A low-cost, iron-based battery system that stores electricity for many days, offering a safe alternative to conventional lithium-ion storage. Built from non-toxic, non-flammable, and fully recyclable materials, the system provides high energy density, excellent rechargeability, and zero toxic emissions. Its modular design makes it suitable for everything from rural microgrids to urban rooftops, reducing dependence on fossil fuels. By enabling equitable energy access and enhancing climate resilience in underserved regions, it supports a just and sustainable transition to clean power.