Scientists have developed a promising new type of energy storage technology that could transform the way renewable power is stored and delivered. Known as iron-air batteries, these systems store electricity using only iron, water, and oxygen from the air—materials that are both inexpensive and widely available. Unlike conventional batteries that rely on complex chemistry or rare metals, iron-air batteries operate through a simple and reversible process of rusting and de-rusting iron.

When the battery discharges, iron particles inside the system react with oxygen from the surrounding air, forming iron oxide—commonly known as rust. This chemical reaction releases stored energy that can be sent to the power grid. When the battery is recharged, an electrical current reverses the reaction, converting the rust back into pure iron and preparing the battery for another cycle. According to researchers, this process can be repeated thousands of times with minimal degradation, making iron-air batteries well suited for long-term use.

One of the most compelling advantages of iron-air batteries is their exceptionally low cost and environmental footprint. Iron is one of the most abundant elements on Earth, and unlike lithium-ion batteries, these systems do not require cobalt, nickel, or other scarce and environmentally damaging materials. This dramatically reduces both manufacturing costs and geopolitical supply-chain risks. Companies such as Form Energy, backed by research from institutions including MIT and Harvard, estimate that iron-air batteries could eventually cost a fraction of today’s lithium-based storage systems.

Equally important is their ability to provide long-duration energy storage. Early testing indicates that iron-air batteries can store electricity for up to 100 hours, far exceeding the 4–12 hours typical of lithium-ion batteries. This makes them particularly valuable for balancing renewable energy sources such as solar and wind, which can fluctuate over several days due to weather conditions. By storing excess energy during periods of high generation and releasing it when production drops, iron-air batteries could help stabilize renewable-powered grids and reduce reliance on fossil-fuel backup plants.

While iron-air batteries are significantly larger and less energy-dense than lithium-ion alternatives, this limitation is less important for stationary, grid-scale applications. Their non-flammable design also improves safety, eliminating the fire risks associated with some conventional battery technologies. For large installations near wind farms or solar plants, size is a manageable trade-off for reliability, safety, and affordability.

Experts believe that as development continues, iron-air batteries could play a crucial role in the global transition to clean energy. By enabling affordable, multi-day energy storage, they may help overcome one of renewable power’s biggest challenges—intermittency—and make clean electricity more dependable for communities around the world.

Sources:
Nature Energy; MIT Technology Review; U.S. Department of Energy (DOE); Form Energy; Harvard School of Engineering and Applied Sciences; Reuters; BloombergNEF.