Environmental Engineering Reference
In-Depth Information
exploited by 2000 (IHA 2000). Europe has exploited
75% of all technically feasible capacity, North America
nearly 70%, but Asia has tapped less than 25% and Africa
less than 10% of this potential. The major advantages of
hydroelectricity are mature dam construction and turbine
manufacturing techniques, high reliability of generation,
ability to run at synchronized zero load (spinning re-
serve), rapid start-up during peak demand periods,
lowest operating cost, and longest plant life compared to
all other options and, of course, the renewability of water
flows. In addition, most hydro projects also provide wa-
ter for drinking or irrigation, control floods, and support
fisheries and recreation uses.
Hydroelectric generation began on a very small scale in
1882 (the same year as thermal production), and before
1900 new turbine designs and newly discovered dyna-
mite brought rapid advances in construction of increas-
ingly higher dams in Alpine countries, Scandinavia, and
the United States. After WW I came the start of state-
supported development of large hydro projects in the
United States (most notably the Tennessee Valley Au-
thority), and in the USSR (part of Lenin's drive for elec-
trification). The Grand Coulee dam, the large U.S.
project on the Columbia River, was completed in 1942.
Post-WW II worldwide expansion turned hydro power
from a globally marginal contributor to a source of nearly
20% of all electricity. The thermal equivalent used to
convert primary electricity to a common denominator
made global hydroelectricity generation equal to less
than 3% of global primary energy in 1950 and to just
over 6% in the year 2005.
The total number of newly built dams peaked in Eu-
rope and North America during the 1960s, in Asia and
Latin America during the 1970s, and in Africa during
the 1980s (WCD 2000). In 2000 the United States had
the largest number of plants with capacities in excess of 1
GW as well as the largest installed capacity (98.5 GW),
followed by Canada (66.8 GW), China (65.1 GW), and
Brazil (56.8 GW). The next year China took second
place, and by 2002 these four countries accounted for
43% of all installed hydro capacity and for 44% of all
hydrogeneration, which supplied 17% of global electric-
ity. Canada, the world's largest producer (just ahead of
China), derived nearly 60% of its electricity from water.
Hydrogeneration is even more important for many mod-
ernizing countries; the shares are over 90% in many Afri-
can countries and 80%-90% in South America. Most of
these countries also have considerable potential to de-
velop small-scale hydro resources, the sites with capacities
below 2 MW; China has led these efforts.
Peak technical achievements in large dam construction
are displayed in the earth-and-rock-fill Rogun Dam on
the Vakhsh River in Tajikistan (335 m high), completed
in 1985; the Nurek Dam on the same river (330 m high);
the Bratsk Dam on the Yenisey River in Russia (reser-
voir capacity @170 Gm
3
); Yacyretˆ embankment dams
(@65 km) on the Paran´ River between Paraguay and Ar-
gentina; and dam volumes in excess of 200 Mm
3
. The
largest turbines, invariably Francis machines, have rated
capacities of 700 MW; there are 26 of them in the
world's largest hydro station, China's 18.2-GW Sanxia
(Three Gorges) on the Yangtze (Chang) River. Other
large projects are hydroelectric plants at Itaip
´
on the
Paran
´
River between Brazil and Paraguay (12.6 GW),
Guri on the Caroni River in Venezuela (10.3 GW),
Grand Coulee on the Columbia River in the United
States (7.079 GW), and Sayano-Shushensk on the Yeni-
sey River in Russia (6.4 GW).
Hydrogeneration demands much space. The reservoirs
behind the world's large dams (higher than 30 m) now
