WRAPUP 1-US Senate Democrats to unveil climate bill Sept 30

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By Ayesha Rascoe

WASHINGTON, Sept 24 (Reuters) - U.S. Senate Democrats will unveil legislation to cut greenhouse gas emissions next Wednesday, kicking off what is likely to be a battle in Congress due to concerns over additional energy costs.

The bill has not been released formally but will be coauthor by Massachusetts Senator John Kerry and California Senator Barbara Boxer, a Congressional source said on Thursday.

"The overall architecture of the Senate bill is going to be very similar to the House version of the bill," a separate source at an environmental group said via telephone from the G20 summit in Pittsburgh.

The House narrowly passed a climate change bill in June that would establish a system capping carbon dioxide emissions.

The House bill called for a 17 percent cut in carbon emissions below 2005 levels by 2020, and about an 80 percent reduction by 2050.

It would also require companies to acquire permits for the right to emit carbon. Initially about 85 percent of the carbon permits would be provided to companies for free.

Another source said the Senators are contemplating requiring a 20 percent cut in greenhouse gases by 2020.

Any climate legislation in the Senate likely faces an uphill battle, as lawmakers from heavy industrial states in both parties have raised concerns about burdening companies with additional energy costs.

Republicans, in particular, have characterized so-called cap and trade legislation as a massive energy tax that will kill jobs and hurt the economy as it recovers.

If the Senate is able to pass its version of the climate bill, then lawmakers will have to hammer out any differences before the bill becomes law.

Senate Majority Leader Harry Reid has said he hopes to bring this legislation to the floor for a vote by the end of this year. He has also said he plans to combine the bill, with a comprehensive energy package that was approved by the Senate Energy and Natural Resources Committee earlier this year.

The announcement comes as U.S. President Barack Obama hosts a meeting of major economies in Pittsburgh, where they are are expected to discuss how industrialized nations could provide financial support to developing nations dealing with climate change.

This summit is a precursor to negotiations over an international climate accord in Copenhagen in December. (Reporting by Timothy Gardner and Tom Doggett; Editing by Marguerita Choy)