Ellison's office says it's asking the Minnesota Public Utilities Commission not to approve the deal unless Xcel and Google can prove its electronic service agreement "is reasonable, consistent with the public interest, or meeting the stringent requirements of the applicable law."

State law requires "all costs attributable to the utility's very large customers" be charged to those customers, but Ellison's office alleges the utility has not provided proof that Google subsidiary Echo Zone, LLC, will cover all costs during the service agreement's term.

Ellison's office says Xcel also hasn't confirmed if "customers will be protected from paying for stranded costs if Google reduces its demand or leaves Xcel's system," which would also be in violation of state law. They also allege a lack of transparency, noting the utility provider "has redacted almost all of the dollar amounts of these potential impacts, however, and has not provided specific explanations for some of its redactions."

Xcel says the deal provides more than $1 billion in savings for taxpayers. Ellison's office says its assessment actually puts a $1.1 billion in net costs to customers.