Coal—Black Rocks From a Dark Hole
By Awake! writer in Australia
“BLACK—you don’t know the meaning of the word until you’ve been down a mine shaft,” yells my friend Bernie over the noise of machinery. Gazing at the yawning hole in front of me, I start to wonder if I really want to find out what Bernie means. Our destination is a coal seam buried a third of a mile [half a kilometer] beneath my feet.
We pass a column of miners trudging toward the showers. The men have broad shoulders and broad Australian accents. When they smile, their eyes and teeth seem almost luminous against their coal-dust blackened faces.
Soon we board the small train that takes us down to the coal face—the exposed surface of coal. The descent is so steep that the driver’s seat is designed to swivel, hanging from the ceiling like a swing. Strapped to my side are a sparkproof battery, which powers my helmet lamp, and an emergency breathing device ominously called a self-rescuer. As the train inches down the slope, the sky behind us shrinks to a blue dot surrounded by black.
More With Less
The coal mine I am visiting is one of dozens in southeastern Australia. My guide, Bernie, is one of the 25,000 miners who extract eight thousand million dollars’ [Australian] worth of coal from Australian mines each year. Globally, there are ten million coal miners working either underground down dark shafts or on the surface in vast opencut mines. But their numbers are dwindling. The United Kingdom saw the number of union coal miners plummet from 1.2 million in 1978 to about 13,000 workers by the turn of the century. In the United States, the number fell from 705,000 miners in 1924 to fewer than 82,000. China reduced its coal work force by 870,000 in a recent five-year period.
The declining number of miners, however, does not mean there is less demand for coal. In fact, it is forecast that the demand will rise by 11 percent in industrialized countries by the year 2020, while China and India are expected to build a combined total of over 750 new coal-fired power stations during the same period. The reduction in personnel is largely a result of new technology, which enables companies to produce more coal with less labor. The massive machine that Bernie is about to show me is one example of this superior technology.
Down the Dark Shaft
“This is pit bottom,” Bernie says as we squeeze ourselves out of the train. “All the tunnels in the mine lead off from here.” Fluorescent lights line the low ceiling. Rows of small logs, wedged between floor and roof, support narrow crossbeams. Thousands of bolts stud the ceiling. These expansion bolts are rammed seven feet [2 m] into the roof and lock the overhead rock in place to prevent cave-ins.
I am surprised to see that the walls are, not black, but white. “The walls are coated with powdered limestone,” Bernie explains. “The limestone reduces the risk of an explosion caused by methane gas and coal dust. An accidental spark can ignite the methane. In turn, the methane, like a detonator, can set off a larger explosion in the airborne coal dust. About 70 cubic feet [2,000 liters] of methane a minute is pumped out of this mine and is used to produce electrical energy for the mine.” To avoid the possibility of sparks igniting any leaking gases, I had to leave my camera, my tape recorder, and even my battery-powered watch on the surface.
Down inside one of the multitude of tunnel entrances that branch off from pit bottom, we find a squat, yet powerful, diesel transporter. To the roar of its motor, we lurch off into one of the tunnels. Lights rapidly fade behind us, and I find my helmet lamp reflecting off a ceiling that flashes past just inches above my head. As we speed past numerous side tunnels, I catch glimpses of other helmet lamps flickering like fireflies in the blackness. In a tunnel parallel to ours, a three-mile- [5 km]long conveyor belt hauls its load of coal from the coal face.
The Longwall Mining Machine
Arriving at the coal face and peering through a mist of water vapor and coal dust, I see three figures clad in suits, hoods, and masks. These men work as a team to control the 900-foot- [250 m]wide machine known as a longwall miner. Two rotating drums, each of them seven feet [2 m] in diameter, slowly travel across the coal face for the full width of the machine. These drums are armed with metal spikes that chew two feet [half a meter] into the coal face as they pass across it. The machine is equipped with a conveyor belt that whisks the coal down a side tunnel, where the chunks are crushed to uniform size and dumped onto the main conveyor.
The rock ceiling is prevented from caving in by a row of thick hydraulic legs that support large steel plates over the operators’ heads. After the drums with metal spikes travel the width of the machine, the whole contraption—the drums, the hydraulic legs, and the steel-plated roof—slides itself forward two feet [half a meter]. When the machine slides forward, it leaves behind an unsupported ceiling of rock. This ceiling stays briefly suspended. Then, boom!—it crashes down with a bone-jarring thud. “We mine a thousand tons of coal an hour this way,” shouts Bernie. “Once a quadrant of coal is removed, the machine is pulled apart and moved to the next sector.”
Daylight, at Last!
Bernie and I return to our transporter and travel back along three miles [5 km] of bumpy tunnels before stopping at a large cavern. A vertical shaft, about 30 feet [10 m] in diameter, connects this cavern to the surface. “The main conveyor belt dumps its load here,” yells Bernie over the deafening roar of the coal falling into a large metal bin. “The bin you see being filled is called a coal skip. It holds 18 tons of coal.” As Bernie is speaking, the newly filled bin rockets skyward, pulled by a cable. Seconds later a second bin drops from the hole in the ceiling, and the loading starts again.
With the tour now complete, we board the train, which slowly hauls us back up to the entrance of the mine and into delightful sunshine—or so I hoped. However, we had been down in the mine so long that the sun had set and the moonless sky had turned black. Although it is a very dark night, I now understand Bernie’s comment—‘You don’t know what black is until you’ve been down a mine shaft.’
[Box on page 13]
Coal’s Future—A Hot Issue
▪ Coal and Pollution: “Smoke and small particles from burning coal cause more than 50 000 premature deaths and 400 000 new cases of chronic bronchitis a year in 11 of [China’s] large cities,” states a United Nations Environment Programme report. The Worldwatch Institute blames over one and a half million deaths a year globally on pollution from coal. The technology to remove much of this pollution is available but is considered too expensive for many power-starved countries to purchase.
▪ Coal and Climate Change: The burning of coal already produces over two thousand million tons of carbon dioxide gas each year. And coal is forecast to remain the second-largest source of carbon emissions, at about 34 percent in 2020. Many see these statistics as cause for alarm.
“Hastening coal’s decline is imperative if climate change is to be slowed in the next century,” says Seth Dunn, associate researcher at the Worldwatch Institute.
[Box on page 14]
Hooked on Coal
▪ Over 70 percent of the steel produced worldwide is processed by coal-burning blast furnaces. In addition, the makers of bricks, tiles, cement, plastics, dyes, and explosives use chemicals derived from coal.
▪ By far the biggest consumer of coal, however, is the power industry. Australia generates 84 percent of its electric energy from coal-fired power plants. In China, South Africa, and Denmark, approximately three quarters of the electricity is generated from coal. The United States relies on coal for over half of its electric power. Worldwide, more than a third of the electricity produced comes from coal.
▪ To put it another way, if you own an electric stove, you consume approximately half a ton of coal a year. Two tons of coal will power your electric water heater for the same period, and your electric refrigerator will devour a further half ton annually.
▪ Scientists estimate that one million million tons of coal remain in the earth’s “cellar”—enough to last hundreds of years at the present rate of consumption.
[Diagram/Pictures on page 12, 13]
(For fully formatted text, see publication)
Underground Coal Mine
Mine access drift
Part of a three-mile [5 km]-long conveyor belt
[Picture on page 13]
Logs and crossbeams secure older tunnels