The House on Thursday adopted a minor amendment that the Senate added prior to its passage of House Bill 1275 earlier this week on a 23-8 vote.

Brophy convinced most of his fellow Senators that Colorado needed to improve the tax climate for wind farms this year because a federal energy production tax credit is schedule to expire next year.

"I don't have any doubt that is the kind of tax policy that will absolutely stimulate economic development in the form of wind farms in eastern Colorado," Brophy said. "We really were facing this deadline with the federal protection tax credit going away before any new wind farms got built here."

Some senators questioned the constitutionally of the bill because it changes the taxation of new wind farms based on the amount of electricity produced, while existing wind farms, mostly in Prowers and Bent Counties, will continue to be taxed on the equipment, which depreciates over time.

Sen. Dan Grossman, D-Denver, who also is an attorney, said an opinion from Legislative Legal Services failed to resolve the constitutionality issue.

"The opinion is an interesting study in legislative power," Grossman said. "In a close call like this, we have to err on the side of the plenary power of the Legislature. Should it ever come to litigation, and I doubt it ever will, the benefit of the doubt certainly will rest in our plenary power of the Legislature.

A spokesman for the governor said Owens has not yet considered the windfarm bill.