John Dunlop's electricity bill last month tilted toward windmills.

Dunlop, who orders 100 percent wind power from Xcel Energy, noticed that for the first time his alternative energy of choice was cheaper than the power company's standard fuel rate.

An engineer for the American Wind Energy Association, he was delighted to note an 80 cent savings on the $101.87 July bill for his house in Minneapolis.

Steve Mudd, Denver-based manager of Xcel's "Windsource" program, confirmed the first-time flip. But Mudd said it's more anomaly than energy revolution -- even at the utility that is the nation's leading supplier of wind-generated electricity.

Here's the math: Customers like Dunlop pay an extra charge each month that obligates Xcel to produce at least enough wind energy to cover their use that month.

In July, that Windsource charge was 3.5 cents per kilowatt hour.

All other customers pay an extra "fuel cost" charge on their monthly bills, which is how the utility passes along rising natural gas prices to its customers.

Last month, that was 3.6 cents per kilowatt hour. Wind was cheaper.

August isn't shaping up as a repeat performance, though, as the summer peak in gas prices passes. Mudd said August's fuel charge is going down to about 3.2 cents.

Still, Dunlop thinks July's flip will come as news to most Xcel customers.

"When I talk to people, they all seem to be aware of the extra charge for the Windsource program," he said, "but they're not aware that it excuses them from paying another extra charge, the fuel charge."

H.J. Cummins • 612-673-4671