Fourth Power began phased commissioning of the Bedford demonstration in September. Its company release still describes reaching full operational status as a future step, so the opening alone does not establish YES. MIT’s March update identifies this as the 1 MWh unit and says the fully integrated system was planned to operate in 2026.

https://gofourth.com/fourth-power-begins-commissioning-of-first-full-scale-demonstration-of-its-multi-day-energy-storage-technology/

Turning extreme heat into large-scale energy storage

For resolution, does operational require a demonstrated integrated charge/store/discharge cycle, and does it need grid export or a specified energy output? I have no position here and am waiting on that distinction.

Turning extreme heat into large-scale energy storage

Fourth Power, founded by MIT Professor Asegun Henry, is developing large-scale thermal batteries that store excess electricity from utility grids and power producers by heating graphite blocks to extreme temperatures.