Exhibit 21.01 NORTHERN STATES POWER COMPANY, MINNESOTA AND SUBSIDIARIES Subsidiaries of Registrant Name State of Incorporation Purpose Northern States Power Electric and gas Company (Wisconsin) Wisconsin utility First Midwest Auto Owns and manages Park, Inc. Minnesota a parking ramp United Power and Land Real estate Company Minnesota holding company Cormorant Corporation Montana Former owner of interest in coal and lignite properties NRG Energy, Inc. Delaware Owns and manages non-regulated energy subsidiaries of the Company Cenerprise, Inc. Minnesota Natural gas marketing and energy services Viking Gas Transmission Delaware Natural gas Company transmission Eloigne Company Minnesota Owns and operates affordable housing units Northern Power Wisconsin Formed for Corp. Wisconsin purposes of Merger Agreement Seren Innovations, Inc. Minnesota Automated communications systems to provide energy management, security control and business information services