Small Hydro Development in Nayar river valley in Lesser ... - ESHA

Small Hydro Development in Nayar river valley in
Lesser Himalayas – A Case Study
Devadutta Das
Professor (Hydro-electric)
Department of Water Resources Development & Management
Indian Institute of Technology, Roorkee
Uttarakhand, INDIA – 247667
1

WHY SMALL HYDRO?
As many of the economical sites got exhausted, a re-look
was necessitated towards the abandoned sites as well as
for new small hydro sites, as a Governmental thrust for
exploiting renewable energy, of which the hydro and
notably small hydro are the most eligible candidates due
to their negligible impact on the environment.

Project Area
4

Bhagirathi River
Dev Prayag
2975 m
NOTE: Distances shown are approximate
25.30 Km
SANTOODHAR - I SHP
2 x 1000 KW
POND LEVEL : 733.0 m EL
TAIL WATER LEVEL : 702.6 m EL
PAURI
Alaknanda River
WESTERN NAYAR RIVER
44.50 Km
15.60 Km
SANTOODHAR - II SHP
2 x 1000 KW
POND LEVEL : 589.0 m EL
TAIL WATER LEVEL : 566.2 m EL
NAYAR RIVER
3.60 Km
˜ 6.0 Km 7.0 Km
10.70 Km
SCHEMATIC DIAGRAM SHOWING HYDRO-ELECTRIC PROJECTS UNDER CONSTRUCTION
& UNDER PLANNING IN THE NAYAR RIVER VALLEY
11.0 Km
SATPULI
EASTERN NAYAR RIVER
67.70 Km
KHATTAL GAD
BYALIGAON SHP
2 x 1125 KW
LANSDOWNE
3098 m
POND LEVEL : 628.0 m EL
TAIL WATER LEVEL : 606.0 m EL
MARORA DAM
NAYAR HEP 3 x 5666 KW
POND LEVEL : 516.0 m EL
TAIL WATER LEVEL : 458.5 m EL
BAIJRO
DUNAO SHP 2 x 750 KW
(Under Construction by Uttarakhand
Jal Vidyut Nigam Ltd.)
POND LEVEL : 1095.5 m EL
TAIL WATER LEVEL : 1032.5 m EL
POWER HOUSE NEAR KHANDASAIN VILLAGE
GANGA
Vyas Ghat RISHIKESH
HARDWAR
5

VIEW OF THE DIVERSION DAM SITE FOR NAYAR SHP NEAR MARORA PALA VILLAGE

VIEW OF THE DIVERSION DAM SITE FOR BYALI GAON SHP
7

VIEW OF THE DIVERSION DAM SITE FOR SANTOODHAR - I SHP
8

VIEW OF THE DIVERSION DAM SITE FOR SANTOODHAR - II SHP
9

River Discharge in cumec
400
350
300
250
200
150
100
50
0
FLOW DURATION CURVE FOR NAYAR RIVER DISHCRAGE
GAUGED AT BUNGA GAUGING SITE
0 10 20 30 40 50 60 70 80 90 100
River Flows Available for the %Time of year (Equalled or
Exceeded)
FLOW DURATION CURVE FOR NAYAR RIVER
DISCHARGE GUAGED AT BUNGA GAUGING SITE
10 YEARS
50% Dependable Year
75% Dependable Year
90% Dependable Year
10

Characteristics
Byaligaon
SHP
Santoodhar – I
SHP
Santoodhar – II
SHP
Maximum discharge (cumec*) 198.51 120.19 165.18
Minimum discharge (cumec*) 1.02 0.62 0.85
50% dependable discharge (cumec*) 6.47 3.91 5.30
75% dependable discharge (cumec*) 4.35 2.63 3.61
90% dependable discharge (cumec*) 3.10 1.86 2.56
Maximum Flood (cumec*) for flood
marks
1010 325 785
Maximum Flood (cumec*) (Dicken’s) 2402 1648 2092
Dicken’s empirical formula is given in equation
Q = C.A 0.75
Where, Q = Flood discharge in cumec
C = A constant varying between 11 and 14
A = Catchment area in square kilometer
For the Himalayan area, it has been found that a value of 14 for the constant C is
appropriate, and hence adopted.
11

SELECTION OF DIVERSION STRUCTURE
The rivers in Himalayas carry very heavy sediment load
and bed load during rainy season.
For small hydro power projects, the diversion
arrangements may be one of the following depending
upon the site conditions and cost factors:
Trench Weir
Un-gated overflow type raised weir
Gated weir
Dam with gated spillway
12

