Clean energy storage facts


Energy storage is critical to an efficient, clean electric grid. It enables us to produce clean energy when it’s abundant, store it, and put it back into the electricity grid when needed. Just as the refrigeration changed how people consumed food, energy storage can revolutionize how we use energy.


This first-of-its-kind study details clean energy’s potential to unlock economic growth and achieve majority renewable electricity generation within the next decade.


1,350 MW

U.S. battery storage jumped from 59 MW in 2010 to 1,358 MW in 2020.


Lithium-ion battery pack prices have fallen 89% from above $1,100/kWh in 2010 to $137/kWh in 2020.

17 GW

Large-scale battery storage capacity will grow from 1 GW in 2019 to 17 GW in 2050, according to the U.S. EIA.

Enhancing reliability, reducing costs, and increasing grid resilience.

Benefits of Clean Energy Storage

Energy storage is a potential game-changer for American clean energy. It allows us to store energy to use at another time, increasing reliability, controlling costs for consumers, and ultimately helping build a more resilient grid.

Enhancing grid reliability

Energy storage enhances reliability, ensuring the seamless, synchronized delivery of electricity to consumers and businesses.

A more flexible, nimble grid

Storage increases flexibility for the grid and helps provide uninterrupted power for consumers, businesses, and other users.

Reducing consumer costs

Storage can offset costs by storing energy when prices are low and discharging it during peak periods when rates are higher.

Protecting productivity

During brief outages, energy storage can help businesses avoid costly disruptions and continue normal operations.

Minimizing power outages

Energy storage protects consumers from lost food and medicines as well as other inconveniences of electrical blackouts.

Making clean energy more viable

Energy storage enables us to power the grid using renewables like solar and wind, even when the sun is down or the wind is not blowing.

Smoothing out variable energies

Energy storage helps smooth out intermittent resources’ output by discharging during periods of low production.

Higher energy density

Compared to other generation systems, battery storage systems take up little space for the amount of power they release.

How energy storage works

Mechanical energy storage

The oldest and most common form of energy storage is mechanical pumped-storage hydropower.

Water is pumped uphill using electrical energy into a reservoir when energy demand is low. Later, the water is allowed to flow back downhill, turning a turbine that generates electricity when demand is high.

How energy storage works

Electrochemical energy storage

Electrochemical energy storage is the most common and fastest-growing form of energy storage.

This approach uses batteries, which store and discharge electricity through chemical reactions. The most common chemistry for battery cells is lithium-ion, but there are several other options as well.

How energy storage works

Thermal energy storage

Thermal energy storage is most commonly associated with concentrated solar power (CSP) plants, which use solar energy to heat a working fluid that drives a steam turbine to generate electricity.

In some cases, reservoirs of the heated working fluid can be stored and used by the steam generation system minutes or even hours after solar generation has fallen.

How energy storage works

Energy storage facilities

Energy storage facilities differ in both energy capacity (total amount of energy that can be stored, measured in kilowatt-hours or megawatt-hours), and power capacity (amount of energy that can be released at a single point in time, measured in kilowatts or megawatts).

How energy storage works

Designed for specific needs

Energy storage systems are designed to meet specific storage needs, such as short-term to better regulate the output of a wind or solar plant, or longer-term to better match plant supply and grid demand.

What you should know about energy storage.

Frequently asked questions

Applications of energy storage

Is energy storage necessary to integrate renewable energy sources like wind and solar?

No, but energy storage is one of several technologies that can make the grid more flexible and allow us to integrate renewable energy resources more easily and effectively. However, studies and real-world experience demonstrate that interconnected power systems can safely and reliably integrate high levels of renewable energy without new energy storage resources. Several states like Iowa, Kansas, and Texas now generate a significant amount of their electricity using wind and solar, without widespread deployment of storage. In many systems, energy storage may not be the most economic resource to help integrate renewable energy, and other sources of system flexibility can be explored, including transmission expansion, increasing conventional generation flexibility, and changing various operating procedures, among others.

How does energy storage help make renewables like wind and solar more practical and reliable?

Energy storage can allow us to incorporate more wind and solar into the grid by smoothing out the variable generation from these rapidly growing renewable energy sources. As more wind and solar resources are added, storage will become more important for an efficient, reliable, and clean grid.

