What are the most important technologies for energy storage

 In Storage Systems

Many analysts and important academics believe that to experience a fast and successful transition between fossil fuel and renewable energies, and finally move forward towards a sustainable future, we still need to work on one final piece of the puzzle: energy storage.

Vaclav Smil, a professor at the University of Manitoba, who has done significant studies around similar energy transition in human history (from coal to oil, for example), has no doubt in this sense: “Give me mass-scale storage and I don’t worry at all. With my wind and [solar] photovoltaics I can take care of everything… but we are nowhere close to it” he told to Science Magazine during an interview.

The inherent problem of renewable energies is the fact that we can only use them when they are available to us – during the daytime for solar energy or when the wind is blowing for eolic energy.

However, the idea of energy storage is not a new one.

For a long time, energy storage systems have been used for many purposes such providing support to the main grid in case of emergencies or a time when the grid is under massive demand or to provide energy for underserved populations in remote areas.

Let’s take a look at the of the most important technologies for energy storage available today.

Hydro storage systems

There are several technologies currently available, but the most evolved and widely used around the world is undoubtedly pumped hydro storage.

Put in simple terms, this is essentially the technology that uses large quantities of water available in reservoirs to produce energy.

When additional energy is required, the water is moved to through large turbines, and their movement creates energy.

Hydro storage is by far the most important technology to store energy – it accounts for 96.2% share of energy storage capacity worldwide (153GW).

Distribution of energy storage capacity worldwide in 2017, by technology

However, it’s a technology that requires significant investments, a particular type of geography and large rivers. It’s not surprising that only a few countries in the world like China, Brazil, and Canada can fully benefit from this form of energy storage.

Other energy storage technologies

Other widely used electricity storage technologies are:

  • electrochemical (batteries);
  • electro-mechanical (flywheels and compressed air);
  • thermal energy storage (biomass, ice storage).


The dominant solution after hydro storage, it’s an approach which is undergoing much development, especially if we consider the commercial batteries market, as it is regarded as the one with the most potentials and possibilities in terms of uses.

The total capacity of this technology accounts for 2.3GW.

Thermal energy

This technology is becoming more and more widely used, and it currently has a capacity of 2.3GW per year.

Thermal storage systems can capture heat generated by thermal energy sources (such as geothermal resources, biomass, etc.) – for later use.

Depending on the storage technology used, stored thermal energy can be converted into electricity or used directly for heating and cooling.


Counting for 1.3GW of capacity, flywheel energy storage works by accelerating a rotor (flywheel) to a high speed and keeping the energy in the system as rotational energy.

Flywheels can be used as a short-term reserve for temporary regulating a grid and balancing sudden changes between supply and consumption.

These three technologies have massive potential, but they still need to be developed further to catch up with hydropower.

Still, it’s important to notice how different storage technologies can really work with each other.

Batteries, for example, can offer flexible support close to where needed, whereas hydro can give greater power output for more extended periods of times.

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