Summary

  • Microsoft is expected to take electricity from 2028 under a 20-year agreement, funding the generation and transmission needed for its load.
  • NiSource's $1.75bn savings forecast covers several data-centre contracts. Earlier announcements already described how large customers would contribute to bill credits.

An electricity customer does not pay a forecast. They pay a bill. That is what makes NiSource's latest data-centre agreement worth following beyond its impressive headline: the company expects a new, very large power user to help lower costs for people already connected to the system.

On 16 October, NiSource announced a 20-year energy agreement for Microsoft's planned campus in northwest Indiana. Service is expected to start in 2028. Alongside it came a larger forecast: approximately $1.75bn in savings for existing NIPSCO electricity customers over the lives of data-centre contracts, up from $1.4bn. The company described the benefit as as much as $140 per customer annually.

The attraction is easy to see. A new neighbour with an enormous electricity appetite could contribute to the existing network while paying for the extra equipment it needs. The difficulty is following that arrangement all the way to an individual account. The $140 figure is an upper estimate, not a promise that every household will receive an identical annual credit.

The saving already had a history

NiSource did not invent this mechanism for Microsoft. Its April announcement paired an agreement with an Alphabet subsidiary with an expanded Amazon arrangement. At that point, expected customer savings were about $1.25bn. The planned GenCo-owned generation pool was approximately 340 MW, supplemented by seasonal market purchases of up to 175 MW. Those were April's figures, not a ready-made inventory of today's system.

By June, the forecast had reached $1.4bn. NiSource reported that the Indiana Utility Regulatory Commission had approved the Amazon settlement, special contract and related power-purchase agreement on 17 June, with generation resources approved in a separate order. That account concerns Amazon; it does not establish approval of the later Microsoft deal.

The August explanation was more explicit about the customer benefit. Large-load users would pay for using NIPSCO's existing electricity system, alongside funding the infrastructure required for their needs. NiSource described $1.4bn in expected direct bill credits over 15 years. It also renamed NIPSCO Generation LLC as NiSource Generation Company LLC, or GenCo, calling this a name change rather than a new strategy.

There is, then, a stated route to a lower bill. What the October release does not provide is a complete reconciliation from that earlier forecast to the new total, contract by contract and customer by customer. Subtracting $1.4bn from $1.75bn produces $350m; it does not turn the difference into a separately disclosed Microsoft payment. Nor should August's 15-year forecast period be silently attached to either October's total or Microsoft's 20-year service term.

A battery with more than one customer

Microsoft's financing commitment is specific: NiSource says it will fully fund the generation and transmission required for its own load. The GenCo-owned pool is to grow by approximately 1,100 MW of generation resources. That is an addition to the pool, not its total size or a disclosed measurement of the campus's contracted demand.

Storage makes the shared arrangement particularly tangible. GenCo has contracted 600 MW of battery storage through a long-term tolling agreement, with an AGP Group affiliate to develop and build the facility. The resource will join a pool serving several large-load customers. Calling it Microsoft's private battery would erase that important part of the announcement.

The units matter as much as the ownership shorthand. Megawatts describe power. To know how much energy the battery holds, a reader needs megawatt-hours; to know how long it can deliver at a given output, a reader needs a duration. The release supplies the 600 MW figure, but not those other specifications. A large power rating alone cannot answer how long the storage will support demand.

NiSource plans to give further operational and financial details at its 28 October results call. As of this update, that call is still ahead. So are Microsoft's expected service start and the work needed to supply it. The company itself identifies risks around approvals, construction, financing and customers changing their capacity commitments.

The deal offers a plausible bargain: new demand helps pay for the system, while new users fund the infrastructure their demand requires. Its most persuasive evidence will eventually be less spectacular than a billion-dollar announcement—a credit on a bill, supported by a calculation the customer can follow.

Updated 26 October 2026: Added the June and August announcements and corrected the distinction between battery power, stored energy and duration. Original publication date and URL retained.