Oil Sands Development: A Health Risk Worth Taking?
Tenenbaum, David J., Environmental Health Perspectives
As traditional petroleum supplies dwindled and prices soared over the past few years, oil companies have shifted their attention to oil sands, a mix of sand, water, and a heavy, viscous hydrocarbon called bitumen that can be converted to oil. With the plunge in oil prices in fall 2008, many producers began canceling or postponing plans to expand oil sands development projects, but this turn of events could yet reverse, as Canada's vast oil sands deposits are lauded as a secure source of imported oil for the United States. At the same time, however, oil sands present troubling questions in terms of the environmental health effects associated with their development.
Oil sands are found in about 70 countries. Alberta, Canada, is home to the largest known oil sands deposits, underlying about 140,000 square kilometers of boreal forest. In the 2006 report Alberta's Energy Reserves 2005 and Supply Outlook 2006-2015, the entity then known as the Alberta Energy and Utilities Board estimated the amount of recoverable oil in Canada's oil sands at 175 billion barrels, second only to Saudi Arabia's reserves (which consist largely of conventional oil).
Other major deposits are located in Venezuela and Utah. According to figures cited by Argonne National Laboratory, the Utah deposits, if developed, could yield 12-19 billion barrels of oil. However, says Philip Smith, a professor of chemical engineering and director of the Institute for Clean and Secure Energy at the University of Utah, the Utah bitumen cannot be recovered using the water-intensive technologies pursued elsewhere for one simple reason: "In Utah, we just do not have that kind of water."
Over the past five years, production at Canada's oil sands has reached about 1.3 million barrels per day, more than 1% of global oil production, according to the Canadian Association of Petroleum Producers (CAPP). This constitutes the bulk of the 1.9 million barrels Canada exported to the United States each day in 2008, an amount equal to 12% of U.S. total petroleum consumption, says Greg Stringham, vice president for oil sands at CAPP. In North American Oil Sands: History of Development, Prospects for the Future, a report last updated in January 2008, the Congressional Research Service estimated production would soar to 2.8 million barrels per day by 2015.
Shallow deposits containing about 8-20% of Alberta's oil sands (depending on the estimate) are surface mined using giant shovels and enormous trucks. Deeper deposits more than 75-80 meters underground are accessed using methods such as steam-assisted gravity drainage, in which steam is used to heat the bitumen so it becomes fluid enough to be pumped to the surface. This is known as in situ production.
Unprocessed oil sands contain 3-18% bitumen by weight, along with 2-10% water and 80-85% mineral matter (sand, clay, etc.). Bitumen is composed chiefly of polycyclic aromatic hydrocarbons (PAHs), sulfur, lead, mercury, arsenic, nickel, vanadium, chromium, and selenium. It contains for more carbon and far less hydrogen than conventional crude oil; mixed with crushed stone, bitumen forms asphalt pavement. Once the bitumen is separated from the ore, it is "upgraded" through the addition of hydrogen and the subtraction of carbon, and natural gas is added to enable the material to the pumped to a refinery for processing. The remaining water and solids, including a small amount of unextracted bitumen, are discharged into vast tailings ponds.
Tailings: A Threat to Water Quality
A good deal of the controversy about oil sands development centers around those tailings ponds, which cover more than 130 square kilometers in northern Alberta, according to the 2008 report 11 Million Litres a Day: The Tar Sands' Leaking Legacy from Canada's Environmental Defence. Some large tailings ponds are separated by earthen dikes from the Athabasca River, which joins the Mackenzie River to form the major watershed of Northwest Canada. …