Energy Storage

Depending on weather, the amount of electricity generated from renewables, like solar and wind, can vary. Energy storage plays an important role in addressing those weather dependent resources, especially during periods of high demand. Our focus continues to be on expanding both short and long-duration energy storage.

Across the company, we are continually assessing resource adequacy as we prepare for significant demand growth, increased extreme weather events and planned plant retirements. We have approximately 90 MW of grid-tied battery storage in service today and 65 MW under construction. 

The company currently has more than 2,400 MW of pumped-storage technology on its system and plans to have more than 6,000 MW of energy storage capacity by 2035. We project nearly 30,000 MW of energy storage by 2050. 

Battery Storage

Batteries support the integration of renewables by either storing excess energy during periods of low customer demand or providing stored electricity during periods of high customer demand. The versatility of battery storage technology allows us to maximize benefits to customers and the grid. These benefits help reduce costs for customers and increase operational efficiencies.

How do batteries work?

There are several types of batteries, but at the simplest level, batteries store electrical energy so it can be released when needed. Today, the most widely used battery for utility-scale projects is lithium ion. It’s efficient and proven making them a popular choice, but researchers are testing other storage options and battery chemistries that might last longer.

Long Duration Energy Storage

Long-duration energy storage includes a wide range of technologies capable of storing energy for days, weeks or even seasons. These technologies are at various stages of development. Pumped hydro systems are the most mature of these technologies and has been in operation in our fleet for over 50 years. 

Pumped Storage

Pumped storage hydro plants are a flexible, dynamic and efficient way to store and deliver large quantities of energy. They generate energy by moving water between two reservoirs at different elevations. We currently operate two pumped storage plants – Jocassee (1973) and Bad Creek (1991) – which provide a majority of the energy storage within Duke Energy’s system. These two stations provide approximately 2,400 megawatts of storage capacity. 

Due to the significant amount of renewable energy generation expected across our service territories during Bad Creek’s planned 40-to-50-year operating license, we are evaluating opportunities to add more pumped-storage generating capacity at the Bad Creek site.