Hyperscale builders test aluminum-air generators as a diesel replacement for data center backup

The module was unveiled Oct. 9 at a partner site outside Madison, according to the hub, with technical staff from Danfoss, Microsoft, Schneider Electric and Vertiv watching. E+E Leader reported that the main goal was to confirm that each subsystem works. The hub picked Phinergy, which trades on the Tel Aviv Stock Exchange, from more than 70 responses to its call for low-carbon backup power, and the two announced the project in October 2025. ENR reported Nov. 6 that the module is now under test at the hub.

Nothing burns inside the unit. Aluminum plates react with oxygen drawn from outside air, and the cells sit in cabinets about the size of a refrigerator, ENR reported. To start, an electrolyte gel is fed between the cell layers, and ENR said spin-up time is comparable to a diesel generator tied into switchgear. It is not a rechargeable battery. Spent aluminum plates are swapped for new ones, and Phinergy says the system is designed to run up to 48 hours before that is needed, E+E Leader reported.

The next step is the first full-size system, rated 500 kW and 10 MWh, which is already being assembled. E+E Leader worked out that this is about 20 hours at full output and listed what is still unproven: reliable starts during outages, steady power under changing loads, maintenance intervals and the cost of supplying and recycling the aluminum. Phinergy's US partner is the electrical contractor Rosendin Electric. In a white paper released Nov. 2, the two pitch the units for cutting a data center's grid demand at peak hours as well as for backup.

Diesel is the target because of local pushback. Alberto Ravagni, the hub's CEO, told ENR that diesel generators are now what opponents of data centers point to first. Hyperscale builders asked the hub to find clean alternatives, he said.