Progress Energy was the first U.S. utility to test two emission-reduction technologies and the first in the Southeast to pilot another.

At the company's Asheville Plant in Buncombe County, N.C., Progress Energy is the first company in the Southeast to combine the injection of natural gas and a urea compound to reduce NOx emissions beyond the 55 percent decrease already achieved at the plant since 1995. Additional reductions for NOx and sulfur-dioxide are planned.

At its Cape Fear Plant in Chatham County, N.C., Progress Energy is the first company in the United States to install and test a Swedish NOx-reduction technology that uses rotating overfire air, or ROFA, to create turbulence in a boiler to promote more complete combustion of coal. NOx emission reductions of 50 percent to 60 percent are being achieved at Cape Fear.

And at the Roxboro/Mayo plants in Person County, N.C., Progress Energy installed North Carolina's first selective catalytic reduction (SCR) technology. The first unit began operating during the ozone season in 2001. Since that time, two additional SCRs have been installed, with additional installations planned by 2004.

At its Weatherspoon Plant near Lumberton, N.C., Progress Energy is witnessing 35 percent reductions in emissions of nitrogen oxides (NOx) using a technology developed at the St. Petersburg Polytechnic Institute in Russia and brought to the United States by the Research Triangle Institute. The system, known as WIR, is operating in more than 20 coal-fired boilers in Central Europe, but Progress Energy's plant is the first to demonstrate the system in the U.S. That technology was expanded to the Lee Plant near Goldsboro in 2000.

Coal- and oil-fueled electric power plants, vehicles and numerous industrial processes produce nitrogen oxides. Ground-level ozone, the primary component of smog, is formed when NOx reacts in the air with hydrocarbons on hot, sunny days. So-called ozone season runs from May through September.

Progress Energy has taken a leadership position in demonstrating emission-reduction technologies.

How the WIR Technology Works

"WIR," loosely translated as "vortex," aptly describes the technology.

The Progress Energy demonstration of WIR is in a tangentially fired boiler, which is shaped like a large metal can. Burners on the boiler's furnace wall blow pulverized coal and air into the furnace at an angle, creating a spinning effect. This vortex produces more efficient combustion of coal, resulting in lower emissions of NOx.

WIR involves re-aiming the burners and injecting new flows of air at the bottom of the "can." These air flows produce a pair of horizontal vortices beneath the normal vertical one. "This creates more turbulence plus the ability to fine-tune the turbulence," said Dr. John Cleland of the Research Triangle Institute, which helped bring the technology to the United States. "This has beneficial effects on the combustion process."

First, it makes a larger combustion region in which the coal remains for a longer time and burns at a lower temperature than normal. These conditions produce less NOx than normal, without undue increases in other emissions such as carbon monoxide and fly ash. Second, an oxygen-starved region forms in the lower part of the boiler furnace. In this region, the chemistry of combustion breaks NOx apart, destroying potential polluting emissions.

Nitrogen to form NOx comes in part from coal and in part from air, which is 78 percent nitrogen.

"The idea is to send nitrogen back into the atmosphere," Dr. Cleland said. "We can't stop nitrogen from getting into the boiler, so we want most of it to just pass on through."