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AN INTEGRATED POWER SUPPLY SYSTEM FOR

WATER PUMPING AND LIGHTING IN A RURAL

VILLAGE, UTILIZING RENEWABLE ENERGY SOURCES

Name : J.A.C.K.J. Bandara

Student No: 740112A152

Local Supervisors: Dr. N.S. Senananyake

Mr. Ruchira Abeyweera

KTH Supervisor: Prof. Peter Hagström

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Bachelor of Science ThesisEGI-2012-xx

Title: An Integrated Power Supply System for Water

Pumping and Lighting in a Rural Village, Utilizing

Renewable Energy Sources

Name1: J.A.C.K.J. Bandara

Name2

Approved

Date

Examiner

Name

Supervisor

Prof. Peter Hagström

Dr. N.S. Senananyake

Mr. Ruchira Abeyweera

Commissioner

Contact person

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Abstract

This report consists of the design and development of a renewable energy based

integrated power system for a community living in the village, Kahambana in the district of

Monaragala, Sri Lanka, recognized as rural area. Agriculture is still the source of income of

more than half of the people in the area. The area is water stressed and pumping of water

required for agricultural works is obtained from a nearby reservoir by means of gasoline

fueled engine driven pumps. Further, no national grid electricity is available because the

village situated away from the main grid. In order to address these difficulties, this study

formulated a low cost water pumping system together with an electricity generation system

running on renewable energy for the benefit of community living in the village.

The proposed system did not consider the conventional direct water pumping method by

wind energy as some of energy deficiencies and lack of required capacity were identified.

The proposed system consists of irrigation pump powered by electricity generated by a wind

turbine. Main components of the system are electric water pump designed for irrigation

with necessary controls, power generation wind turbine and controls, battery bank and

water storage tank. Energy consuming components such as pumps, motors and variable

frequency drives were selected in order to operate at the best possible efficiency. For

household electrification, efficient lighting was assumed. Net irrigation, required to be

pumped does not remain constant as water requirement varies with the crop, crop maturity

and rain fall which varies over the year. On the other hand wind speed varies over the year.

Therefore, the wind turbine was selected so that even at lowest available wind speed, it

produces energy required for water pumping. Wind speed data published by the National

Renewable Energy Laboratory (NREL) for the district of Hambantota (lying in the same

region in the wind atlas as the selected village) was used for the design calculations. Excess

energy generated in certain periods of the year could be used for household electrification

with a proper storage system.

Finally, the cost of construction and installation of the system was estimated and hence a

comparison of unit generation cost of proposed system with present rates has been

prepared. It shows the water pumping system is economical than the present engine driven

system. However, the electricity generation rate is much higher than the rate of grid

electricity. But, because of the difficulty (or high cost) of extending the national grid to this

area, this is much feasible method to provide electricity to the village.

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Table of Contents

Abstract .......................................................................................................................................................... 3

1 Introduction .......................................................................................................................................... 9

2 Methodology ....................................................................................................................................... 12

2.1 Identifying the village ................................................................................................................ 12

2.2 Collection of data and information ......................................................................................... 12

2.3 Conducting literature review in view of finding a possible solution for the problem ..... 12

2.4 Estimation of the agricultural water requirement of the selected village .......................... 12

2.5 Estimation of energy requirement for water pumping and household electrification .... 12

2.6 Selecting the components of the proposed System .............................................................. 13

2.7 System configuration ................................................................................................................. 13

2.8 Comparison of cost associated with proposed system ........................................................ 13

2.9 Project Execution ...................................................................................................................... 13

3 The village selected and relevant information ............................................................................... 14

3.1 Location ...................................................................................................................................... 14

3.2 Data and Information ............................................................................................................... 14

3.3 Wind data .................................................................................................................................... 15

4 Literature Review ............................................................................................................................... 18

5 Agricultural Water Requirement ...................................................................................................... 23

5.1 Water Requirement for Paddy Cultivation............................................................................. 23

5.2 Calculation of Required Pump Capacity ................................................................................ 27

6 System Design .................................................................................................................................... 28

6.1 Energy Requirement for Water Pumping .............................................................................. 28

6.2 Household Electricity Demand ............................................................................................... 39

6.3 Calculation for System Components ...................................................................................... 41

6.4 Water Storage System ................................................................................................................ 50

6.5 System Configuration ................................................................................................................ 51

6.6 Energy Flow Diagram ............................................................................................................... 52

6.7 Cost Comparison ....................................................................................................................... 53

7 Project Execution ............................................................................................................................... 55

7.1 Work Breakdown Structure (WBS) ......................................................................................... 55

7.2 Scheduling ................................................................................................................................... 56

7.3 Stakeholder Management ......................................................................................................... 60

8. Discussion .......................................................................................................................................... 63

9. Conclusion ..................................................................................................................................... 6364

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10. References....................................................................................................................................... 6365

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List of Figures Figure 01: A Satellite Photo of the Selected Village and Site Location Figure 02: Wind Speed and Power by Hour Figure 03: Frequency of Wind Speed and Percent of Power by Hour. Figure 04: Conventional Water Pumping Wind Mill Figure 05: Piston Cylinder Arrangement of a Typical Wind Water Pump Figure 06: Water Level required at each Crop Growing Stage Figure 07: Location of Water Source and Piping System Arrangement Figure 08: Chart of Motor Efficiency Vs with Rated Power Figure 09: Chart of Motor Efficiency Vs Percentage of Full Load Figure 10: Variation of Efficiency of Variable Frequency Drives with Percentage of Full Load Figure 11: Excess Energy Production and Lacked Energy over the Day Calculated Hourly Figure 12: Wire Diagram of the System (Single Line) Figure 13: Energy Flow Diagram Figure 14: Work Breakdown Structure Figure 15: Gant Chart for project Scheduling Figure 16 : Stakeholder Analysis Matrix

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List of Tables Table 01 - Average Annual Wind Speed by Hour (Extracted from Figure -02) Table 02 - Average Wind Speed by Hour at each Month (Extracted from Figure -02) Table 03 - Monthly Average Rainfall of Monaragala District Table 04- Pumping Capacity of the Products Manufactured by Ironman Windmill Co. Ltd. by

Different Turbine Sizes Table 05 - Required Water Level at each Crop Growing Stage (Extracted from Figure 04) Table 06 - Average Irrigation Required per Day at each Time Period of the Year Table 07 - Required Water Pumping Flow Rate at each Time Period of the Year Table 08 -Types of Pumps to be considered for Calculation Table 09 - Equivalent Length of Suction and Discharge Pipes Table 10 - Head Required by each Pump Type at the Maximum Required Flow Rate

Table 11 - Head Required by each Pump Type at the Maximum Required Flow Rate Table 12 - Variation of System Head with Flow Rate Table 13 - Brake Power Delivered by each Considered Pump Type to Discharge the Required

Water Flow Rate Table 14 - Brake Power and Efficiency of Considered Pumps at Desired Flow Rate Table 15 - Electrical Power Required by each Pump Type to Pump the Desired Flow Rate Table 16 - Hourly Energy Demand and Total Energy Units Consumed by Households Table 17 - Electric Power Needed to Pump the Required Water amount in each Time Period Table 18 - Time Taken to Pump the Required Water Amount Table 19 - Wind Turbines with Specifications and Prices Table 20 - Generated Power by each Type of Wind Turbine based on the wind speed from January 1st to 25th Table 21 - Produced Energy by each Type of Turbine from January 1st to 25th Table 22 - Excess and Lacked Energy over the 24 hours of the Day (1st to 25th January) Table 23 - Excess and Lacked Energy per Day in each Time Period Table 24 – Activity List of Project of System Installation Table 25 - List of Stakeholders

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Nomenclature

A Swept Area of Wind Turbine (m2)

C Constant for Pipe Material

CB Battery Bank Capacity (Ah)

D Pipe Diameter

DOD Depth of Discharge (%)

E Evaporation Rate (mm)

EFR Effective Rainfall (mm)

EL Electrical Load (kWh)

ET Evapotranspiration (mm)

g Gravitational Acceleration (m/S2)

h Head of Water column (m)

H Total Head of Water to be Pumped (m)

H1 Head Loss due to Pipe Friction (m)

H2 Head Loss due to Pipe Fittings (m)

H3 Static Head of the Water Column (m)

H4 Head Required at the End of Pipe (m)

H5 Pump Internal Head Loss (m)

B Battery Efficiency (%)

IR0 Irrigation Requirement in Pre Saturation Period (mm)

IR1 Irrigation Requirement at crop age of 0-15 days (mm)

IR2 Irrigation Requirement at crop age of 16-45 days (mm)

IR3 Irrigation Requirement at crop age of 46- 85 days (mm)

IR4 Irrigation Requirement at crop age of 86-110 days (mm)

IRi Irrigation Requirement in different Growing Stage (mm)

L1 Total Length of Pipe (m)

L2 Equivalent Length of Fittings (m)

N Number of Batteries in Battery Banks

NIR Net Irrigation Required (mm)

P Total Pressure Developed by Water Pump (bar)

PA Available Power of Wind (W)

Q Water Flow Rate through Pump (l/min)

a Density of Air (kg/m3)

RP Required Pond Depth (mm)

w Density of Water (kg/m3)

S Saturation Water (mm)

SP Seepage & Percolation (mm)

v Wind Speed (m/S)

VB Battery Voltage (V)

WD Initial Depth of Flooding (mm)

WR Water Requirement (mm)

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1. Introduction

1.1. General Introduction

Today the economy of Sri Lanka is running on three major sectors, Agriculture, Industry,

and service. The share of agriculture together with fishery is about 12%, while the industrial

sector that includes manufacturing, construction, mining & quarrying and electricity, gas &

water contributes 29.2 for the GDP of the country. Service sector being the predominant

economic player, contributes 58.6 to the economy. Early era of post-colonial rule (from 1948

BC) the key contributor to the economy was agricultural sector that consists of plantation

crops such as tea, rubber and coconut and other minor exporting such as cinnamon, clove,

pepper etc. However due to the price fluctuation of these commercial crops in the world

market, this economy could not sustain and was changed to import substation economy in

which the industrialization that country produce all possible public needs started. Later the

political authority realized that this economy was not sufficient for the development of the

country and transformed to the export oriented economy. Economy was opened partly in

1965. After 1977 the present economic model, fully open economy that results for the rapid

economic growth was initiated.

With that considerable foreign investments came in to the country and industrial zones

were established. Foreign funded projects were commenced. Most remarkable project was

the Mahaweli Development Project, a multipurpose project run on Japanese loan that

diverts the river Mahaweli, the longest river starting from Central Hills and ending at east

coast of the country, towards the north central region of the country. Large reservoir dams

were constructed and major hydropower projects were initiated increasing the capacity that

was a basic need both for industrialization and community electrification. Further the water

needs in agricultural activities were fulfilled with the initiation of project. The outputs of

those projects were foreign earnings to the country that could help to settle the foreign

loans. However one major difference of development of economic models in Sri Lanka

compared to other developed countries of the world is that it directly transformed to a

service dominated economy from agriculture dominated economy. Industrial sector have

not been the main player in Sri Lankan economy forever.

