A brief about the non-conventional energy resource and generation involving water as a source of power generation available at different terrain at different amounts at the different head. Looking into the means and ways to utilize it for green power generation

1. Small Hydro Power System

2. Syllabus
• Overview of micro, mini and small hydro systems
• Hydrology
• Elements of pumps and turbine
• Selection and design criteria of pumps and turbines
• Site selection and civil works
• Speed and voltage regulation
• Potential of small hydro power in India

3. Introduction
• Conventional more concentration on developing large sites for hydro plants
• Uptill now smaller sites regarded as uneconomic
• Technological advancement in turbines for smaller sites
• Electronic load controller for small hydro
• Countries with advanced technologies : China, Malaysia, Indonesia,
Phillipins, USA, France
• Indian prospective : 5000 MW
• Alternate hydro energy centre at Roorkee

4. • Available sites : Mountain range, plains, even at sea level
• Range from few kW to Few MW
• Bulb turbine (100 KW) and tube turbine (1MW)
Impression regarding small hydro
• High capital cost
• High managerial and administrative cost
• Low utilization
• Low design consideration
Advantage
• Non polluting
• Small effect on ecology
• Low investment, operating cost
• Grid synchronization
• IG based power generation
• use of existing canal and irrigation system

5. Limitations
• Low operating efficiency
• sudden loss of unit
• Transport difficulties
• Transmission Cost and losses
Small Hydel Development
– Output limited to 5 MW
– Height head constraint
– Micro upto IMW = 1000kW
– Mini upto 5 MW = 5000 kW
– Two Types
– Small discharge at higher head
– High discharge at small head

6. Classification of small Hydro
1. Depending on Capacity
2. Depending on Head
Size Unit size Installation
Micro Upto 100 kW 100 kW
Mini 101 to 1000 kW 2000 kW
Small 1001 to 6000 kW 15,000kW
Ultra low head < 3m
Low head <300m
Medium head 30 -75 m
High head > 75m

7. Components of Hydroelectric
Scheme

8. Hydro-Electric Power Plant

9. Arrangement of Small Hydro Power Station

10. Components of Hydroelectric Scheme
1. Diversion and intake
2. Desilting chamber
3. Water conductor system
4. Forebay/ balancing reservoir
5. Surge tank
6. Penstock
7. Power house
8. Tail race channel

11. 1. Diversion and intake
• Dam barrages, solid boulder structure and trench
• Trench: where rock is not available in the river bed
• Solid Boulder : Rock is encountered in the river bed within 1m depth
: Safety is the key issue
2. Desilting chamber
• When water contains course silt to minimize erosion damage to turbine runner etc.
• Extent of desiliting depends on quantum and type of silt carried
• Effect more pronounced in High head system
• Medium Head : 0.2 – 0.5 mm
• High Head : 0.1 – 0.2 mm

12. 3. Water conductor system
• Ensure least loss of head, water due to seepage
• Canal to be lined with tiles, low density poly ethylene (LDPE)
4. Forebay/ balancing reservoir
• Used as balancing reservoir, storage for 4-6 hrs
• If used as transit point storage time for 02 minutes
5. Surge tank
• Necessary if Length of water conduit is 5 times the head of machine
• Impulse type turbine: pressure surges avoided with deflection of jet (eliminates
ST)
• Reaction type turbine : use of air vessel or relief tank for governor instability

13. 6. Penstocks
• Hydraulic (diameter consideration) or structural (thickness of penstock) design
• Steel pipes, hume pipes and PVC pipes with bell mouth entry
• Use of sloped trash racks : to prevent debris and trash
7. Power House
• To accommodate turbine, generator, control panel, auxiliary equipment
• Use of RCC or stone masonary work
8. Tailrace
• Trapezoidal or rectangular channel for transporting water from the turbine outlet

14. a) Low head plant
• Operating head is less than 15m.
• Vertical shaft Francis turbine or Kaplan turbine.
• Small dam is required.

15. a) Medium head plant
• Operating head is less than 15 to 50m.
• Francis turbines.
• Forebay is provided at the beginning of the penstock.

16. a) High head plant
• Operating head exceed 50m.
• Pelton turbines.
• surge tank is attached to the penstock to reduce water hammer effect on the
penstock.

17. Nature of Small Hydro Development
For hilly areas
• Simple feature but high grade small civil work
• Divert flow of hill stream/flow
• Small water conductor system : channel , buried, conduits,
• Power house building
• Small Transmission line
• Local load
For plain areas
• Low head
• High discharge
• development over small river and canals
• Differential input and discharge

18. Turbines and generators for small Hydro Electric
Types of Turbines
1. Bulb or Tubular Turbine
2. Tube Turbine
3. Straflo Turbine
• Reference Study
https://www.youtube.com/watch?v=ZqDK-niW_CQ Small hydro in Colorado 8.17 min.
https://www.youtube.com/watch?v=k0BLOKEZ3KU types of turbines 2.30 min.
https://www.youtube.com/watch?v=CqTnwPYXdLs bulb turbine animation 2.15 min.
https://www.youtube.com/watch?v=X5Asr3RK2tM&t=108s small hydro project 3.40 min.

