This thermochemical energy storage startup heats metal oxide pellets to store heat energy

(Photo credit: RedoxBlox)

RedoxBlox, a San Diego-based energy storage startup, is focused on decarbonizing two critical areas of the economy: industrial heat for difficult-to-decarbonize sectors and renewable energy storage for the grid. The company says its high-temperature thermochemical battery has energy densities comparable to lithium-ion batteries at a lower cost, and it has just raised millions of dollars in funding.

The startup announced it was awarded $8.9M from the California Energy Commission (CEC) and $6.7M from the U.S. Department of Energy (DOE). These grants follow the company’s $9.4M Series A financing led by Khosla Ventures for a total of $25 million to support demonstrations of RedoxBlox’s thermochemical energy storage (TCES) technology, which the San Diego-based company says can deliver zero-carbon electricity and heat.

The RedoxBlox storage module features a vessel filled with a proprietary metal oxide material that the company describes as “abundantly available” and low-cost. To charge, renewable electricity heats the metal oxide pellets from 1000-1500°C, triggering a chemical reaction that releases oxygen and stores heat in the form of chemical energy. Later, when stored energy is needed, air is directed through the module and the metal oxide consumes oxygen to reverse the reaction and release heat to the air.

Hot air from the RedoxBlox module can then deliver heat to an array of industrial processes or to a gas turbine to generate electricity, which the company says is meant to serve as a drop-in replacement for natural gas. RedoxBlox says it is positioned to use existing natural gas-powered industrial infrastructure and replace some natural gas with renewables-based heat – which could help reduce infrastructure costs.

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“Our goal is simple: use electrification and thermochemical energy storage to compete as a zero-carbon replacement for natural gas,” RedoxBlox’s co-founder and CTO, Dr. Joerg Petrasch, said. “We have proven the science. Our focus now is to scale up to commercially relevant sizes. Funding from the DOE and CEC across two large markets and the partnerships with our customers across multiple industrial sectors are key enablers.”

In partnership with the University of California, San Diego (UCSD) and the Electric Power Research Institute (EPRI), the CEC selected RedoxBlox to pioneer long-duration energy storage solutions. Hosted by UCSD, the project will leverage RedoxBlox’s technology to power a turbogenerator, aiming to provide up to 24 hours of energy storage capacity.

Similarly, the DOE’s Industrial Efficiency and Decarbonization Office selected RedoxBlox for an industrial-scale TCES, conducted in partnership with Dow and EPRI. This application will showcase the decarbonization of industrial steam at the Dow West Virginia plant through electrification using long-duration TCES. Both projects mark a pivotal step towards the decarbonization of industrial heat and grid storage at scale.

In addition to Khosla Ventures, RedoxBlox is backed by several climate technology firms, including Breakthrough Energy Ventures (BEV). BEV led the company’s Seed round and participated in its Series A fundraising.

Originally published in Power Engineering.