Xcel Energy seeks $138 million electric rate increase

If approved by the PUC, typical residential rates would increase by $3.96 a month starting in 2015. An additional increase in 2016 and 2017, in the form of a bill rider, would add an additional $1.06 per month. Small-business customers would see average bills rise by a total of $8.21 a month.

The overall 4.9 percent hike "isn't chump change," said William Yeatman, a utility analyst with the Competitive Enterprise Institute, a free-market think tank.

Yeatman for years has expressed concerns about the $980 million cost of Xcel's compliance with the Clean Air-Clean Jobs Act. But he said Tuesday that he's more worried about the ongoing higher costs of generating power with natural gas, compared with coal.

Gas is relatively cheap now, he said, "but I can't forget what commodity prices were like only six years ago. If that were to happen, in a newly gas-dependent Colorado, everyone would flip out."