Energy Storage: How It Works at Home and on the Grid

How Does Energy Storage Work?

Energy storage systems capture energy for a certain period before converting it back into usable electric power. But that process can vary widely from one energy storage project to the next. Let’s take a look at just a few types of energy storage systems.

Battery energy storage

The first electrical system was developed by Nikola Tesla in the late 1800s, and led to the development of the battery storage systems that we know today. Now, lithium-ion batteries are used to power electric vehicles and even entire houses.  

The high density of lithium-ion batteries makes them useful for everyday devices, but they’re only capable of short-duration storage and need to be charged often.  

Vanadium flow batteries that store electricity in liquid electrolyte tanks may be more suitable for large-scale energy storage projects. Other battery technologies include lead-acid, sodium sulfur, and metal air batteries, all of which could play a role in the green energy transition.

Kinetic energy storage

Not all energy storage solutions require batteries. The Beacon Power facility in New York uses some 200 flywheels to regulate the frequency of the regional power grid. By using electricity to spin flywheels incredibly fast, the flywheels can store energy and return it to the power grid later.  

This facility has a capacity of 20 megawatts, making it more suitable for frequency regulation than long-term electricity storage.

Compressed air energy storage (CAES)

Compressed air can be used to store electricity by being forced into a chamber at high pressure and being used to spin a turbine on the way out. Since it requires reservoirs (usually underground), this technology is only in limited use around the world. A new CAES plant is in the works in Texas, with a projected capacity of 317 megawatts.

Thermal energy storage

Storage of thermal energy uses variations in temperature to capture and store electrical energy. The most common example is concentrated solar power (CSP), in which solar energy is focused on a heat-transfer fluid that can be used to power a generator.  

The largest CSP facility in the world is in the Mojave Desert in California, and has a capacity of 399 megawatts.

Hydroelectric storage

Water can be used to store energy too. In fact, pumped storage hydropower (PSH) is the technology behind 93% of all large-scale storage systems in the U.S., and it could become a key player in global energy storage systems.  

Unlike traditional hydro power plants, which don’t store energy, PSH pumps water into an upper reservoir and converts it into electricity on its way down.

How Much Energy Storage Do We Need?

The amount of energy storage we need depends on where we live and what our goals are. Since every power grid has a different mix of power sources, some regions of the world may need more storage capacity than others.  

On a global scale, the International Energy Association (IEA) calculates that we’ll need 266 gigawatts of storage before 2030 “in order to keep global warming below 2 degrees Celsius.” Is that achievable? Bloomberg thinks so: it believes we’ll reach that target and surpass 942 gigawatts by 2040.  

But what about regional power grids? How much storage capacity does Texas need in order to avoid a repeat of the 2021 blackouts?  

As of 2021, the Texas power grid was capable of generating up to 90,000 megawatts of power, but only had 460 megawatts of storage capacity. The Electric Reliability Council of Texas (ERCOT) aims to increase storage capacity to 3,008 megawatts by 2022.  

In addition to storing wind and solar power and delivering it to the grid when it’s needed, energy storage systems could be used to operate natural gas plants during blackouts, or as a backup power source in local communities.

Note: Reprinted from Just Energy