WASHINGTON -- Utilities would have to generate at least 10 percent of their electricity from renewable sources under a measure the Senate approved yesterday.

Separately, a package of environmentally friendly tax incentives was advanced by a committee, as senators made clear their intention to fashion a sharply different energy bill from one passed by the House.

Electric utilities would have to rely more heavily on wind turbines, solar energy, biomass from garbage or plants and other non-fossil fuels to generate electricity under the provision approved by a 52-48 vote.

Among regional lawmakers, the renewable sources provision was supported by Sens. Arlen Specter, R-Pa., and Jay Rockefeller, D-W.Va. It was opposed by Sens. Rick Santorum, R-Pa.; Mike DeWine and George Voinovich, both R-Ohio; and Robert Byrd, D-W.Va.

Opponents argued that the mandate, which would begin in 2020, would force higher electricity prices in regions of the country where such renewable fuels are not widely available.

But Sen. Jeff Bingaman, D-N.M., the measure's chief sponsor, said any modest price increase would be offset by lower natural gas prices, as utilities shift from gas to other energy sources. He said 18 states already have requirements for utilities to use some renewable fuels, including some that are much more ambitious that his proposal. California, for example, is requiring 20 percent of its electricity to come from renewable sources by 2017; Maine is requiring 30 percent by 2011, Bingaman said.

The Senate Finance Committee advanced $18 billion in energy tax breaks that lean heavily toward promoting energy efficiency, renewable alternative motor fuels and clean coal technologies.