Energy storage plays, undoubtedly, a fundamental role in the process of total decarbonization of the global economy that is expected to take place in the coming decades.

The energy transition to a renewable and sustainable generation will be the solution to reduce greenhouse gas emissions and thus achieve the European Commission´s goal of becoming the world´s first decarbonized economy.

This is why energy storage becomes indispensable, since it makes more flexible the intermittence of green energy generation systems (such as solar and wind), releasing energy when demand is high and storing it when demand is lower.

But how do we store energy?

The solution is to transform electrical energy into other types of energy that can be stored. In fact, many technologies allow transforming and storing that energy efficiently:

These two last types of energy storage -hydrogen and batteries- have been considered by the European Union as strategic values to make the transition to a competitive, sustainable and safe economy a reality.

In the case of hydrogen, the European Commission has just launched what has been called the "European Strategy for Hydrogen", a key commitment to decarbonize transport, building and industry, among other sectors, with a roadmap that leads to a situation of zero emissions in 2050.

On the other hand, the battery sector has seen how the strategic plan of the European Commission has led to the development of some relevant initiatives such as BatteRIes Europe and its derivatives Batteries 2030+ (with a long-term roadmap) or Horizon 2020 (with medium-term objectives), this last one with 4 CIC energiGUNE projects approved in the last year: SAFELiMOVE, HIGREEW, COFBAT, and 3beLIEVe. These initiatives will help consolidate Europe as one of the world leaders in the battery sector, promoting an industrial network that can reach 250,000 million euros in 2025.

Lithium-ion batteries

In this context of betting on electrochemical storage, there is a clear preponderance towards lithium-ion batteries.

Despite being one of the smallest elements in the periodic table, Lithium has a high electrochemical potential and is can accumulate large amounts of energy very efficiently. Furthermore, this type of battery has a low weight, making it ideal for mobility, as is the case with the electric vehicle.

Much of lithium batteries´ popularity was due to the expansion, from the 90s onwards, of the market for electronic devices (laptops, cell phones...). Moreover, in recent years due to its use in the electric automotive sector.

And although there are still some challenges to be faced in terms of safety, cost and useful life, it is considered that lithium batteries will continue to be a reference technology, at least until 2030.

In fact, the OECD (Organization for Economic Cooperation and Development) foresees a development of lithium batteries categorized in 4 phases:

  • Phase 1: Consolidation of current batteries until 2025
  • Phase 2: Penetration of the new generation of hybrid batteries, for example, combining the current lithium-ion with new rechargeable technologies, such as zinc-air or supercapacitors (two of the research lines on which we are already working at CIC energiGUNE) as a way to lower costs and develop competitive solutions in some applications.
  • Phase 3: Development of what is known as advanced lithium, where solid electrolytes will become more relevant.
  • Phase 4: Beginning of the beyond-lithium phase (post-Li).

This last phase is estimated to correspond to the 2030s; a challenging yet exciting stage, where there will not be a single technology that will cover all the applications, according to the different challenges that each of them has (cost, security, lifetime, energy density...). Instead, it will lead to the coexistence of different technologies such as metal-air, lithium-sulfur, redox flow... which, also, will specialize in different segments of storage: stationary, mobility, portability...

And even though lithium has come to stay, the great demand for this raw material, which is expected to be needed for the several existing applications, opens up new research streams such as sodium-ion.

Sodium-ion batteries and solid-state batteries

That is why at CIC energiGUNE, we are focusing our efforts on developing research related to sodium-ion batteries.

In fact, the abundance of sodium in nature (it is the sixth most abundant element which decreases its cost) and its similarity to lithium-ion chemistry makes it a strong candidate to displace the latter.

But if this type of battery is also combined with the advantages of a solid electrolyte, you get a safer battery (without the risks of a flammable liquid electrolyte) and a lower cost than lithium-ion batteries.

In terms of energy density, lithium batteries still outperform sodium-ion batteries (although CIC energiGUNE is already working on improving this issue), so solid-state lithium batteries are now considered the future of energy storage systems for the electric vehicle.

Thermal energy storage

Despite all the potential of electrochemical storage, we cannot talk about energy transition without emphasizing those who are the biggest energy consumers; that is, industry, with about 35% of total consumption.

Here is where thermal storage takes relevance.

In full swing, this sector allows not only to optimize the production of clean and sustainable energy in solar concentration plants (the area where SENER is the market leader), but also to take advantage of the residual heat in industrial processes.

This is why the European Commission has promoted numerous projects that aim to improve the efficiency of heat management in industries such as steel, glass and cement.

One of them is the European REslag project of the Horizon 2020 program, led by CIC energiGUNE. Thanks to this project, a prototype has been implemented with a thermal storage system that allows the recovery of residual heat from molten slag at the Arcelor Mittal steel plant in Sestao (Bizkaia).

But in addition, in order to be able to tackle the main problems resulting from poor thermal management of industrial processes (especially the reduction of technical performance and the useful life of products), CIC energiGUNE has created Thermlab; an advanced infrastructure in thermal analysis and testing that allows companies to improve the competitiveness of their products and services by implementing new innovative concepts of thermal management, in a safe and facilitating environment.

The future in the hands of research

Although it is clear that renewable energies are linked to a system of energy storage, there is still a broad scope for improvement to achieve the most appropriate system in each scenario.

For this same reason, research into different types of energy storage is so important, as it is the only way to achieve the desired total decarbonization and thus win the battle against the climate change crisis.