UPDATE 1-US carbon emissions to rise next two years-EIA

* Emissions to rise 1.5 pct this year, 1.7 pct next year

* Power sector emissions to keep rising (Adds details on Obama greenhouse gas policy, emissions)

WASHINGTON Jan 12 (Reuters) - U.S. carbon dioxide emissions from fossil fuels like coal and oil should rise this year and next as the economy recovers, making the Obama administration's goal to cut emissions by 2020 a tougher task, the government's top energy forecaster said on Tuesday.

U.S. emissions of the main planet-warming gas should rise 1.5 percent this year to 5.53 billion tonnes as "projected improvements in the economy" boost demand for the fuels, the Energy Information Administration said in its monthly short-term energy outlook.

Emissions of the chemical, which represent about 80 percent of overall U.S. greenhouse gas output, should rise another 1.7 percent in 2011, on expected increases in coal burning at power plants and slightly higher oil demand from transportation fuels.

"It does mean the U.S. target will be more challenging," said Kevin Book, an analyst at ClearView Energy Partners LLC in Washington. "Everyone expects that fossil fuel demand from transportation will eventually flatten out, but electricity demand only goes up, even with efficiency gains," he added.

President Barack Obama pledged at the U.N. climate talks in Copenhagen in December that the country would cut greenhouse gas emissions to 17 percent below 2005 levels by 2020.

Compared to 1990, the base year used by the European Union and many developed countries, the U.S. pledge corresponds to a 3 percent reduction in 2020.

The recession made Obama's pledge look easy to achieve.

U.S. carbon emissions fell 6.1 percent in 2009 to 5.45 billion tonnes as the recession cut driving and electricity demand, the EIA said. That was about 8.9 percent below the 2005 level of 5.98 billion tonnes.

But expectations of an improved economy will push industrial demand for electricity up 2.2 percent in 2010 and 2.5 in 2011, the EIA said. The burning of coal, which emits more carbon dioxide than any other fossil fuel, generates about half of the electricity in the United States. (Reporting by Timothy Gardner; editing by Jim Marshall)