fundamentals of small hydro power technologies

8/12/2019 Fundamentals of Small Hydro Power Technologies

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L.B. Kassana/Training Workshop for

GTIEA & Cogen Africa Projects -NairobiKenya, Nov 9-10, 2007 1Wednesday, March 12, 2014

1

Renewable Energy and Energy Efficiency Partnership (REEEP) Training

workshop

for

GTIEA

&

Cogen Africa Projects

November 1011, 2007Nairobi, Kenya


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GTIEA & Cogen Africa Projects -NairobiKenya, Nov 9-10, 2007 2

Presentation Outline:

A. Hydropower in GeneralB. Fundamentals of Small HydroTechnologiesC. Barriers to the DevelopmentImplementation of SHPD. New Financing Model for SHP


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GTIEA & Cogen Africa Projects -NairobiKenya, Nov 9-10, 2007Wednesday, March 12, 2014

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A. Hydropower in General AspectsHow Hydropower Works

Water constantly moves through a vast global cycle, evaporatingfrom lakes and oceans, forming clouds, precipitating as rain or

snow, then flowing back down to the ocean.

Hydropower is using water to power machinery or make electricity.

Hydropower uses water as fuel that is not reduced or used up in theprocess. Because the water cycle is an endless, constantly

recharging system, hydropower is considered a renewable energy.


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Types of Hydropower Facilities


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Advantages and Disadvantages of Hydropower

Advantages:

1. Hydropower is fuelled by water, so it's a clean fuel source.2. Hydropower doesn't pollute the air like power plants that burn fossil fuels,

such as coal or diesel.

3. Hydropower relies on the water cycle, which is driven by the sun, thus it's

a renewable power source.

4. Hydropower is generally available as needed; engineers can control theflow of water through the turbines to produce electricity on demand.

5. Hydropower plants provide benefits in addition to clean electricity.

Impoundment hydropower creates reservoirs that offer a variety of

recreational opportunities, notably fishing, swimming, and boating. Most

hydropower installations are required to provide some public access to

the reservoir to allow the public to take advantage of these opportunities.

6. Other benefits may include water supply and flood control if you have

storage scheme.


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Disadvantages:

1. Fish populations can be impacted if fish cannot migrate upstream pastimpoundment dams to spawning grounds or if they cannot migrate

downstream to the ocean. Remediesare fish ladders or elevators, or by

trapping and hauling the fish upstream by truck. Other remedies can be by

maintaining a minimum spill flow past the turbine.

2. Hydropower can impact water quality and flow. Hydropower plants can

cause low dissolved oxygen levels in the water, which can be remediedby

various aeration techniques, which oxygenate the water.

3. Hydropower plants can be impacted by drought. When water is notavailable, the hydropower plants can't produce electricity. What is the

remedy for this ? Subject for discussion for all!!!

Advantages and Disadvantages of Hydropower - cont


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GTIEA & Cogen Africa Projects -NairobiKenya, Nov 9-10, 2007Wednesday, March 12, 2014 8


GTIEA & Cogen Africa Projects -NairobiKenya, Nov 9-10, 2007

B. Fundamentals of SHP Technologies:

Design and General Aspects


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Introduction to Small Scale Hydropower

1st Question: Why bother develop it afterall?' Why not leave waterfalls and the

beautiful landscape intact?Exercise for the

participants!! The following elements will be covered:

The Process of Evaluating a Site

The water resources and its potential

Civil Engineering Works

Electromechanical Equipment

Economical Considerations & Evaluation


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The Process of Evaluating a Site Identification of the Site

Evaluation of the water resources available for the plant andconsequentially its annual energy production

Preliminary Definition and Cost Evaluation of the Plant

Preliminary Evaluation of Economics of the Scheme afterresearching on financial alternatives, benefits available from

governments, tax incentives, etc.

Review of Regulatory requirements and its administrativeprocedures.


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The Water Resources and its Potential Hydrology:

Velocity-Area method Dilution Methods

Flow measuring structures e.g rectangular weir, V-noth weirs, flumes. Slope-Area method:

Sizing a power plant: FDC provides means of determining quickly how much of the

available water resources can be used by turbines of different sizes.

