Investigators Blame Coal Dust For Blast

July 29, 1998|By Peter Kendall and Oscar Corral, Tribune Staff Writers. Tribune staff writers Stephanie Banchero, Laurie Cohen, Mark S. Warnick, Jeremy Manier, Lisa Black, Eleanor Yang, Hermione Malone and Jodi S. Cohen contributed to this report.

The very thing that makes coal so useful also makes it frightfully dangerous.

Ground to dust, coal becomes an explosive blend of carbon and volatile gases that can be fed into furnaces to make electricity. But outside those furnaces, gathering beneath conveyor belts or hanging in the air, the dust is just as explosive.

On Tuesday morning, 17 workers were hurt when a fireball exploded through a coal-burning power plant on the shores of Lake Michigan on the Illinois-Indiana border.

Four of the injured workers were critically burned--their lungs were scalded--and will require extensive skin grafts in coming weeks.

The explosion knocked the power plant off-line and caused a "voltage sag"--the opposite of a surge--that blacked out factories and upset the electron-sensitive chips in countless computers around the region.

As the electricity grid convulsed, lights flickered across the region--a winking reminder of the expansive interconnections of the power system and all its potential vulnerabilities.

With the State Line Generating Station in Hammond out of service for an indefinite period, the explosion at least temporarily nudged Commonwealth Edison closer to the possibility of running short of electricity on a hot afternoon this summer.

ComEd sold the plant to a Georgia-based utility in December but now buys all the electricity it produces. The 490 megawatts of power the plant generates is roughly the margin that saved ComEd from initiating "rolling blackouts" on June 25, when there nearly wasn't enough electricity to meet demand.

The power plant, an architectural jumble of 1920s brick and 1960s aluminum, was still smoldering Tuesday evening.

One witness described the explosion as a "sonic boom" that thundered through the area just before 8 a.m. Though investigators had not determined what triggered the explosion, they speculated that a short circuit or a spark may have ignited coal dust on or beneath a conveyor belt, which rumbles over an old, unused coal storage bunker.

"We tried to keep the coal containers as clean as we can, but they are always dangerous areas," said Steve Owen, asset manager for Southern Energy Inc., the subsidiary of Southern Co. that owns the station.

In fact, some of the injured workers were on a cleaning crew sent to remove coal dust from the bunker.

When scrambling workers opened a door to escape, a rush of fresh air fed a second, smaller explosion, a booming backdraft, fire officials said.

The conveyor belts that wend through the massive plant to carry coal from the yard to the furnaces became a carrier of fire, spreading the flames throughout the complex.

Making matters more difficult, the explosion shattered pipes, cutting water pressure firefighters needed to douse the flames. The power outage also left firefighters without pumps to shoot water onto the burning roof of the 118-foot-tall building.

Fires are not altogether uncommon in old, sprawling coal plants, where tons of coal are moved from train cars to furnaces. Jostling grinds it into explosive powder rich in burnable carbon and explosive gasses.

More rigid environmental regulations in the 1970s persuaded ComEd to switch from high-sulfur Illinois coal to Wyoming coal, which has a lower sulfur content but is much more explosive. Softer than Illinois coal, the Western variety breaks down more easily into the dangerous dust.

Although dust-protection measures at State Line and other ComEd plants were upgraded when the plants converted to Western coal, fires still break out.

A coal-dust explosion at a ComEd plant in Lockport Township in January injured two workers, and the resulting fire took more than a day to extinguish.

On Wednesday, ComEd hopes to restart one of the generators at its Powerton Station near Peoria that was knocked out of service several weeks ago by a coal fire.

Coal dust has been a problem at the State Line plant before. In May 1997, inspectors for the Hammond Department of Environmental Management found that coal-crushing hammermills at the plant were being operated without a dust collector. ComEd, then the owner, agreed to pay a civil penalty of $6,450 to settle the complaint, according to city records.

Old power plants such as State Line, which is running on two boilers of 1955 and 1962 vintage, are operating longer than many had anticipated. In the 1970s, the federal Clean Air Act exempted old coal plants from many environmental restrictions, partly on the belief that they would not be operating much longer.

Critics say those exemptions have made the plants much cheaper to run than newer ones, extending the older plants' lives.

"Some things just don't get better with age, and power plants are among them," said John Thompson of the Illinois Environmental Council. "Just as your automobile gets less reliable over time, so do these power plants."