As large hydropower projects were commenced in the decade 1980s till the, year 2014 in

which second phase of large coal power plant (600 MW) was commissioned, the dominant

power generation technology had been hydropower. As per the energy policy of Sri Lanka

published by a gazette extraordinary in 2008 the country’s main energy goals in related to

renewable energy development are,

1. Generate 10% of electricity using NCREs by 2010 and further growth up to 20% by

2020

2. 20% share of bio diesel in transport sector by 2020.

3. Increase the household electrification up to 100% by 2016 (Present electrification is

96%).

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As SL electricity sector had been hydropower driven there is not any influence from the

outside to increase renewable portion or GHG reduction technologies, however SL

government has defined this energy policy. By today there are about 11 wind power plants

in the range of 1 to 30 MW, (Total capacity about 90 MW) installed over the coastal and

central hill region of the country and connected to the main grid.

From the beginning of the written history of Sri Lanka, the People have been sustained

their livelihood with agriculture mainly paddy and other food crops. From about the century

3rd Ad to 12th CE they had been constructing lakes for the purpose of collecting excess

water in rainy season and save for the off rain season, as majority of the country had been

living in water stressed areas called as “dry zone” of the country that lies about two third of

the country.

With foreign invasions majority of people moved to south west region which is water

blessed area and present main city, Colombo is located. Due to the lack of maintenance and

not taking care some of them are vanished and most of lakes are now not as initial

construction and not possible for irrigation as usual.

1.2 Problem Formulation

At present water is pump from the lakes to the paddy fields by means of pumps driven by

gasoline fueled engine. If the electricity is available people can directly use pumps powered

by electricity. However, 4% of the country’s population still lives without electricity, as up

to now only 96% of households have been electrified. Even though main grid is available for

some rural areas, it is only for households and not reachable for the farming areas. The CEB

does not provide electricity without a permanent consumer unit (building,

industrial/residential or commercial). On the other hand the SL Government does not have a

plan for providing electricity for those areas. The people engaged in farming have arranged

themselves for irrigation water supply by engine driven pumps. The engines used are small

gasoline fuelled ones and with very low efficiency. Even a turbo charged, intercooled

medium size engine consumes about 2.5 to 3 liters of diesel to produce one kilo watt hour of

electricity, making the generation cost too high compared with present electricity generation

and selling rates in Sri Lanka. If considerable farming lands are used the water pumping cost

gets too high and the out flowing of foreign exchange will be higher. If a sustainable, high

efficient process can be introduced, this problem can be eliminated or mitigated.

Taking the need of rural electrification (in order to achieve 100% target) and reducing low

efficient gasoline engines in irrigation works together, it will be worthwhile to develop an

off- grid, renewable based power generation system that fulfill the requirement of water

pumping and electrification. The area we focused is wind driven power system as it is the

most viable option for Sri Lanka.

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1.3 Objective

The objective of this project is to design an integrated power generation system that

will replace the present low efficient, and expensive agricultural water pumping

method in rural areas of the country with a more efficient agricultural water pumping

method utilizing renewable energy sources

will provide electricity generated by renewable energy sources, especially for lighting

purpose, to the rural community, where the supply from the national grid is not

possible

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2. Methodology

2.1. Identifying the village

A village with majority of people make livelihood through agriculture especially paddy

cultivation and without grid electricity was identified.

2.2. Collection of data and information

The basic information like population, number of families, approximate area of the

village, and land area utilized for farming were obtained through a site survey. A suitable

location for installing the plant was selected considering the topography and the close

proximity to the available water resource. Data required for designing the system was

collected by referring relevant resources and from the local agencies responsible for

agriculture. The collected data were wind speed pattern and monthly average rainfall. From

the Department of Agriculture, data required to calculate water demand in paddy cultivation

such as seepage losses, evapo-transpiration, evaporation etc., under the environmental

conditions in Sri Lanka was obtained.

2.3. Conducting literature review in view of finding a possible

solution for the problem

Literature relevant to paddy cultivation, wind energy, wind power potential in Sri Lanka,

pump and piping, and water pumping wind mills were reviewed in order to determine the

most suitable options for the selected village.

2.4. Estimation of the agricultural water requirement of the

selected village

Agricultural water requirement at each crop growing stage and hence in each time period

of the year was determined using the available data. Inputs were the monthly rainfall, and

other data collected from Department of Agriculture.

2.5. Estimation of energy requirement for water pumping and

household electrification

After calculating the water demand, the possibility of developing wind water pumping

was studied and realized that the available systems were not sufficient to deliver the

required water flow. Then it was decided to go for electricity driven water pumps and

suitable pump and other components were selected and then the energy demand for water

pumping system was determined. About 7 pump types with different specification such as

horsepower, inlet/outlet diameter, flow rate and head were taken for calculation. The Hazen

Williams Equation was used for calculating the system head. System head varies with the

each pump size and by plotting the system head Vs water flow rate for a particular pump on

the pump performance curve, the duty point of each pump could be marked. Out of the

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considered seven pumps, the one giving best efficiency was selected. This is the pump that

consumes lowest electricity for pumping required amount of water. Here the manual

calculations and plotting were performed, but there are number of software available for

pump selection. One software is “PUMP- FLO”, but some pump manufacturers provide the

software for pump selection, while others take the selection part to their hand and the

buyer need only to provide the initial data.

The energy required for household electrification was calculated. Low energy consuming

LED bulbs were proposed to be used.

2.6. Selecting the components of the proposed System

The wind turbine that matches to the system requirements was selected by considering

several sizes and makes. Total energy produced by each turbine with the available wind

energy was estimated. Turbine manufacturer’s power curve was used for selecting optimum

turbine. Here also manual calculation was performed, however for turbine selection also

software can be used. One powerful software is “Homer”. Homer is developed for designing

power systems that may consist of both electricity and thermal loads, with cost optimization

and several other factors such as limiting CO2 emission etc.

Assuming three consecutive zero wind days an energy storage system, a battery bank was

proposed. The size of the battery bank was determined accordingly.

2.7. System configuration

The system was configured as resulted in above calculations.

2.8. Comparison of cost associated with proposed system

Estimate for installation, including the construction works was prepared and hence the

cost to produce one energy unit was determined and a comparison of unit cost with existing

electricity rates was made. The cost amounts are given in Sri Lankan Rupees (LKR), and

current exchange rate is 140.49. (Central Bank of Sri Lanka, 2015)

2.9. Project Execution

Finally, basic information required for project execution part was included. It contains

Work Breakdown Structure (WBS), Activity List, Gant Chart, and Stake Holder Analysis.

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3. The village selected and relevant information

3.1. Location

Selected area lies approximately between the Latitudes of 6.7714 to 6.778665 and

Longitudes 81.374808 to 81.362000. Name of the village is Kahambana near to Ambagolla

and in the district of Monaragala in Uva Province. Figure 01 is a satellite image of the

selected village.

Figure 01: A Satellite Photo of the Selected Village and Proposed Site Location

(Google, 2014)

3.2. Data and Information

Population of the Village - 211

No. of Households - 47

Land Area - 1.92 km2 (Approximately)

Land use for Agriculture - 30 ha (Approximately)

Proposed Location for the pump

station

Proposed Location for Storage

Tank

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3.3. Wind data

Wind speed data shown in Figure 02, were extracted from the Wind Energy Resource Atlas of Sri Lanka and Maldives published by National Renewable Energy Laboratory (Elliott D., Schwartz M., Scott G., Haymes S., Heimiller D., George R. Wind Energy Resource Atlas of Sri Lanka and the Maldives,2003,pp 104,). The average wind speed and power variation during the day in each month is given in above document. This page includes the data collected in the Hambantota measurement site. It is the closest site to our location and therefore these data are taken for our calculations.

Figure 02- Wind Speed and Power by Hour (National Renewable Energy Laboratory, 2003)

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Table 01 shows the average annual wind speed at each 4th hour of the day hour extracted from above Figure 02. Table 01 – Average Annual Wind Speed by Hour (Extracted from Figure -02)

Hour of the Day 0 4 8 12 16 20 24

Wind Speed (m/S) 6 5 5 8 10 7 6

The average wind speed in each month is given in the table 02 that is extracted from Figure 02. Table 02 – Average Wind Speed by Hour at each Month (Extracted from Figure -02)

Month

Wind speed (m/s)

Hour of the Day

0 4 8 12 16 20 24

January 6 5 5 8 9 7 6

February 5 4 4 6 10 8 4

March 4 4 4 7 9 7 4

April 4 3 2 6 7 6 3

May 4 4 4 8 10 7 5

June 7 7 7 10 10 8 4

July 7 7 7 10 10 8 7

August 7 7 6 10 11 8 7

September 6 5 5 10 12 8 6

October 6 5 5 10 10 7 6

November 5 4 4 7 7 5 4

December 6 5 4 7 8 7 6

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Figure 3 shows the frequency of wind speed and percent of power by hour.

Figure 03: Frequency of Wind Speed and Percent of Power by Hour. (National Renewable Energy Laboratory, 2003) Table 03 shows the monthly average rainfall of the District Monaragala that the village lies in. Table 03-Monthly Average Rainfall of Monaragala District

Average Rainfall (mm)

Month

Jan

uar

y

Feb

ruar

y

Mar

ch

Ap

ril

May

Jun

e

July

Au

gust

Sep

tem

ber

Oct

ob

er

No

vem

ber

Dec

emb

er

For Month 58 47 101 143 91 59 48 55 71 151 188 118

For Day 1.93 1.57 3.37 4.77 3.03 1.97 1.6 1.83 2.37 5.03 6.27 3.93

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4. Literature Review

Water Pumping Wind Mills

Even though the term “conventional” is used to describe the system, it is an improved

system by today from its initial state. This system is said to be started in 9th Century and the

historical development during past centuries made the present wind water pump. Figure 04

shows a typical water pumping wind mill. It consists of following major components

Figure 04: Conventional Water Pumping Wind Mill (Agriculture and Agri -food, Canada, 2014)

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Wind Turbine The turbine is manufactured as multi bladed, typically in the range of 15 -40 steel or

Galvanized Iron blade, in order to develop a high torque. The turbine starts to rotate at 2.5-

3m/S wind speeds and increases rotating speed (RPM) and hence water flow rate with wind

speed. Once the wind speed comes down to about 2.5m/S the turbine stop rotating. The

starting and stopping speed slightly varies from type to type depending on the turbine

construction and the turbine manufacturer provides this speed with the specification.

Gear Box Gearbox is driven by the turbine and converts by its special mechanism, the rotational

motion to the linear (up and down) motion.

Tower Tower is a structure made of hot rolled steel profiles that carries the turbine and gearbox

mechanism. Tower typically consists of three or four legs mounted on concrete footings

provided at ground level.

