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ICHPSD-2015
PROSPECTS OF DEVELOPING PUMPED STORAGE PROJECTS
UTILISING THE RESERVOIR OF EXISTING HYROPOWER
PROJECT IN THE STATE OF UTTARAKHAND
Rajendra Chalisgaonkar1 and Mukesh Mohan2
Chief Engineer, Projects/Garhwal, Irrigation Department, Uttarakhand, Dehradun.
2
Superintending Engineer, Irrigation Department, Uttarakhand, Dehradun.
1
ABSTRACT
The growing economy with corresponding increase in power demand causes more challenges
in power sector of developing countries. In India, the increase in peak power demand
necessitates energy storage schemes over and above the storage—hydro, oil and gas based
peak power plants to ensure power system stability. This growing energy demand has proved
to be one of the biggest challenges in ensuring a healthy economic growth rate of the country
and needs to exploit all its available natural resources to the fullest in order to bridge the
widening demand-supply gap in the power sector. Pumped storage hydroelectricity is a
method of storing and producing electricity to supply high peak demands by moving water
between reservoirs at different elevations. At times of low electrical demand, excess electrical
capacity is used to pump water into the higher reservoir. A pre-feasibility study conducted on
the Construction of Additional Pumped Storage Project on Ichari Dam Project has been
described in detail in the paper. The study clearly indicates that the Project is technoeconomically viable.
1.0
DEVELOPMENT OF PUMPED STORAGE PLANTS
The first known conceptual demonstration of pumped storage was seen in Zurich, Switzerland
in 1882 in which a reciprocating pump was proposed for energy storage. The first official
facility was opened in 1909 in Schlaffhausen, Switzerland with a capacity of 1500 kW and a
separate pump and turbine. Additional installations followed throughout Europe over the next
few decades. The extent of its development was largely increased by two particular
installations: The first plant over 20MW near Dresden, Germany in 1928, and the first largescale North American installation in Connecticut in 1929 which featured a reversible pumpgenerator. Early arrangements typically included a horizontal arrangement of a separate
pump/turbine assembly aligned with the generator/motor. Eventually, in the 1930s, reversible
pump turbines were introduced, the first installation occurring in Baldeney, Germany. This
advancement typically saved the cost approximately 30% while compromising on complicated
starting modes, efficiency, and long changeover times. Although this resulted in an efficiency
loss through compromise, the capital savings and system simplification were significant. This
particular technology underwent major development in the 1960-70s and is often used to date.
Since then, number of Pumped Storage Schemes have been constructed and are running
successfully all over the world.
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In India to fulfill the peak hour demand of electricity and due to increasing imbalance of
thermal: hydel mix, need for developing pumped storage schemes was realized as early in
1960. In India first pumped storage plant was built at Nagarjunasagar in Andhra Pradesh in the
year 1970 with an installed capacity of 700 MW. Since then, 11 pumped storage plants having
3604 MW total capacity have been successfully constructed in India, which includes
Srisailam(900 MW), Purulia(900 MW), Kadampani(400 MW), Ghatghar (250 MW),
Kadana(240 MW), Bhira(150 MW) Pumped Storage Projects and 1200 MW Sardar Sarovar
and 1000 MW Tehri Pumped Storage Plants are under construction. 56 major Pumped Storage
Schemes with total installed capacity of 96000 MW have been identified in the different part
of India.
2.0
FEASIBILITY OF CONSTRUCTING PUMPED STORAGE PROJECTS IN THE
STATE OF UTTARAKHAND
Being a very young and fortunate state, with rich biodiversity and natural resources,
Uttarakhand has the golden opportunity to adopt a sustainable development model of Pumped
Storage Projects for the comprehensive progress of all sections of the society, and to set an
example to other states of the union. In the context of the State of Uttarakhand, it is observed
that hydropower projects can run at their full potential only in the months of monsoon, when
water is available in plenty. For rest of the year, the water in the rivers is scanty and the power
generation varies accordingly and it is insufficient to cater the peak hour demands of the state.
