A lab-scale prototype validated the technology, and researchers were able to create a computer model showing that a commercial-scale device would retain more than 95% of its heat for at least five days.
“Lithium-ion batteries have pretty much cornered the market with 2-4 hour storage capacity, but if we want to meet our carbon reduction goals we will need long-term energy storage devices that can store energy for several days. ” said Jeffrey Gifford. NREL postdoctoral researchers involved in the development said in a media statement. “Particle thermal energy storage does not rely on rare earth metals or materials that have complex and unsustainable supply chains. For example, there is a lot of talk about the challenges of mining cobalt more ethically in lithium-ion batteries. ”
In addition to TES, Gifford’s expertise is in computational fluid dynamics. This knowledge is important because the sand must pass through storage equipment. Other of his TES mediums include concrete and rock. These retain heat easily and stay firmly in place.
“Heat transfer is much higher, faster and more effective when moving media,” Gifford says.
at a lower cost
TES also has another important advantage: cost. Lead researcher Zhiwen Ma calculated that sand is the cheapest option for energy storage when compared to four competing technologies, including compressed air energy storage (CAES), pumped hydropower, and two types of batteries.
CAES and pumped storage can only store energy for tens of hours. The cost per kilowatt hour for CAES ranges from $150 to $300, compared to about $60 for pumped storage. Lithium-ion batteries cost $300 per kilowatt-hour and have a capacity to store energy for only one to four hours. With a duration of hundreds of hours, the cost of sand as a storage medium ranges from $4 to $10 per kilowatt-hour. To ensure low costs, heat is generated using off-peak, low-cost electricity.
Molten salt, already used to temporarily store energy, freezes at about 220 degrees Celsius and begins to decompose at 600 degrees Celsius. The sand that Marr intends to use comes from the ground in the American Midwest and has significantly more heat in the 1,100°C range, which does not need to be protected from “freezing” and can store heat for power generation. You can keep it. Or it can replace burning fossil fuels as industrial heat.
“This represents a new generation of storage beyond molten salt,” Ma said.
On the other hand, increasing the amount of energy stored in sand is as simple as adding more sand.
“This is the marginal cost of adding additional storage capacity,” said Craig Turchi, also a participant in the study. “You need storage that lasts from minutes to months. Batteries have worked very well in terms of scale in the range of minutes to hours. And when it comes to storing them for months, they typically require long-term storage. However, for periods between a few hours and two weeks, there is currently no suitable suitability. Hydrogen is too expensive for that. The battery is too expensive.”
The components needed to turn the superheated sand back into electricity require an initial cost. “But once you pay for it,” Turki said, “you can’t afford it.” “If you just want the power to last longer, it’s much cheaper to add sand than the alternative of keeping adding batteries.”