TRENCH WEIR
Catches the bed load especially the shingles thereby
removal of heavier material in the desilting tanks makes
the latter larger in size and thus cost.
With low gradient river slopes the shingles excluder
length becomes very long thereby increasing the cost.
13

UNGATED OVERFLOW TYPE WEIR
Has the advantage over the trench weir as it lends to
increase in head appreciably incase of low and
medium head projects thereby contributing to
increasing power.
Entry of bed load especially the shingles into the water
conductor system can be prevented at the intake by
keeping the sill level at a higher level than the bed level
of the river.
18

WEIR WITH GATES
22

DIVERSION WEIR
To be designed to pass the probable maximum flood
through gates.
With narrow diversion sites the cost of constructing a
weir with gates becomes higher due to excavation
cost for widening the river section to provide enough
section to pass the flood.
For Santoodhar – II
- Cost of ungated overflow weir Rs. 34.33 Million
- Cost of gated weir Rs. 52.45 Million
Hence, overflow type ungated weir
with under sluice adopted.
25

4 ROWS OF
C.C.BLOCKS OF SIZE
1500X1500X1000
4 Rows of CC
Blocks of Size
1.5 m x 1.5 m and
1.0 m height
3000
POND LEVEL
FLOW
5000
597.0
HFL 596.0
FLOW
RIVER BED
582.0 m
Firm Rock
6000
Stop
Log
582.0 m
1000
7500
Gate
7500
2.5 : 1
579.0
D/S Wing 589.0
30000
SECTION: B-B' THROUGH UNDERSLUICE
FLOW
1500
PLAN OF WEIR
Reverse Slope
5 : 1
2500
1000
Chute blocks @
1.60 m spacing at
end of sloping
glacis
A A'
B
6000
3100
589.0
R 6000
1000
DIVIDE WALL
FLOW
8000
32000
600 2000 600
1000
1000
Friction Blocks
12000
20000
2000
600
600
600 1000
600
600
Stilling
Basin
FLOW
Slope Lined with M20
Two Rows of Friction
Blocks of Size
0.6 m x 0.6 m,
staggered @ 1.5 c/c
HFL 588.0
6 ROWS OF
C.C.BLOCKS OF SIZE
1500X1500X1000 582.0
9000
FLOW
4 ROWS OF C.C.BLOCKS
OF SIZE 1500X1500X1000
RIVER BED 582.0 m
6 Rows of CC
Blocks of Size
1.5 m x 1.5 m and
1.0 m height
B'
6000
U/S HFL
596.0
POND LEVEL 589.0
597.0
SANTOODHAR – II SHP
589.50
RR STONE
MASONRY 1:6
1000
2.5
1
ROCK SLOPE
FACING WITH CC M20
1000
2000 7500 4000
21250
10250
SECTION: A-A' THOURH OVER FLOW WEIR
UNDER SLUICE & OVER FLOW WEIR
2500
1000
581.0
1000
589.0 D/S Wing
588.0 D/S HFL
6 ROWS OF
C.C.BLOCKS OF SIZE
1500X1500X1000
9000
26
3000

DE-SILTING BASIN
The rivers in the Himalayan region carry a heavy amount
of sediment load predominantly angular quartz particles.
The recommended practice for eliminating the sediment
load in India are as below:
Low Head = 0.5 mm and above
Medium and High Head = 0.2 mm and above
27

SECTIONS INDICATED :
- Stone Masonry
POWER CHANNEL
- Rectangular Reinforced Cement Concrete
- Trapezoidal Cement Concrete Lined Sections
30

Stone Masonry
POWER CHANNEL
Larger Sections – Cost saved in channel lining is more
than offset by higher excavation cost
RCC Channels
Channel on hill slopes in Himalayas are prone to frequent
damage due to falling rocks and under cutting due to rain
water seeping between the channel bed.
Lined trapezoidal section
Hydraulically the best and cost effective
31

Comparative Physical Features and Costs of Rectangular
RCC Section & Trapezoidal lined section
Channel Geometry
Base
width
meter
Depth
meter
Velocity
m/sec
Discharge
cumec
Cost
Rs.
Million
Trapezoidal section- cement
concrete lined 2.50 2.50 1.89 13.26 39.27
Rectangular- RCC 2.75 2.75 2.15 13.15 57.60
As the cement concrete lined trapezoidal section is cheaper by
about 32%, the same has been adopted.
34