Piston Pump The linear up and down motion produced by gearbox is transferred to the piston of the

pump (See figure 05) by means of pump rod. Pump consists mainly piston, cylinder and two

check valves. The cylinder is placed in water straight below the turbine tower and piston is

housed in the cylinder to move up and down. One check valves is fixed to the bottom of

cylinder and it opens upwards as the piston moves up, allowing water to come in to the

cylinder. Other check valve is fixed to the bottom of the piston that retain at close position

during the upward motion. When piston moves down, checks valve opens and allows water

in the cylinder to come on the piston. This water then comes upward again in the next

motion of piston to upward direction. The difference of this pump with the reciprocating

pump is the motion of water in the pump is towards the same direction. Pump rod transfer

the motion from gearbox to piston.

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Figure 05: Piston Cylinder Arrangement of a Typical Wind Water Pump (Agriculture and Agri -food, Canada, 2014)

Discharge Pipe

Water lifted by piston is delivered to the storage tank or directly to the field through

discharge pipe.

The piston type water pumps used in this application has the capacity maximum about 1 l /S

(60 l/min) therefore it is suitable for lesser irrigation requirements.

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Commercial Wind Water Pumping Systems

Ironman Windmill Co. Ltd is a leading manufacturer of water pumping wind mills. Our site

requirement for pumping needs to lift water 21m from its existing level. As per the product

specifications of Ironman Windmill Co Ltd , there largest turbine is 6m. Below is a calculation

table provided by the manufacturer to calculate the flow rate at different turbine sizes and

wind speeds for a particular pumping height. The height can be varied from 0.5 m to 360 m

and the calculator gives the flow rate at each speed.

Table 04- Pumping Capacity of the Products Manufactured by Ironman Windmill Co. Ltd. by Different Turbine Sizes (Ironman Windmill Co. Ltd, 2014)

22M PUMPING ELEVATION

WINDMILL DIAMETER > 2.4M 3.6M 4.8M 6.0M

STRONG WINDS 1598 3752 8857 20410

MEDIUM WINDS 879 2063 4871 11226

LIGHT WINDS 399 938 2214 5103

PUMP DIAMETER IN MM 80 120 200 250

Values shown are LITERS pumped PER HOUR.

At moderate wind speeds it can pump maximum 11.23 m3/h of water to a height of 22 m

with 6 m diameter turbine.

At medium wind speeds (6m/s) the available wind energy for a 6m diameter turbine is

given by the following equation.

PA = 0.5aAv3

= 0.5 X 1.2041 X X 32 X 63 = 3680 W

Energy of Pumped Water (22 m at 11.23 m3/h) = Qwgh = 11.23 X 1000 X 9.81 X 22/3600 W = 673 W

Overall efficiency of the system is then 18.31% (673/3680) a very low conversion process

compared with wind electricity generation system. Typical wind turbine can generate about

1500 W at 6 m/s wind speed.

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Wind Speed of Sri Lanka

Wind speed and energy distribution in Sri Lanka are provided in Wind Energy Resource Atlas of Sri Lanka and Maldives published by National Renewable Energy Laboratory (Elliott D., Schwartz M., Scott G., Haymes S., Heimiller D., George R. National Renewable Energy Laboratory (August 2003)

Wind resource maps, indicating the poor to excellent wind energy potentials, energy per unit area are included. These maps were created at the National Renewable Energy Laboratory (NREL) using Geographic Information System (GIS) software used in computerized wind mapping system. Wind speed data required for the calculations were taken from this document.

Electricity Generation Wind Turbines

The power generation wind turbines range from small to large depending on the requirement of the power developer. In our case it falls under the small wind turbine. In general, DC power is generated by wind turbines and finally is converted to AC power by the inverter. As our system is a standalone one a storage battery system is to be additionally installed.

Available Power of a wind stream is given by

Pa = 0.5Av3

Where, A is the swept area of the wind turbine, v is the wind speed and is the density of air. Hence A slight increase in wind speed can cause to increases the available power by a large amount.

The actual power extracted by the wind turbine Pt is

Pt = Cp.Pa

As Cp varies with the wind speed the variation of output power Pt with the speed does not have that much of magnitude. Usually the wind turbine manufacturer includes the power curve of a particular wind turbine in to the technical data sheet there is no need of calculating these things and can directly find the turbine power at any wind speed from the curve. Power curves of each wind turbines that are taken in to our consideration are given in annex C1 to C7.

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5. Agricultural Water Requirement

5.1. Water Requirement for Paddy Cultivation

Water Level required to be maintained at Different Growing Stage is illustrated in Figure 06.

Figure 06: Water level required at each Crop Growing Stage

(Zawawi, Mustapha and Puasa, 2012) As per the figure 06, the paddy cultivation season is divided into four age groups as pre saturation, vegetative, reproductive, and ripening, during which the water demand by crop varies. The table 05 shows the water requirement by crop during each crop growing stage. Table 05: Required water level at each crop growing stage (Extracted from Figure 04)

Crop Growing Stage Age of Crop ( Days) Duration (Days) Water Level Required

(mm)

Pre Saturation - 60 200

Vegetative 0-15 15 100

Vegetative 16-45 30 20-50

Reproductive 46-85 40 100

Ripening 86-115 25 0

Water loss in paddy fields depends on the atmospheric and soil condition of Sri Lanka and

lies in following range.

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Seepage losses 1-2mm Evaporation losses 1.5-2mm Evapotranspiration losses 3-6mm

In general farmers of Sri Lanka do farming for paddy in two seasons an year. Main season

starts in March and ends in August. From September to February it is minor season. About

four months they take for cultivation (from seeding to harvesting) and about two month

time before seeding is left for pre saturation for the ground and ground preparation.

However this is dependent on when the rain starts and our farmers arrange themselves the

cultivation accordingly.

From Table 05, water demand in each month is calculated. For the calculation we take the

worst case (i.e. maximum value of the reference range of water requirement). For example;

seepage losses is between 1-2 mm, but it is taken as 2 mm for our calculation.

Below is the calculation of irrigation at each growing stage of the paddy cultivation for the

main Season (March to August)

To calculate irrigation requirement during pre-saturation (60 days, from the 1st of March to the 30th of April) the following equation was used.

IR0 = S +WD + E + SP-EFR S = 150mm (From Table 04, pre saturation) WD = 100mm (From Table 04, 0-15 days) E = 2mm/ day X 60 days SP = 2mm/ day X 60 days EFR = 101 (March) +115 (April) [Since the rain fall is not much high, no spilling or flooding can be expected. Therefore, total rainfall is taken as effective rainfall]

IR0 = 150+ 100+2 X 60+2 X 60 – (101+143) = 296mm

To calculate the irrigation requirement during growing stage the following equation was used.

IRi = ET + SP+ (RP-WD) -EFR For crop age of 0-15 days (From 1st May to 15th May, 15 days)

ET = 6mm/day SP = 2mm/day RP = 100mm

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WD = 100mm EFR = 2.97mm/day

IR1 = 6 X 15+ 2X 15+ 100-100-3.03 X 15 = 74.45mm

For crop age 16-45 days (From 16th May to 15thJune, 30 days) ET= 6mm/day SP= 2mm/day RP= 50mm WD= 100mm EFR= 2.97mm/day (for May), 1.97mm/day (for June) RP-WD = 50-100= -50 mm When RP-WD <0, then it is substituted as zero. Therefore, RP-WD=0

IR2 =6 X 30+2 X 30 +0- (2.97 X 15+1.97 X 15) = 166.9mm

For crop age 46-85 days (From 16th June to 25th July, 40 days) ET= 6mm/day SP= 2mm/day RP= 100mm WD= 50mm EFR= 1.97mm/day (for June), 1.60mm/day (for July)

IR3 = 6 X 40+2 X 40 +100-50- (1.97 X 15+1.6 X 25) = 300.45mm

For crop age 86-110 days (From 26th July to 20th August, 25 days) ET= 6mm/day SP= 2mm/day RP= 0 mm WD= 100mm EFR= 1.6mm/day (for July), 1.83mm/day (for August) RP-WD = 0-100= -100 mm When RP-WD <0, then it is substituted as zero. Therefore, RP-WD=0

IR4 =6 X 25+2 X 25 +0- (1.6 X 5+1.83 X 20) = 155.4mm

-26-

Similarly the irrigation requirement for minor season (September to February) is

calculated and all the calculated results are tabulated. The irrigation required per day during

each growing stage is also calculated and shown in the table 06.

Table 06 - Average Irrigation Required per Day at each Time Period of the Year

Period Crop Growing

Stage Age of Crop

(days)

Irrigation Required -IR

(mm)

Duration -d (days)

Average Irrigation

Required per day (mm/day)

1st March to 30th April

Pre- Saturation

- 296 60 4.93

1st May to 15th May

Vegetative 0-15 74.45 15 4.96

16th May to 15th June

Vegetative 16-45 166.9 30 5.56

16th June to 25th July

Reproductive 46-85 300.45 40 7.51

25th July to 20th August

Ripening 86-110 155.40 25 6.22

1st September to 30th

October

Pre- Saturation

- 268 60 4.47

1st November to 15th

November Vegetative 0-15 25.95 15 1.73

16th November to

15th December

Vegetative 16-45 57 30 1.90

16th December to 25th January

Reproductive 46-85 262.8 40 6.57

25th January to 20th

February Ripening 86-110 158.5 25 6.34

-27-

5.2. Calculation of Required Pump Capacity

Daily water pumping requirement and hence the minimum pump flow rate required were

calculated as follows.

For pre- saturation period (1st March to 30th April) Irrigation required per day = 4.93mm It means 4.93 liters of water is required per one Square meter agricultural land. For 30 hectares, Water Requirement = 4.93 X 104 X 30 = 1479m3/ day Assuming pump operating time to be 15 hours per day, Minimum pump flow rate required = 1479/ (15 X 60) m3/min = 1.64 m3/min Table 07 gives the required minimum pump flow rate for each time period. Table 07- Required Water Pumping Flow Rate at each Time Period of the Year

Period Crop

Growing Stage

Duration (days)

Average daily Irrigation

Required -IR/d

(mm/day)

Average pumping Required (m3/day)

Required Pump Flow rate (m3)/min

1st March to 30th April

Pre- Saturation

60 4.93 1479 1.64

1st May to 15th May Vegetative 15 4.96 1489 1.65

16th May to 15th June

Vegetative 30 5.56 1669 1.85

16th June to 25th July Reproductive 40 7.51 2253 2.50

25th July to 20th August

Ripening 25 6.22 1866 2.07

1st September to 30th October

Pre- Saturation

60 4.47 1341 1.49

1st November to 15th November

Vegetative 15 1.73 519 0.58

16th November to 15th December

Vegetative 30 1.90 570 0.63

16th December to 25th January

Reproductive 40 6.57 1971 2.19

25th January to 20th February

Ripening 25 6.34 1902 2.11

-28-

6. System Design

As the conventional wind water pumping system and commercially developed one (By

ironman Windmills Co. Ltd) do not give the sufficient capacity that is required, the only

option is to use electricity driven pumps and to generate the required electricity by means

of wind turbine designed for electricity generation. On the other hand the efficiency of the

process can be improved in this type of system more than other methods.

