEP’s experience in deploying batteries to support the power grid

Year Deployed Project Benefits 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
2008Three 2 MW/14.4 MWh NaS batteriesProvided peak load shaving and demonstrated increased reliability by providing backup power in Milton, W.Va., Churubusco, Ind., and Bluffton, Ohio.
20104 MW/ 24 MWh NaS batteryTransmission capital deferral while providing back-up power to the town of Presidio, Texas
2018 (Expected)4MW energy storage combined with hydroHybrid storage/hydro system at the Buck and Byllesby hydroelectric power plants in southwest Virginia to provide ancillary services to the grid

Energy storage can sometimes be the most cost-effective, efficient solution to a reliability issue.

New policies, such as those recently put forth by the Federal Energy Regulatory Commission, support energy storage and recognize the variety of services these resources can provide. Additionally, storage technologies will become more cost-competitive as the industry matures, similar to what has happened with wind and solar. We will continue to explore opportunities to leverage the unique aspects of energy storage resources for expanded use in transmission, distribution and wholesale market applications.