The Scalding Potential of Sand
Picture a scorching day at the beach where the sand scorches your feet – a common example that vividly illustrates how well sand retains heat. This natural trait is set to become beneficial, as breakthroughs in sand-based technology are shaping up to revolutionize energy storage systems.
Emerging Alternatives to Traditional Batteries
Batteries are generally the go-to choice for storing energy yet other strategies are emerging. While pumped storage hydropower has its place, it is geographically constrained. Thermal Energy Storage (TES), utilizing materials like molten salt or heated rocks, is starting to appear as a cost-effective substitute, especially with sand being abundant and geologically flexible.
According to Zhiwen Ma, a Thermal Energy Systems Group mechanical engineer, “Sand’s abundance, eco-friendliness, stability across a broad temperature spectrum, and low cost make it a top contender for energy storage.”
Long-Term Storage as the New Frontier
With proprietary methods formulated at the National Renewable Energy Laboratory (NREL), sand’s temperature can be elevated utilizing renewable energy sources. This heated sand is then stored in silos, potentially providing energy for electricity or industrial process heat later on. A laboratory prototype has exhibited impressive heat retention capabilities, and simulations suggest a commercial-scale model could maintain over 95% of its heat for multiple days.
“For long-duration storage applications far exceeding the capabilities of lithium-ion batteries, particle thermal energy storage becomes fundamental as we aim for significant carbon reduction,” articulated Jeffrey Gifford, an NREL postdoctoral researcher.
Gifford further highlighted the environmental and supply chain advantages of sand-based storage over batteries that depend on problematic rare-earth materials, like cobalt.
Cost Efficiency and Implementation of Sand TES
TES stands out not just for its sustainability, but also for its cost-effectiveness. Ma’s research points to sand being the most economical choice compared to other technologies, including CAES and various battery types. Sand can store energy hundreds of hours at a fraction of the cost, leveraging low-price, off-peak electricity to heat the sand.
Ma spearheaded the ENDURING project, showcasing the practicality of sand for energy storage. A major demonstration is slated for 2025 at the Flatirons Campus in Boulder, Colorado, which will exemplify sand’s potential to store energy for prolonged periods without CAES or hydropower’s siting restrictions.
Although molten salts are in use today, the sand in Ma’s vision offers higher temperature thresholds and better energy retention, paving the way for a new storage innovation beyond molten salt’s limitations.
Choosing the Right Sand for Heat Storage
Not all sand is made equal when it comes to heat storage. NREL’s exploration into different solid particles earmarked certain types of sand as ideal for their flow and heat retention properties. For instance, although man-made ceramic materials exceeded in performance, their exorbitant cost didn’t justify the incremental benefits over sand, which is not only affordable but also abundantly available in ultra-pure forms in the Midwest.
Craig Turchi, of NREL’s Thermal Energy Science and Technologies Research Group, explains that expanding energy storage within sand is effortlessly scalable. The primary costs are in the initial conversion setup since increasing storage duration just means adding more sand – a solution decisively cheaper than accumulating batteries.
As our energy storage demands continue to evolve, innovative solutions like sand-based thermal energy storage have the potential to redefine how we preserve and utilize energy, bridging the gap between short-term battery storage and the quest for sustainable, long-duration energy solutions.