The topography of the State provides an opportunity to build a number of Pumped Storage
Projects in different valleys of the State. As Pumped Storage Projects do not require a large
Reservoir as compared to the Conventional Hydropower Projects, the suitable sites can be
identified at various locations where a reasonably Small Reservoirs can be constructed at
different elevations. Pumped Storage Projects shall require Small Storage for 6 to 8 hrs. to
generate power during peak demand period and the water can be recirculated to the upper
reservoir by pumping from the lower reservoir during off peak hours. Also, due to small
reservoirs, such Projects will not have much Rehabilitation and Resettlement problems, which
is a big and problematic issue in conventional hydropower projects. Considering the variation
in power tariffs during peak and off peak hours, the Pumped Storage Projects can prove to be
techno-economically feasible alternative as the number of such Projects are running
successfully all over the world. Having realized the great important role to be played by
pumped storage plants as a means of meeting peak hour electricity demand, a pre-feasibility
study conducted on the Construction of Additional Pumped Storage Project on Ichari Dam
Project utilizing the existing reservoir has been described in detail in the paper and has been
discussed in detail in succeeding paragraphs.
3.0
ICHARI DAM PROJECT
Ichari reservoir is located on river Tons in the lower Shiwalik region of the Himalaya. The
river u/s of the dam flows forming loops. Tons valley is very narrow and the intervening hills
between the two main loops of the river between 3 km to 9 km upstream of the dam axis are
high and steep rising from about 900 m to 1500 m above the river bed level, the average river
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ICHPSD-2015
bed slope being of the order of 1/160. Under Yamuna Hydel Scheme Stage - II, a 155m long
and 59.25m high concrete dam was constructed at Ichari about 60 km from Dehradun across
river Tons, a tributary of river Yamuna, for diverting river water into a 7.0m DIA and 6287m
long concrete lined tunnel to feed the underground power station at Chhibro. Different views
of Ichari Dam Project have been depicted in Fig. 1.
The main tributaries of Tons river are Hate, Bamber, Rupin and Paber. The Tons river at
Ichari has a catchment area of 4913 km2. The catchment comprised the mountainous region,
partly covered with vegetations and varying in elevation from 608.000m to about 549.000m.
The annual rainfall in the catchment varies from 1200 mm to 1900 mm.
D/S View of Ichari Dam
3.1
U/S View of Ichari Dam
Fig. 1 : Ichari Dam Project
Ichari Dam Reservoir
Water Availability for Generating Power through PSP
The total storage capacity of the Ichari Dam at El. 644.75m is estimated to be about 5.59Mm3.
It is proposed to use Ichari Dam as Lower Reservoir and 380200m3 of water(about 9.20 % of
total storage capacity) of Ichari Dam has been proposed to be used for recycling for
generation of hydropower during eight peak hours. The water availability details and lowering
of water levels in the Ichari Dam are given in Table-1.
Table 1: Details of Lower Reservoir(Ichari Dam) Operation
Assuming Inflow Discharge to Upper Reservoir
a)
Reservoir at Full Capacity
Storage Capacity of Ichari Dam at 644.75m
Volume required for 8-hour generation(peaking hours) at 12 cumec
Total volume including 10% volume of water as evaporation, and
other losses
Dead Storage of Ichari Reservoir(Elevation 640.00m)
Live storage of Ichari Reservoir
% volume of water used for generation
Lowering in lower reservoir level (in 8 hours)
Lowering in lower reservoir level per hour
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12.0 cumec
5.59 Mm3
345600 m3
0.3802 Mm3
1.460
4.130
9.20
0.36
0.05
Mm3
Mm3
%
m
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International Conference on Hydropower for Sustainable Development
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Since only small fraction of the total storage capacity of the Ichari Dam shall be used for
generating hydropower, it has been assumed that almost for a year, the water shall be available
for generating hydropower during peak hours.
3.2
Artificial Upper Reservoir
It is proposed that an Artificial Upper Reservoir of size 200m x 200m x 15.5m shall be
constructed at an altitude of about El.1200.00m, nearly 500.00m above the Ichari Dam. The
artificial upper reservoir shall store about 380200 m3 of water for generating hydropower and
shall be connected to the lower reservoir by 1.00km long 1.75m diameter penstocks to
generate 50 MW of hydropower with gross head of 500m. It is assumed that total quantity of
water for 8-hours (both peaking) will be pumped in single pumping to the upper reservoir,
however, generation will be done twice. The location of the upper reservoir and water
conveyance system for the proposed Additional Pumped Storage Scheme for Ichari Dam has
been marked on the Satellite image obtained from Google Earth Software and the site
photograph in Fig. 2 and the design details of the Upper Reservoir are given in Table-2.
