In the heart of Spain, a groundbreaking study is challenging the status quo of solar energy storage, offering a glimpse into the future of renewable energy. Led by Sergio González-Barredo from the Rey Juan Carlos University in Madrid, the research, published in the journal Applied Sciences (Applied Sciences is translated from Spanish as Applied Sciences), delves into the potential of solid particles to outshine molten salts in concentrated solar power (CSP) plants, with intriguing implications for the energy sector.
Spain’s energy transition is a complex dance, balancing the need to manage renewable energy curtailment—the process of limiting renewable energy output due to grid constraints—with the goal of enhancing the competitiveness of CSP technologies. González-Barredo’s study, conducted with colleagues from the Department of Chemical and Energy Technology, explores two innovative strategies to tackle this challenge.
The first involves replacing molten salts, the current standard for thermal energy storage in CSP plants, with solid particles. The second proposes integrating surplus electricity from the grid into these plants using Carnot batteries, a type of thermal energy storage system. “The idea is to use the excess electricity that would otherwise be curtailed to heat the storage medium, thereby increasing the overall efficiency of the plant,” González-Barredo explains.
To test these concepts, the team modeled a Gemasolar-type plant, a leading CSP plant in Spain, under four scenarios: using molten salts with and without curtailment integration, and using solid particles with and without curtailment integration. The results were revealing. Solid particles led to a 7.4% increase in annual electricity production compared to molten salts, primarily due to improved power cycle efficiency. Moreover, integrating curtailed electricity further boosted output, with the solid particle Carnot battery scenario achieving the highest performance—up to 19.0% sun-to-electricity efficiency and a 69.7% capacity factor.
However, the journey to commercial viability is not without hurdles. While solid particles showed a lower levelized cost of energy (LCOE) than salts (192 vs. 211 USD/MWh), the integration of Carnot batteries increased costs. Additionally, the round-trip efficiency for curtailment storage was limited to around 25–27%. “The economic viability of Carnot batteries remains constrained by current cost and operational limitations,” González-Barredo acknowledges.
So, what does this mean for the future of the energy sector? The study suggests that solid particles offer clear advantages over molten salts, potentially paving the way for more efficient and cost-effective CSP plants. As for Carnot batteries, while they show promise in enhancing plant performance, their commercial viability will depend on overcoming current technological and economic challenges.
This research is more than just a scientific study; it’s a beacon of innovation in the renewable energy landscape. As Spain and other countries strive to decarbonize their energy systems, findings like these could play a pivotal role in shaping the future of solar energy storage. The energy sector is watching, and the potential is immense. The question now is, how quickly can these innovations be scaled up and integrated into the grid? Only time, and continued research, will tell.