HRW. Issue: July 2009
Подождите немного. Документ загружается.
www.hydroworld.com July 2009 / HRW 19
Wind turbines provided about 10 percent of the elec-
tricity production in Spain. Spanish utility Iberdrola,
the largest producer of wind energy in the world,
had installed wind capacity worldwide of 9,302 MW.
The utility is building pumped-storage facilities to
help fi rm the variability of its wind capacity.
http://hrw.hotims.com RS #13
Visit us at Waterpower XVI, Booth 4012
peak electricity demand.
After conventional hydro, pumped-
storage plants are the best choice to rm
the variability of wind. Power from these
plants is available without the restrictions
inherent in conventional hydro plants.
A disadvantage of this technology is its
“fuel cost.” However, in systems with a
signi cant quantity of thermal generation,
this risk is quite limited because off-peak
prices usually drop considerably due to
the fact that these stations cannot perform
start ups and shutdowns on a daily basis.
Conventional thermal
The start-up and shutdown capacity of a
conventional thermal plant is limited, for
two reasons. First, its start-up process
requires a substantial amount of energy,
which involves a substantial cost. Sec-
ond, performing continuous start ups
this type of plant, the main disadvantage
is their high fuel cost (40 percent greater
than those of combined cycle plants).
Combined cycle
From the exibility point of view, these are
and shutdowns signi cantly reduces the
service life of the plant.
The regulation velocity of conven-
tional thermal stations is limited to about
1 percent per minute, due to their high
thermal inertia. However, their control
range is acceptable, given that the tech-
nical minimum lies at about 45 percent
of maximum power.
Open cycle gas
This type of technology involves signi -
cant exibility for continuous start ups and
shutdowns. In addition, it allows relatively
rapid power variations, with a change ve-
locity of about 4 percent per minute.
On the other hand, the minimum power
of these plants usually is about 60 percent
of full load, which limits their regulation
capacity to 40 percent of rated power.
Despite the technical advantages of
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
______________
Our HyService is electrifying!
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
www.msw.de
Why do more hydro power owners
choose Voith Hydro as their reliable
partner for services, products and
solutions? Because of our exper-
tise. We are the preferred supplier
of state-of-the-art hydro power
generation equipment, solutions
and service: HyService!
Our service, maintenance and
operational skills are unsurpassed.
Whether you want us to trouble-
shoot a generator or upgrade an
entire facility, you get the best
service through HyService!
www.voithhydro.com
http://hrw.hotims.com RS #14
Visit us at Waterpower XVI, Booth 1000
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
____
_______________
22 HRW / July 2009 www.hydroworld.com
http://hrw.hotims.com RS #15
Visit us at Waterpower XVI, Booth 606
Because of its rapid development of new
wind turbine installations, Iberdrola is
continuously seeking to broaden its port-
folio of pumped-storage stations. It can be
dif cult to nd suitable sites that permit
the construction of pumped-storage sta-
tions at a moderate investment cost. Even
in systems where suitable sites are avail-
able, the investment cost of this type of sta-
tion is very high, which obliges developers
to assume a very high risk during the long
periods of amortization required.
Iberdrola’s most recent activity to add
to its pumped-storage portfolio involves
expansion of the existing 635-MW La
Muela plant with the installation of a sec-
ond powerhouse. La Muela began operat-
ing in 1989. Construction of 852-MW La
Muela 2 began in 2006 and is expected
to be complete in 2012. The new power-
house will contain four sets of generators
In the case of systems with low levels
of hydro generation, a mixture of open
cycle and combined cycle power plants
is the most viable alternative to rm the
variability of wind.
Iberdrola’s pumped storage
development activity
Iberdrola has always sought to develop
technologies that provide low greenhouse
emissions. In fact, the company has about
10,000 MW of hydro capacity world-
wide, including more than 8,800 MW
in Spain. Of this 8,800 MW, more than
2,300 MW is pumped storage. Ibderdro-
la’s plants represent 47 percent of the
installed hydro capacity in Spain. This
large portfolio of hydropower plants has
allowed Iberdrola to maximize the prof-
itability of its wind turbine installations
from the moment of their construction.
between conventional thermal stations and
open cycle turbines. Thus, with respect to
conventional thermal stations, they are
more robust to perform continuous start
ups and shutdowns, due to the greater
exibility provided by the gas turbine.
