Have you ever wondered how much solar heat is stored in the deserts of the world and wasted. Imagine if it could be utilized! We all know under the threat of climate change that cost-effective energy storage solutions is a world-wide objective to enable the transition from fossil to renewable forms of energy. Different storage media have been discovered so far such as gravity, lithium-ion batteries, supercapacitors, and molten salts. Recently, a Finnish start-up company Polar Night Energy demonstrated the potential of ultra-cheap sand for energy storage, which is totally green with reported power up to 100 MW, capacity up to 20 GWh, and efficiency as high as 99%. While it sounds like too good to be true, the core idea is to use solar or wind electricity to heat sand to 600-1000 °C and reuse the thermal energy to heat buildings or regenerate electricity. Then here goes one of the most fascinating points—the thermal energy can be stored for months before it degrades. Furthermore, the infrastructure of the sand system is straightforward, sands and pipes in cylinders at smaller scales or sands and pipes in canyons at larger scales, with vacuum containment for insulation. Due to abovementioned merits, the Polar Night Energy already is working to build energy storage facilities world-wide. See full story at Advanced Science News.