6.1. Energy Requirement for Water Pumping

Calculation of Required Pump Head To deliver above water flow rate (maximum 2.5 m3/min), one duty pump of above

capacity and parallel standby pump (two pumps with capacity 2.5 m3/min) will be installed.

From the catalogue of a world’s leading pump manufacturer’s website (Barkley- USA) as the

first step, for determination of system head seven pump sizes given in the table 08 having

different suction and discharge diameters are taken into consideration.

Table 08- Types of pumps to be considered for calculation

Pump Size Type 1 Type 2 Type3 Type 4 Type 5 Type 6 Type 7

Discharge Pipe Size (mm) 65 80 100 125 150 200 250

Suction Pipe Diameter (mm)

80 100 125 150 200 250 300

Figure 07 is the site arrangement drawn as per the measured dimensions. Water has to be pumped from the water source to the higher elevation where the storage tank is proposed to be constructed. From this higher location water flows to the paddy fields by gravity.

4m

6m 3m26m

14m

4.5m

29.53m

Water Level

Water PumpPipe Line

(Discharge Side

Pipe Line

(Suction Side)

Storage Tank

Location

Down towards

Paddy Fields

Figure 07: Location of Water Source and Piping System Arrangement

-29-

As per the site location and the measurement taken, Level difference between water source and highest

Suction = 4m Discharge = 14m Total = 21m

Horizontal Distance Suction= 6m Discharge= 3+26+4.5 =33.5m Total= 39.5m

Pipe Length

Suction = 6+4 =10m Discharge = 6+ (262+142)0.5+4.5 =44.03m Total = 54.03m

Total Head (H) = H1+ H2 + H3 + H4 + H5 + H6

To calculate H1 + H2, Apply Hazen- William Formula

L = Total pipe length (L1) + Sum of Equivalent lengths of fittings (L2) Calculation of L2

From the Annex I, equivalent length of each fitting and hence the sum of equivalent

lengths can be determined. For pump type 4, the equivalent length of fittings L2 is calculated

as in the table 09. Since suction and discharge diameters are not the same, H1 + H2 for both

suction and discharge sides should be calculated separately.

Table 09- Equivalent Length of Suction and Discharge Pipes

Fitting Suction Side (6 "/150mm) Discharge Side (5 "/125mm)

No of Fittings

Equivalent Length (m)

Total Equivalent Length (m)

No of Fittings

Equivalent Length (m)

Total Equivalent Length (m)

Gate valves 1 1.1 1.1 3 1.1 3.3

Tees 1 8.6 8.6 1 8.6 8.6

450 Elbows

3 2.3 6.9

900 Elbows 3 2 6 4 2 8

Sum of Equivalent Lengths 15.7 26.8

-30-

(* Note – Since the table has not provided the equivalent lengths for 5” pipe size the values of 6” are taken for calculations)

For Suction side L2= 15.7m L1= 10m

L= 15.7 +10m = 25.7m Q= 2500 l/min C= 120 for Galvanized Steel form Annex I D= 150mm Applying in Hazen- Williams Equation for suction side,

H1 +H2 = 1.08m

H3 = 4m H4 = 0 (for suction side) H5 = 0 (for suction side) So, H = 1.08 + 4 = 5.08m

For Discharge side, L2 = 26.8m L1= 40.1m L= L1+L2 =66.9m Applying the same formula (Hazen Williams) to calculate H1 + H2,

H1 +H2 = 6.84m H3= 20m H4= 2m H5= 2m (Varies slightly with different brands/Models and constructions of pump) H = 6.84+20+2+2 = 30.84m

The pipe friction head loss and hence the total head required varies with the pipe size and

therefore total head required for different pipe sizes is calculated accordingly. For the flow

rate of 2.5m3/min, head required by each pump is calculated by following same procedure

and shown in table 10.

-31-

Table 10 - Head Required by each Pump Type at the Maximum Required Flow Rate (2.5m3/min)

Pump Size Type 1 Type 2 Type3 Type 4 Type 5 Type 6 Type 7

Suction side

L1 (m) 10 10 10 10 10 10 10

L2 (m) 8.73 11.11 15.7 15.7 20.3 26.2 26.2

L (m) 18.73 21.11 25.7 25.7 30.3 36.2 36.2

d (mm) 80 100 125 150 200 250 300

C 120 120 120 120 120 120 120

Q (l/min) 2500 2500 2500 2500 2500 2500 2500

P (bar) 1.682 0.640 0.263 0.108 0.031 0.013 0.005

H1+H2 16.82 6.40 2.63 1.08 0.31 0.13 0.05

H3 (m) 4 4 4 4 4 4 4

H4 (m) 0 0 0 0 0 0 0

H5 (m) 0 0 0 0 0 0 0

H (m) 20.82 10.40 6.63 5.08 4.31 4.13 4.05

Discharge side

L1 (m) 40.1 40.1 40.1 40.1 40.1 40.1 40.1

L2 (m) 11.85 14.99 18.93 26.8 26.8 35.2 45.3

L (m) 51.95 55.09 59.03 66.9 66.9 75.3 85.4

d (mm) 65 80 100 125 150 200 250

C 120 120 120 120 120 120 120

Q (l/min) 2500 2500 2500 2500 2500 2500 2500

P (bar) 12.828 4.949 1.789 0.684 0.281 0.078 0.030

H1+H2 128.28 49.49 17.89 6.84 2.81 0.78 0.30

H3 (m) 14 14 14 14 14 14 14

H4 (m) 2 2 2 2 2 2 2

H5 (m) 2 2 2 2 2 2 2

H (m) 146.28 67.49 35.89 24.84 20.81 18.78 18.30

Total head ( m) 167.10 77.88 42.51 29.92 25.13 22.91 22.35

-32-

From the pump manufacturer’s performance curves the available head (maximum) and flow rate (maximum) of each pump is extracted. (See table 11). Table 11 - Head Required by each Pump Type at the Maximum Required Flow Rate

Pump Size Type 1 Type 2 Type3 Type 4 Type 5 Type 6 Type 7

Discharge Pipe Size (Inch) 2.5 3 4 5 6 8 10

Suction Pipe Diameter (Inch)

3 4 5 6 8 10 12

Flow rate (m3/ h)

Required 150 150 150 150 150 150 150

Available (Maximum)

104 190 280 360 700 1250 1700

Head (m)

Required 167.10 77.88 42.51 29.92 25.13 22.91 22.35

Available (Maximum)

100 95 140 120 70 55 52

NPSH (m)

Required 20.82 10.40 6.63 5.08 4.31 4.13 4.05

Available (Maximum)

8.5 10 5 21 8 14 12

As per above table, the Type 1 pump (First column) cannot develop the required head

therefore this pump is removed from our list and will no longer be considered.

Selection of Pump

With above calculated values, for a particular pipe diameter we now calculate the head

(H) by varying the flow rate (Q). The variation of H Vs Q is plotted accordingly. This is the

system curve for each pump. Table 12 includes the variation of system head with flow rate.

Table 12 – Variation of System Head with Flow Rate

Flow Rate (m3/h) System Head (m)

Type1 Type2 Type3 Type4 Type5 Type6 Type7

0 22.00 22.00 22.00 22.00 22.00 22.00 22.00

25 27.27 24.03 22.75 22.29 22.11 22.03 22.01

50 41.01 29.32 24.69 23.04 22.41 22.12 22.05

75 62.25 37.50 27.69 24.20 22.87 22.25 22.10

100 90.53 48.39 31.69 25.74 23.48 22.43 22.17

125 125.56 61.88 36.64 27.65 24.23 22.65 22.25

150 167.10 77.88 42.51 29.92 25.13 22.91 22.35

175 214.99 96.32 49.28 32.53 26.16 23.21 22.47

Discharge Pipe Size (Inch)

2 1/2 3 4 5 6 8 10

Suction Pipe Diameter (Inch)

3 4 5 6 8 10 12

-33-

From pump manufacturer, performance curve of each pump can be obtained and by

plotting both the system curve and pump curve on the same graph, the best suited pump is

selected. The main criterion considered in pump selection is the pump to operate at its best

efficiency point (BEP). Annexes A1- A10 are the performance curves of all pump types

considered here.

However we can see that the head is higher for smaller pumps due to the pipe losses and

losses at bends. Therefore if we use smaller pumps the system head gets higher and more

energy is required for pumping. For example (See Table 11) the system head for Type 4 at

150m3 /h is29.92, while that is for Type 5 is 25.13. Then the water energy (Qgh) gets higher

for smaller pump accordingly. Then the operation at best efficiency would not be much

important, but the brake power is the main consideration. BEP is the key consideration only

if two similar sized pumps (Suction & Discharge diameters) are considered.

The pumps Type 6 and Type 7 are designed for higher flow rates (1250 & 1700 m3/h and

they operates at very low efficiency between our required ranges) and therefore not suited.

From the set of performance curves few curves, which falls between our ranges were

selected for our pump selection process.

As our maximum required flow rate is 150 m3/h, a point above 150m3/h should be

considered.

Now Let us consider four types, Type 2, Type 3, and Type 4 & Type 5. As per the Plot---,

for Type 2 the system curve intersects with the pump curve at 2200rpm just above the flow

rate 150m3/h (164 m3/h) and between the Brake power curves 60hp (44.7kW) and 75hp

(55.9kW). Head is 86.5m and efficiency is about 74%.

To calculate the pump brake power at the point,

Energy of pumped water = Qgh =164 X 1000 X9.81 X 86.5W/3600 = 38.66kW Efficiency = 74 % Pump Brake power = 38.66/74% =52.24kW

Similarly for following pumps, above calculation was performed and the pump brake

power and efficiency was determined (See table 13). It is important to remember that the

system has only a minimum flow rate requirement and no upper limit as the irrigation water

need is to be pumped within 15 hours. Therefore the system curve should intersect the

pump curve at a higher flow rate than 150m3/h (2.5m3/min). Then with a higher flow rate

the time required for pumping will decrease from initial desired time.