With regard to the regulation veloc-
ity, it is about 2.5 percent per minute,
slightly lower than open cycle turbines,
because of the higher thermal inertia of
the combined cycle’s conventional part.
Lastly, the minimum power of these
plants is nearly 50 percent of the power
at full load.
After conventional hydro and pumped
storage, combined cycle plants are the
next most likely option to rm the vari-
ability of wind. These plants can render
regulation services at a moderate variable
cost, although qualitatively higher than
conventional hydro or pumped storage.
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
___________
www.hydroworld.com July 2009 / HRW 23
http://hrw.hotims.com RS #16
(supplied by Alstom) and pump-turbines
(supplied by Voith Hydro). Fomento de
Construcciones y Contratas, S.A. (FCC)
of Spain is the civil contractor for La Mu-
ela 2, and a consortium of Alstom, Sacyr
Vallehermoso, and Cavosa is supplying
the penstock. Ingenieria y Construccion
S.A.U. (Iberinco) is performing the engi-
neering work for La Muela 2.
In addition to this plant currently
under construction, Iberdrola plans to
develop the Alto Tomega hydroelectric
complex in Portugal. Construction of
the 1,200-MW complex involves build-
ing four dams and four power stations,
two of which will be pumped-storage fa-
cilities. The two pumped-storage plants
will be 779-MW Gouvaes and the 112-
MW Pradoselos. Construction on this
complex is proposed to begin in 2010
and be completed in 2018.
Accordingly, Iberdrola is involved in the
development of several of these plants.
When completed 2018, they will provide
nearly 1,750 MW of capacity to the elec-
trical system in Spain and Portugal.
■
Note
1
Nielsen, Henrik Aalborg, et al, et al. “From
Wind Ensembles to Probabilistic Informa-
tion about Future Wind Power Production
– Results from an Actual Application,”
9th International Conference on Probabi-
listic Methods Applied to Power Systems,
Royal Institute of Technology, Stockholm,
Sweden, 2006.
Reference
Carlsson, Frederik, and Viktoria Neimane,
“A Massive Introduction of Wind Power.
Changed Market Conditions?” Elforsk
Report, Elforsk, Sweden, June 2008.
Finally, Iberdrola is considering sev-
eral other locations for pumped-storage
facilities. Among these is the 750-MW
Santa Cristina plant in Spain.
Summary
Wind power is a generating technology
that is included in many countries’ electri-
cal systems and permits a substantial re-
duction in emissions of greenhouse gases.
However, the increasing penetration of
this technology in current electricity sys-
tems requires a substantial increase in the
resources required to balance generation
and demand, as well as additional invest-
ments to guarantee the continuity of elec-
tricity supply when wind intensity is low.
Of all of the available technologies in
current electricity systems, pumped-stor-
age plants constitute the most attractive
option for rming the variability of wind.
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
___________
____________
___
24 HRW / July 2009 www.hydroworld.com
Marla Barnes is Publisher,
Hydro Group, for
PennWell Corporation
B
y 2020, a fth of all energy consumption in
European Union (EU) member countries
must come from renewable sources — hydro,
wave, solar, wind, and biomass. This mandate,
which EU leaders signed in March 2007, is part of
a proposal designed to cut greenhouse gas emis-
sions by 20 percent (compared with 1990 levels).
For hydroelectric power, this mandate trans-
lates to signi cant growth in development of new
capacity and in upgrading of existing facilities
throughout Europe.
Several new conventional hydroelectric proj-
ects entered commercial operation in the past
few months … something not seen in several de-
cades. Examples of new projects include: Sonna
in Norway (270 MW), Glendoe in the United
Kingdom (100 MW), and Blanca in Slovenia
(42.5 MW).
For small hydro (less than 10 MW), devel-
opment opportunities are signi cant. Provided
the mandate by EU member countries is imple-
mented on a timely basis, the European Small
Hydropower Association (ESHA) estimates that
installed small hydro capacity could reach 16,000
MW by 2020 — a more than 4,000-MW increase
over current levels.
