I've been on several field trips to power plants and the battery banks they use for emergency backup are impressive. One plant in Kentucky had two rows of cells, each row about 100 feet long, and each cell was a clear plastic tub about 2' square and 3' tall. You could see the plates and electrolyte inside. They string them into 120 or 240 volt circuits to run the plant's controls and instruments.
Where I work we make electricity meters, and we always have to design in the option to power them from 120/240 VDC or -48VDC. I was surprised at how many small private generating facilities (gas turbine, wind farm, etc.) use telecom power supplies as backups for their instrumentation.