U.S. CO2 emissions fall to lowest first-quarter level in 20 years: EIA

WASHINGTON (Reuters) - Carbon dioxide (CO2) emissions from energy use in the first quarter of this year fell to their lowest level in the U.S. in 20 years, as demand shifted to natural gas-fired generation from coal-fired electricity due to record low gas prices, the energy department said.

Energy-related carbon emissions fell 8 percent from the same period a year ago to 1.134 billion metric tons (1.25 billion tons), according to the latest monthly energy review by the Energy Information Administration (EIA) - the energy department's statistics arm.

In the U.S., the first quarter usually represents the time of year when greenhouse gas emissions are at their highest because of strong demand for fossil-fuel generated power for home heating.

Emissions from coal use fell sharply by 18 percent to 387 million tonnes in the January-March 2012 period - the lowest-first quarter tally since 1983 and the lowest for any quarter since April-June 1986.

The contribution of coal in U.S. energy use is likely to continue its demise, with plant owners and operators reporting to the EIA last month that they plan to retire 27 gigawatts (GW) of capacity, or 8.5 percent, at 175 coal-fired facilities between 2012 and 2016.

Looming federal carbon and mercury regulations being developed by the Environmental Protection Agency (EPA) are also likely to force the retirement of more coal plants.

Energy analysts at political risk consultancy Eurasia Group said in a research note this week that it expects around 50GW of coal capacity to be shuttered as a result of pending regulations and cheap natural gas.

"These closures would create roughly 5-6 bcf/day of incremental new gas demand in the currently oversupplied US market," according to a Eurasia Group analysis.

The EIA said that in addition to low natural gas prices, a mild winter and reduced demand for gasoline also contributed to the first-quarter emissions drop.

(Reporting by Valerie Volcovici)