Why Scientists Are in Alarm Mode Over the Keystone XL Pipeline
Continued from previous page
Listening to Woodwell explain the role of the tundra and forests in carbon sequestration, it became evident where his years of scientific research and the Keystone XL pipeline intersect. The tar sands are largely mined in northeastern Alberta in an area classified as boreal forest.
The boreal forest, or taiga, is the largest forest in the world. It is a circumpolar biome—a community of related plant and animal species fostered by a similar climate—occurring at high-altitudes across Alaska, Canada, Northern Europe, and Russia. The boreal forest exists on 14.5 percent of the earth’s surface, but contains over 30 percent of the earth’s terrestrial carbon. The forest in its natural state is considered a sink: a repository for carbon. If disrupted, it becomes a source, releasing carbon back into the atmosphere.
Mining the Tar Sands
Techniques used to extract the tar sands are more akin to mining than drilling, both in the methods employed and amount of land destruction necessary for the removal of a tarry, viscous hydrocarbon called bitumen. Two techniques are used: in situ recovery and surface mining.
In situ recovery begins with drilling wells into bitumen deposits then injecting steam into the reservoir. The steam reduces viscosity and enables the bitumen to be pumped to the surface.
Surface mining, also referred to as strip mining, entails clearing large swaths of land. The forest is first cut down, followed by the removal of carbon-rich peat (the peat is put in storage for later usage in required remediation efforts). The bitumen and surrounding soils are then gouged out by heavy equipment. The usable hydrocarbon is separated on site using a caustic hot-water process, with the resultant wastewater sent to facilities for processing. The water is eventually stored in outdoor tailing ponds.
The tailing ponds, collectively covering more than 19 square miles, contain fine particulate matter and toxic chemicals (naphthenic acid and polycyclic aromatic hydrocarbons). These open ponds, also a part of required reclamation, allow fine particles to settle. The estimated time for settlement varies from several decades to 150 years.
The total amount of energy used in tar sands extraction and production results in greater amounts of greenhouse gas (GHG) emissions than from conventional sources of oil. The amount of increased emissions remains an issue of concern and calculation, though not all studies are equal.
The Department of Energy’s National Environmental Technology Lab estimated the GHG emissions of tar sands production to be “approximately 17 percent higher than gasoline from the 2005 average mix of crude oil consumed in the U.S.,” while a study conducted by TIAX, LLC, found emissions “only 2 percent higher when compared to gasoline from Venezuelan heavy crude.”
That’s a difference of 15 percent, though both reports used a “well-to-wheels” calculation. A well-to-wheels calculation factors in GHG emissions from extraction, processing, distribution, and combustion. But what about the additional emissions as a result of deforestation and the destabilization of associated soils—what scientists refer to as “land-use change”?
From Sink to Source
To some degree, this question is addressed in a paper by Yeh et al. (2010). In tar sands surface mining, by “removing the functional vegetation layer at the surface of a peatland, the disturbed ecosystem loses its ability to sequester CO2 from the atmosphere.” When peat is put into storage for later reclamation purposes, it decomposes, releasing CO2 and CH4 (commonly known as methane, one of six identified greenhouse gases). Over time, tailing ponds also produce CH4 emissions—a gas “25 times more potent than CO2.”
GHG emissions from land-use change factors in the loss of a sink (a natural system known to capture carbon), as well as the addition of sources (gases produced from stored peat and tailing ponds). I queried the State Department on whether these emissions had been considered in their estimates. The first spokesperson responded, “off the record, no.” The question was also submitted to the Clean Energy Branch of Alberta Environment, who quickly replied, “We have supported some scientific research in this respect; that work is currently in the peer review process so we cannot report on that work at this point in time.”