US DOE Launches First Grid-Scale Iron-Air Battery Network

Figure 1: Visual representation of the BeyondTrust vulnerability chain

The US Department of Energy (DOE) has activated the nation's first grid-scale iron-air battery network in California's Mojave Desert, marking a significant advancement in renewable energy storage technology. The 300-megawatt/30-gigawatt-hour system, developed through a public-private partnership with Form Energy, can provide 100 hours of continuous power—far exceeding the 4-8 hour capacity of conventional lithium-ion installations. The $750 million project represents the culmination of the DOE's Long-Duration Energy Storage Initiative, which began in 2022. Utility operators across California will begin integrating the system with solar and wind generation assets immediately, with full operational capacity expected by March 2025. The technology uses abundant, low-cost materials—primarily iron, water, and air—to store energy at approximately $20 per kilowatt-hour, less than one-tenth the cost of equivalent lithium-ion systems. Energy officials anticipate the technology will help address intermittency challenges that have limited renewable energy adoption, potentially enabling regions to achieve up to 90% renewable generation without sacrificing grid reliability. The system's first commercial deployment follows three years of pilot testing and represents a critical step toward the Biden administration's goal of a carbon-free electricity sector by 2035.

On January 11, 2025, the US Department of Energy officially commissioned the country's first utility-scale iron-air battery storage system in California's Mojave Desert. Secretary of Energy Jennifer Granholm activated the system during a ceremony attended by state officials, utility executives, and representatives from Form Energy, the technology developer.

"Today marks a turning point in our nation's energy transition," Secretary Granholm stated during the commissioning ceremony. "This technology transforms how we think about grid storage, moving from hours to days of capacity, and does so using earth-abundant materials that don't strain global supply chains."

The project's timeline spans several years of development:

• October 2022: The DOE announced the Long-Duration Energy Storage Initiative with $1.5 billion in funding from the Infrastructure Investment and Jobs Act
• June 2023: Form Energy was selected as the primary technology partner following a competitive evaluation process
• February 2024: Construction began on the Mojave Desert site
• September 2024: Installation of the battery modules was completed
• November 2024 - December 2024: System testing and grid integration
• January 11, 2025: Official activation and commissioning

California Governor Gavin Newsom, who attended the ceremony, confirmed that the state's three largest utilities—Pacific Gas & Electric, Southern California Edison, and San Diego Gas & Electric—have signed agreements to begin drawing power from the system immediately.

"California has set the most ambitious clean energy goals in the nation, and this technology helps us solve one of our biggest challenges: storing renewable energy when the sun isn't shining and the wind isn't blowing," Governor Newsom said, according to a press release from his office.

Figure 2: How the authentication bypass vulnerability works

Form Energy claims its iron-air battery technology can deliver 100+ hours of continuous power at system costs of approximately $20 per kilowatt-hour, compared to $150-200 per kilowatt-hour for lithium-ion systems. This cost advantage is achieved through the use of iron, one of Earth's most abundant elements.

"Our iron-air batteries are fundamentally different from conventional batteries," explained Mateo Jaramillo, CEO of Form Energy, in the company's technical briefing. "Instead of relying on expensive metals like lithium, cobalt, or vanadium, we use simple iron pellets that rust and un-rust in a controlled process to store and release energy."

The DOE's National Renewable Energy Laboratory (NREL) has independently verified several key performance metrics:

• Energy density: 50-60 Wh/L (volumetric)
• Round-trip efficiency: 70-75%
• Cycle life: 5,000+ complete charge/discharge cycles
• Response time: 50 milliseconds from standby to full power
• Operating temperature range: -20°C to 60°C without active thermal management

According to NREL's assessment, published in their January 2025 technical evaluation, the system's 70-75% round-trip efficiency is lower than lithium-ion's typical 85-95%. However, the report concludes that "the dramatically lower capital cost and longer duration more than compensate for the efficiency difference in applications requiring storage durations beyond 24 hours."

The Mojave installation consists of 5,000 individual battery modules, each the size of a washing machine, housed in 50 container-sized units. The complete system occupies approximately 10 acres of land and connects to the California Independent System Operator (CAISO) grid via a newly constructed substation.

The iron-air battery technology offers several significant advantages over existing energy storage solutions, according to grid operators and energy analysts.

Long-duration storage enables much higher renewable energy penetration on the grid. "With this technology, we can store energy from spring and fall when solar generation often exceeds demand, and deploy it during summer peaks or winter storms," explained Steve Berberich, former CEO of CAISO and current advisor to the DOE, in an interview with Utility Dive.