Artificial Upper
Reservoir
Power
House
Power
House
Google Image
Site Location
Fig. 2: Location of Additional Pumped Storage Project for Ichari Dam
Table 2: Design of Upper Reservoir
Total Volume of water required for 8-hour generation including 10%
volume of water as evaporation, and other losses
Diameter of Penstock (D)
Minimum water cover over centre line of pipe = 1.5D
Minimum clearance of pipe from reservoir bed
Minimum drawdown height from reservoir bed = 2 + 1.75/2 +2.625
= 5.50
Assuming size of reservoir as 200m x 200m, area =
Depth of water required
Taking operation margin & free board, provide Overall Depth of
Artificial Upper Reservoir
Thus, Overall size of Artificial Upper Reservoir : 200m x 200m x 15.5m
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0.3802 Mm3
1.75 m
2.625 m
2 m
5.50 m
40000 m2
9.50 m
15.50 m
ICHPSD-2015
3.3
Head Available for Power Generation and Installed Capacity
The gross head available for generating hydropower during peak hours shall be about 500m
and 12.0 cumec discharge shall be used for generating the hydropower through 1.0km long
1.75m diametre penstock. The head losses in penstock shall be of the order of 6.40m, thus net
head available for generating hydropower during peak hours shall be about 493.60m. Details
of Power generation are given in Table-3.
Table 3: Power Generation
Gross Head
Discharge
Diametre of Conveyance pipe
Velocity in conveyance pipe
Head Loss in Pipe
Length of pipe
Friction Factor
Head loss in pipe
Taking 10% minor losses, total head
loss
Net Head for power generation
Combined efficiency of turbine and
generator
Power Generation
500
12
1.75
4.99
m
cumec
M
m/s
1000 m
0.008
5.79 m
6.40 m
493.60 m
0.90
say
52.30 MW
50.00 MW
Based on the design discharge of 12.0 cumec, net head of 493.60 m and the combined
efficiency of machines as 90% for Turbine and Generator, the power potential is worked out
to be 50.0 MW. Machine availability has been assumed as 90%. Thus, two units of 25.00MW
are proposed for installation to utilize full available potential. The energy generation during 8peak hours from 50.0 MW Plant will be 138.7 million units per year.
4.0
TECHNO-ECONOMIC AND FINANCIAL VIABILITY
4.1
Civil Works Proposed for Additional PSP
For the proposed Additional Pumped Storage Project for Ichari Dam, the layout of scheme
shall comprise of Construction of Artificial Upper Reservoir connected to the Ichari Dam by
1.00km long penstock with surface power house located near Ichari Dam with two reversible
turbines of 25.00 MW each. Intake structures at Upper and lower reservoirs shall also have to
be constructed.
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4.1.1
Upper reservoir
An artificial upper reservoir of size 200mx200mx15.5m shall be constructed at El. 1200.00m.
The sides and bed of the upper reservoir has been proposed to be suitably lined to prevent
seepage and leakage. An intake with vertical gate shall also be provided at the upper reservoir
with trash rack to prevent any debris into the penstock.
4.1.2
Lower reservoir (Ichari Dam)
An intake arrangement shall have to be constructed at the Ichari Dam so that sufficient suction
head is available during pumping.
4.1.3
Penstock
1.0km long Steel pipes shall be provided to connect the upper reservoir and lower reservoir to
generate hydropower and pumping operations. The economical diametre of the Steel Penstock
was worked out to be 1.75m. The thickness of the pipe for different heads have been presented
in Table 4.
Table 4: Thickness of Penstock Pipes for Different Heads
Section
0 to 250m
250 to 500m
500 to 750m
750 to 1000m
4.1.4
Thickness Required,
mm
23.6
17.7
11.8
5.9
Actual Thickness,
mm
25.0
20.0
16.0
8.0
Power house & other E & M works
A surface power house and other E&M works as per the requirement and specifications of
reversible turbines shall be constructed to generate 50.0 MW hydropower.
4.2
Cost Estimate
The cost of various items have been taken on the basis of prevailing rates for similar items and
our experience. The details are as follows:
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Table 5: Tentative Cost of Project
S.
No.
1
2
3
4
5
6
Item
Quantity
Unit
Rate
Upper Reservoir Excavation
Water Proofing Treatment
Intake Pipe - supplying, fabrication
and laying etc. complete
Power House including all electrical
installations @Rs 1.5 crore/MW
Costs of Project roads including
construction of breast wall, retaining
wall where ever necessary
Other Items including Cost of
Project buildings, Land, Survey,
Instrumentation, Contingency etc.
