Multi-day iron-air battery startup nets $450 million investment


Solar and wind power have intermittency in their productive hours, as multi-day weather events can impact output. Therefore, multi-day storage that is cost effective is an important feature in grid reliability.

Boston startup Form Energy developed technology to address this need, creating multi-day iron-air batteries. The company said its batteries can store renewables-sourced electricity for 100 hours at system costs competitive with conventional power plants. At full-scale production, Form Energy said the modules would deliver electricity at tenth the cost of lithium-ion batteries.

The iron-air battery is composed of cells filled with thousands of iron pellets that are exposed to air and create rust. The oxygen is then removed, reverting the rust to iron. Controlling this process allows the battery to be charged and discharged.

The technology has garnered significant interest from investors. Most recently, it raised $450 million in a Series E funding round led by TPG Rise Climate. Also joining the Series E round are GIC and Canada Pension Plan Investment Board (CPP Investments), along with existing investors ArcelorMittal, Breakthrough Energy Ventures (BEV), Capricorn Investment Group, Coatue, Energy Impact Partners (EIP), MIT’s The Engine, NGP ETP, Temasek, Prelude Ventures, and VamosVentures.

“The development of reliable, long duration energy storage technology is critical for the global transition to renewable energy,” said Leon Pedersen, Managing Director and Head of Growth Equity at CPP Investments. “By introducing new storage solutions to the market, Form Energy can contribute to the energy transition process while also providing attractive risk-adjusted returns for the CPP Fund.”

The technology is less energy-dense than its lithium-ion counterparts, making it a better fit for large grid-scale applications. This may come as an advantage for the company, as EV batteries are in competition for lithium, a metal with geo-political mining concerns and battery fire risks.

Image: Form Energy

Form Energy said an individual battery module is about the size of a side-by-side washer/dryer set and contains a stack of approximately 50 one meter-tall cells. The cells include iron and air electrodes, the parts of the battery that enable the electrochemical reactions to store and discharge electricity. Each of these cells are filled with water-based, non-flammable electrolyte, like the electrolyte used in AA batteries.

These battery modules are grouped together in environmentally protected enclosures. Hundreds of these enclosures are grouped together in modular megawatt-scale power blocks. Depending on the system size, tens to hundreds of these power blocks can be connected to the electricity grid. For scale, in its least dense configuration, a one megawatt system comprises half an acre of land. Higher density configurations would achieve >3 mw/acre.

The company’s first project is a 1 MW / 150 MWh pilot installation with Minnesota-based utility Great River Energy, located near the American Iron Range. Form Energy said it expects to have the facility deployed at a Great River Energy power plant by 2023.

Upon the funding announcement, Form Energy CEO Mateo Jaramillo said, “Form was founded with a unified mission to develop a multi-day energy storage battery that would unlock the power of extremely low-cost renewable energy to transform the electric grid. Over the last five years, through rigorous R&D and product engineering, our 100-hour iron-air battery product is ready to scale. The Series E funding will accelerate our ability to responsibly build a globally competitive U.S. battery manufacturing supply chain and advance American innovation.”

Form Energy said it is currently engaged in a site selection process for its first full scale battery manufacturing facility. Starting with identifying over 100 initial sites across 16 states, Form said it has narrowed the site selection to three states, and expects to make an announcement in this regard before the end of the year.

The funding round builds on last year’s $200 million in Series D funding. This round was led by $25 million from ArcelorMittal’s XCarb innovation fund. ArcelorMittal will non-exclusively supply the iron materials for the battery system production, and Form Energy said it intends to source its iron domestically, manufacturing the batteries near where the iron was sourced.

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