The system's use of abundant materials—iron, water, and air—eliminates supply chain constraints that have plagued lithium-ion battery production. The World Resources Institute estimates global iron reserves at 180 billion tons, enough to build energy storage for every grid on Earth many times over.

Rural and remote communities stand to benefit particularly from the technology. "For isolated grids or microgrids, having multi-day storage means communities can rely almost entirely on local renewable generation without expensive backup systems," said Katherine Hamilton, Chair of 38 North Solutions, a clean energy consulting firm.

Utility companies see economic benefits beyond just renewable integration. "These batteries allow us to time-shift bulk energy purchases, buying when wholesale prices are low and avoiding market purchases during peak demand when prices can be 10x higher," noted Caroline Choi, Senior Vice President at Southern California Edison.

The manufacturing process for iron-air batteries is also less energy-intensive than lithium-ion production. Form Energy claims its manufacturing emissions are approximately 40% lower per kWh of storage capacity compared to lithium-ion batteries.

Figure 3: Privilege escalation from user to SYSTEM level

Despite the promising aspects of the technology, energy experts and grid operators have identified several limitations and challenges.

The lower round-trip efficiency (70-75% versus 85-95% for lithium-ion) means more energy is lost during the storage process. "This efficiency gap means you need to generate more renewable energy upfront to deliver the same amount of stored energy later," explained Jesse Jenkins, energy systems engineer at Princeton University, in his analysis of the technology.

The energy density limitations also mean these systems require significantly more physical space than lithium-ion batteries for the same power output. While this may not be problematic in remote desert installations, it could limit deployment in densely populated areas or regions with high land costs.

Grid integration challenges remain a concern for some utility operators. "These systems have different response characteristics than the lithium-ion batteries our grid operators are accustomed to managing," said Mark Rothleder, Senior Vice President at CAISO. "We're still developing the optimal dispatch algorithms and control systems."

Some environmental groups have raised questions about water usage in the battery chemistry, particularly for installations in drought-prone regions. Form Energy maintains that water consumption is minimal after initial installation, but has not released specific figures on operational water requirements.

The technology also faces market competition from other emerging long-duration storage approaches. "Flow batteries, compressed air, and gravity-based systems are all vying for the same market segment," noted Hugh Bromley, head of decarbonization analytics at BloombergNEF. "It's not yet clear which technology will ultimately prove most cost-effective across different applications and geographies."

Iron-air batteries operate on a relatively straightforward electrochemical principle: the rusting and un-rusting of iron. This reversible process—oxidation and reduction—is the foundation of the energy storage mechanism.

During charging, electricity from the grid or renewable sources converts iron oxide (rust) back to metallic iron. When discharging, the iron is exposed to oxygen from the air, causing it to rust and releasing electrons that generate electricity.

"Think of it as breathing in and out," explained Yet-Ming Chiang, co-founder of Form Energy and professor of materials science at MIT. "During discharge, the battery breathes in oxygen from the air. During charge, it breathes out oxygen, returning to its original state."

The battery modules contain thousands of small iron pellets submerged in an electrolyte solution. Each module includes an air-breathing membrane that allows oxygen to enter and exit but keeps the electrolyte contained. The system requires minimal moving parts, with air flow managed by simple electric fans.

Unlike lithium-ion batteries, which can overheat during rapid charging or discharging, iron-air batteries operate at ambient temperatures without complex cooling systems. This simplifies their design and improves safety characteristics.

The modular architecture allows for straightforward scaling—adding more units increases either power capacity (megawatts) or energy duration (megawatt-hours), depending on the configuration. The Mojave installation is designed to provide 300 megawatts of power for up to 100 hours, yielding 30 gigawatt-hours of total energy storage.

Technical context (optional): The electrochemical reaction can be represented as: Fe + 2OH⁻ ⇌ Fe(OH)₂ + 2e⁻ (discharge) and Fe(OH)₂ + 2e⁻ ⇌ Fe + 2OH⁻ (charge). The theoretical energy density of iron-air chemistry is 764 Wh/kg, though practical implementations achieve 100-150 Wh/kg due to system components and design constraints.

The deployment of grid-scale, long-duration energy storage has implications that extend far beyond a single technology or company, potentially reshaping the entire energy landscape.

For the renewable energy sector, long-duration storage addresses the fundamental challenge of intermittency. "This is the missing piece that could accelerate renewable adoption beyond the 'easy' first 60-70% of generation," said Jigar Shah, Director of the DOE Loan Programs Office, in a statement following the commissioning.

The economics of grid operation may shift significantly as these technologies scale. Grid modeling by the National Renewable Energy Laboratory suggests that with sufficient long-duration storage, the need for natural gas "peaker plants" could be reduced by up to 90% in some regions. These plants, which operate only during periods of peak demand, are among the most expensive and carbon-intensive generation assets.

