Environmental Engineering Reference
In-Depth Information
via agricultural commodity markets. For example, if a soy fi eld in the US is switched
to corn to make ethanol, than soy production will likely expand elsewhere either do-
mestically or internationally. A full accounting of the demand and supply curves of the
various agricultural crops, biofuels, and their coproducts is beyond the scope of this
project, but is an active area of research [18, 29-31].
Estimating the areal impact of fossil fuels was done in an analogous manner.
The EIA analyses divided domestic coal production into three geographic regions
(Appalachia, Interior, and West). We separated the coal produced in each region into
the proportion mined underground and the proportion mined at the surface, using
EIA's factsheet on coal production in the US. Then, using data on the amount of coal
removed per unit area, we calculated area impacted (Table 2). For this analysis, we
ignore the relatively small areal impact of coal burning power plants, which comprise
a small fraction of the areal impact of coal mining.
For oil production, the EIA estimated imports as well as domestic production from
three geographic regions: the land surface of the contiguous 48 US (lower 48 onshore);
water bodies in or close to the contiguous 48 US (lower 48 offshore) and the state of
Alaska. Note that because EIA assumes existing law will continue, including the ban
on new oil drilling in the Arctic National Wildlife Refuge, Alaska oil production actu-
ally falls slightly under all scenarios. Based on historical data from the United States
Geological Survey (USGS), we estimated the proportion of oil production that is from
oil wells (as opposed to incidental production from gas wells) and the average number of
barrels per day per development well (Table 3). We also estimated the number of devel-
opment wells that are abandoned per year. Using these data, we calculated the number of
new development wells needed to maintain current production and the number of wells
needed to achieve any production increase forecasted by the EIA. By using this approach
we are accounting for the tendency of older wells to fall in production over time and be
abandoned, necessitating new wells just to maintain current production levels.
Table 3.
Land-use intensity of oil and natural gas production.
Natural
Resource
Proportion from
well type
Average produc-
tion
Most
compact
(ha/well
Least
Compact
(ha/well)
Notes
Oil
0.862 from oil wells
for onshore produc-
tion in lower 48,
0.636 for Alaska.
1.14 m3/day of
crude from lower
48 onshore, 56.13
m3/day of crude
from Alaska
onshore.
5.67
32.38
See text for estimation of trends in
oil production. Pinedale Anticline
spacing is taken as most-compact
estimate and Jonah fi eld spacing as
least-compact estimate.
Natural Gas
0.948 from natural
gas wells for U.S.
onshore.
5.67
32.38
As above.
2,821 m3/day of
dry natural gas
from U.S. onshore.
For each geographic region (lower 48 onshore, lower 48 offshore, and Alaska), we used estimates of the proportion of
the resource that is withdrawn from each type of well and average well productivity, as well as least-compact and most-
compact estimates of the area affected by each well, in hectares per well. Impact for wells is defi ned as both the well
area and the surrounding habitat fragmented by wells, access roads, and other structures. See text for details on impact
calculations of oil and gas pipelines.
doi: 1 0.1371 /journal.pone.0006802.t003
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