The biofuels industry claims its fuel is
unfairly singled out by potential regulatory policies that
focus on greenhouse gas (GHG) emissions associated with land
use change. It argues that petroleum also causes land use
change impacts and should be similarly judged in any such
regulatory scheme. In an effort to contribute to the scientific
analysis of this debate, an international research team, led by
University of CaliforniaDavis research engineer Sonia
Yeh, has published one of the first estimates of land use
change GHG emissions from petroleum production.
The teams findings conclude that emissions released
from land disturbed by certain fossil fuel extraction methods
can be comparable to, or are higher than, emissions from land disturbed by
farming crop-based biofuels (when measured as tons of
carbon emitted per unit of land
disturbed). However, when measured per unit of energy produced,
the land impacts of even the most high-impact fossil fuels are
a tiny fraction of those of biofuels.
We started this because of the current policy debates, said Ms. Yeh,
who acknowledged that regulators and researchers believed the
land use impacts of petroleum production were minimal when
compared to biofuels. She and her team, under contract with the
California Air Resources Board, set out to test this belief.
It turns out that, while many researchers have looked at
land use impacts of biofuels, few have looked at the
land use impacts associated with oil.
The research team focused on the land use impacts of heavy
crude oil extracted in California and in Albertas
Canadian oil sands (Fig. 1). The study examined conventional
extraction methods, such as drilling, which occurs in
California and Alberta, and nonconventional extraction methods
in Alberta. Nonconventional extraction methods include surface
strip mining of the bitumen soil and in-situ recovery, where
steam is injected into a deep well. The researchers first
estimated the amount of land impacted by the different
processes, and then calculated the GHG emissions from the land
Fig. 1. Oil sands
operation in Athabasca, Alberta, Canada.
Photo courtesy of NASAs Earth
To estimate the amount of land affected by conventional
processes (about half of Albertas output is
conventional), they applied a custom software program to Google
Earth images of the land disturbances, such as well pads,
pipelines, access roads and seismic surveys. They found that
the land use impacts of conventional oil extraction methods are
limited, compared to nonconventional oil sands processes.
To estimate the land use impacts of oil sands processes, the
study relies on the earlier findings of co-authors Sarah
Jordaan and David Keith from the University of Calgary. Land
disturbance for in-situ recovery includes central processing facilities and networks of seismic
lines, roads, pipelines, well pads, and upstream land use
disturbance for natural gas production (a key fuel used in the
in-situ production process). In surface mining, a large area is
cleared of all vegetation and then excavated. The total land
disturbance includes a mine site, overburden storage, and
tailings ponds, which not only cover large areas of
land but are also high in chemical wastes and toxic substances.
The team found that the impacts of the oil sands processes can
be significant for three reasons.
First, the surface mining process disturbs enormous amounts
of land rich in carbon deposits. Second, only 12% of
the total oil sands surface mining area in Alberta is reported
as reclaimed, which means the land impact is prolonged. Third,
the use of tailings ponds makes the land unavailable for
reclamation and carbon sequestration.
Improved restoration practices could significantly reduce
GHG emissions and, therefore, the land and GHG impact, said Ms.
Yeh. Companies can reduce emissions from tailings ponds by
employing strategies to facilitate sedimentation, reduce
tailings size, and more quickly return the land to its natural