Another area of signi cant growth for the
hydropower sector in Europe, especially in the
central region of the continent, is in pumped stor-
age. In addition to supplying additional electricity
during times when demand for power is highest,
pumped storage’s ability to balance power pro-
duction and regulate the transmission network, in
light of increased use of intermittent renewables,
particularly wind, is attractive.
As many as ten pumped-storage facilities are
under construction, including 178-MW Avce in
Slovenia, 540-MW Kopswerk 2 in Austria, 480-
MW Limberg 2 in Austria, and 141-MW Nestil
in Switzerland. Several more potential projects
are being investigated.
Europe also is an established leader in research
and development of new technologies — ocean,
wave, and hydrokinetic. Thirty years ago, the
United Kingdom had the most aggressive wave
power research and development program in the
world. This commitment to research and devel-
opment, as well as to commercialization of new
designs, continues today throughout Europe.
Installed hydropower in Europe totals ap-
proximately 179,000 MW. European countries
with the largest amounts of hydro include France,
Italy, Norway, and Spain. Maintaining and, in
many cases, upgrading, this existing infrastruc-
ture continues to be an important focus through-
out Europe.
The emphasis in Western Europe is retro tting
hydro plants with modern equipment, usually
upgrading the capacity of the plant. In Eastern
Europe, the focus is rehabilitating aging plants
that often were allowed to deteriorate during the
era of the Soviet Union.
Numerous utilities are committing signi cant
resources to upgrade entire portfolios. For ex-
ample, here in France, national utility Electricite
de France (EDF) is investing more than 2 bil-
lion euros (US$2.5 billion) as part of France’s
economic stimulus program, including spending
on modernization of hydroelectric projects. In
recent months, EDF has issued several solicita-
tions for hydropower equipment and other work
for its many projects, including up to 50 turbine-
generators over ve years.
— Editors of HRW magazine and HydroWorld.
com continually track European project construc-
tion and rehabilitation progress. To regularly follow
hydropower development and rehabilitation activity,
bookmark www.hydroworld.com.
■
Hydropower in Europe:
Current Status, Future Opportunities
Outlook
By Marla J. Barnes
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
http://hrw.hotims.com RS #17
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
26 HRW / July 2009 www.hydroworld.com
Imran Sayeed is chief
(geology) for NHPC Limited,
which develops and
operates hydroelectric
projects in India.
This article has been evaluated
and edited in accordance with
reviews conducted by two or
more professionals who have
relevant expertise. These peer
reviewers judge manuscripts for
technical accuracy, usefulness,
and overall importance within
the hydroelectric industry.
Civil Construction
Project Development in the Himalayas:
Solving Geotechnical Challenges
During hydro project construction in the Himalayas, Indian utility NHPC Limited has faced
multiple geotechnical challenges. To overcome these, the company has implemented a
number of solutions, including providing adequate reinforcement for rock slopes and choos-
ing tunneling practices to best deal with the rock conditions.
layas. In addition, construction is under way on
800-MW Parbati 2 with its 31.5-kilometer-long
headrace tunnel and 3,000-MW Dibang with a
288-meter-high dam, which will be the highest
concrete gravity dam in the world.
Hydro development in the Himalayas
The Himalayas are the world’s highest moun-
tain range, with more than 100 peaks attaining
a height above 7,200 meters. In India, the Hima-
layas run, from west to east, through the states of
Jammu and Kashmir, Himachal Pradesh, Uttra-
khand, Sikkim, Arunachal Pradesh, and Assam.
The Indus, Ganges, and Brahmaputra riv-
ers arise in the Himalayas and ow toward the
northern plains in India. These rivers are fed
by the permanent snow line and glaciers in
the summer and by heavy rainfall during the
monsoon season. This arrangement of a steep
fall in the Himalayan river beds, together with
perennial discharge, forms an ideal setting for
hydropower development.
