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Oil Sands May Irrevocably Tar the Climate


Red lights are flashing, but Ben Johnson pays them no mind. The long, lean, weathered engineer rests against a counter lined with computer monitors, describing life in the tar sands mines of Alberta, Canada. His task is to take a mud made of ore and water and “liberate the bitumen,” a tarlike oil that can be refined into conventional crude oil. He and two colleagues man a monitoring station that sits near the base of a cone-shaped structure the size of a three-story building. Mud and hot water flow into the middle of the inverted funnel. Bitumen rises to the top and spills over onto surrounding grates.

One time in 2012 bitumen bubbled up so fast that it cascaded down the sides of the cone and flooded the building shin high. To keep this kind of thing from happening again, sensors track temperatures, pressures and other parameters, and if something is amiss, a warning goes off. This happens so often—“1,000 alarms a day,” Johnson says—that the engineers have taken to keeping the sound turned off. “It's not going ‘bing, bing, bing,'” he says, “because that would drive us crazy.”

Suncor Energy's North Steepbank mine, where Johnson operates one of many “separator cells,” is a tiny portion of the current output of Alberta's tar sands, which underlie an area the size of Florida. High oil prices over the past decade have made such tar sands mines profitable, and Canada has rapidly expanded production. In 2012 alone Alberta exported more than $55 billion worth of oil, mostly to the U.S., so it is no wonder that Johnson's crew does not pause for alarms.

The rush to exploit the Alberta tar sands is triggering alarms of another kind, however—from climate scientists. Carbon dioxide emissions from burning fossil fuels are driving the world quickly toward a greenhouse gas threshold—an atmospheric concentration of 450 parts per million, which corresponds to two degrees Celsius or more of warming—beyond which some scientists fear that climate change could prove catastrophic. Coal constitutes a bigger source of fossilized carbon, but the Alberta sands require more energy to mine and refine than conventional oil, adding an extra overhead in greenhouse gas emissions. And the tar sands operations are growing far more quickly than most other sources of oil. Releasing the carbon now trapped in the tar sands would most likely dash any hope of avoiding the two degree C threshold.

The fate of Alberta's tar sands—and the climate, for that matter—now seems to be converging on the proposed Keystone XL pipeline. Keystone XL, which would run from Alberta to refineries in Texas along the Gulf of Mexico, would serve as a primary conduit for tar sands crude. For a decade or more advocates of Alberta's operations have argued that the tar sands constitute a much needed source of oil for the U.S. that is not subject to turmoil in the Middle East and abroad. All that was needed was a way to transport the tar sands oil from Canada to where it would be used—to the U.S. and beyond to Europe and Asia. And if a pipeline like Keystone XL could not be built, then other pipelines or rail could do as well. But independent experts suggest that Keystone XL is critical to the continued growth of Alberta's tar sands industry.

None of this had come to light when President Barack Obama postponed a decision on whether to build the Keystone XL pipeline during his reelection campaign. When the issue comes up again, a great deal more will be riding on his decision.

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Alberta's tar sands represent a lot of buried carbon, the remains of countless algae and other microscopic life that lived hundreds of millions of years ago in a warm inland sea, pulling CO2 out of the atmosphere via photosynthesis. With today's technology, about 170 billion barrels of oil could be recovered from Alberta's tar sands, which would add roughly 25 billion metric tons of carbon to the atmosphere if burned. An additional 1.63 trillion barrels of oil—which would add 250 billion metric tons of carbon—waits underground if engineers could figure out a way to separate every last bit of bitumen from the sand. “If we burn all the tar sands oil, the temperature rise just from burning those tar sands will be half of what we've already seen,” or roughly 0.4 degree C of global warming, notes mechanical engineer John P. Abraham of the University of St. Thomas–Minnesota.

Surface mining can reach deposits as deep as 80 meters, but that accounts for only 20 percent of the tar sands. In many places, the tar sands lie hundreds of meters underground, and energy firms have developed a method—known as in situ production—to melt out the bitumen in place.

In 2012 Cenovus Energy melted more than 64,000 barrels of underground bitumen every day at Christina Lake, a facility in Alberta named after nearby waters. The operation is one of the frontier camps of this latest tar sands boom. Clouds of steam rise from the nine industrial boilers on-site, burning natural gas to heat treated water into 350 degree C steam. Cenovus employees in a control room even bigger than Suncor's inject the steam deep below the surface to melt the bitumen, which is then sucked back to the surface through a well and piped off for further processing. Greg Fagnan, Christina Lake's director of operations, likens the complex to a giant water-processing facility “that happens to produce oil as well.” Every once in a while, a blowout shoots steam and partially melted tar sands into the sky, like one Devon Energy caused in the summer of 2010 by using too much pressure.