Importantly, energy storage can help shift clean energy generation to when it is needed most. For example, peak power usage in most of the U.S. occurs on summer afternoons and evenings, just as solar generation is declining. Temperatures can be hottest during these times, and people who work daytime hours get home and begin using electricity to cool their homes, cook, and run appliances. Energy storage allows us to shift renewable energy to the evening peak hours when demand is highest. It provides the potential for the grid to be powered around the clock by renewables, even when the sun is down and wind isn’t blowing.

Combining energy storage with wind and solar—either at project sites or at the grid scale—also helps smooth out variations in how wind and solar energy flow into the electric grid. Both wind and solar energy production fluctuates based on the availability of wind and solar resources; they are inherently intermittent. A passing cloud, for example, can rapidly change a solar plant’s output. Storage can help smooth intermittent resources’ output to the grid by discharging during periods of low production for the source power plant.

Can energy storage work with all fuel sources?

Yes, energy storage systems are technology- and fuel-neutral. Electricity can be generated by any number of technologies, including renewables like wind and solar as well as oil, natural gas, coal, and nuclear power. Since conventional generation is less variable in nature, it tends to benefit less from integrated energy storage, but in some cases there are benefits to optimize supply and demand, shift generation to peak demand, and provide grid management.

Cost implications of energy storage

How much does it cost to build a solar-plus-storage plant?

The DOE’s Office of Energy Efficiency and Renewable Energy provides useful data to understand the costs of solar-plus-storage and how duration of storage impacts cost. It may seem counterintuitive, but energy storage costs actually decrease with longer duration because the cost of inverters and other hardware account for more of the total system’s costs over a shorter period of time, according to DOE data. A standalone 60 megawatt storage system will decrease in cost per megawatt-hour (MWh) as duration increases. In other words, the longer your storage lasts, the lower the cost per MWh.

Energy Storage Basics

What is the relationship between energy storage capacity and duration?

The DOE’s Office of Energy Efficiency and Renewable Energy provides useful data to understand the relationship between megawatts and storage duration. Consider their example using a 240 megawatt-hour (MWh) lithium-ion battery with a maximum capacity of 60 megawatts (MW). A 60 MW system with four hours of storage could work in a number of ways:

  • You can run the battery at maximum power for four hours
  • You can run the battery at half power for eight hours

Taking that example another way, you could use that same storage system to produce a lot of power in a short amount of time or less power over a longer period of time. That means a 240 MWh battery could power:

  • 60 MW over 4 hours
  • 30 MW over 8 hours
  • 15 MW over 16 hours

However, depending on a system’s capacity, it may not be able to get 60 MW of power instantly. That is why a storage system is referred to by both the capacity and the storage time (e.g., a 60 MW battery with 4 hours of storage) or—less ideal—by the MWh size (e.g., 240 MWh).

While this example focuses on batteries—since most energy storage being built today is battery-based—the same concept of megawatts to hours of usage applies using any storage system to store and release electricity.

Understanding the U.S. energy storage market

How large is the battery energy storage market?

Large-scale battery storage systems are increasingly being used across the power grid in the United States. According to the U.S. Energy Information Administration (EIA), in 2010, seven battery storage systems accounted for only 59 megawatts (MW) of power capacity—the maximum amount of power output a battery can provide in any instant—in the United States. By 2015, 49 systems accounted for 351 MW of power capacity. This growth continued at an increased rate for the next three years, and the total number of operational battery storage systems has more than doubled to 125 for a total of 869 MW of installed power capacity as of the end of 2018. According to Wood Mackenzie Power & Renewables, the U.S. market deployed 310.5 MW in 2018—a 44% increase over 2017 as costs declined and capabilities continue to improve. They project that annual deployments in 2024 will reach 4.4 GW—and a $4.7 billion market.

Is there a U.S. domestic manufacturing supply chain for energy storage systems?

Currently, this is a very narrow subsector of the energy storage market with few manufacturers. Tesla is the primary manufacturer of battery energy storage in the United States, although a growing market will inevitably attract more investment in domestic manufacturing, along with the jobs and economic benefits that follow these facilities. Currently, design, engineering, construction and other local contracting represent the largest local domestic supply chain for energy storage.

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