-34-

Table 13–Brake Power Delivered by each Considered Pump Type to Discharge the Required Water Flow Rate

Pump Type

Pump Size Impeller

Size (inch)

Pump rpm

Flow rate

(m3/h)

Head (m)

Qgh (kW)

Efficiency

Pump Brake Power (kW)

Remarks

Type 3

4 X 5 X 10 BM

10.44

159 44.20 19.15 82% 23.35 2200rpm

4 X 5 X 9.5 BH

9.5

138 42.00 15.79 75% 21.06 2200rpm

4 X 5 X 12 BH

1750 166 45.40 20.54 78% 26.33 12.563"

4 X 5 X 13 BH

13.5

166 45.40 20.54 79% 26.00 1600 rpm

4 X 5 X 13 BH

1750 164 45.10 20.16 80% 25.35 12.375"

Type 4 5 X 6 X 10H 10.44

168 31.40 14.37 80% 17.97 1800rpm

5 X 6 X 10H

1750 154 30.48 12.79 78% 16.40 10.438"

Type 5

6 X 8 X 13BL 13.5

182 26.20 12.99 72% 18.05 1400 rpm

6 X 8 X 9L 8.5

154 25.9 10.87 48% 22.64 2100rpm 6 X 8 X 13BM

13.5

225 28.3 17.35 83% 20.91 1300rpm

According to table 13, following pumps can be taken in to further consideration as they

give the lowest brake power or highest efficiency of each type.

Type 3-Pump sizes 4 X 5 X 10BM & 4 X5 X9.5BM Type 5-Pump sizes 6 X 8 X 13BL & 6 X 8 X 13BM

From Type 4 it is the same pump size, but with different conditions (Varying impeller size

at a 1750rmp and varying impeller size at Impeller size of 10.44”). The two cases give

different values for brake power and efficiency. Therefore they are considered separately.

In order to select the pump with best performance, it should be taken in to the account

the influence of other components of the pump such as motor and Variable Frequency Drive

(VFD).

Figure 08 is a graph that shows the efficiency variation of a 4 pole 50Hz motor with the

rated power. As per the EU directives IE3 will be the efficiency level from 1st January 2014

and it will be considered in these calculations.

The pump sizes 4 X 5 X 10BM of type 3 runs with a maximum brake power of 125hp

(93.2kW), thus the size of the motors is determined accordingly. As per the figure 08,

efficiency of the 93.2 kW motor is 95.5%.

-35-

Figure 08: Chart of Motor Efficiency Vs with Rated Power (Wikipedia, 2014)

When a motor does not run at its full rated load, the efficiency drops and the relationship

between the efficiency and the percentage of motor full load is shown in the figure 09. As

the motors do not operate their full load, the efficiency of motor at operating load should be

calculated. For this pump, brake power is 23.35kW; hence the percentage of full load the

motor running is 25% (23.35/93.2). Figure 09 gives the efficiency as 68% as a percentage of

full load efficiency at 25% motor load.

Figure 09: Chart of Motor Efficiency Vs Percentage of Full Load (Sustainable Productivity, 2014.)

Hence the overall motor efficiency = 68% X 95.5% = 64.94% Motor Power required = 23.35/64.94% = 35.96kW

-36-

In order to select the VSD first the motor Full Load Current (FLC) and power should be

obtained. The rated power of the motor as explained above is 93.2 kW (125 HP).

As the starting current is very high, the recommended size of the VFD (for variable

torque) is between 110% -150% of full load, but our application is well below the rated

power of the motor. Therefore, 125HP VFD with 110%overload is selected. The rated current

is 170 A.

Figure 10 shows the variation of efficiency of VFDs with the percentage of full speed.

Figure 10: Variation of Efficiency of Variable Frequency Drives with Percentage of Full Load (Facility

Dynamic Engineering, 2014)

The efficiency curve of 125 HP (93.2kW) VFD is not given in the above graph, therefore a

linear interpolation between 100 and 150 is to be made. The VFD running load, 35.96kW is

38.51% of its full load (93.2kW). From the graph it is about 78% for 125HP VFDs.

With above efficiency calculation, total efficiency of the electrical components (motor &

VFD) can be determined as,

Efficiency of Electrical Drivers = Efficiency of Motor X Efficiency of VFD = 64.94% X 78% = 50.65% Hence the Total Electrical power required= Pump Brake Power/ Efficiency of Electrical Drivers = 23.35kW/50.65% = 46.10 kW

-37-

For other pumps the Total Electrical Power requirement has been determined and listed

in the 1 B.

We observed that even though the high pump efficiency and hence lower brake power

could be achieved by these pumps, high electric power is required due to the low electrical

efficiency. Losses at electrical components are high. Therefore in order to maintain the

electrical power requirement of the water pumping system at a lower level a high overall

efficiency should be achieved. Smaller motors running at full load (or close to full load)

would reduce the electrical losses and hence increase the efficiency. If two or three smaller

pumps coupled in parallel will need smaller motors. Following are the options to fulfill the

system requirements.

Option 1- Two pumps running at half capacity coupled in parallel Option 2- Three pumps running at capacity coupled in parallel

The previously calculated Head and Flow rate values are plotted again on the system

curves of Type 1 & Type 2 pumps.

The Annex A9 is the plot of system curve on Type 1 curve. Three parallel pumps are

considered here, therefore the flow rate is one third (1/3) of maximum required flow rate

(50m3/h).

The Annex A10 is the plot of system curve on Type 2 curve. Two parallel pumps are

considered here; therefore the flow rate is a half of maximum required flow rate (75m3/h).

Table 14 shows the brake power and efficiency at operating point of each pump

Table 14- Brake Power and Efficiency of Considered Pumps at Desired Flow Rate

Pump Type

Pump Size Impeller

Size (inch)

Pump rpm

Flow rate

(m3/h)

Head (m)

Qgh (kW)

Efficiency

Pump Brake Power (kW)

Remarks

1 2.5 X 3 X 6M 6.5 3200 50.64 41.76 5.76 70% 8.23 3200rpm

2 3 X 4 X 6M 6.5 3200 81.02 41.76 9.22 80% 11.52 3200rpm

-38-

Total electrical power requirement and overall electrical efficiency of each of above pumps is given in table 15. Table 15–Electrical Power Required by each Pump Type to Pump the Desired Flow Rate

Type 1 Type 2

Pump Size 2.5 X 3 X 6M 3 X 4 X 6M

Pump Brake Power (kW) 8.23 11.52

Efficiency 70% 80%

Motor Size (kW) 11.20 18.60

Pump Brake Power as a Percentage of Motor Full Load (%)

73.50% 61.96%

Motor Efficiency (%)

Full Load Efficiency (%) 91.50% 93.00%

Efficiency as a Percentage of Full

Load 100.00% 100.00%

Overall Motor Efficiency (%)

91.50% 93.00%

Motor Running Power (kW) 9.00 12.39

Motor Running Power as a Percentage of VSD Size (%)

80.33% 66.62%

VSD Efficiency (%) 92.00% 92.00%

Overall Efficiency of Electrical Components (%) 84.18% 85.56%

Total Electrical power Drawn (kW) 9.78 13.47

As per the above table, pump Type (Size -2.5 X 3 X 6M) need 9.78 kW to deliver one third

of flow rate hence the arrangement of three parallel pumps (to deliver the requirement) the

electricity requirement is 29.34 kW.

Pump Type 2 (3 X 4 X 6M) at 6.5” impeller size running at 3200rpm needs 13.47kW to

deliver the half of flow rate and hence total requirement is 26.94kW.

As this is lower than the optimum pump of previously compared set, (The pump size with

lowest electrical power requirement on previous set is 4 X 5 X 9.5BM and electricity

requirement is 30.13kW) the Type 2 (3 X 4 X 6M) of impeller size 6.5” and 3200rpm is

selected for pumping system. Motor and VFD are selected accordingly. The power

requirement (Maximum) for water pumping is 26.94kW (approximated to 27kW). This

requirement exists during 16th June to 25th July, in which high water demand occurs. In

other time periods of the year the Power requirement is less than above value if the system

-39-

operates for the same number of hours for pumping (15 hours) as above. Adding 2 kW for

system losses the power requirement is set to 29 kW.

6.2. Household Electricity Demand

The energy demand of this small village was calculated assuming that all energy efficient

lighting and other appliances are used. It is provided only for the household electrification

and does not supplied for any other industrial application. Further except the said number of

houses there is no any other commercial or institutional type building such as schools,

Hospitals, temples, church etc. These necessary places are located about 4 to 6 km away

from this village and a bus service has been provided from the village. The electricity

demand by individual household and hence total electricity demand and its variation during

the day at each hour of the day is shown in the table 16.

-40-

Table 16–Hourly Energy Demand and Total Energy Units Consumed by Households

No of Household 47

Population 234

Description Loads Per one unit (W)

For all (kW)

Hour

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Lighting 10 X 15W 150 7.05 2.1 2.1 2.1 2.1 3.5 3.5 2.1 0 0 0 0 0 0 0 0 0 0 7.1 7.1 7.1 5.6 4.2 3.5 2.1

Refrigerator 1 X 75W 75 3.525 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8

Fan 2 X 20 W 40 1.88 0 0 0 0 0 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 0 0 0 0

TV & Radio 35W 35 1.645 0 0 0 0 0 1.6 1.6 1.6 0 0 0 0 0 0 0 0 0 1.6 1.6 1.6 1.6 1.6 0

Ironing 1 X 1000W

1000 47 0 0 0 0 9.4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Total Demand per hour (kW) 3.9 3.9 3.9 3.9 15 8.8 7.4 5.3 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 11 12 12 9 7.6 6.9 3.9

Total of Household

Hourly Demand (kWh)

Peak Demand (kW) 12.3 (At hour 19 & 20)

Total Demand per day (kwh) 147.3

-41-

6.3. Calculation for System Components

Turbine Selection The turbine output should be 29 kW in the period of 16th June to 25th July as mentioned

above. Power demand during the entire year is calculated in the same way as above and also

shown in the Table 17

Table 17– Electric Power Needed to Pump the Required Water amount in each Time Period

Time Period of the Year

Required Water Flow rate

(m3/h)

Pump Brake Power (kW)

Electric Power

Requirement (kW)

Pump Efficiency

(%)

Motor Efficiency

(%)

VFD Efficiency

(%)

Total Efficiency

(%)

1st March to 30th April

98 5.38 19.52 72% 93.00% 80.00% 53.57%

1st May to 15th May

99 5.41 19.40 73% 74.40% 75.00% 40.73%

16th May to 15th June

111 6.33 20.28 74% 79.05% 79.00% 46.21%

16th June to 25th July

150 9.70 23.42 79% 92.07% 90.00% 65.46%

25th July to 20th

August 151 9.70 23.42 79% 92.07% 90.00% 65.46%

1st September

to 30th October

89 4.91 19.85 69% 75.33% 79.00% 41.06%

1st November

to 15th November

35 3.89 9.68 63% 55.80% 72.00% 25.31%

16th November

to 15th December

38 4.34 9.91 63% 57.66% 76.00% 27.61%

16th December

to 25th January

131 7.94 21.80 77% 80.91% 90.00% 56.07%

25th January to

20th February

127 7.58 21.56 76% 79.05% 89.00% 53.47%

-42-

The system runs with two parallel pumps except in the period from 16th November to 25th January as the water flow rate is below the half of pump capacity

According to the calculations above, the maximum required electric power for our system

is 27kW. However about 10% is to be added to the demand as a fluctuation as well as the

other losses and power requirements such as controlling, pump house energizing or lighting

etc. With that the demand is estimated as 30kW.

