Sunnyvale Tech Powers Wind Storage Scale

Antora Energy and POET said on May 19 that they had commissioned a 5-gigawatt-hour thermal battery system at POET’s bioprocessing plant in Big Stone City, South Dakota, marking Antora’s first commercial deployment. The system stores electricity as heat in solid carbon blocks and sends that energy back out as industrial heat, with the option to convert heat to electricity through thermophotovoltaic cells, according to Antora and ARPA-E. The project advanced from initial construction to delivering energy in under 12 months and is scheduled to be fully operational later in 2026, the companies said. Antora’s manufacturing base for the thermophotovoltaic component sits in Sunnyvale, California, where the company said in 2023 that it had opened the world’s first dedicated production line for those cells. ### How does the system actually store wind power? ARPA-E said Antora’s thermal battery charges by using grid electricity to heat carbon blocks to temperatures above 2,000 degrees Celsius. When discharged, the hot blocks can deliver heat directly to industrial equipment or radiate energy toward thermophotovoltaic panels that convert heat into electricity, according to the agency. (poet.com) POET said the South Dakota project is designed around a long-term heat offtake agreement under which the ethanol producer pays for delivered thermal energy. Otter Tail Power, the regional utility partner, enables charging during off-peak and low-cost periods, according to project statements cited by industry publications and POET’s release. (arpa-e.energy.gov) ### What is being made in Sunnyvale? Antora said on January 24, 2023, that it had begun production of thermophotovoltaic, or TPV, cells at a new manufacturing facility in Sunnyvale. The company said the line had an initial annual capacity of 2 megawatts of TPV cells and was the first dedicated TPV manufacturing line. Antora said at the time that the Sunnyvale line had demonstrated heat-to-electricity conversion efficiency above 40%. (mgrid.org) CEO Andrew Ponec told pv magazine that the cells are based on III-V semiconductors and are intended for thermal storage applications that convert high-temperature heat into electricity. ### Why is the Midwest deployment tied to an ethanol plant? POET said the Big Stone City installation sits next to its ethanol facility and is meant to provide firm thermal energy for industrial operations that run continuously. (antora.com) The American Coalition for Ethanol described Antora’s pitch in March as delivering 24/7 steam to ethanol plants by charging on low-cost local electricity and storing that energy as heat in solid carbon blocks. South Dakota reporting this week said the project stores excess wind power that might otherwise be curtailed because of grid limits, then uses that energy at the plant later. Andrew Ponec told local and regional outlets that the system is built around the mismatch between when wind blows and when industrial demand arrives. (poet.com) ### How big is this first commercial project? POET and Antora said the system totals 5 gigawatt-hours of multi-day thermal energy storage and includes more than 200 thermal battery units. The companies said the project is intended to deliver 50 megawatts of round-the-clock energy and, once complete, rank among the world’s largest energy storage projects by capacity. (aberdeennews.com) Grok Ventures provided project-level financing as the sole external investor, according to trade coverage published on May 21 and May 22. Antora has not publicly disclosed the total project cost, but local reporting said Ponec described the majority of Big Stone’s costs as privately financed. ### What public funding helped Antora reach this point? (businesswire.com) ARPA-E said Antora first received support through its DAYS program to develop a thermophotovoltaic heat engine for converting stored heat into electricity. In June 2024, Antora said ARPA-E had selected it for up to $14.5 million in SCALEUP funding to expand TPV manufacturing capacity and accelerate its combined heat-and-power product. (ess-news.com) The U.S. Department of Energy also said in 2024 that Antora, based in Sunnyvale, would use a $14.5 million award to scale production of thermal battery technology for industrial facilities. Separately, Antora said in November 2023 that it had received more than $4 million from the California Energy Commission and ARPA-E to expand TPV production. (arpa-e.energy.gov) ### What comes next after Big Stone City? POET said on May 19 that the Big Stone City system would be fully operational later this year. Antora said in June 2024 that it had also signed a letter of intent with Shell to evaluate deployments of its combined heat-and-power product in industrial processes including chemicals production. (poet.com) (utilitydive.com)