Sand as a Battery?

One of the challenges with renewable energy is storage.  That is, if you use solar panels, what do you do at night?  Scientists are experimenting with using sand as a battery.  You heard that right.  Sand.  It turns out that sand can be heated up a lot – to nearly 1000 degrees, using electricity created by solar panels.  And sand retain this heat for months.   Meaning that the heat can be used a long time later on for energy.   You can read all about it here:  https://www.msn.com/en-us/weather/topstories/engineers-invent-genius-battery-solution-for-storing-clean-energy-without-lithium-the-first-in-the-world-to-do-something-like-this/ar-AA15PWVn?ocid=winp1taskbar&cvid=321daead7a8d49bac0e1af41d11fbe24&ei=8