Sen. Lindsey Graham, who worked for months on legislation to cap carbon emissions, is backing an alternative aimed at curbing greenhouse-gas emissions through incentives for energy conservation.

The new bill, offered Wednesday by Sen. Richard Lugar, a Republican from Indiana, would require new homes, businesses and appliances to use less energy, encourage states and utilities to adopt more renewable power and provide incentives for building nuclear reactors and retiring coal-fired power plants.

The Senate will take up “comprehensive clean-energy” legislation next month, Senate Majority Leader Harry Reid, a Nevada Democrat, has said, without setting out the provisions. Graham in April dropped support of a measure he helped develop calling for a “cap-and-trade” system to limit carbon emissions and create a market in pollution allowances, starting with utilities.

“The carrot-stick approach is the basis of cap-and- trade,” Graham, a South Carolina Republican, said at a news conference Wednesday where he endorsed Lugar’s measure. “This is a carrot-stick approach, but there are more carrots than sticks.”

Lugar’s bill may be able to muster the 60 votes needed for Senate passage because it wouldn’t cap emissions or expand offshore drilling, two controversial issues in the Senate, Graham said.

Graham had worked with Senators John Kerry, a Massachusetts Democrat, and Joe Lieberman, a Connecticut independent, to develop the earlier measure. He dropped his support after Democrats began talking of taking up legislation on immigration first. He later said the BP Plc oil spill in the Gulf of Mexico made it impossible to pass that effort at a compromise, which included plans for more offshore exploration.

Lugar said his legislation would cost $3.75 billion over five years, reduce dependence on foreign oil by more than 40 percent and decrease national energy consumption by 11 percent by 2030.

Energy Secretary Steven Chu commended Lugar’s efforts to reduce U.S. dependence on oil and increase energy efficiency while faulting the measure’s failure to incorporate carbon limits.

“We need comprehensive legislation that puts a price on carbon and makes clean energy the profitable kind of energy,” Chu said in a letter today to the senator.

The legislation would “fail to cut global warming emissions to the level scientists say is necessary to avoid the worst of consequences of climate change,” the Union of Concerned Scientists, an environmental advocacy group based in Cambridge, Mass., said in a statement.

The bill was called an “amnesty for big polluters” by Frank O’Donnell, president of the Washington, D.C.-based environmental group Clean Air Watch. He said the measure would let utilities avoid certain requirements of the Clean Air Act.