Electric power plants are Oregon's largest stationary sources of greenhouse gas emissions, a

indicates, accounting for more than two-thirds of the state's global warming emissions from large sources.

Oregon's only coal-fired plant --

's Boardman generation plant -- topped the

's list of 2010 emissions for Oregon, followed by five natural-gas fueled power plants throughout the state.

Boardman released nearly 4 million metric tons of carbon dioxide equivalent, equal to the annual emissions of roughly 800,000 passenger vehicles, EPA says. But the plant, not huge by power industry standards, was only the 194th largest emitter nationwide.

The Boardman plant is

. PGE could shift to natural gas, which releases less carbon than burning coal,

Burning biomass could release as much carbon or more, though those emissions may not be counted under U.S. green energy policies.

All told, eight electric generating plants in Oregon, including Boardman and seven natural gas-fired plants, accounted for 9.4 million metric tons of releases in 2010.

That was 70 percent of the state's 13.4 million total from 51 Oregon sources included in the EPA's first large source inventory.

Landfills, which release methane when garbage rots, were the next largest Oregon category, at about 1.5 million tons, followed by pulp and paper mills at just under 1 million tons.

's Durkee plant was the largest industrial emitter, at 455,000 tons in 2010.

EPA's large source inventory, mandated by Congress in 2008, captures most direct emissions from electricity generation and industrial sectors.

It does not reflect emissions from transportation, agriculture and residential and commercial fuel use, such as burning natural gas in home furnaces.

Oregon's large-source total -- about 0.4 percent of the nationwide tally -- was less than the state's 1.2 percent share of the U.S. population.

Oregon's share of power plant emissions was lower, reflecting emissions-free hydropower production and imports of electricity from other states.

With the exception of pulp and paper mills, Oregon has less heavy industry and mining than many other states. It also has no large oil refineries, which account for 6 percent of large-source emissions nationwide.

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