King Coal at the Crossroads
One of Canada’s largest mines lies right in Edmonton’s backyard, little known except to the thousands who work there. But what future is there for Highvale and other coal mines in a carbon-constrained world?
by Michael McCullough
But the ultimate fix sought by the coal industry worldwide is the advent of “clean coal” technology. A closed-loop process that would virtually eliminate carbon dioxide emissions was demonstrated in a CanMET (Canadian Centre for Mineral and Energy Technology) laboratory in Ottawa between 2001 and 2006. Now several utilities, most notably Italy’s Enel SpA with a proposed pilot project at Brindisi, are attempting to scale the technology up to a real power plant. It sounds fanciful, but the low cost and high energy density of coal, combined with the powerful economic interests behind it, bode well for a technological solution.
While the debate and the furious research effort shape up around the world, the excavation continues at Highvale.
Opened in 1970, the mine was first exploited along its western flank near the Sundance plant, where the coal lies closest to the surface. With Pit 8, the deposit steers to the south of Keephills. “We’ll start mining the new pit as early as next spring,” says Ralph Leriger, TransAlta’s manager of stakeholder relations, who leads our tour. The 1.8 million tonnes a year to come out of this pit will match the additional demand from Keephills 3.
The same layer of coal blankets much of Alberta, only here it is relatively thick, pure (notably low in sulphur) and near the surface, ranging in depth between 30 and 80 metres amid soft sedimentary rocks. It’s actually composed of six distinct seams, five of which are rich enough to mine.
While TransAlta owns both the mineral rights and the equipment, the job of mining Highvale is contracted out to Prairie Mines & Royalty Ltd. (formerly Luscar Ltd.), a subsidiary of Sherritt International Corporation with operations in Alberta and Saskatchewan.
Driving east from Keephills in a company van equipped with buggy whips visible to the haulers, we pass the gleaming white spars of a new, Wisconsin-made Bucyrus dragline under assembly. It will be one of the biggest in the world, with a “throw” (drag radius) of 132 metres. The largest pieces of equipment – the draglines, power shovels and oilsands-sized dumpers – are actually used to remove not the coal itself but the topsoil or “overburden,” in mining parlance, which is set aside for future reclamation of the site. Once a pit is cleared down to the level of the coal seams, explosives are used to break up the coal if necessary and smaller (but still outsized) front-end loaders scoop up the mineral and pile it into 160-tonne articulated bottom dumpers. These trucks then haul the coal to handling sites alongside the power plants where the different seams are blended according to the tastes of each of the six boilers at Sundance and the two at Keephills.
Under the looming smokestacks of Sundance, we stand and watch as a bulldozer driver moves the piles around to create just the right recipe. Invisible beneath our feet runs a conveyor belt in a tunnel. Somewhere under the pile there’s a drain through which the coal pours onto the conveyor, carrying the raw material into the plant. There it is crushed to a powder the consistency of flour and blown into the boiler, creating the kind of unimaginable temperatures to create the pressurized steam that turns the turbines and runs the generators. What comes out of the plant is bottom and fly ash (which is either sold to cement producers or disposed of in ponds and pits), a river of innumerable electrons running along high-tension wires and the villain CO2.
Improving productivity in a mature industry like mining is a challenging game of inches and minutes. It means economies of scale as well as precision.
“Productivity means the trucks load as fast as the shovels work,” says our driver, mine engineer Ross Van Bostelen. At a huge mine site like Highvale, where the pit may be right near the power plant or 10 kilometres away, that requires an efficient dispatch system headquartered in what looks like an air-traffic control tower at Sundance. Likewise crucial is the planning of where to mine next. GPS (global positioning system) technology, meanwhile, has taken a lot of the guesswork out of the equipment operators’ jobs; they know within inches how deep to dig before reaching the floor of a seam at any one location. “That way you’re always where you should be,” says Van Bostelen.
Lights overlooking the pits allow the mining to take place 24 hours a day, seven days a week. Between that infrastructure and the needs of the electric behemoths digging into the slopes, “we’re constantly building and moving power lines in the mine site,” Leriger says.
Once a pit is exhausted, the overburden is filled back in, the drainage managed so as not to enter Lake Wabamun and, over a period of years, the site is returned to either agricultural or natural uses. So far TransAlta has reclaimed 1,310 hectares of the 4,362 disturbed. “TransAlta has more reclaimed land than any other company in Canada,” Leriger boasts as we gaze over the “Rose Bowl,” a picturesque duck pond fringed with cattails and surrounded by rolling hayfields where a pit used to be. The company leases the farmland to local producers, though in the fullness of time it intends to sell the property outright. It also operates its own experimental farm here. Unlike mining metals, mining thermal coal leaves no toxic legacies, Leriger points out.
TransAlta estimates the mine, currently producing 13.8 million tonnes a year, can continue producing for the life of the power plants – in the case of Keephills 3, another 50 years or more. Whether we’re still mining coal to produce electricity at that point, however, is open to question.
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