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.