Local angleThe only facility in Clark County to land on the list of the top air polluters is Clark Public Utilities’ River Road Generating Plant. The combined-cycle combustion turbine, installed in 1997, burns 42 million cubic feet of natural gas per day to generate 248 megawatts of electricity. That is enough to serve about half of the public utility district’s load. The River Road plant has received all of the necessary permits to discharge its air emissions.According to the utility, air pollution is reduced by a selective catalytic reduction system for control of nitrogen oxides that result from burning natural gas. Carbon monoxide emissions are controlled by using combustion controls and an oxidation catalyst.The utility operates the River Road plant based on the demand for electricity and the cost of electricity available to be purchased from other suppliers.SEATTLE — Washington state’s major industrial sources released about 6 million more metric tons of greenhouse gases in 2013, a 30 percent jump from the previous year, according to the latest data from the U.S. Environmental Protection Agency. The state’s only coal burning power plant in Centralia topped the list, emitting 7.5 million metric tons of carbon dioxide and other gases blamed for global warming. Emissions from the plant spiked up about 82 percent from 2012, after experiencing a big drop the previous year.