Batteries can be used for backup, but could also be used to put power back out onto the grid when needed. "How energy users can become energy providers is a really interesting conversation, and data centers can be at the center of that if they choose to be."

Data centers are already investing in batteries which are unused most of the time, and could be earning revenue - but along the way, they have to get approval: "Utilities may support battery use, but when you get to a municipality you have to get through a whole different set of permitting requirements - in particular the Fire Department," she said.

City University of New York (CUNY) is working on guides to make it easier to get batteries approved for safe deployment indoors and outdoors in New York.