FACTBOX: Possible Obama steps on climate change

WASHINGTON, Feb 11 (Reuters) - President Barack Obama is expected to offer more details in Tuesday's State of the Union address on how the administration will fulfill his inaugural pledge to respond to the threat of climate change, according to energy policy analysts.

The Environmental Protection Agency (EPA), bolstered by a 2007 Supreme Court ruling that required the EPA to regulate greenhouse gases, will likely take the lead in targeting the biggest carbon emitters - power plants, refineries and cars. The President can also use other methods to sidestep Congress to tackle the heat-trapping gases.

Below are ways Obama could carry out his goal of cutting carbon emissions using or expanding existing authorities:

New power plants: The EPA is expected to finalize the first U.S. rules to target carbon emissions for power plants and large industrial sources this spring. The agency's emission performance standard would require any new facility to emit under 1,000 lbs per megawatt hour, the average rate of a natural gas-fired facility. Under this standard, a new coal-fired plant would not be able to be built without carbon capture technology, which is not yet available at commercial scale.

Tax reforms: The White House may find ways to provide incentives for clean energy technology by reforming the tax code. The Treasury is reviewing how direct taxes, such as those on fuels, can decrease emission rates. The tax code can also be reformed to extend tax breaks offered to oil and gas companies, to renewable energy projects to level the playing field.

Green government procurement: A 2009 executive order directed federal agencies, the largest consumers of energy in the U.S. economy, to increase efficiency and promote the use of green technologies. The president could expand on this by directing office building retrofits or securing long-term contracts for renewable energy.

Capturing methane from natural gas production: Some green groups are urging the EPA to regulate leaks of methane, a potent greenhouse gas, from natural gas production. Requiring producers to capture vented, leaked or otherwise wasted natural gas from wells while the gas is readied for extraction could save money while lowering greenhouse gas emissions, they argue.

Combined heat and power: In August, Obama issued an executive order to increase the number of facilities that generate thermal and generating power simultaneously by 50 percent by 2020, a move that would boost industrial energy efficiency and slash carbon emissions by 150 million tons per year. Under the order, agencies such as the DOE, EPA and USDA to coordinate their policies on this to encourage more investment.

(Reporting By Valerie Volcovici; Editing by Ros Krasny and Leslie Gevirtz)