620000
m3
790.00
M.T.
400
L.S.
12500
0
50.00
MW
150
7500.00
5
Km
100
500.00
L.S.
1458.70
Total
13226.20
Crore Rs.
133.0
Say
4.3
Amount,
lac Rs.
2480.00
300.00
987.50
Generation Cost
The levellised tariff for the 35 year period for 50.0MW Project will be about Rs. 4.70 per unit.
The details of financial viability are given in Table 6.
Table 6: Financial Viability
Rate of interest on loan
Cost of Project without IDC
Cost of Project with IDC
Electricity Generation from Project
Loan Repayment Period
Useful Life of the Project
Rate of electricity for pumping
Annual electricity required for pumping
5.0
12%
133.00 Crore
162.53 Crore
138.7 MUnits
15 Yr
35 Yr
Rs. 2.5 per unit
177.5 MUnits
CONCLUSION
The future belongs to hydropower as it conserves our fossil fuel reserves, is in abundance, a
self-renewing supply, is non-polluting and produces no waste streams. Pumped storage from
hydropower is the environmentally most acceptable form of storing energy during base-load
phases while making this energy available to the grid for peaking supply needs and system
regulation. The whole country is suffering from shortages in peaking power. The conventional
power plants or gas turbines when operated for low load factor are not economical from the
view of investment and energy cost, though they can meet the demand for peaking power.
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The case presented here has highlighted the necessity of utilizing existing hydropower projects
with an example of Ichari Dam in district Dehradun, State of Uttarakhand to generate
hydropower during peak hours using pump storage plant. The scheme has been so designed
that it does not affect the original purpose of the Ichari Dam for generating electricity and only
10 percent of the water storage shall be used for generating the hydropower during peak hours
through Additional Pumped Storage Project. The following inferences can be drawn from the
study:
1.
2.
3.
The site at El. 1200m for Artificial Upper Reservoir and Surface Power House has to
be suitably investigated and selected for geological and geotechnical parameters.
The proposed Additional Pumped Storage Project for Ichari Dam with an installed
capacity of 50MW is recommended for detailed investigation and preparation of
Detailed Project Report.
The levellised tariff for the 35 year period for 50.0MW Project of about Rs. 4.70 per
unit appears to be on higher side. But considering that energy becoming dearer day by
day, the installation of 2 x 25.00 MW is worth for consideration, as during peak hours
the per unit charges are very high.
6.0
REFERENCES
1.
Chalisgaonkar R. and Mukesh Mohan(2010) Pre Feasibility Report-Additional
Pumped Storage Scheme for Ichari Dam Project(2X25MW), Irrigation Department,
Dehradun, January(Unpublished).
Chalisgaonkar R., Mukesh Mohan and Singh, Sanjay(2012) 25 MW Hydropower
generation during peak hours using Bhimtal Lake - A Pre Feasibility Study,
Proceedings of National Conference on Hydraulic and Water Resources(HYDRO
2012), Indian Institute of Technology, Bombay, Dec. 7-8.
Kewal Krishnan(1995) Criteria For Installing Pumped Storage Schemes In Indian
Context With Reference To Hydro Thermal Mix, Journal of Irrigation & Power pp.15, January – March.
Ramesh Chandra and Gupta, Anup Kumar(2005) Pumped Storage Hydroelectric
Projects and their requirement in India, International Conference on Sustainable
Development of Hydro & Pumped Storage Schemes - Strategies and Roadmap, New
Delhi, Feb 20-21.
Sivakumar N., Das, Devadutta and Padhy NP, Senthilkumar AR, Nibedita
Bisoyi(2013) Status of pumped hydro-storage schemes and its future in India,
Renewable and Sustainable Energy Reviews (Elsevier), Vol. 19, pp. 208-213, March.
Varma. C.V.J., Rao. A.R.G.(2007) Pumped storage schemes in India, Central Board
of Irrigation and Power, New Delhi, November.
--------(1989) Indian Standard Code of Practice, Guidelines for Selection of Turbines,
Preliminary Dimensioning and layout of Surface Hydroelectric Power Houses, Part 2Pumped Storage Power House, IS 12800(Part 2), Bureau of Indian Standards, New
Delhi.
2.
3.
4.
5.
6.
7.
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