types of energy storage systems

How is Electricity Stored

When it comes to electricity production, ever since Nikola Tesla first petted a cat and realized that electricity exists and that it can be harvested, scientists have been inventing ever more creative ways to both generate and store this type of energy.

The thing about electricity is – you can produce it in a myriad of different ways.

Whether it’s by using the power of water to generate electricity through a hydroelectric plant, putting a guy on a bicycle that’s attached to a dynamo machine, or harvesting it by using wind or solar power, making electricity has become fairly easy. It’s just a matter of how efficient the means of making it is that dictates in what way it will be produced.

For example, the state of electricity generation today is that nuclear power plants and thermal power plants seem to still be the most effective way of doing it. Renewable sources of energy, on the other hand, although fairly attractive to most people, can’t yet compete with the two aforementioned electricity-producing methods, so to speak.

Now, while generating electricity is not a big deal nowadays, storing it effectively has always been a big issue.

The thing is, when it comes to storage, electricity is like water in your palm – no matter how hard you try, it will slowly start seeping away sooner or later. Not all is hopeless, though, as nowadays more and more effective and ingenious methods are used to successfully store energy for later use.

In this article, we are going to talk about how electricity is stored. As you will see, there are several ways of doing it and we will explain how each of these works in detail.

Without further ado, here’s the deal.

Flywheel energy storage

While by far the most well-known way of storing electricity is using batteries, other ways are used to achieve the same or at least a similar result.

Flywheel energy storage (FES) works on a fairly simple principle. Since electricity is notoriously difficult to store even in high-quality batteries, with FES, the electricity is turned into rotational energy.

The electricity that is supposed to be stored powers a flywheel (hence the name for the entire system), which rotates at high speeds. When you want to take some energy back and use it for something else, this energy is again ‘translated’ from rotational energy into electricity.

This causes the flywheel to lose some of its speed and momentum until more energy is used to power it back up to its optimal working speed.

One of the most important aspects of this way of electricity storage is reducing the friction within the entire system to a minimum so that little energy is wasted in the process of powering it up and maintaining its speed.

Although this system does operate with some inevitable losses due to its mechanical build, it’s also true that by using it you can save considerable amounts of electricity that would have otherwise gone to waste.

This type of electricity storage is mostly used for large machines such as electric trains, aircraft launching systems, but it also has some other applications in laboratories and other large facilities that are in constant need of a steady supply of energy.

Interestingly, this same system is also often used in some toys, as well as in some amusement rides, such as roller coasters, for example.

Battery energy storage

Otherwise also known as ‘BES’ represents one of the most commonly known ways to store electricity.

Although there are many different types of batteries, most of them work on roughly the same principle. Batteries contain acid that can keep the electricity flowing within the circuit of the battery, thus preserving it for later use.

Of course, this process of circulation cannot go on forever, as even the best batteries will inevitably run out of electricity if they’ve not been used in a while. For example, if your motorcycle or car battery has been sitting idle (meaning – you haven’t driven the vehicle for an extended period), then you run the risk of your battery running dry or even completely dying. If this happens, you have to recharge the battery to be able to use it again.

The underlying principle of battery energy storage is that a battery stores a special chemical mixture (containing acid) that enables the electrons to run from one material to the other (within the battery).

Depending on the material and size of the electrodes as well as the type of acid used, a battery will have different voltage and it will be able to store a certain amount of energy.

As far as the uses of batteries are concerned, they are used everywhere from aircraft to industrial machines, to the automotive industry, and your remote control.

Thermal energy storage

One of the common ways of utilizing electric energy even when there is no direct flow of current involved, so to speak, is to ‘store’ the energy thermally by using the technique called thermal energy storage (TES).

The way this is achieved is fairly simple.

For example, many homes in Europe but also around the world use electric storage heaters. These contraptions use electricity to heat the interior of the heater, which is typically made out of a special sort of bricks that store heat fairly well.

The way these are then used is that most people tend to turn them on during the night when electricity is less expensive (often 6-7 times less expensive), so the heaters within this appliance can heat the surrounding bricks.

After the bricks have gathered enough heat, the heater can be turned off and the hot bricks will still emanate heat for 10 or more hours. This way, by powering this heater up for a couple of hours, you get heating that lasts double or triple the amount of time.

Of course, other than in households, this type of energy storage is also commonly used on a larger scale. For this purpose, large silos, or the so-called ‘accumulation towers’ are built, and all of them function on pretty much the same principle as the aforementioned electric storage heater. Since the size of these towers and silos is massive, instead of ten or so hours of heating that you can get with a storage heater, these large buildings can emanate heat for weeks or even months before they need powering up again.

Compressed-air energy storage

One of the most ingenious ways to store electricity that doesn’t involve batteries would be by simply compressing air.

This technique, shortened to CAES, works in the following way:

  • Electric energy is used to power air compressors, which then compress air in special canisters. This process also generates heat. (For saving money, this process is also typically done during the night, similarly to the heat-storing method from the section above.)
  • Once the compressed air is in canisters, it can stay there for an indefinite period.
  • If someone wants to use this energy and convert it to electricity, the compressed air can power special turbines which then, in turn, produce electricity.

Now, while the process itself has some inevitable losses of energy along the way, it certainly can be of great use when it comes to saving electricity that would have otherwise gone to waste.

Pumped-storage hydroelectricity

Shortened to PSH and also known as pumped hydroelectric energy storage (PHES), is a method of producing electrical energy that relies entirely on the day-and-night cycle of the price for electrical power.

As we mentioned earlier, electricity is typically significantly less expensive during the night and this is used to run this system.

The way it works is fairly simple. Typically, there is a certain natural elevation where water can be pushed upwards. So, the pumps used for this method push the water that sits in a certain basin or a pool to higher ground. This process requires a lot of energy and it’s therefore put to practice during the low-cost cycle of continuous energy supply. (So, typically, during the night.) Once the water has been displaced to higher ground, it can be released back to its initial position during the day, when electricity is more expensive.

The way this works is because there is a turbine that this water powers as it’s coming back down, so electricity can be produced without any pumps used – simply thanks to the gravity pushing the water downwards.

The main goal of this type of energy preservation or ‘recycling’ would be to increase the revenue of a power station by using the low-price, high-price electricity mechanism. This also means that such a power plant can’t produce much electricity, unless, of course, it has another source of water such as a lake or a river nearby that can power its turbines all the time.


All things considered, electricity storage is more and more becoming a focus of various scientists’ studies and technological development, especially as ecology and preservation of the environment are becoming more and more important. The more technological advances we see in this field, the more readily available electricity will be worldwide – and at a lower cost, too.

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