Xcel Energy and Tri-State Generation and Transmission Association filed applications with the Colorado Public Utilities Commission. The transmission lines would stretch from the San Luis Valley in south-central Colorado to Pueblo.
Xcel Energy gets power from a SunEdison solar plant in the San Luis Valley.
The utilities must get approval from local governments for the transmission lines. The project is expected to cost about $180 million and be in service in 2013.
"We are combining our resources and assets to put forward a strong plan that addresses load growth and supports future renewable energy development," said Kent Larson, Xcel Energy's vice president for transmission and operating services.
Xcel Energy spokesman Tom Henley said the application is the first joint project proposed for renewable energy zones identified by the Legislature.
Minneapolis-based Xcel Energy is Colorado's largest provider of electricity. Westminster-based Tri-State supplies wholesale power to 18 electric cooperatives in Colorado, New Mexico, Wyoming and Nebraska.