Electrical grids only function when electricity is being generated in the same amounts as it is consumed. About 96 percent of the world’s energy-storage capacity comes in the form of one technology: pumped hydro, which uses water and dams to generate energy on demand. A startup from Switzerland thinks it has a more efficient alternative to pumped hydro that involves stacking concrete blocks with cranes. Take a look here to see how this surpassingly effective energy storage system works.