Backed by technology powerhouses Bill Gates and Jeff Bezos, startup Form Energy is going to turn the tides in renewable energy storage with its groundbreaking iron-air battery system.
For large electrical grids to move toward 100% renewable energy, grid operators need clever, affordable, practical and eco-friendly ways to store up energy that’s generated at inconvenient times, and then release it when demand is outstripping supply. This needs to happen on different timescales; some of this grid smoothing needs to happen on a daily basis, and that’s an area where lithium “big battery” projects are already doing a great job. But lithium is less suited to longer-duration storage; it doesn’t like staying fully charged for days or months at a time, so other, slower, bulk storage options are being developed to buffer energy grids against multi-day bad weather spells and seasonal lulls in renewable generation.
Form Energy is working in the multi-day space, commercializing a relatively simple, modular battery solution based around the rust cycle of iron. Charging these washing-machine-sized battery modules up uses electricity to convert rust, or iron oxide, into metallic iron, and releases oxygen as a by-product. Discharging the batteries requires oxygen to be put back into the system, and turns the metallic iron to rust, releasing energy in the process.