As mentioned earlier the water pumping duration is set to 15h and energy required for

water pumping is then calculated as 450kWh (30kW X 15h). This is the maximum energy

requirement per day and exists from 16th June to 25th July as this period needs the

maximum water demand. Above Table shows that the system operating at higher overall

efficiency when the flow rate and hence the pump brake power is higher. At lower flow rates

the overall efficiency decreases as the motor and VFD operate below the full load. Therefore

the system should be operated at its optimum flow rate (2.5m3/min) and a control system

that switches on and off the system depending on the generator output power will be

provided. Then the system will run at maximum power (30kW) and pumping time will vary

with the water demand.

For the period from December16thto 25th January, the water requirement per day is

1971 m3/day.

If it is pumped at a flow rate of 150m3/h, the pumping time can be reduced to 13.14h

(1971/150). Total energy required for pumping is 394.2kWh (30kW X 13.14h)

During each time period the pumping time and the required energy is given in the Table 18

Table 18–Time Taken to Pump the Required Water Amount

Time Period of the Year Irrigation

Requirement (m3/day)

Time taken for pumping (h)

Energy required for pumping (kWh)

1st March to 30th April 1479 9.86 295.80

1st May to 15th May 1489 9.93 297.80

16th May to 15th June 1669 11.13 333.80

16th June to 25th July 2253 15.00 450.68

25th July to 20th August 2260 15.00 452.02

1st September to 30th October 1341 8.94 268.20

1st November to 15th November 519 3.46 103.80

16th November to 15th December 570 3.80 114.00

16th December to 25th January 1971 13.14 394.20

25th January to 20th February 1902 12.68 380.40

-43-

Based on this average wind speed and the power requirement in each month, the

required turbine should be selected. Most of the wind turbine manufacturers in the world

have designed and developed their products to suit for the range 10-15m/S, the most

expected range of wind speed. But in Sri Lanka and most of South Eastern countries the

average wind speed lies between 6-8 m/s.

Following (in the table 19) are the considered turbines including their prices. The turbine

WT1 to WT4 are manufactured by Aeolos Wind Energy Limited, a UK originated company

and the WT 5 is a vertical axis turbine manufactured by another Chinese company.

Since the power requirement for water pumping was determined above as 30kW, the

turbine should be equal to or more than that.

This manufacturer does not produce a 35 or 40 kW rated wind turbine, therefore WT 6

and WT7 from another two US made products were taken into consideration. The price of

turbine 7 was assumed to be a linear variation between turbines WT2 &WT3 as this

manufacturer had not responded for our price requests. Assumed price is 104,000 USD.

Table 19 – Wind Turbines with Specifications and Prices (See Annex D)

WT 1 WT 2 WT 3 WT 4 WT 5 WT 6 WT 7

Manufacturer

JBS Energy

LLC Polaris

Country

USA USA

Model No Aeolo-H20kW

Aeolo-H30kW

Aeolo-H50kW

Aeolo-H60kW

RCVA 60kW

PGE20/35 P15‐39.9

Axis direction Horizontal Horizontal Horizontal Horizontal Vertical Horizontal Horizontal

Rated Power

(kW) 20 30 50 60 60 35 39.9

Rated Wind Speed (m/S)

10 10 9.5 9 12 11 9.5

Rotor Diameter (m)

10 12 18 22.5 8 19.2 15.2

Tower Height (m)

18 24 30 30 18

30

Weight (kg) 820 980 6800 7800 4500

6443

Price (USD) 43,010.00 62,680.00 143,400.00 159,040.00 102,100.00

For the period, January 1st to 25thpower generation by each turbine is given in the below table. It is based on the power curve provided by each turbine manufacturer (See Annexes C1 to C7). Generated power by each turbine type at each hour of the day relevant to the wind speed is given in the table 20.

-44-

Table 20 – Generated Power by each Type of Wind Turbine based on the wind speed from January 1st to 25th

Hour of the day

Wind Speed

Generated Power

WT1 WT2 WT3 WT4 WT5 WT6 WT7

1 6 5.10 7.37 11.96 19.53 18.00 15.40 16 2 6 5.10 7.37 11.96 19.53 18.00 15.40 16 3 6 5.10 7.37 11.96 19.53 18.00 15.40 16 4 6 5.10 7.37 11.96 19.53 18.00 15.40 16 5 6 5.10 7.37 11.96 19.53 18.00 15.40 16 6 5 3.50 4.26 5.99 9.70 12.00 9.10 9 7 5 3.50 4.26 5.99 9.70 12.00 9.10 9 8 5 3.50 4.26 5.99 9.70 12.00 9.10 9 9 8 10.21 16.35 32.18 47.91 35.00 27.1 35

10 8 10.21 16.35 32.18 47.91 35.00 27.1 35 11 8 10.21 16.35 32.18 47.91 35.00 27.1 35 12 8 10.21 16.35 32.18 47.91 35.00 27.1 35 13 8 10.21 16.35 32.18 47.91 35.00 27.1 35 14 9 13.64 23.31 45.81 59.56 43.00 30.90 40 15 9 13.64 23.31 45.81 59.56 43.00 30.90 40 16 9 13.64 23.31 45.81 59.56 43.00 30.90 40 17 9 13.64 23.31 45.81 59.56 43.00 30.90 40 18 9 13.64 23.31 45.81 59.56 43.00 30.90 40 19 9 13.64 23.31 45.81 59.56 43.00 30.90 40 20 8 10.21 16.35 32.18 47.91 35.00 27.1 35 21 8 10.21 16.35 32.18 47.91 35.00 27.1 35 22 7 7.2 11.65 20.53 32.88 26.00 21.7 24 23 7 7.2 11.65 20.53 32.88 26.00 21.7 24 24 6 5.10 7.37 11.96 19.53 18.00 15.40 16

Total Generated (kWh)

208.81 334.607 630.91 904.77 699 538.2 656

As per the above table the WT1 and &WT2 do not deliver the required energy

(394.2kWh/day) for water pumping. The turbine WT6 rated as 35kW delivers 538.2kWh/day

and WT 7 rated as 39.9 kW delivers 656kWh/day. According to the Specifications of WT6, its

rotor diameter is 19.2m and is higher than that of WT6, even though it is rated lower than

WT7. Therefore another assumption that the price of WT6 is higher than WT7 is not unfair.

Then turbine W7, having higher rated power and lower price than WT6 that is able to

generate the required power, is best suited for our application for the period January 1st to

25th. However, to select the turbine energy delivered and energy required for pumping in

the rest of the year should also be considered.

-45-

Based on above hourly power generation, total energy delivered by each turbine per day in

each month is given in the table 21.

Table 21- Produced Energy by each Type of Turbine

Period Time taken

for pumping

(h)

Energy Required

for Pumping

(kWh)

Total Energy Delivered by wind Turbine (kWh/day)

WT1 WT2 WT3 WT4 WT5 WT6 WT7

1st March to 31st March

9.9 296 163 252 461 655 529 399 482

1st April to 30th April

9.9 298 150 232 426 620 501 384 463

1st May to 15th May

9.9 298 171 263 469 669 545 422 498

16th May to 31st May

11.1 334 171 263 469 669 545 422 498

1st June to 15th June

11.1 334 283 442 772 1074 877 647 753

16th June to 30th June

15.0 451 283 442 772 1074 877 647 753

1st July to 25th July 15.0 451 283 442 776 1074 883 648 753

26th July to 31st July

15.0 452 283 442 776 1074 883 648 753

1st August to 20th August

15.0 452 282 435 767 1033 866 635 726

1st September to 30th September

8.9 268 258 392 690 919 797 576 656

1st October to 31st October

8.9 268 230 349 625 833 683 518 602

1st November to 15th November

3.5 104 89 126 203 327 306 248 263

16th November to 30th November

3.8 114 89 126 203 327 306 248 263

1st December to 15th December

3.8 114 184 287 534 805 634 501 604

16th December to 31st December

13.1 394 184 287 534 805 634 501 604

1stJanuary to 25th January

13.1 394 209 335 631 905 699 538 656

25th January to 31st January

12.7 380 209 335 631 905 699 538 656

1st February to 20th February

12.7 380 208 316 534 767 644 485 558

-46-

Above table shows that in each month, the daily energy extraction by WT7 is higher than

the energy requirement for water pumping, therefore it is selected for our system.

As excess energy is delivered per day in each period by the turbine WT7, it is to be

checked whether could be used for another application. Most important application is

household electrification through an off grid network.

The demand per day is estimated as 147.3kWh making the assumptions the loads to be as

in the 2nd column. The energy saving bulbs are proposed for household electrification.

It can be clearly seen that, in every month the excess energy produced by the selected

turbine, after drawing power for pumps, is sufficient for household electrification provided

the necessary battery bank for energy storage, if it is assumed that the above annual and

monthly average wind speed remains same.

The table 21 refers the energy details of the period from 1st to 25th January. The

4thColumn gives the energy utilized to drive water pumps. It is set to the hours with higher

wind speeds and hence high power generation in order to minimize the size of battery bank.

Next column shows the household energy demand during the day in each hour. Column 6 is

the total energy requirement (Sum of Column 4 & Column 6). Excess energy produced at

higher wind speeds and lower energy consuming hours are in the 6th Column, while column

7 shows the under generated energy than the total demand at poor winds and high demand.

Table 22 shows the excess and lacked energy during the day at each hour for the period of 1st to 25th January.

-47-

Table 22- Excess and Lacked Energy over the 24 hours of the Day (1st to 25th January)

Hour of the

day

Wind Speed

Generated Power

Power drawn

for pumps (kW)

Required Energy for Household

Electrification

Total Energy

Required (kW)

Excess Energy

Lacked Energy

1 6 16 3.88 3.88 12.12 0.00

2 6 16 3.88 3.88 12.12 0.00

3 6 16 3.88 3.88 12.12 0.00

4 6 16 3.88 3.88 12.12 0.00

5 6 16 14.69 14.69 1.31 0.00

6 5 9 8.81 8.81 0.19 0.00

7 5 9 7.40 7.40 1.60 0.00

8 5 9 5.29 5.29 3.71 0.00

9 8 35 30 3.64 33.64 1.36 0.00

10 8 35 30 3.64 33.64 1.36 0.00

11 8 35 30 3.64 33.64 1.36 0.00

12 8 35 30 3.64 33.64 1.36 0.00

13 8 35 30 3.64 33.64 1.36 0.00

14 9 40 30 3.64 33.64 6.36 0.00

15 9 40 30 3.64 33.64 6.36 0.00

16 9 40 30 3.64 33.64 6.36 0.00

17 9 40 30 3.64 33.64 6.36 0.00

18 9 40 30 10.69 40.69 0.00 0.69

19 9 40 30 12.34 42.34 0.00 2.34

20 8 35 30 12.34 42.34 0.00 7.34

21 8 35 30 9.05 39.05 0.00 4.05

22 7 24 7.64 7.64 16.36 0.00

23 7 24 6.93 6.93 17.07 0.00

24 6 16 3.88 3.88 12.12 0.00

Total (kWh) 656 390.00 147.35 537.35 133.07 14.42

For this period, as per the table, 99.64 kWh of energy has to be stored during 24th hour to 17th hour of next day and 40.99kWh of energy will be utilized from 18th to 23rdhour. Battery Bank Selection

Storage system should be capable of fulfilling the requirement of energy storing for

uninterrupted service. The idea is to store redundant energy at higher wind speeds and

discharge the stored energy to the system at lower wind speeds. Before determining the size

of battery bank, excess and lacked energy per day in each month should be calculated. The

storage requirement in each month is given in the table 23.

