How do energy storage systems work?

Battery storage can be used in many ways that go beyond the simple emergency backup in the event of an energy shortage or blackout. Applications differ depending on whether the storage is being used for a business or a home.

For commercial and industrial users, there are several applications:

Most of us are familiar with certain kinds of electrical energy storage, or ESS. If you’ve ever used a household battery or driven an electric car, then you know that it’s possible to store electrical energy in a form that can be used again later.  

But as the country faces increased strain on its electricity grids — such as the blackouts that hit the Texas power grid in 2021 — energy storage is more important than ever.  

Let’s take a look at how energy storage technology works, which devices are best for storing electric power, and how you can use energy storage systems at home. 

What Is Energy Storage? 

Energy storage refers to any type of physical or chemical system that stores electrical energy for later use. For example, batteries use chemical energy, which can then be used to power your smartphone, laptop, or electric vehicle.  

Although batteries are some of the most common energy storage devices, they aren’t the only options, and they aren’t always cost-effective for large-scale projects.  

In addition to batteries, energy can be stored using gravity, compressed air, and other technologies to create utility-scale energy storage solutions.  

Energy storage systems can be used to store electricity off-grid — for use during power outages and blackouts — or they can be used to build more resiliency into the regional power grid to keep it functioning during times of peak demand for power. 

Why Is Energy Storage Important? 

Energy storage is important because existing energy grids aren’t built to store power; they’re built to keep a balance between supply and demand.  

Electricity grids must maintain a stable frequency — in the U.S., that’s 60 hertz — in order for electricity to run smoothly along transmission lines.  

If a grid produces too much power, the frequency will surpass its upper limits. If it doesn’t produce enough, the frequency will drop too low. Both situations can result in temporary blackouts or catastrophic power grid failure.  

That’s why power plants may need to be shut down, or entire neighborhoods removed from the power grid, for the sake of frequency regulation.  

By incorporating energy storage into the power system, regulators have more options for keeping the system in balance. For example, researchers at Stanford University found that “grid stability could be obtained by linking together currently available batteries with storage durations of four hours or less.” 

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What Kind of Energy Is Stored? 

Nearly any kind of electricity can be converted into stored energy, regardless of how it’s produced. But energy storage is especially important for renewable energy sources like wind and solar power because their output varies over time.  

Power plants that run on fossil fuels like coal and natural gas can operate around the clock, and it’s easier to add and remove capacity as needed.  

Solar power is more variable, since it only produces energy when the sun is out, and wind power greatly depends on the weather.  

Although clean energy sources produce substantial amounts of power — up to 40% of all the energy used in Texas — that power isn’t always available at the right time.  

By incorporating energy storage systems into the power grid, surplus electricity could be saved for later and added back to the power grid when it’s needed. That would make for a more stable power supply and keep energy prices low for consumers. 

How Does Energy Storage Work? 

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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? 

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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?  

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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. 

What Is the Best Energy Storage System? 

Every energy technology has its pros and cons. Lithium-ion batteries can pack a lot of power into a small volume, but they aren’t capable of storing power for long periods of time, and they require large quantities of lithium and cobalt.  

Pumped storage hydropower (PSH) and compressed air energy storage (CAES) can store large quantities of energy with few chemicals or emissions, but require massive facilities and may have unforeseen impacts on the ecosystem.  

Rather than relying on a single storage system to prop up an entire power grid, some communities are building microgrids, or self-contained grids, that can kick in during blackouts or periods of high demand.  

An effective clean energy transition will require a combination of energy systems that are tailored to each region’s environment, power grid, and energy needs. 

What Are Home Energy Storage Devices? 

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Energy storage devices aren’t just for large-scale power systems. If you’ve ever looked into a backup power source for your home, then you’ve probably encountered systems like the Tesla Powerwall, a lithium-ion battery pack for household use.  

Each Powerwall can store around 13 kilowatt-hours of power, and is designed to store energy collected from rooftop solar panels.  

Even electric carmakers like Ford are touting their EV batteries as a backup power source: the F-150 Lightning can power a typical house for up to three days.  

Keep in mind that installing a home energy system can take some effort: you’ll have to choose between an AC or DC-coupled battery, and you might need to install multiple units to get the amount of power you’re looking for. 

What Is Energy Storage Capacity? 

When choosing a home energy unit, don’t be confused by the difference between power capacity and storage capacity. As the National Renewable Energy Laboratory explains: power capacity is measured in kilowatts (kW) and refers to “how much power can flow into or out of the battery in any given instant.”  

The energy capacity or storage capacity refers to how much energy can be stored, and is measured in kilowatt-hours (kWh).  

For example, a battery that’s intended to be used for backup power should have a high storage capacity, but may not need a high power capacity. On the other hand, a system that’s intended for frequency regulation should be able to charge and discharge quickly, but it may not need to store very much power at any given time. 

Shop Around to Get the Best Energy Prices 

Whether you’re looking for the most reliable energy provider, or you just want to make sure you’re getting the best energy prices, it pays to shop around. Since Texas has a deregulated market, you can have your pick from dozens of energy providers.  

Some companies, like Just Energy, offer green energy plans that you can use to offset the emissions generated in the production of your electricity.  

And of course, you can always follow these tips to improve your energy efficiency at home and reduce your electricity costs. 

Brought to you by justenergy.com

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