Environmental Engineering Reference
In-Depth Information
thermal as two different energy production techniques, and we follow their convention
in our analysis. The EIA partitioned solar photovoltaic use between end-users, as-
sumed to have negligible land-use implications in our analysis, and large-scale genera-
tion, which does have signifi cant areal implications. We track end-use and large-scale
generation separately in this and other cases, following EIA's methodology.
Table 2.
Land-use intensity of production for coal mining.
Geographic
region
Proportion
surface
mining
Most compact
ha/mmt
Least Compact
ha/mmt
Notes
Appalachia
U.S.
0.352
11.6 pit, 79.1 surface
115.7 pit, 791.4 surface
Proportion of surface mining from
EIA's 2006 Coal production in the
United states fad sheet (uses 2003
data). Surface coal yields most
compact fi gure based on Spitzley
and Keoleian [3], least compact
fi gure on Flattop mine has 2.3
million tons of coal on 600 acres.
Pit mining assumed 10% of area as
surface mining.
Interior U.S.
0.643
11.6 pit, 79.1 surface
115.7 pit, 791.4 surface
As above
Western U.S.
0.898 11.6 pit, 79.1 surface 115.7 pit, 791.4 surface As above
Import 0.671 11.6 pit, 79.1 surface 115.7 pit, 791.4 surface Proportion surface mining assumed
to be same as overall U.S.
average.
For each geographic region of coal, we show the proportion of the coal that is from surface mines versus pit mines, as
well as least-compact and most-compact estimates of the area requirements of coal mining, in hectares per million metric
tonnes of coal. Impact for coal mines is defi ned as the area directly surrounding the mine site.
doi:1 0.1 371/journal.pone.0006802.t002
The EIA forecasts biofuel (ethanol, biodiesel, and other liquids from biomass)
production and total use, with the vast majority of use being ethanol in transportation.
Moreover, they estimate the proportion of domestic ethanol production from corn, cel-
lulose, and other feedstocks, as well as net imports of ethanol and biodiesel. For each
type of biofuel and its feedstock, we estimated least compact and most compact esti-
mates of the number of m
2
of feedstock cropland per liter of biofuel. In general, least
compact estimates are for current agricultural yields (kg/m
2
) and biofuel production
effi ciencies (l/kg), while most compact estimates are a product of future agricultural
yields and biofuel production effi ciencies. For some crops like soy, the difference in
least compact and most compact estimates is primarily due to a predicted increase in
yield, while for other biofuels like cellulosic ethanol the difference is largely due to
differences in biofuel production effi ciency.
For many biofuels, farmers also make a portion of their income from coproducts,
portions of the crop that are not used to make biofuels but have another economic
market. We use a market-value allocation approach, defi ning the actual increase in
production area of a crop as a function of the fraction of the economic value of the
crop that is embodied in the biofuel [28]. Note that our methodology tracks the direct
land-use needs of biofuel production, and does not consider indirect effects on land-use
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