19. Bulb or Tubular Turbine
• Generator and turbine enclosed inside the conduit from headrace to tailrace
• Bulb is tightly housed within the horizontal channel
• Kaplan or propeller type turbine
• Turbine directly coupled to generator though gear set
• Low head type : 3- 18 m Output Range: 2000 kW – 5000 MW

20. Tube Turbine
• Turbine is housed in the conduit, located in tubular channel
• Water guided through vanes and controlled through wicket gates
• Water flows in an axial direction through the channel with runner
• Modified for Kaplan type for water head below 15m
• Use of horizontal or inclined shaft

21. Straflo Turbine
• No separate rotor provided for generator
• Poles are mounted on the periphery of turbine runner
• Use of special seals to prevent water entering into the generator
• Horizontal shaft design and water flow axially

22. Generators
• AC generators are used
• Generator to withstand turbine runaway
speed i.e. sudden loss of load
• Brushless systems are also used in small hydro
power stations
• Advantage : reduced maintenance cost and
time

23. Speed Regulation
• Problem related to
– Size, type of machine and load
– Standalone or grid connected system
• High Cost of speed governor system
• Regulation provided by flow control
• High inertial system are required

24. Advantages of Small Scale Hydroelectric
1. Shorter developing time
2. Simple construction
3. Running cost is negligible
4. Simple operation and maintenance
5. Pollution free
6. No or very little socioeconomic constraint
7. Less impact on ecology

25. Limitations of Small Scale Hydroelectric
1. Lack of awareness and benefits
2. Non availability of indigenous equipments
3. Remoteness of sites

26. Conclusion on Small Hydro Electric Power
• Mini, micro and small hydro as new source of renewable energy
• More economical
• Save fossil fuel
• Reduces transmission losses
• Suitable for isolated load
• Easy to install and operate
• Use of standardized equipments

27. Ocean Energy

28. Ocean Energy : An Introduction
• Energy is the basis of life and development
• Attempts have been made to harness renewable form of energy such as
wind and solar energy
• But ocean energy is yet to be significantly tapped
• The potential energy of ocean can be seen as catastrophic events such as
cyclones
• Sea breeze, ocean currents and seasonal winds all influence the
temperature, rainfall and humidity of the place
• India has a large coastline.

29. Indian Coastline
A Vast Source of Ocean Energy

30. Terms to Describe Ocean Waves

32. Introduction
• Ocean source of energy
– Ocean thermal energy conversion (OTEC)
– Wave energy
– Hydrological cycle : surface water evaporation by solar heating
– Tidal Energy
• Except tidal each source is because of solar absorptions by seas and
oceans

33. OTEC or Solar sea power plants (SSPP)
• Conversion of stored heat energy into electrical energy
• Oceans are virtually inexhaustible source of energy (70% of
earth’s surface is of sea and oceans)
Operation of OTEC
• Based on thermodynamic principle
• Heat source at higher temperature and heat sink at lower
temperature it is possible to utilize temperature difference
in a machine or tubine that can convert part of heat into
mechanical energy and then into electrical energy

34. Tidal Energy
• Periodic rise and fall of water level of sea
• Gravitational pull of the sun and moon on the water
of the earth
• Primarily caused by lunar
• Tidal range: few cms to about 8-10 m
• Extremely High capital cost

35. Ocean Wave Energy
• A vast history to attempt to tap wave energy
• More of conceptual work
• Limited to small prototypes
• No major development
• Majorly used for navigational aids

36. Hydro Electric Energy
• Rains result of hydrological cycle
• It causes rivers to flow
• Forms source of high or low head hydroelectric
energy

37. Syllabus
• Ocean energy resources
• Ocean energy routes
• Principle of ocean thermal energy conversion
systems
• Ocean thermal power plants
• Principle of ocean wave energy conversion
• Tidal energy conversion

38. Tidal Energy
Tidal power, also called tidal energy, is a form of hydropower that converts the
energy of tides into useful forms of power - mainly electricity.
Tides are the waves caused due to the gravitational pull of the moon and also
sun(though its pull is very low).
During high tide, the water flows into the dam and during low tide, water flows out
which result in turning the turbine.

39. 1/13/2023 Footer text here
Ocean tides are the periodic rise and fall of ocean water level occurs
twice in each lunar day.
During one lunar day (24.83 H) the ocean water level rises twice and
fall twice.
Time interval between a consecutive low tide and high tide is 6.207
hrs.
Tidal range is the difference between the consecutive high tide and
low tide.

