Idaho Power Co. wants regulators to let it hike residential customers' rates by an average of $3.56 monthly, to pay for a new natural gas power plant that's nearly completed.

Idaho's biggest utility filed the request with the Idaho Public Utilities Commission Tuesday.

It could have been bigger.

But the company has also filed additional regulatory paperwork for a revenue-sharing deal.

That will help offset the rate increase from the $391 million Langley Gulch power plant in southwestern Idaho.

Idaho Power built the Langley Gulch plant to meet demand and accommodate the addition of hundreds of megawatts of wind power that's become part of its system.

When wind doesn't blow, Langley Gulch will take up the slack during peak demand periods.

The request will be subject to public hearings.