Teng and his WPI team made an aqueous battery, a small lab-scale prototype that operated in the water-based electrolyte, using electrodes made mostly from abundant elements such as iron oxides and hydroxides. While the team hasn’t calculated the cost, the use of earth-abundant materials should tip the scale in their favor, Teng says. The U.S. produces over 15 million tons of scrap iron wastes that are not recycled each year, many of which exist in the form of rust. Therefore, the reported rechargeable alkaline iron battery chemistry helps repurpose the iron rust waste materials for modern energy storage.