40. Basic Principle of Tidal Power
•Tides are produced due to gravitational attraction of the moon and the sun
on water of solid earth and ocean
•Tides 70 % lunar and 30% sun gravitational pull
•Surface water is pulled away from the earth on the side facing the moon,
and at the same time the solid earth is pulled away from water on the
opposite side
•High tides occur in these two areas with low tides at intermediate points
•As the earth rotates the position of a given area relative to the moon
changes
•So the tide also changes
•Periodic successions of high and low tides

41. •Two tidal cycle occurs in a lunar day of 24
hours and 50 minutes.
•Known as semi-dinural tides
•This implies the time between high tide
and low tide is little over 6 hours
•High tide is experienced at a point which
is directly under the moon
•At same time at a point diametrically
opposite to will also experience the high
tide due to dynamically balance.
•Thus high tide is experienced during full
moon and no moon
•Rise and fall of water level follows a
sinusoidal curve.
•Tidal range: the difference between the
high and low water level

42. •At times when near full moon or new
moon , earth-moon- sun are mostly
aligned
•Maximum gravitational pull during this
time
•Exceptional tides (higher and lower
against average)
•Such tides are spring tides
•Neap tides first and third quarters of
moon, sun and moon are at right angles
•Neap tides are exceptionally small
•Spring neap tidal cycle lasts one half of
lunar month

43. •Tides are periodic phenomena
•No two tides are alike: change in orientation and relative distance between sun,
moon and earth
•Autumn equinox experience comparatively higher tides
•Mean tidal range varies from place to place
•Interaction between sea and coast line
•Resonating and dampening effect of tidal phenomenon
•Western coast or Gulf of Kutch has 7-8 m high tidal range
•Kerala has nearly 1m high tidal range
•Bay of Funday (Canada) has tidal range of 20 m
•Tides are amenable to mathematical analysis
Important Points

45. How to Harness Tidal Power

47. How do tides changing = Electricity?
• As usual, the electricity is provided by spinning turbines.
• Two types of tidal energy can be extracted: kinetic energy of currents
between ebbing and surging tides and potential energy from the
difference in height (or head) between high and low tides.
• The potential energy contained in a volume of water is
E = xMg
where x is the height of the tide, M is the mass of water and g is
the acceleration due to gravity.
• Therefore, a tidal energy generator must be placed in a location with
very high-amplitude tides.

48. • The generation of electricity from tides is very similar to hydroelectric
generation, except that water is able to flow in both directions and this
must be taken into account in the development of the generators.
• The simplest generating system for tidal plants, known as an ebb
generating system, involves a dam, known as a barrage across an estuary.
• Sluice gates on the barrage allow the tidal basin to fill on the incoming
high tides and to exit through the turbine system on the outgoing tide
(known as the ebb tide).
• Alternatively, flood-generating systems, which generate power from the
incoming tide are possible, but are less favored than ebb generating
systems.

49. Ebb Generation
• The basin is filled through the sluices
and freewheeling turbines until high
tide. Then the sluice gates and turbine
gates are closed.
• They are kept closed until the sea level
falls to create sufficient head across the
barrage and the turbines generate until
the head is again low. Then the sluices
are opened, turbines disconnected and
the basin is filled again.
• The cycle repeats itself.
• Ebb generation (also known as outflow
generation) takes its name because
generation occurs as the tide ebbs.
Estuary
Ebb generating system with a bulb turbine

50. Components of Tidal Power Plants
• Dam or barrage
• Power House
• Sluice ways from basins to the sea and vice
versa

51. DAM or BARRAGE
• Barrage more synonymous to tidal power scheme
• Need to withstand only fraction of structure height
• Modest stability problem
• Tidal structure to support low head
• Need to withstand continuously changing shock and pressure
• Mostly barrage have smaller length due to shorter basin
• Mostly tidal plants do not have heads exceeding 20 m

52. DAM or BARRAGE
• Need to provide channels for the turbines in prestressed or
reinforced concretes
• Need to have a firm base/ flat land so as to bear the weight of
the construction
• Barrage construction influences the tidal amplitude, bay
resonance
• Good sites : high tidal range, good head, bays and estuaries

54. Gates and Locks
• Tidal basin to be filled and emptied
• Regular operation of gates
• Should use minimum power
• Leakage is tolerate
• Gates to have cathodic or paint protection against corrosive sea
water
• Mostly vertically lift gates are employed
• Currently substituted by pressure opened flap gates

55. Power House
• Large power house structure
• Turbines, electric generators and auxiliary equipments
• Large turbines because of small heads
• Use of bulb type turbines mostly Kaplan type
• Turbines to be bidirectional and self locking type