Geotechnical challenges and solutions
In the Himalayas, the geological challenges
occur in part from the fact that this mountain
range evolved due to the collision of the Aus-
tralasian and Eurasian plates. The rocks were
thrown into several folds and fault zones, giv-
ing rise to a disturbed rock mass traversed by
several discontinuities. Geotechnical challenges
that must be solved include: assessing foundat ion
conditions, ensuring stability of high cut rock
slopes, securing rock slopes during construction
I
n India, the Himalaya mountain range has
enormous untapped potential for hydro devel-
opment. According to the Central Electricity Au-
thority of India, about 80 percent of the 148,700
MW of hydro potential in the country comes from
rivers that arise in the Himalayas. In fact, only 2
percent of the potential in northeastern India and
24 percent of the potential in northern India has
been developed.
One signi cant challenge in developing this
potential is the structurally unsound rock and
other issues related to the complexity of the re-
gion’s geology. Throughout 33 years of develop-
ing hydro projects in this area, NHPC Limited
(formerly known as National Hydroelectric Power
Corporation Limited) has developed solutions to
a number of geotechnical problems. For example,
it is possible to successfully excavate underground
powerhouses or make high cut slopes for spillways
or surface power stations in the Himalayas by
carrying out detailed investigations and using ap-
propriate rock support systems. Other challenges
for which NHPC has developed solutions include
dealing with dif cult foundation conditions, lo-
cating construction materials, and tunneling in
uncertain rock conditions.
Experience shows that it is feasible to build
large dams in the Himalayas despite constraints
the geology imposes. For example, the highest
concrete gravity dam (Bhakra Dam), highest
rock ll dam (Tehri Dam), longest headrace tun-
nel (associated with the 1,500-MW Nathpa Jhakri
project), and largest underground powerhouse
cavern (Tehri) in the country are all in the Hima-
By Imran Sayeed
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
www.hydroworld.com July 2009 / HRW 27
Visit us at Waterpower XVI, Booth 3005
http://hrw.hotims.com RS #18
build a rock ll dam on a site with shal-
low bedrock.
Other factors — such as availability
of construction materials and capacity
required for the spillway — also plan a
major role in selecting the type of dam.
For concrete dams, proper investiga-
tion is required to determine the sub-sur-
overburden to this depth is feasible
without much dif culty. Deeper excava-
tion involves problems of seepage, slope
stability, and time required to complete
the work. However, if suf cient materials
are available for construction of a rock-
ll dam and an adequate spillway can be
provided, it could be less expensive to
of above-ground powerhouses, locating
construction materials, and tunneling
in uncertain rock conditions.
Assessing condition of the foundation
Rivers that arise in the Himalayas have a
high-velocity ow of water because of the
steep fall. The rivers often follow weak
zones of rock, such as faults. In these ar-
eas, deep erosion in the river bed may be
covered by loosely consolidated deposits.
These rivers often ow through narrow
gorges that may be the result of a major
discontinuity. Because of this situation,
there is a general tendency of an irregu-
lar deep bedrock pro le in many river
sections. Choices of viable dam sites of-
ten are limited, so proper site selection
in the deep gorges or even in relatively
wider valley sections that may have bur-
ied channels is quite challenging.
Choosing a site for a dam in the Hi-
malayas primarily requires careful as-
sessment of foundation conditions. For
rivers with deep bedrock (30 meters or
more deep), building a rock ll or con-
crete-faced rock ll dam (CFRD) with a
positive cutoff, such as a plastic concrete
diaphragm wall, is an effective measure
to avoid the need to excavate down to
the bedrock. For example, NHPC built
a CFRD at 280-MW Dhauliganga 1,
where the bedrock was 65 to 70 meters
deep. NHPC also used this solution at
520-MW Parbati 3, which features a
conventional rock ll dam with a clay
core and a cutoff wall to a depth of 40
meters. Rock ll was chosen over CFRD
for this site because it is less expensive
than excavating to bedrock and avoids
the construction risk involved in this
practice. In addition, transporting a
large quantity of cement to the remote
location would be challenging.
