Small Hydro Training Module
- 1. Cook Legacy College Training Module M-200: Fundamentals of Small Hydro
- 2. 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
- 3. Fundamentals of Small Hydro SH 101: Overview and Background SH 102: Fundamentals SH 103: Review and Quiz 3
- 4. What is Small Hydro Small 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 4
- 5. 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=Flow C=Discharge coefficient l=Length of the weir h=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. 5
- 6. Calculating Power Potential Power is given as: P=HQkG Where: P=Power in watts H=Head (the difference in elevation between the intake and the powerhouse Q=Flow in m^3/s G=Gravity (9.8 m/s^2) k=Turbine efficiency A quick estimate is to take 7 * Q* H Head (m) Flow (m3/s) Power in kW 6 7 x Head x Flow
- 7. What is Small Hydro What counts as small hydro? Typical Power Micro Mini 100 to 1,000 kW Small 7 < 100 kW 1 to 50 MW
- 8. 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 8 • Significant damming usually required
- 9. Process for Sizing Site 9
- 10. Process for Sizing Site • 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) Flow-Duration Curve Flow (m³/s) 50.0 40.0 30.0 20.0 10.0 0.0 0 10 20 30 40 50 60 70 80 90 100 Percent Time Flow Equalled or Exceeded (% ) 10
- 11. Process for Sizing Site Picking the Turbine at various points on the FDC Flow-Duration Curve 40.0 • 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. 11 Flow (m³/s) • Estimate the installed capacity 50.0 30.0 20.0 10.0 0.0 0 10 20 30 40 50 60 70 80 90 100 Percent Time Flow Equalled or Exceeded (% ) 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.
- 12. 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. Small Hydro Cost Estimate Other 10% Electrical 10% Mechanical & Controls 25% 12 Civil Cost 55%
- 13. Small Hydro Major Components The major components for the site are: • Intake structure • Penstock • Powerhouse – the primary components of the powerhouse are: o Turbine-generator o Switchyard 13
- 14. Intake Structure The 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. 14
- 15. Turbine Types 15
- 16. 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. 16
- 17. Turbine Types 17
- 18. Turbine Types 18
- 19. Low Head Hydro: Natel HydoEngine In the low head space, we offer complementary process equipment to a range of turbine designs. 19
- 20. Low Head Hydro: Cleanpower Turbinator 20
- 21. 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. 21
- 23. Design Considerations Intake Design Turbine Selection • Side intake • Coanda • Head • Flow • Fish Technical Penstock Design • Distance • Pressure 23 T&D Design • Distance • Connection Type
- 24. Design Considerations Cap-Ex Funding Sources • Civil • Mechanical • Consultancy • NGO • Private Funding • Equipment Financial Cost of Capital Payback of Components • Cheap & swap • Long term value 24
- 25. Design Considerations Water Grid Connection Regulatory Permitting Agency 25 Construction Permits
- 26. Design Considerations Social Fisheries • Build projects good for people • Don’t screw landowners. Be fair. • Improve diversion • Improve survival Environmental Land Use • Intake • T&D 26 Proper O&M
- 27. Review Questions 27 What are the components of calculating power capacity? What are the balance of plant benefits of a Coanda intake