Although natural gas prices are expected to be flat in a September to September comparison, Xcel Energy customers could still see larger bills than last month.

The natural gas commodity price proposed to the Public Utilities commission would increase residential and small business bills by about 2 percent.

Natural gas commodity adjustments are filed monthly, but Xcel and the PUC have agreed to quarterly adjustments starting this month.

On Sept. 17, Xcel estimates that natural gas bills for the fourth quarter of 2009 would be 7 percent to 9 percent lower than the same period in 2008.

Xcel estimated that a typical residential customer’s monthly bill will be $72.76 in the fourth quarter of 2009, based on average monthly consumption of 94.4 therms. This compares to $79.89 for the fourth quarter of 2008, based on average monthly consumption of 93.7 therms during the quarter.

Typical small-business customers are expected to see monthly bills of $308.50 in the fourth quarter, based on an average monthly consumption of 413 therms. This compares to monthly bills in the fourth quarter of 2008 of $333.10, based on the same monthly consumption of 413 therms.

Xcel Energy’s natural gas commodity rates proposed to the Colorado Public Utilities Commission for residential and small-business customers will decrease approximately 13 percent from a similar period last year, to a quarterly average of $0.5596 per therm for residential customers and $0.5620 per therm for small-business customers. The fourth quarter 2008 commodity rate estimates were $0.6453 for residential and small-business customers.

The filing submitted Sept. 17 would take effect Oct. 1 if approved by the PUC.