If the bedrock is shallower than 30
meters, construction of a concrete dam
may be a better option. Excavation of
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
_______________
28 HRW / July 2009 www.hydroworld.com
Construction of a positive cutoff wall is one solution for dealing with deep bedrock conditions in rivers in the
Himalayan mountain region.
face bedrock pro le, as well as the founda-
tion conditions. In situations where there
is a large deviation in foundation depth,
problems may include increased excava-
tion, water seepage, and large increases
in concrete. This can cause problems
with regard to a project’s construction
schedule. In addition, provisions may be
required for treatment of shear zones. For
the concrete dams built to impound water
for the 540-MW Chamera 1 and Parbati
2 projects, NHPC was able to use a care-
fully planned drilling program to predict
the bedrock conditions quite accurately.
Ensuring stability of rock slopes
There are several projects in the Hima-
layas that may involve slope cuts more
than 50 meters high. This includes ex-
cavating for building side channel spill-
ways at rock ll dams or for removal of
weathered or slumped rocks, which typi-
cally are present at many sites in the Hi-
malayas. Removal of these rocks may be
needed to provide a sound foundation
for placement of the dam and a proper
junction between the dam body and
abutments, or for building side channel
spillways at rock ll dams. Rock condi-
tions play a pivotal role in the design of
such slopes and the need for adequate
rock reinforcement.
For 280-MW Dhauliganga 1, a high
Building above-ground powerhouses
For hydro projects in the Himalayas that
involve surface powerhouses, slope sta-
bility is a problem. Because of the narrow
con guration of the valleys, space must
be created for powerhouses by cutting the
hill slope. For Parbati 2, a surface power-
house with hill cutting of 100 of 125 me-
ters was planned. This powerhouse is in
meta-basics and chlorite schists/phyllites
with three sets of joints. This slope has
suffered three collapses due to the deep
cutting. Redressing of the slope with
heavy supports is under way. The sup-
port elements consist of 35-meter-long
cable anchors, 6- to 12-meter-long rock
anchors, shotcrete, and wire mesh. The
entire slope is expected to be completed
by the end of 2009.
As the above example illustrates, ex-
ecution of slopes, particularly in adverse
rock conditions, remains a challenge.
Depending on the slope height and rock
conditions, heavy supports may be re-
quired. Generally, for high slopes there
is considerable provision of support
measures. These supports include long
rock bolts or anchors (9 to 15 meters),
cable bolts, treatment by injection of
grout, and/or use of reinforced concrete
plugs to make small horizontal tunnels
into the slope. Proper drainage arrange-
ments also are necessary.
Accordingly, it is important to provide
suf cient time in the schedule for instal-
lation of systematic supports during
excavation. The amount of time needed
depends on the magnitude of the work.
The Bureau of Indian Standards
publishes codes of practice for geologi-
cal investigation for dams and power-
houses,
1
which are followed in India to
perform river valley investigations. In
view of the problems faced in the Hi-
malayas and also based on the successes
achieved at some projects, the following
steps are recommended for deep open
slope cut was to be executed on the right
bank in strong biotite gneiss of Pre-Cam-
brian age. However, the joint patterns of
this rock were such that prominent un-
stable wedges formed. When the excava-
tion work began in 2000, blocks as large
as 10,000 cubic meters in volume started
to fall from the cut slope.
To solve this problem, NHPC engi-
neers proposed special support measures
apart from modifying the slope of the
rock. Rock supports already proposed
for the situation included 18-meter-long
cable bolts; 9-, 12-, and 15-meter-long
rock anchors; shotcrete; and wire mesh.
The special measures involved reinforc-
ing the rock mass by driving 30-meter-
long tunnels, with additional cross-cuts,
into the hill slope and then back- lling
the tunnels and cuts with concrete and
steel. This solution stabilized the slope
and enabled the project to be commis-
sioned on schedule in March 2005.
In this case, the large size of the blocks
was detrimental to slope stability and
necessitated modi cations to the slope
angle, as well the support measures. The
key to success for a high slope excavation
lies in proper investigations, design, and
support provisions and careful execution.
This arrangement is described below for
surface powerhouses where high open
cuts may be involved.
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F
||| | | |
Previous Page Contents Zoom in Zoom out Front Cover Search Issue Next Page
HRW
B
A
M
S
a
G
E
F