There are industrial infrastructures that, when they stop being useful, end up blending into the landscape without making much noise, turned into concrete ghosts. The old grain silos, which for decades were the vibrant heart of the agricultural economy of many towns, are today the best example of this reality in rural Spain.
However, the energy transition has brought them a destiny that is as unexpected as it is promising. The region of Extremadura has decided to give a second life to these abandoned giants next to roads and plains, transforming them into enormous facilities to store renewable energy.
Silos in batteries. All of this materializes under the THESILO projecta cross-border initiative that has just been officially presented in the small town of Torremocha in Cáceres. There, the City Council has donated a disused silo to house the first experimental pilot that will test this technology in real conditions.
The urgency of this essay is better understood when looking at the sector’s figures: over the last year, according to data from Red Eléctrica de España (REE)nearly 10,000 MW of new renewable power were installed in the country. The conflict arises when this enormous production is concentrated at specific times of the day, especially with photovoltaic technology. In very sunny regions like Extremadura, the electrical grid collapses as it cannot absorb all the available energy, causing the dreaded “dumps”: plants that must stop their production because there is nowhere to store the electricity and the energy is wasted.
So the solution proposed by THESILO is brilliant in its simplicity: take advantage of these enormous concrete structures to store electrical surpluses in the form of heat.
Nordic inspiration. Although visually it may seem like science fiction, this concept already has a solid precedent in northern Europe. In Finland already operates successfully the system Power to Heat (energy to heat) through gigantic “sand batteries”. In the town of Pornainen, a silo filled with 2,000 tonnes of crushed soapstone is capable of storing heat at temperatures of up to 500°C for months, achieving an efficiency of between 85% and 90%.
The Extremaduran project It is based on the same principle: When renewable production skyrockets and electricity loses value in the market, that excess energy will be used to power high-efficiency resistors that will generate heat. This heat will be trapped inside the silo using very low-cost granular materials as a storage medium. There is no need to use construction sand; The use of recycled waste from quarries, industrial by-products and demolition materials that resist high temperatures in a stable and economical manner will be investigated.
Once stored, the objective is that this heat can be distributed through thermal exchange systems to supply the local agri-food industry, public buildings or homes in the surrounding municipalities. The project, whose execution It is scheduled between January 1, 2026 and December 31, 2028, and is structured around four main axes, ranging from the adaptation of the silos to the analysis of their legal and environmental viability.
X-ray of the project. To understand the magnitude of THESILO you have to look at its figures: framed in the European Interreg POCTEP programthe project manages a budget of more than 1.5 million euros, largely supported by FEDER funds. The cross-border consortium is led by the Iberian Center for Research in Energy Storage (CIIAE), which has built a strategic network with Spanish and Portuguese allies such as AGENEX, INTROMAC, ADAI, AreanaTejo, the Polytechnic of Portalegre and ITECONS.
An essential union of forces to cover the EUROACE euroregion (Extremadura, Alentejo and Central Portugal), an extensive territory where today 1,050 disused silos await with the potential of becoming the thermal battery network of the future.
An impact that crosses borders. Beyond the technological component, the socioeconomic impact is the true driving force of the initiative. The Secretary General of Science, Technology and Innovation, Javier de Francisco Morcillo, stressed during the presentation that the ultimate objective is the “boost of business growth and the revitalization of rural communities.” According to the secretary, Europe demands that the knowledge generated “leads to a transfer of results that results in immediate socioeconomic improvement.”
Furthermore, he highlighted the capacity of Extremadura to lead these cross-border funds, recalling that the region has captured between 2021 and 2025 more than double the funds from the Horizon Europe program compared to the 2014-2020 period, according to data from the CDTI.
The future involves recycling the past. There are still unknowns to clear up and regulatory procedures to overcome to demonstrate that this model works on a large scale. The Torremocha pilot will be the true test of fire to evaluate how the original structure of the silo responds to high temperatures and certify whether the investment makes sense compared to other solutions that are gaining ground, such as hydraulic pumping or chemical batteries.
However, THESILO perfectly summarizes where the energy transition in Europe is headed. Decarbonization cannot depend solely on newly built pharaonic infrastructures; It also requires projects that embrace the circular economy. Reusing already built infrastructure not only reduces costs and avoids new construction, but also brings forgotten giants back to life, attracting investment and employment to areas that have been losing population for years. A demonstration that the solution to tomorrow’s energy challenges may be hidden in plain sight in the towns of rural Spain.
Image | Xataka
Xataka | Finland has found a cheap way to store energy all winter: a tower of 2,000 tons of sand
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