At Christina Lake, engineers inject roughly two barrels of steam to pump back out one barrel of bitumen. All that steam—and the natural gas burned to heat it—means melting bitumen results in two and a half times more greenhouse gas pollution than surface mining, itself among the highest emitters for any kind of oil production. Greater production by this melting method has caused greenhouse gas emissions from Alberta's tar sands to rise by 16 percent since just 2009, according to the Canadian Association of Petroleum Producers. In 2012, for the first time, underground production of tar sands in Alberta equaled that of surface mining, and thanks to efforts such as Christina Lake, it will soon become the primary mode of production.

In situ production works only for bitumen that is buried below 200 meters, however. That leaves a gap of 120 meters or so that is too deep for surface mining but too shallow for in situ. So far engineers have not figured out how to tap the gap, which means burning all the fuel contained in the tar sands deposits is an unlikely prospect at present.

Yet burning a significant portion of tar sands will go a long way toward blowing the planet's carbon budget. The only way to do so and stay on budget would be to stop burning coal or other fossil fuels—or to find a way to drastically reduce tar sands' greenhouse gas emissions. Neither prospect seems likely. Tar sands “emissions have doubled since 1990 and will double again by 2020,” argues Jennifer Grant, director of oil sands research at the Pembina Institute, a Canadian environmental group.

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Is it unfair to single out the tar sands? After all, other forms of fossil fuel add more to the world's carbon budget, yet they do not draw as much ire. Perhaps they should. In 2011 U.S. coal-fired power plants emitted nearly two billion metric tons of greenhouse gases—roughly eight times the amount produced by mining, refining and burning tar sands. Many coal mines around the world create just as visible a scar on the landscape and an even bigger climate change legacy. Yet mines like those in Montana and Wyoming's Powder River Basin are not the targets of high-profile protests such as those facing Keystone XL; protesters do not tie themselves to the tracks to block the kilometers-long trains that carry coal from the basin day after day. The U.S. Geological Survey suggests that basin alone holds 150 billion metric tons of coal that could be recovered with existing technology. Burning it all would send the world flying beyond any trillion-metric-ton carbon budget.

Australia's plan to expand coal exports to Asia could add 1.2 billion metric tons of CO2 to the atmosphere each year when that coal is burned. That amount dwarfs emissions from even the most optimistic tar sands expansion. The U.S. and countries such as Indonesia are also planning coal expansions. Shutting down or even curtailing the U.S. coal industry would more than compensate for any tar sands development as a result of Keystone XL, although the two fossil fuels are used for different purposes—coal for electricity, oil for transportation.

Canada also offers a target of some convenience, given that it is a friendly democracy susceptible to environmental pressure. Producers of “heavy oil”—similar in pollution to tar sands bitumen—in Mexico, Nigeria or Venezuela do not find themselves under as much scrutiny despite high rates of CO2 pollution. In fact, scouring such heavy oil from an old field in California is the single worst CO2 polluter among all oil-extraction efforts in the world, including the melted tar sands. “If you think that using other petroleum sources [than tar sands] is much better, then you're delusional,” says chemical engineer Murray Gray, scientific director of the Center for Oil Sands Innovation at the University of Alberta. “Increasing coal use worldwide gives me a lot more pause.”

These other sources of petroleum are not growing anywhere near as fast as Alberta's oil sands, where in the past decade production increased by more than a million barrels a day. To keep to the atmospheric carbon budget, the world must produce less than half of the known and economically recoverable oil, gas and coal reserves. That means much of the fossil fuel—especially the dirtiest forms of petroleum, such as that produced from the tar sands—will have to stay buried.

Economic forces may come to the aid of the global environment. Fracking for oil in North Dakota's portion of the Bakken Shale has begun to depress U.S. demand for Canada's dirty oil; in response, new infrastructure projects in Alberta's tar sands, such as the $12-billion Voyageur mini refinery, have been dropped. New mandatory fuel-efficiency standards for U.S. cars will reduce demand as well, at least in the short term. Regardless, the tar sands will be there, waiting, an ever tempting target for future extraction once the easier oil runs out.

If the Keystone XL pipeline is approved or other means are built to get the tar sands oil to China, exports could continue to rise, accelerating the invisible accumulation of CO2 in the atmosphere. Instead of reducing emissions by 2.5 percent a year, starting now—the effort Oxford physicist Allen calculates is necessary to keep the planet clear of the two degree C threshold—global greenhouse gas pollution will continue to increase. Every bit of carbon from burning fossil fuels—tar sands or otherwise—counts. 

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