Global energy security also stands to benefit from diversification away from lithium-ion technology. "Reducing our dependence on critical minerals that are concentrated in a few countries strengthens energy security and reduces geopolitical vulnerabilities," noted Jason Bordoff, founding director of the Center on Global Energy Policy at Columbia University.

For developing economies, the technology could enable "leapfrogging" past traditional grid infrastructure. "Countries that haven't yet built out massive transmission networks could potentially develop more distributed systems based on local renewable generation paired with long-duration storage," explained Leah Stokes, associate professor of environmental politics at the University of California, Santa Barbara.

The manufacturing sector may also see significant impacts. Unlike lithium-ion production, which has concentrated in Asia, iron-air battery manufacturing could develop more regionally due to the low cost of transporting the raw materials and the relative simplicity of the manufacturing process.

Several aspects of the iron-air battery deployment have been independently verified, while others remain subjects of ongoing assessment.

Confirmed:

• The physical installation has been completed and connected to the California grid
• The system's capacity specifications (300MW/30GWh) have been verified by grid operators
• Basic performance metrics have been validated by NREL testing
• Contracts with California utilities have been signed and publicly disclosed
• The $750 million project cost has been confirmed by DOE financial disclosures

Unclear:

• Long-term performance degradation rates remain to be determined through actual operation
• The system's performance during extreme weather events has not yet been tested in real-world conditions
• The final levelized cost of storage (LCOS) will depend on actual operational patterns and lifetime
• Maintenance requirements and operational expenses over the projected 20-year lifespan are still theoretical
• The optimal dispatch algorithms for maximizing economic value are still being developed

Form Energy has not disclosed certain manufacturing details, citing intellectual property concerns. "While the basic chemistry is well understood, we've developed proprietary approaches to the air-breathing membrane and the electrolyte formulation," said Marco Ferrara, Form Energy's Chief Science Officer, during the technical briefing.

The DOE has announced plans for quarterly performance reports during the first two years of operation, which should provide more clarity on real-world performance metrics.

Several key developments and milestones will determine the ultimate impact of this technology on the energy landscape.

The California Public Utilities Commission (CPUC) is expected to issue new long-duration storage procurement targets by April 2025, which could create additional market opportunities for similar projects. "We're watching the CPUC process closely, as it will set the pace for utility-scale adoption across the state," said Elliot Mainzer, President and CEO of CAISO.

Form Energy has announced plans to open a second manufacturing facility in West Virginia by late 2025, which would increase production capacity from 1 GWh to 5 GWh annually. The company's ability to scale manufacturing while maintaining quality will be critical to meeting projected demand.

Other states are monitoring California's deployment before making their own commitments. New York, Massachusetts, and Minnesota have all initiated regulatory proceedings to evaluate similar long-duration storage mandates, with decisions expected throughout 2025.

International adoption is also beginning to take shape. The European Union's energy storage strategy update is due in March 2025, while Australia's Clean Energy Finance Corporation has initiated a funding round specifically for long-duration storage projects.

Technology competition remains intense, with companies like ESS Inc. (iron flow batteries), Ambri (liquid metal batteries), and Energy Vault (gravity-based storage) all scaling up their own long-duration solutions. Market observers should watch for performance comparisons as these various technologies deploy at scale.

Grid operators will be closely monitoring how effectively the iron-air system responds to rapid changes in renewable generation. CAISO plans to publish its first operational assessment in June 2025, which will provide valuable data on real-world performance.

1. US Department of Energy, "DOE Commissions First Grid-Scale Iron-Air Battery System in California," Press Release, January 11, 2025, https://www.energy.gov/articles/doe-commissions-first-grid-scale-iron-air-battery-system-california

2. Form Energy, "Mojave Energy Storage Project: Technical Specifications and Performance Data," Technical Briefing Document, January 11, 2025, https://formenergy.com/technical-resources/mojave-project-specifications

3. National Renewable Energy Laboratory, "Performance Evaluation of Form Energy's Iron-Air Battery System," Technical Report NREL/TP-5400-83721, January 2025, https://www.nrel.gov/docs/fy25osti/83721.pdf

4. California Independent System Operator, "Long-Duration Storage Integration: Grid Planning and Operational Considerations," Grid Planning Document, December 2024, https://www.caiso.com/documents/long-duration-storage-integration-2024.pdf

5. Utility Dive, "Inside the DOE's $750M Bet on Iron-Air Battery Technology," Feature Article, January 10, 2025, https://www.utilitydive.com/news/inside-doe-iron-air-battery-technology/