Power available from flow varies with time since Q is varying & isgiven by P = QHwhere Q is discharge, H is net head, is specificweight of water (9.81 kN/m3), is overall efficiency (may initially est.to be 0.8).

Annual energy production:

Can be estimated to a 1st approximation by measuring the usablearea under the FDC, converting to an actual qty of water in m3 in aspecific time, multiplying that by 9.8 and the net head (averaged) andmean efficiency (estimated). The result is annual energy in kJ which isconverted to kWh by dividing by 3600.


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Typical Basic Layout & Schematic Diagram

Civil Engineering Works


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Civil Engineering Works Dams/Weirs: has 2 functions:

To increase the available head To create a reservoir to store water

Intakes: have the following functions: To conduct water into the penstock or power

canal/tunnel

To minimise the amount of debris and sedimentcarried by the incoming water.

Waterways:

Tunnels/Canals: these convey water either directly orvia penstock to the turbines Forebay: designed to provide only enough storage to

provide extra volume needed during the turbine start-up

Penstocks: these are pressure pipes conveying waterto the turbines

Tailraces: these return water back to rivers afterpassing thru the turbines

Powerhouse: location for turbines, generators, etc 100 m head, the size is governed by diameter of thegenerator casing.


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Electromechanical Equipment

Hydraulic Turbines: They convert potentialenergy to mechanical energy. 3 categories

of conventional turbines:

Kaplan & Propeller turbines: these are axial flowreaction turbines used for low head

Francis turbines: these are radial flow reactionturbines with fixed runner blades and adjustable

guide vanes used for medium heads.

Peltons: these are impulse turbines with single ormultiple jets, each jet issuing thru a nozzle with a

needle to control the flow. They are used for

both medium and high heads.


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ElectromechanicalEquipment-cont.

Classification of Turbine types


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Electromechanical Equipment-cont.

Turbine types based on Head and Discharges


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Electromechanical Equipment - cont

Turbines: Type, geometry and dimensions depends

primarily on: Net head

Rated (design) discharge

Specific speed, Ns: determines the type & basic shape of

the runner & other parts of the unit. N=Ns*H(5/4)/P whereN is synchronous speed in rpm (N=(60f)/#of poles), H ishead and P is power

Runaway speed: theoretical speed that can be attainedwhen hydraulic power is at its max and electrical load is

disconnected.

Ratio power to net head:

Cost, of course!!


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Electromechanical Equipment-cont.

Generators: these transform mechanical energy toelectrical energy. There are two choices:

Synchronous alternators equiped witha DCexcitation system and Asynchronous Generator

which draws excitation from the grid.

Control equipment: Governors that can be mechanical or electrical

Switchgear panel and protection

Automatic control

Powerstation auxiliary electrical equipment Station service transformer

DC control power supply Outdoor substation

E i l C id ti


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Economical Considerations

Preamble: Profitability of a scheme is a function its

capital and of the revenuesfrom the sale of electricity. Main parameters influencing costs and revenues:

Type of turbine

Number of Units; turbines with murtiple runners or

multiple nozzles Speed of rotation

Turbine setting

Control equipment

Size of powerhouse

Sale of electricity

E i l C id ti t


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Economical Considerations-cont Type of turbine:

For the same head, certain turbines are more difficulty tomanufacture than others consequently they are more

expensive. E.g for low heads, aPropeller is cheaper than aKaplandesigned for the same rated discharge. In mediumheads, a cross-flowturbine is cheaper than a Franciswhose runner is more complex.

Number of Units: Turbines with multiple runners or multiple nozzles

Speed of Rotation: Higher specific speed mean smaller turbine dimensions

and higher speed generators. Since the turbine cost

decreases with an increase in speed, there is a majorincentive to use ever higher specific speed. Furthermore, insmall units, if the speed is high enough, a standardgenerator may be directly coupled to the turbine, thussaving the cost of the gear box

E i l C id ti t


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Economical Considerations-cont Turbine Setting

The negative aspect of high specific speeds, requiring adeeper setting to avoid cavitation, must also be included in the

assessment:

Additional foundation excavation

Extra dewatering costs

Higher costs of draft tube gate because of higher tailwater headetc

Control Equipment Turbines like Kaplan with double regulation (if both runner

blades & guide vanes are adjustable) require a more complex

control system that increases the costs. But others like thePelton wheel accept rather rudimentary control system like a

deflector infront of the nozzle.

