small hydro training module
TRANSCRIPT
Cook Legacy College
Training Module M-200:
Fundamentals of Small
Hydro
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Goals of This 15-Minute Module
Know what small hydro is.
Understand major features,
components, and selection criteria
Understand technical and financial
considerations when assessing a
site
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Fundamentals of Small Hydro
SH 103:
Review and Quiz
SH 102: Fundamentals
SH 101: Overview and Background
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What is Small HydroSmall Hydro (also called small hydroelectric or small hydro) refers to the generation of electrical power by using diverted water to rotate a turbine.The major components include:• An intake• A penstock• A turbine & generator• A switchyard for connection to the power pole
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What is Small Hydro
The most commonly used form in intake structure design is the “Discharge Equation.”Different forms are used for flow over the spillway, Coanda accelerator, measurement weirs, and various secondary spills.Generally the value of C, the discharge coefficient, will adjust based on some empirical test.The basic discharge equation is Q=Clh^3/2
Where:Q=FlowC=Discharge coefficientl=Length of the weirh=head above the crest
The most important thing when selecting and implementing a discharge equation is ensuring it matches in all respects the condition it was intended for.
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Calculating Power Potential
Power is given as:P=HQkGWhere:P=Power in wattsH=Head (the difference in elevation between the intake and the powerhouseQ=Flow in m^3/sG=Gravity (9.8 m/s^2)k=Turbine efficiencyA quick estimate is to take 7 * Q* H
Head (m)Head (m)
Flow (m3/s)
Power in kW 7 x Head x Flow
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What is Small Hydro
What counts as small hydro?
Typical Power
Micro < 100 kW
Mini 100 to 1,000 kW
Small 1 to 50 MW
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What is Small Hydro
Type of grid
– Central-grid: Generated power is sold back
to a power grid such as a utility.
– Isolated-grid or off-grid: Generated power is
used locally near the point of generation.
Type of civil works
– Run-of-river
• No water storage
• Power varies with flow available from river:
lower firm capacity
– Reservoir
• Higher firm capacity year-round
• Significant damming usually required
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Process for Sizing Site
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Process for Sizing Site
Flow-Duration Curve
0.0
10.0
20.0
30.0
40.0
50.0
0 10 20 30 40 50 60 70 80 90 100Percent Time Flow Equalled or Exceeded (%)
Flo
w (
m³/
s)
• Estimate flow duration curve based on
Measurements of flow over time
Size of drainage above site, specific run-off, and shape of flow
duration curve
The easiest way to mess up a high head site is to overestimate the
flow (as this is the only variable)
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Process for Sizing Site
Flow-Duration Curve
0.0
10.0
20.0
30.0
40.0
50.0
0 10 20 30 40 50 60 70 80 90 100Percent Time Flow Equalled or Exceeded (%)
Flo
w (
m³/
s)
Picking the Turbine• Estimate the installed capacity
at various points on the FDC
• Estimate the cost of
equipment cost associated
with those. This includes
questions such as the size of
the equipment and how many
nozzles will be used.
• Integrate the area under the
curve with various scenarios
and pick the best payback.
Sometimes this can be
approximated by simply slicing
the FDC into a few scenarios.
For example:
The green line has high
capacity to “catch” high flow
events, but may not run
enough to be worth the cost.
The blue line will be cheaper,
but may leave power on the
table. The red line may be the
best return.
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Small Hydro Major Components
The most expensive cost component for a small hydro plant is the Civil Cost. Much of our approach is in lowering the civil cap-ex.
Civil Cost55%
Mechanical & Controls25%
Electrical10%
Other10%
Small Hydro Cost Estimate
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Small Hydro Major Components
The major components for the site are:• Intake structure• Penstock• Powerhouse – the primary components of the powerhouse are:
o Turbine-generatoro Switchyard
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Intake StructureThe intake structure needs to deliver clean water to the penstock
Traditional intakes include a coarse screen
with secondary screening and settling
basins to remove sand.
Coanda screens eliminate secondary
screening need & use overflowing water to
stay clean.
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Turbine Types
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Pelton Turbine Details
As Coanda Screens are most suitable for medium and high head sites they
are commonly paired with Pelton Machines
Peltons have a series of nozzles controlled by actuated needle valves, that
spray water onto the runners.
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Turbine Types
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Turbine Types
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Low Head Hydro: Natel HydoEngine
In the low head space,
we offer
complementary
process equipment to
a range of turbine
designs.
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Low Head Hydro: Cleanpower
Turbinator
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Other Powerhouse Components
The generator is connected to the turbine.
A generator can be either synchronous (i.e. designed to work with an existing
load) or asynchronous.
For very small sites an induction motor can be used in place of the generator.
Additional components are the plant controls and basic facility requirements
like lighting, fire protection, personnel protection, and monitoring equipment.
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Design Considerations
Technical Financial
Environmental Regulatory
Plant
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Design Considerations
Intake Design
• Side intake
• Coanda
Turbine Selection
• Head
• Flow
• Fish
Penstock Design
• Distance
• Pressure
T&D Design
• Distance
• Connection Type
Technical
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Design Considerations
Cap-Ex
• Civil
• Mechanical
• Consultancy
Funding Sources
• NGO
• Private Funding
• Equipment
Cost of Capital Payback of Components
• Cheap & swap
• Long term value
Financial
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Design Considerations
Water Grid Connection
Permitting AgencyConstruction Permits
Regulatory
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Design Considerations
Social
• Build projects good for people
• Don’t screw landowners. Be fair.
Fisheries
• Improve diversion
• Improve survival
Land Use
• Intake
• T&D
Proper O&M
Environmental
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Review Questions
What are the components of calculating
power capacity?
What are the balance of plant benefits of a
Coanda intake
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