NiSource Inc. (NYSE: NI) has announced a 20-year energy agreement with Microsoft to supply approximately 1,100 MW of generation resources to a northwest Indiana data center campus, with service expected to begin in 2028.

Under the agreement, Microsoft will fully fund all generation and transmission infrastructure required to serve its load through NiSource's generation subsidiary, NiSource Generation Company LLC (GenCo). The structure is designed to shield existing Northern Indiana Public Service Company LLC (NIPSCO) electric customers from incremental costs associated with serving the data center.

NiSource said the deal expands projected savings for existing NIPSCO electric customers to approximately $1.75 billion over the life of its data center contracts, up from a previously disclosed $1.4 billion figure. The company said this equates to as much as $140 per customer annually.

In connection with the agreement, GenCo has contracted 600 MW of battery storage under a long-term tolling agreement. The facility will be developed and constructed by an affiliate of AGP Group and will be added to GenCo's pool of resources serving multiple large-load customers.

NiSource President and CEO Lloyd Yates said in a statement that the agreement reflects a "balanced approach" intended to attract investment while protecting existing customers. Microsoft Senior Director of Energy Markets Jeff Riles said the company is "committed to paying our own way" and that the agreement is structured to avoid increasing electricity prices for other ratepayers.

Additional financial and operational details are expected to be disclosed during NiSource's third-quarter earnings call.