E i l C id ti t


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Economical Considerations-cont Size of the Powerhouse

The powerhouse concrete volume can be determinedbased on a number of units and their throat diameter. Often

the cost of the civil work is higher than the cost of theequipment. Reducing the cost of the unit size decreasesthe cost of the powerhouse.

Sales of electricity

The revenue from the sale of electricity produced by oneunit is given by the following equation: R=9.81*Q*Hn*nTa where

Q is discharge in m3/s Hn is net head in m

n is overall efficiency of the system = running time Ta is electricity tarriff

E i l E l ti


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Economical Evaluation

Static Methods: Payback (recovery or break even period) Method:

determines # of years required for invested capital to beoffset by resulting benefits.

Return on Investment Method: calculates average annual,net of yearly costs, such as depreciation, as a percentage

of the original book value of the investment.

Dynamic Methods: these take into account totalcosts & benefits over the life of the investiment and

the timing of the cash flow

Net Present Value (NPV) Benefit-Cost ratio (B/C)

Internal Rate of Return (IRR)


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C. Barriers Challenging the Development &

Implementation of SHPs

1. Investor confidenceis lacking

2. Financing: Financial institutions are generally notfamiliar with small hydropower sector.

3. Technical capability: The engineering and consultingfirms in Africa have limited experience with carrying

out F/S, design & Construction of SHP. Without highquality assessment & F/S then investment will notcome in this sector

4. Lack of infrastructure for manufacturing, installationand operation. Most of the countries in Africa do not

have any facility to manufacture even the mostrudimentary turbines or parts that might be critical inmaintenance of the schemes.


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D. New Financing Model for SHP This is an entrepreneurial centered approach featuring a combination

of services and financing.

Under this model, a financier works to bring small, privately ownedcompanies together with a commercial investor to back SHPs.

The financier provides a range of services to privately owned coyswho want to supply clean electricity to their factories and communities

around to help them improve their lives and income

The financier provides the following services:

Accepting project risks

Offering convertible debt (i.e. Debt that may be converted to equity) atreasonably attractive terms.

Providing debt and equity financing options appropriate for the size of theentreprise and market conditions

Providing support services to the developer b4 and after an investment

Forstering partnership and relationship with social investors and partialrisk sharing lenders

D New Financing Model for SHP cont


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D. New Financing Model for SHP - cont

The entrepreneurial model should work as follows:

The financier provides first the seed money to pay for legal,engineering or environmental preparation

The funding can range from USD 100,000 to USD 3 Milliondepending on the size of the project and it is a case by case. For

our case, if we are superimpose GTIEA Project - FSP phase on

this model, the seed money comes to about USD 2.8 Million.

The financier acts like as an advisor helping and entrepreneurwith the business plan development , working with banks to get

the construction funding, negotiating PPAs and training

developers on approaches to business management andexpansion.

Once an enterprise begin to meet its objectives, it may beappropriate to provide a growth loan


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D. New Financing Model for SHP - cont

The entrepreneurial model would look like:

Financiere.g.

GEF/Gvt/IDA

Private Enterprisee.g.

Tea companies

thru EATTA

Commercial Investor

e.g. development

& commercial banks

Partnership


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GTIEA & Cogen Africa Projects -Nairobi

Kenya, Nov 9-10, 2007 29

1. Small hydro has proven itself as a major contributor to electrification

in developing countries, e.g China & India as examples where small

hydro has been developed in large parts of the countries.2. The interest in small hydro on the African continent as emerged over

the last couple of years, has resulted in a number of projects that will

pave the way for large scale introduction of small hydro. The current

interest by African Governments, international donors, development

banks and the private sector in increasing energy access in Africa willfacilitate the uptake of this robust, environmentally friendly form of

energy. GTIEA Project is a result of this interest!

3. The challenge upon us now is to maintain the momentum created

and ensure that the current interest will be translated into more small

hydro plants installed.

CONCLUSION

fundamentals of small hydro power technologies

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