56. Operation Methods of Utilization of Tidal
Energy
• Important for generation to have head difference
• Rise and fall of tides
• Basin may be natural or artificial
• Two specific arrangements
– Single basin
– Double basin

57. Ocean Power

62. Ocean Energy
• Open and Close OTEC Cycle
• Working Principle and operation
• Advantage and Limitations

63. Open Cycle OTEC System

64. Open Cycle OTEC System
(Elaborated Schematic)

65. Limitations of OTEC open Cycle System
• Use of large ocean mass and volume flow rate
• Use of physically very large turbine
– Use of very low pressure turbine
– Use of specific volume more than 2000 times the conventional power plant
• Need of degasifers (deaerators)
• To remove dissolved gases in the sea water
• High installation and parasitic cost
• Advantage: No heat transfer problem in evaporator

66. Closed OTEC Cycle (Anderson Cycle)
• Need of closed OTEC cycle because of some limitations imposed by open
OTEC cycle
– Open OTEC cycle uses steam as working fluid
– Requirement of large volumes of water, thus large physical turbine requirement
– working fluid which has low operating (saturation pressure) and low condensation
temperature at the boiler
– High specific volume
• Working fluid in closed OTEC cycle
– low boiling point, high saturation pressure, high condensation temperature
• Example: Ammonia, propane or Freon

67. Components of Anderson Cycle
• Heat exchanger (Evaporator and Condensor)
– Exploit : Transfer significant amount of low quality heat of the low
temperature difference
• Turbine – Generator set
• Pump-Sump for Hot surface water and deep cold water
• Working fluid pump-sump system

68. General Schematic of Anderson Cycle

69. Ammonia Cycle Closed OTEC System
• Requires separate working fluid
• Receives and rejects heat to the source and sink via heat
exchanger
• Working fluid: Ammonia, propane or Freon
• Arrangement requires low temperature difference between
boiler and condensor
– For efficiency of 2% heat rejected is 50 times the output of the plant

70. Ammonia Cycle Closed OTEC System
(Schematic)

71. Heat Exchangers for OTEC

72. Ammonia Cycle Closed OTEC System
(Working)
• Difference between the open &
Closed cycle OTEC is the heat
exchanger
• Transfer heat more efficiently
across the heat exchanger surface
• Transfer coefficient is measured in
W/oK/m2.
• Heat transfer to metallic alloy and
then to ammonia
• For condenser reverse heat
transfer is characterized

73. Heat Exchangers (Evaporators)
• Efficiency of conversion oh heat into mechanical work
(electrical output) depends on drop in temperature of
working fluid in its passage through the turbine
• Efficiency = (Temperature Gradient)/Input Temperature
• Efficiency = (Output Temperature-Input Temperature )/Input Temperature
• Efficiency = (10+273)-(20+273)/(273+20) = 3.4%

74. • For maximum efficiency : Tubine entering fluid should be as high
as possible and existing temperature should be as low as possible
• Low efficiency of OTEC system compensated by enormous amounts
of heat available
• For economical operation, water to be pumped in and out of heat
exchanger at a very high rate
• Example: 100 MW of electrical power 500 million gallons per hour
flow rate to be maintained
• But for such a system heat exchnager surface area to be about 1
million sq. m.

75. • Important : This leads to have effective heat transfer in the
heat exchanger
• How?
• Material : Good heat conductivity, resistive to corrosion and
erosion because of ocean water
• Material Example:
– Titanium
– Aluminium or Aluminium alloy
– Alloy of copper (90%) and Nickel (10%)
– Plastic

76. Titanium
• Corrosion and erosion resistive
• Good Mechanical strength
• Expensive material
Aluminium
• Cheaper than Titanium
• Corrosion prone
• Work on Alloy to cut down the cost
Copper Nickel Alloy (90/10)
• Extensively used in land-based and shipboard power plant
• Ocean water as coolent
• Cost midway between Titanium and Aluminium
• Corrosion resistive to ocean water but not good for ammonia plant

77. Plastic
• Relatively inexpensive
• Lower heat conductivity
• But can be increased with use of graphite
• Good mechanical strength and corrosion/ erosion resistive

78. Bio-Fouling

79. Bio Fouling
• Growth of micro-organisms on the cooling water side of heat
condensor is called biological fouling
• Problem in most power plants
• Expected due to rise in both evaporator and condesor
• Less with Copper based heat exchangers
• Copper acts as biocide

80. • It affects rather reduces heat transfer efficiency
• Usually dealt with by chemical or mechanical means
• Chlorination/ brushes/rubber ball means are followed
• Increased flow rate reduces the chances of attaching to the
heat surface of heat exchanger
• Caution : High flow rate can cause erosion
• Bio fouling largely depends on location
• Bio fouling favorable where the warmer water would be
conductive to the growth of marine organism