Energy storage, how does it work?

If generating renewable energy is important, having it available to users thanks to energy storage is equally or even more important, but do we know how it works?

Our society is heading towards a greener future. A future where the decarbonization of our economy is crucial to achieving climate neutrality and, therefore, a more sustainable and environmentally friendly world. The generation of electrical energy is key in this process of energy transformation, thanks to the emergence of renewable energies, which allow the generation of green energy. However, this type of energy is not always available for our use, and it depends on two factors: weather conditions and the schedule of demand. This is why electrical storage is a key solution to achieving our decarbonization goals. But have you ever wondered how energy storage works? Let’s see how.

As we said before, we can’t program the wind to blow when we need it, or make the sunlight shine to power our solar panels. So, how can we make renewable energies feed our electricity grid with guarantees? The answer is energy storage. Thus, thanks to this, we are able to store the surplus energy generated by renewables when demand is low to supply it to the electrical grid when demand is high. A technological blessing that is based on different solutions that we must know before understanding how storage works.

The most traditional solution, and the most visible today, is the hydroelectric plant. Dams and reservoirs that, when the sun and wind are not enough, release the force of water through their floodgates to power the movement of their turbines and thus generate large amounts of electricity according to the energy demand. This is the solution that we may all be familiar with but that we do not always associate with energy storage, and that is that we see it as another source of renewable energy; although its great virtue is the ability to store that force of water for use when it is most convenient and necessary.

Energy storage with water

We can also include, in this classification, the so-called solar thermal plants, which flourished in the first decade of the 2000s in countries such as Spain, and which store the energy generated by photovoltaic panels thanks to molten salts that later allow the production of steam and the subsequent movement of the turbines that generate electrical energy. This solution, which is distinguished by being a circular surface of photovoltaic panels pointing towards a large tower located in the middle of the facility and where the aforementioned molten salts are located, means that when sunlight disappears and energy demand increases, the supply is available to households. Notable among these are plants such as the Noor Ourzarate II (200 MW) in Morocco, which stores energy for 6 hours.

But if you are reading this article, it is surely because of another type of solution, the most innovative and the most #trendy today. We are referring to the storage of electrical energy in batteries. This technology, which could be compared to the power bank that saves us when our mobile phone starts to run low on battery, is what is revolutionizing our network and is allowing new renewable energy projects to emerge with the guarantee of being able to supply energy at times when weather conditions do not allow renewable energy to be regular. So, let’s see, point by point, how this technology works, which will become crucial in the near future.

A round trip through the electrical grid 

It all starts at the point of energy generation. Let’s use the example of a photovoltaic plant, which we can all, to some extent, have in mind. Thus, from the photovoltaic panels, the energy passes through the electrical installation until it reaches, first, the power converters, which allow us to change the current from direct to alternating current (AC/DC for music lovers): something necessary for it to flow through the grid without problems.

To ensure that the grid doesn’t lose a single one of the valuable watts generated, the equipment at the transformation centers intervene by increasing the voltage and preventing energy losses. Thanks to the work of these centers, the energy arrives “safe and sound” at the electrical substation, which will act as a midfielder—in football slang—distributing the energy between that which goes directly to consumers and that which will be stored in large battery containers for later supply. Well, that’s it, right? The energy has now reached the batteries, and the enigma has been solved. Nothing could be further from the truth; great ideas require great solutions.

Transformation centers are essential for storing energy

At this point, the energy found in the substations must reduce its voltage again and change its current to direct current before being accumulated. That is, it has to pass again through our busy friends called transformer substations, whose technology and reliability are crucial for the integration of renewables. These then leave the energy stored in batteries awaiting the call to action. Thus, when demand rises, this energy is sent back to the transformer substations, which once again “tune” the power by increasing its voltage, sending it to the substation, which will convert its current to alternating current, and then finally, it is fed into the electrical grid to reach the different points of consumption. That’s nothing.

How does energy storage work?

Well, this entire complex electrical system is what allows us, and will allow us, to enjoy the renewable energy generated in a plant in broad daylight at ten o’clock at night to operate our appliances without emitting a single particle of carbon dioxide at night. Do you understand now why this technology is so fundamental? Given the significant benefits it offers for consumers and the planet, the deployment of energy storage is estimated to triple year after year. This means that in just two decades, we will go from the nearly 10 GW of power currently installed worldwide—a figure that is undoubtedly symbolic—to more than 1,100 GW, making the energy transition and a more sustainable world possible. Still have questions? Don’t worry, we’ve prepared a short video in which you can see this complex operation in a simple and interactive way. Don’t miss it!