FOREBAY
Forebay’s Active Volume made equal to 30 sec water
requirement of the power plant at rated load.
PENSTOCK
As length of penstock is less, two separate penstocks
used feeding its turbine
35

FIXATION OF INSTALLED CAPACITY
The installed capacity of each of these projects has been
determined considering the following factors:
Maximum, Minimum and 50% dependable discharge
available,
Net Head availability,
Normative plant load factor for recovery of full fixed
charges fixed by the Uttarakhand Electricity
Regulatory Commission ,
Difficulty in construction of large sized open channels
in the hilly areas, and
Operation and Maintenance expenses.
37

FIXATION OF INSTALLED CAPACITY
Considering difficulty in constructing large width
channel in unstable hill slopes. Maximum 15 cumec
discharge adopted.
Bed slope of 1 in 700 adopted to assist in self
cleaning.
Normative Plant Load Factor for small hydro permitted
by Uttarakhand Electricity Regulatory Commission is
45%.
Installed capacity of 2000 KW for Santoodhar – II
fulfilled the above criteria.
38

TURBINE & GENERATOR
The average net head available for the three SHPs are as under:
Byaligaon
SHP
Santoodhar – I
SHP
Santoodhar – II
SHP
Average Net Head 16.80 m 26.40 m 18.80 m
Maximum Net Head 18.00 m 27.00 m 19.60 m
Minimum Net Head 16.40 m 26.00 m 18.30 m
Type of turbine proposed
Kaplan
(Horizontal)
Francis
(Horizontal)
Kaplan
(Horizontal)
39

TURBINE PARAMETERS AND SETTING
With horizontal shaft alignment leakage from turbine
seal is excessive if turbine is set below tail water
level.
During maintenance, risk of flooding of turbine
floor likely if turbine is set below tail water level.
Therefore, specific speed of turbine so selected as to
have positive suction head or at least a small negative
suction head.
40

Byaligaon
SHP
Santoodhar – I
SHP
Santoodhar – II
SHP
No. of units & unit output 2 x 1225 KW 2 x 1000 KW 2 x 1000 KW
Turbine rotational speed,
rpm
Specific speed, rpm (in
kW-m units)
Turbine Parameters and Setting
500 500 500
506 271 425.5
Runner Diameter (mm) 1150 860 1100
Suction Head, m (-) 0.92 (+) 3.72 (+) 1.06
41

F.S.L.
Trash
Rack
GATE
Motor operated slide gate
586.20
585.20
FLOW
577.38
1000
50000
1800 500
C/L OF PENSTOCK
569.50
CONTROL
ROOM
CABLE
ROOM
1800
500
1100
ROOF TRUSS
L-SECTION OF POWER HOUSE
SANTOODHAR – II SHP
CROSS – SECTION OF POWER HOUSE
12000
SERVICE BAY FLOOR 566.0
2750 3000 1350
4 6 5
1000
1
7
8
2:1
R.C.C.M-20
OVER 150 THICK
P.C.C. M-10
11
9 12 13
576.50
575.0
561.30
1750
558.05
500
559.05
556.90
1000
2000
3000
500
574.50
566.00
DRAFT TUBE GATE
563.40 MIN. TWL
562.30
TOP OF WING WALL
C.C.BLOCKS
INTERCONNECTED
1000X1000X500
5
1
564.70 MAX. TWL
600 mm THICK
INVERTED FILTER
12000
562.5
1000
1000
565.20
500
150
44
350

PROJECTED FINANCIAL PERFORMANCE
PARAMETERS:
Debt to equity ratio : 70:30
Return on equity : 14%
Construction Period : 2 years
Licensing Period : 40 years
Average annual energy production with 95%
availability
45

PROJECTED FINANCIAL PERFORMANCE
Characteristics
Average Annual Energy,
kWhr
Net Energy available for
sale, kWhr
Byaligaon
SHP
Santoodhar – I
SHP
Santoodhar – II
SHP
9.9 x 10 6 9.1 x 10 6 8.9 x 10 6
9.75 8.95 8.79
Plant Load Factor 50.23 51.84 50.92
Estimated project cost,
Rs. Million
205.79 180.92 176.92
Sale price, Rs./kWhr 3.47 3.37 3.29
Levelised sale price,
Rs./kWhr
3.00 2.89 2.85
46

CONCLUSIONS
Sale Price competitive with sale price from other
hydro sources.
Contribute to increased energy availability in the local
rural network.
Improvement in voltage profile
Boost to Cottage, Horticultural and Agro Industries
Energy for lighting homes
Contribute to Socio – Economic Development
47