Harnessing Solar Power Beyond Daylight: Innovations in Thermal Energy Storage for Decarbonization
The thermal solar energy technology stands out among renewable solutions by its ability to generate electricity even during nighttime hours. It primarily functions by concentrating sunlight with mirrors onto a fluid, which then produces steam to drive turbines, generating electricity. A key feature of some plants is thermal energy storage, using molten salts to retain heat from the day for use at night, maximizing efficiency and output.
In Spain, 49 solar projects currently operate with a total capacity of 2,300 megawatts, of which only 40 percent incorporate storage systems. Experts emphasize the need to extend storage facilities across all plants to unlock the full potential of thermal solar power. Regulatory and economic barriers, such as outdated payout regimes and uncertainty over return on investment, hinder this expansion. These constraints discourage companies from investing in large-scale storage solutions needed for reliable nighttime power generation.
The importance of thermal storage is underscored by its proven safety, reliability, and maturity compared to other energy storage options like lithium batteries. Despite advances in battery technology, molten salt storage remains more secure and cost-effective for large-scale applications. China, for example, is investing heavily in thermal energy storage, highlighting its growing global relevance. Integrating storage into existing plants would mitigate issues caused by the declining prices of photovoltaic solar panels, which saturate the grid during the day, often forcing solar plants to cease operations prematurely despite their role in stabilizing the system.
Redesigning regulations to promote thermal storage and reduce grid saturation constraints is critical. Many plants face operational restrictions that limit their contribution, despite their reliable and synchronous energy output, which helps stabilize power networks. Policies should encourage competitive bidding for new plants that recognize their contribution to employment, rural development, and system stability. Enhancing storage capabilities would shift solar production to nighttime hours, aligning generation with demand and contributing to grid resilience.
Beyond electricity, concentrated solar systems can produce process heat for industries, exemplified by a plant in Seville that supplies heat to a brewery, reducing natural gas consumption by 60 percent. This versatility positions solar thermal technology as a crucial component of industrial decarbonization efforts. It is essential to view thermal solar not only through cost metrics but as a multifaceted solution offering renewable energy, long-term storage, system services, and employment opportunities. With each plant generating significant direct and indirect jobs, solar thermal is a strategic asset for energy transition and economic growth.
Spain and other sun-rich regions, including parts of North Africa, South Africa, and South America, possess vast potential to leverage these technologies. Elevating policies, overcoming regulatory barriers, and investing in infrastructure are imperative steps to harness the full capabilities of solar thermal energy. This approach will ensure a resilient, sustainable, and low-carbon energy future, aligned with global climate goals.