Interview to Rocío Barrio

“Storage favours a more distributed and efficient energy generation, without large transportation infrastructures and energy loses between demand and supply”

This month, following our 2020 editorial line about climate challenges, we deal with a technological challenge: innovation in energy storage to reduce costs. We have interviewed Rocío Barrio, researcher of the PV Solar Energy Unit and member of the energy storage group, ALMA, at the CIEMAT.

When we talk about energy storage, the public, in general, thinks about batteries, but are there other kind of energy storage technologies?

Energy storage systems allow us to transform the stored energy to use it whenever it is needed. Indeed, batteries are the energy storage systems most known by the public in general. Mainly because they are massively use in mobile devices −phones, laptops, electrical appliances, etc…− and, lately, lithium-ion batteries are used in EVs. This technology is very mature and very useful for short-term energy storage systems that need to charge and recharge frequently. But there are other technologies for energy storage systems, depending on their application and use, their energy capacity, the response time, the nominal power and their location, among other characteristics.

Apart from the electrochemical storage −not only the renowned lithium-ion or lead-acid batteries−, but there are also large-scale technologies such as: pumped-storage hydroelectricity, fuel cells, supercapacitors and compressed air. All these technologies can be combined to improve the service depending on their application.

What role will they play in the future electric grid? What advantages do they provide to the energy sector?

The different energy storage technologies will play a key and essential role in the energy transition towards a more sustainable future, as it is stated in the Spanish Climate & Energy Plan (PNIEC 2020-2030). This transition implies the transformation of the present energy system, as demand will be met mainly with renewable energy sources. These sources −mainly PV solar energy and wind energy− are variable and hard to manage and they require the integration of storage systems into the electrical grid to make it more flexible, avoid fluctuations and guarantee its quality.

Furthermore, energy storage has the huge advantage of storing energy when there is a generation surplus and use it when there is a shortfall. So, energy loses can be avoided and the dependency of external markets will be reduced in periods of high demand or low availability of renewable resources.

Finally, storage favours a more distributed and efficient generation, without large transportation infrastructures and energy loses between demand and supply.

What are the challenges we must overcome to improve the energy storage systems and implement them in more and more large and small-scale projects?

Generally, all energy storage technologies must overcome a lot of challenges, to name a few:

  • Improvement of the technology to increase their efficiency, energy density, response times, durability, and power. There would be no option but to increase the investment in research and development.
  • Evolution towards the use of abundant and sustainable materials, always considering their reuse and final recycling.
  • Support the industry, as companies are strategic, they impact the economy and help us not to have an external dependence.
  • Improve the competitivity to reduce costs and improve the economic feasibility of energy storage projects.
  • Establish regulatory and retributive frameworks.
  • Knowledge transfer: spread the knowledge and train professional for all technologies in all the steps of the value chain.

How can energy storage systems help to reduce the energy costs?

Now, the price of stored energy is very high, as the costs of any storage technology are still high. However, renewable energy generation plus storage provides reliability and security to the grid, avoids energy loses and makes good use of that energy. These facts allow us not to oversize renewable generation plants to meet the demand, resulting in savings and more energy efficiency. As energy storage favours distributed generation, it also means a reduction in energy transportation costs.

Although, to substantially reduce the price of stored energy, costs of storage systems must be outstandingly lower than the present ones, specially the ones of less mature technologies. In this respect, the present energy transition provides us with the opportunity to research different technologies to improve their efficiency and features, incorporate them into the productive system in a large scale, reducing their manufacture costs. Before this scenario, and if the abovementioned challenges are overcome, energy storage costs are expected to be reduced by 2030.

At the CIEMAT there is a specific working group on energy storage called ALMA, what are the projects you are working in and what are your objectives?

The ALMA group at CIEMAT is made up of several researchers coming from different departments of the centre. They work in different energy storage and renewable energy generation technologies. It is a recently created group −end of 2019− and our main target is to establish an energy storage R&D scientific-technical area at the CIEMAT. It will coordinate all the different energy storage activities developed at the CIEMAT, such as: thermal, mechanical, and electrochemical storage, hydrogen storage or hydrogen carriers, as they are relevant for the energy transition. So, the CIEMAT wants to contribute to the technological and energy challenges the society must face to meet the PNIEC. Our main goal is the decarbonization of the present energy system by implementing renewable energy sources and commit to a more sustainable future.

Rocío Barrio Martín


Rocío holds a PhD in Physics. She joined the CIEMATEnergy, Environmental and Technology Research Centre− in 2004 as a researcher of the PV Energy Unit where she studied PV materials and devices based on silicon. Now, she forms part of the energy storage coordination group, ALMA, at the CIEMAT.