Iron-empty batteries that utilize a reversible rusting mechanism to store and release energy now stand as the first type linked to public power grids. Startup Ore Energy announced on July 30 that the battery developed by Delft University of Technology in the Netherlands is now grid-connected.

These batteries play a crucial role in maintaining a stable power supply by storing renewable energy generated from solar and wind sources, preventing immediate decreases in electricity availability during sudden changes in weather conditions.

“We need to effectively store the surplus of energy generated when the wind blows and the sun shines,” mentions John Joseph Mary from the Faraday Institute, a UK battery research facility. “Essentially, the battery stabilizes the energy output for grid usage.”

While most grid-connected batteries are lithium iron phosphate varieties produced in China, they tend to store only 4-6 hours of electricity and are quite costly, according to Mary. Conversely, the iron-empty batteries created by Ore Energy can store over 100 hours of electricity and are made from inexpensive, readily accessible materials.

“Iron is the most abundantly mined metal globally and is extremely affordable,” says Mary. “When combined with air, which is literally everywhere around us and essentially free, they are among the cheapest materials available.”

Battery systems utilize electricity to convert iron oxide (rust) back into metal iron for energy storage. The iron can discharge energy through a chemical reaction with oxygen from the air, reverting back to rust.

“During discharge, we transform the iron into an innovative kind of rust,” explains Aytac Yilmaz, CEO of Ore Energy. “When charging, we revert the rust to iron, repeating this process continuously while the battery breathes in and out atmospheric oxygen.”

The battery is housed in standard 12-meter shipping containers and holds multiple megawatt-hours of energy. One megawatt-hour can power an average US household for over a month.

Meanwhile, Massachusetts-based Form Energy is executing several iron battery projects across the US, set to be established in New England and the Midwest.

In addition to iron and air, these batteries utilize affordable, plentiful water-based electrolytes, significantly minimizing the risk of battery fires. “I hesitate to say this, but water is undeniably non-combustible,” remarks Mary.

Ultimately, the primary objective of this battery technology is to facilitate the transition of renewable energy resources to supplant fossil fuels within the electric grid.

“Energy companies are still heavily reliant on gas-fired power generation to ensure flexibility when solar and wind cannot provide enough energy,” states Bas Kil, Business Development Manager at Ore Energy. “However, a long-term solution will necessitate various types of flexibility, where these innovative batteries can significantly contribute.”