Environmental Engineering Reference
In-Depth Information
less intrusive than a massive coal pile or a huge sludge
pond of a suburban power plant. A relatively narrow cor-
ridor of land reserved for pipeline and transmission
rights-of-way sustains limited and temporary damage
during construction, and afterwards all the land, except
for the space occupied by towers or pumping stations,
can either return to its natural state or be used for graz-
ing, crop farming, or silviculture.
Still, even the transmission lines restrict land uses and
take away farmland. For farmers, the losses of cultivable
land are more than twice as large for transmission towers
sitting in field headlands than for those on fence rows,
and up to four times as large in row crop cultivation
than in hayfields. In contrast, the land occupied by ex-
traction facilities, buildings, and storage may never return
to its original use, and in the case of nuclear waste dis-
posal sites its occupancy may be indefinite. Land claimed
by surface coal mining illustrates the range of responses.
It can be completely and rapidly reclaimed as pasture,
cropland, forest, or a water reservoir, or left in a derelict
state for decades. Coal's land claims are further compli-
cated by the fact most unit trains share the railway
rights-of-way with other freight.
Nuclear power plants can be more compact than coal-
fired stations. Pressurized water reactors fission the
enriched uranium with densities of up to 300 MW/m
2
of the core's footprint, and the fenced plant sites, includ-
ing cooling towers and on-site storage of radioactive
wastes, rate up to 4 kW/m
2
. The need for substantial
low-population zones around the plants clearly limits the
type of land uses in their immediate vicinity while not
physically claiming any of the affected land. Moreover, it
remains uncertain what areas will be ultimately claimed
by long-term depositories of radioactive wastes. Al-
though they will be located in uninhabited and difficult-
to-access regions, the unending disputes regarding the
U.S. depository at Yucca Mountain in Nevada show that
even in such cases there may be protracted land use con-
flicts (Flynn 1995).
All of these uncertainties, and even more so the con-
siderable ranges of actual power densities for every major
category of harnessing and converting commercial ener-
gies, mean that any proffered global total of the land
claimed by the energy conversion and distribution can
only be a very rough quantitative estimate hiding many
qualitative differences. My calculations (based on liberal
assumptions) result in a maximum of 300,000 km
2
dur-
ing the early 2000s, an Italy-sized area, or roughly 0.25%
of the Earth's ice-free land. But less than 10% of it (an
area smaller than Belgium) is taken up by extraction and
processing of fuels and by thermal electricity generation,
and more than half is the land occupied by water reser-
voirs (fig. 11.3). Many of these have multiple uses (ir-
rigation, industrial and urban supply, recreation), and a
partial attribution of these large areas to electricity gener-
ation would reduce the overall claim to less than 200,000
km
2
. Leaving the reservoirs and transmission rights-of-
way aside, the global fossil-fueled system with through-
put of about 11.5 TW and overall land claims of no
more than 75,000 km
2
would average about 150 W/
m
2
.
A much more accurate, though still far from precise,
assay can be made for the U.S. fossil-fueled energy sys-
tem of the early 2000s, leaving aside not only nonfossil
electricity generation but also the rights-of-way of rail-
roads that are shared by coal trains. Despite its inevitable
deficiencies this calculation is quite revealing. Extraction
of all fossil fuels claims less than 500 km
2
, their process-
ing (including the refining of imported crude oil) needs
about four times as much land, and rights-of-way for oil