-48-

Table 23- Excess and Lacked Energy per Day in each Time Period

Period Energy

Delivered by Turbine (kWh)

Energy utilized for water pump (kWh)

Required Energy for Household Electrification (kWh)

Total Energy Required (kW)

Excess Energy (kWh)

Lacked Energy (kWh)

1st March to 31st March 482 300 147 447 92 58

1st April to 30th April 463 300 147 447 61 45

1st May to 15th May 498 300 147 447 100 50

16th May to 31st May 498 330 147 477 88 67

1st June to 15th June 753 330 147 477 286 10

16th June to 30th June 753 450 147 597 206 50

1st July to 25th July 753 450 147 597 206 50

26th July to 31st July 753 450 147 597 206 50

1st August to 20th August 726 450 147 597 204 76

1st September to 30th September

656 270 147 417 239 1

1st October to 31st October 602 270 147 417 191 6

1st November to 15th November 263 120 147 267 83 88

16th November to 30th November

263 120 147 267 83 88

1st December to 15th December 604 120 147 267 342 6

16th December to 31st December

604 390 147 537 122 55

1st January to 25th January 656 390 147 537 133 14

25th January to 31st January 656 390 147 537 155 37

1st February to 20th February 558 390 147 537 110 89

As per above table, maximum excess energy is 342 and is delivered from 1st December to

15th December. Lacked energy become maximum in the period from 1st to 30th November

and is 88kWh. In general, to determine the battery bank size, it is based on the energy

lacking (Here it is 88kWh) and do the calculations accordingly. The Figure 11 shows the

variation of excess and lacking of energy during the day for the period from 1st to 15th

November.

-49-

Figure 11: Excess Energy Production and Lacked Energy over the Day Calculated Hourly

This figure 11 shows, excess energy stored from 9.00-13.00 hours is discharged to the

system during the morning and evening time. With introducing a battery bank, however

typically about 15-20% of energy wastes as heat at the batteries and those has be taken in to

account. Then only about 80-85% of excess energy stored can be used at energy lacking

hours. The produced excess energy during the day in each time period, given in the 6th

column of above Table even after wasting some amount as heat, are sufficient to be used for

lacking hours as per the table23.

However, it should not be forgotten that all our calculations are based on, the data

published in National Renewable Energy Laboratory (NERL, 2003), the average wind speed

data of each hour throughout the month. That means all the wind speeds of a particular

hour, during the month is measured or collected and averaged to that hour. Therefore

consecutive, low or zero wind days can be expected that would make our system more

dependent on storage batteries. Then the capacity of storage will have to be increased.

It is assumed three consecutive days of zero or low wind speed, to determine the size of

battery bank. Maximum total energy requirement (597kWh per day) comes in the period

from June 16th to August 20th and battery bank should be capable of storing energy for

three days with 597kWh each.

Battery Bank Capacity is given by the formula,

C = EL.SD.DM./(VB.DODmax.Tcf.B)

EL= 600kWh SD= 3 VB= 12V DM= 1.25

-50-

Tcf = 1.08

B= 80% DODmax is set to 50% This gives the batter bank capacity CB = 600 X 1000X 3X 1.25 / (12 X 50% X 1.08 X 80%) CB = 4.34 X 105Ah

From the product catalogue of Trojan Battery Company, Trojan 12AGM (capacity 140Ah

at 20h rated) is selected for the battery bank. Required number of batteries is given by,

N= 4.34 X 105/ 140 = 3100 Cost of one battery (140Ah, 20h) is58USD, Then total cost of battery bank is 241,800 USD.

This amount for battery bank is too high and more you increase the battery bank, the cost

of the system increases. Therefore it is worthwhile to study and introduce another storage

method. Only the storage method here is to construct a tank having enough capacity to

store water for assumed number of days. Earlier assumed (in determining the battery

storage capacity) three consecutive low or zero wind days is taken here for calculation. Then

water required for three days are stored in the tank. However for the daily electricity

requirement, battery bank should be provided that will be sufficient for three days.

Electricity load then reduces to 147kWh (Approximated to 150 kWh) and number of

batteries is 775 and the cost will be reduced to 60450USD.This is a cost saving of 181350

USD.

6.4. Water Storage System

From Table 07, from 16th June to 25th July (reproductive), water requirement is 2253

m3/day and is the maximum of the year. If calculated for three days storage the tank

capacity should be 6759m3, a very high amount of water and the tank cost will be higher

than the battery bank. But if the initial calculations are observed step by step, we can see the

actual required storage capacity will be well below to that.

As initially calculated at reproductive crop growing stage (46-85 days), water requirement

is 2253m3/day and the required water level is 100mm and the crops have grown up to a

considerable height. Further increase in water level by 50mm is not harm for the crop at all.

Now let’s consider if the level height increases by 25mm how much water can be stored in

the paddy fields of 30hactares. It is 30 X 104 X 25 liters and equals to 7500m3 and more than

the required storage of three days. At this stage even 50mm raise of water level is not

harmful to the crop and it can store water even more than six consecutive days. Even at

-51-

vegetative growing stage (Age 0-15 days) the required water level is within the rage 20-

50mm and for our calculation it was taken as 50mm. Therefore it is obvious that the water

storage for zero or low wind days is not a problem and the existing paddy fields can be used

as water storage tanks.

6.5. System Configuration

The system is designed, as described in previous calculation steps, such that it delivers

power for water pumps and excess produced energy will be used for household

electrification. The energy demand for irrigation system remains constant over the day and

varies with the age of crop. A constant power of 29kW (as calculated above) is to be supplied

for water pumps and the time of water pumps being operated varies in each time period.

The energy for household electrification varies hourly and remains constant throughout the

year for the particular hour of the day. Energy produced by wind turbine varies hourly, and

over the year too it varies. Therefore a power control system is to be introduced to the

system. The system always supply the required electricity for households, and when the

system generates 30kW more power than the requirement for households the water pumps

are automatically switched on by the controller and if the excess power generation is less

than it is stored in battery bank. There is not any method to ensure whether the water

required for paddy fields are completely pumped, the switching off is a manual operation

and the automatic switching is recommended at day time. The system is configured in the

figure 12

-52-

Figure 12: Wire Diagram of the System (Single Line)

6.6. Energy Flow Diagram

The extracted energy by the wind turbine subjects to loss at different phases or components. Figure

13, the energy flow diagram shows the energy at each component of the system and the finally

utilized energy. From the figure 13 it is seen that the extracted energy by the wind turbine losses at

battery bank, VFD, electric motor and water pump. The useful energy of the system is 147kW for

electrification and 240kW for water pumping from the total extracted energy of 541kW. Then the

useful power is about 71.5% of the total extracted. This is a good achievement compared with

present low efficient, fuel driven system

Grid off Controller

Battery Bank

Grid off Inverter

Power Controller

Dump

Load Box

To Household

Electrification

To Irrigation Water

Pumping System

-53-

Figure 13: Energy Flow Diagram

6.7. Cost Comparison

Total cost of the system was estimated to be 276,088 USD (See Annex E). The cost for

irrigation system, that included seven eighth (7/8) of pump house, pumping system, storage

tank and 75% of cost of turbine and auxiliaries, was estimated. Assuming 5% of Operation &

Maintenance (O & M) cost and a life cycle of 10, 20, 20 and 10 years for pumping system,

pump house, storage tank and turbine respectively the cost to generate one energy unit

(kWh) in water pumping was calculated (In Annex F1). It was 26.per kWh.

Cost of electricity generation system that included battery bank, one eighth (1/8) of pump

house and control room and 25% of wind turbine and auxiliaries was calculated and with 5%

O & M cost and life cycle as above the cost to generate one unit of electricity was

determined (In Annex F1). It was 60.71 LKR/kWh. Battery lifecycle was assumed to be 5

years.

Comparing the water pumping cost with present method, a gasoline engine consumes

about 3l of fuel to produce one energy unit (1 kWh). Cost of gasoline is 160LKR/l. Then cost

of energy unit produced by present engine driven pumps, even if the engine depreciation

and repair & maintenance cost is neglected, is 53.33 LKR. This figure gets higher with the

addition of engine depreciation and with the wear of parts due to long term use. Anyway it is

obvious that our system can produce an energy unit at a lower cost than present method for

water pumping.

The revised electricity tariff rates of CEB for domestic purposes are given in the annex G.

The average consumption by a single household per month is and as per the CEB tariff

scheme, total electricity bill of a single user will be calculated as follows

0-60 Units - 7.85 X 60 = 471.00

-54-

61-90 Units- 10.00 X 30 = 300.00 91-93 Units 27.75 X 3 = 83.25 Fixed Charges = 480.00 Total Bill = 1334.25 Our system costs 60.71LKR to produce (See Annex F1) an electricity unit and for 93 units

its cost is 5646.03. At a glance above comparison shows that it is not worth to generate

power using this technology because of the very higher generation cost. However it is to be

get clarified whether the present electricity supply system is really advantageous or not by

considering all the factors around it.

Even though CEB supply electricity at this rate its generation cost is much higher to above

rates and above rates are the subsidized rates for the general public. To clarify this let’s see

the annex H in which the feed in tariff approved by the Cabinet of Sri Lanka on 07-03-2014

are given. According to that a local wind power producer will be paid a tariff of 1.33LKR of

escalating component and a three tier fixed rate. For 1-8 years fixed rate is 22.60 and hence

total feed in tariff is 23.93LKR.

With that the producer will be paid 23.93LKR per each kWh and only 36.78 LKR to be

billed to the consumer. However still it is expensive and what will be the final conclusion?

Here it should be remembered that the system is designed for supplying water for

agriculture and the electricity generation for households is only for utilizing excess energy.

Earlier only 3/4 of turbine cost and 7/8 of pump house and control room was taken for

calculation and other portion was left to consider in electricity generation (much fair option).

But if the system is considered only as a water pumping system total cost of turbine and

pump house and control room should be taken as a cost of water pumping system.

