It wasn't quite the mighty wind Naperville was hoping for, but the option to purchase renewable energy through residential utility bills did cause a bit of a breeze in its first year.

City officials hoped to get 5 percent of residential customers signed up this past year for the program that adds energy from wind turbines and solar farms to the Naperville electrical grid.

Since last January, 1,077 residential customers have come on board, representing just 2.2 percent of the homes in Naperville, Public Utilities Director Allan Poole said.

"Our goal for next year would be to double that," Poole said.

The amount of "green" energy being purchased by environmentally conscious Naperville residents translates to the annual output of one and a half wind turbines, he said.

Mayor George Pradel was one of the first 40 residents to sign up for the program.

"I think that when people who aren't involved yet see the results so far, their curiosity will be tapped," he said. "Word-of- mouth will get this around, too."

Residents have the option to purchase monthly blocks of the renewable energy for the city's grid by adding $5, $10, $15 or $20 to their electric bill each month.

"The $5 option is the most popular, but we also have some people paying more than $20 a month," Poole said. "That's less than 1 percent, though."

The environmentally friendly power is purchased through Pennsylvania-based Community Energy, which is required to use the profits from the purchase to add infrastructure to new renewable energy sources. Essentially, Naperville's green power purchasers are paying for new wind and solar farms to be built elsewhere.

Without a renewable energy purchase, the average residential electricity bill in Naperville comes to about $66 a month. Each of the 1,077 customers adding renewable energy to the city's grid is responsible for 283-kilowatt hours per month. The average home uses about 833-kilowatt hours per month.

Only four customers have canceled their participation in the program, Poole said.

"But we don't know if that's because they moved or became dissatisfied in some way," he said.

Participants in the program receive a certificate honoring them for their efforts after a year's worth of contributions. About 500 residents signed up within the first month of the program's operation and will be getting a commendation by March, Poole said.

GRAPHIC: By the numbers

1,077: Number of residential households participating in Naperville's renewable energy program

2.2: Percent of residential households participating

73: Percent of participating households paying $5 monthly

19: Percent of participating households paying $10 monthly

3: Percent of participating households paying $15 monthly

5: Percent of participating households paying $20 monthly

$790: Average yearly electricity bill in Naperville

10,000: Average annual amount of kilowatt hours of electricity used by Naperville homeowners

3,658,000: Annual amount of kilowatt hours of electricity generated by participating households

Source: City of Naperville