Using chemical reactions to store energy is handy and scalable, and there are about a million ways to do it, which is why batteries have basically become synonymous with energy storage. But more groups are starting to think outside the battery. In an effort to cut costs and store lots of energy for long periods of time, researchers and companies alike are getting creative: pumping water into the earth, compressing gas in underground caverns or massive tanks, even lifting giant blocks. As we build more renewable energy capacity in the form of variable sources like wind and solar power, we're going to need to add a lot more energy storage to the grid to keep it stable. Our climate reporter Casey Crownhart has dug into the exciting, busy world of battery alternatives, and what it might take to make them a reality.