Therefore in calculating the cost of water pumping, unlike in previous calculation, now let us

put cost of all the components in to it (See Annex F2).Then the cost per energy unit is

33.58LKR and still less than present engine driven method (53.33LKR). In Electricity

generation, only the addition is the battery bank (Earlier it was mentioned that no storage

batteries are used in water pumping system) and it was taken for the calculation. Then the

cost of generation of electricity is 44.68 and after deducting the feed in tariff it is 20.75. The

cost of 93 units is then 1929.75 and still it is higher than the monthly electricity bill.

However this system is not to be rejected and it is viable as the cost of water pumping

remains below the present cost, according to our analysis.

-55-

7. Project Execution

7.1. Work Breakdown Structure (WBS)

For the purpose of implementation the Work Breakdown Structure (WBS) was prepared (See figure 14). It was basically divided in to five main sections, Foundation, Turbine Installation, Pump house, Pumping system and water storage tank, and each work package is put under main section.

Construction of Foundation for Wind Turbine

Installation of Wind Turbine & Auxiliaries

Construction of Pump House and Control Room

Pumping System Installation

Construction of Water Storage Tank

Excavation & Earth work

Tower Foundation Pipeline Excavation

Screed Turbine Screed Pump Installation

Screed

Reinforcement Control Panel Rubble Work Control Panel Reinforcement

Shutter Inverter Tie Beam Wiring Shutter

Anchor bolts Battery Bank Reinforcement Concrete

Concreting Wiring Shutter Water proofing

Concrete Plastering & Finishing

Columns & Beams

Reinforcement

Shutter

Concrete

Walls

Brick Work

Plaster

Painting

Roof

Structure

Sheeting

Valance Board

Floor Finishes

Reinforcement

Floor Concreting

Power Trowel

Metal Works

Doors & Windows

GI mesh

Electrical wiring

Figure 14: Work Breakdown Structure

-56-

7.2. Scheduling

7.2.1 Activity List

The scope of the project has been defined and the activity list and work program is prepared in order for scheduling the project as follows. Table 24 gives the activity list of the project. Table 24- Activity List of the Project of System Installation Activity ID Activity Description Duration

(days) Predecessors Lag

(days)

Project Start

1 Obtaining Approvals

1.1 CEB 90

1.2 Local Authority 90

1.3 Central Environmental Authority 90

1.4 Forest Department 90

2 Placing the order for import of Material

2.1 Wind Turbine and auxiliaries 20

2.2 Storage Batteries 20

2.3 Pumps and auxiliaries 20

3 Placing the order for Local Material

3.1 Pipes & Accessories 5

3.2 Cement 5

3.3 Reinforcement Steel 5

3.4 Other Construction Material 5

4 Construction of Foundation for Wind Turbine

4.1 Excavation for foundation 2

4.2 Concreting for Screed 1 4.1

4.3 Reinforcement 3 4.2

4.4 Shuttering 1 4.3

4.5 Positioning Anchor bolts 1 4.4

4.6 Concreting 2 4.5

5 Installation of Wind Turbine

5.1 Tower erection 50 4.6 21

5.2 Fixing of Wind Turbine 20 5.1 5.3 Control Panel fixing 7 5.2 5.4 Inverter fixing 3 5.3 5.5 Battery Bank installation 10 5.4 5.6 Wiring of wind turbine system 7 5.5

6 Construction of Pump House and Control Room

6.1 Excavation for foundation 4

6.2 Concreting for foundation Screed 2 6.1

6.3 Foundation Rubble Work 8 6.2

6.4 Reinforcement for tie beam 1 6.3

6.5 Shuttering for tie beam 1 6.4

-57-

Table 24 (Cont.)- Activity List of the Project of System Installation

Activity ID Activity Description Duration (days)

Predecessors Lag (days)

6.6 Concreting for tie beam 1 6.5

6.7 Reinforcement for columns and beams 5 6.6

6.8 Shuttering for columns and beams 3 6.7

6.9 Concreting of columns and beams 3 6.8

6.10 Brick Work 7 6.9

6.11 Laying electrical conduits 1 6.10

6.12 Wall Plastering 15 6.11

6.13 Painting 5 6.15

6.14 Roof Structure fabrication and erection 10 6.9 21

6.15 Roof Sheeting 3 6.14

6.16 Valance Board fixing 2 6.15

6.17 Anti-Termite Treatment 1 6.9

6.18 Floor Reinforcement 3 6.17

6.19 Floor Concreting 1 6.18

6.2 Power Trowel 1 6.19

6.21 Fabrication and Installation of Doors & Windows 3 6.12

6.22 Fixing of GI mesh 1 6.12

6.23 Electrical wiring 6 6.12

7 Pumping System Installation

7.1 Laying and fabrication of pipelines 20

7.2 Pump Installation 2 6.22, 7.1, 7.1

7.3 Control Panel fixing 1 7.2

7.4 Wiring 1 7.3

8 Construction of Water Storage Tank

8.1 Excavation 1 6.1

8.2 Screed concreting 1 6.2

8.3 Reinforcement 4 6.4

8.4 Shuttering 4 6.5

8.5 Concreting 4 6.9

8.6 Water proofing 1 8.5 21

8.7 Plastering & Finishing 6 8.6 3

-58-

7.2.2 Gant Chart

Gant chart indicating critical path and other important information relevant to project scheduling is provided in Figure 15

-59-

Figure 15: Gant chart for the project execution

-60-

7.3. Stakeholder Management

7.3.1 List of Stakeholders

A common approach to identify the associated parties with or less interest and influential is

the stakeholder management. To study the impacts of them on the project and what they expect

it should performed an analysis of the stakeholders. By engaging them positively in project

related works much better result can be expected and obtained. First it is necessary to identify

the stakeholders with their role and responsibility on the project as given in the table 25.

Table 25: List of Stakeholders Stakeholder Role/Responsibility Influence/Power Interest

Political Authority Decision makers, and directing the officers towards the ultimate goal

High High. As their responsibility to provide water for agriculture and electricity for community they are highly interested on it.

Divisional Secretary and other Government Administrative Officers

Coordination between political authority and project owners

High Low to Moderate. On the instruction of political authority and requests by the project owner they work. No any other interest unless above.

Local Government Authority (LGA)

Granting approval and taxation relevant to the assessment

High Moderate

Central Environmental Authority (CEA)

Consulting for Environmental Impact Assessment (EIA)and granting approval for environment related matters

High Low to moderate. Only concern on the environmental impacts of the project. However due to the reduction of GHG emission it is much important for it.

Ceylon Electricity Board (CEB)

Sole authority for transmission and distribution network and issuing permits for independent power producers to start new generation facilities

High High. As their responsibility to electricity for community they are highly interested on it.

-61-

Table 25(Cont.): List of Stakeholders

Stakeholder Role/Responsibility Influence/Power Interest

Local Suppliers Material, Machinery & Equipment

Supply material machinery & equipment for construction and installation on time and at negotiated price

Low to moderate. Their commitment to supply material as agreed directly affects on the success of the project. However they are not influential in any other way

High. As they are financially benefited for a certain period.

Foreign Suppliers Material, Machinery & Equipment

Supply material , machinery &auxiliary components on time and at negotiated price

Low to moderate. Their commitment to supply material as agreed directly affects on the success of the project. However they are not influential in any other way

High. As they are financially benefited for a certain period.

Contractors (Civil/Mechanical/Electrical)

Complete scope of the project on time at negotiated price

Low to moderate. Their commitment to supply material as agreed directly affects on the success of the project. However they are not influential in any other way

Community groups and NGOs

Help to complete the project. Make suggestion, and sometimes do the coordination between each parties

Low High. They are the most benefitted group of this project. However since this is a small project and amount of import is small the interest of some large foreign suppliers may be low.

Local & Foreign Investors Invest for the project and earn the revenue as per the agreement with CEB

High. Main player for the project to be successful.

High. As they are the bidders for project and if selected one of them is the most financially benefitted individual.

Financial Institutions and Donor Agencies

Provide required fund on loan or donation basis

High Low

Industrial Experts and Consultants

Provide technical expertise

Moderate to high. Success of the project highly depends on their consultation

Moderate. As they are hired for the project their interest is only up to a certain period.

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7.3.2. Stakeholder Analysis

Analyzing the stakeholder is an important part in project management and for this project each stakeholder is placed in the matrix below (Figure 16). For example political authority (No.01 has higher power, but their interest on this project is less. The divisional secretariat has the higher power as well as higher interest (As this project benefits the community dealing with it closely

Interest→

Power→

1 2 10

3 5 4 11 12

7

8 6

9

Figure 16: Stakeholder Analysis Matrix

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8. Discussion

1. As the present water supply method to the agricultural lands (almost paddy fields ) of the village that we found during our visit are the pumps driven by gasoline fueled engine and it was found to be expensive in economic point of view as well as not sensible in environmental point of view a renewable based method was considered.

2. Based on that required capacity of the pump was determined. As per the location, the horizontal and vertical distances from the water source to the farming lands were calculated. Barkley a US originated product was considered for pump selection as they have provided the performance curves of each pump. Since the supplier manufactures few types of pumps matching for our requirement, first a set of seven pump types of different in size, head, and flow rate range, were taken in to consideration.

3. For all the pump types the system head by varying the flow rate were calculated and plotted on the pump performance curves. With the Pump with small inlet and outlet, the system needs higher head due to the friction losses. Pump that discharge the lowest brake power while maintaining the required flow rate was selected and duty point was selected considering the best efficiency point. The pumps need Variable Frequency Drives (VFDs) for operation as the selected duty point lies on the performance curve not at rated speed.

4. As the considered pumps are large compared to the requirement the loss at motor and VFD is higher (The efficiency of motor and VFD is low at lower loads). Therefore overall efficiency comes down and energy loss gets higher.

5. By coupling two pumps in parallel the required flow rate reduced a half and a small pump was selected to suit the requirement meet the same criteria as above. Then the required motor and VFD were a small ones and could achieve high overall efficiency. Barkley, 3 X 4 X6M was selected and rpm to be set to 3200. Required electric power for water pumps was 27kW (Taking the losses in to the account it was set to 29 kW and during season that highest irrigation requirement occurs, pumping time is 15 hours.

6. To deliver the required power required turbine was selected out of six wind turbine types. As the average wind speed in this region is less than the rated wind speed of the wind turbine, it needed a turbine rated higher than our required power. Then our calculations found that the turbine Polaris (Model No- P15-39.9), a US product, rated as 39.9kW at 9.5m/S speed (Rotor diameter -15m, Tower Height -30m) can deliver the required power for this application.

7. It was realized that an excess energy is available at the hours in which wind turbines are not in operation as well as higher wind speeds occur and can be utilized for household electrification, provided a proper storage system.

8. Electric power required for household electrification was calculated assuming that an energy efficient lighting and other appliances are used. Peak demand was 12.3 kW and energy was 247kWh per day)

9. The battery bank size was determined to store the energy for three consecutive days without sufficient wind and it was 3100 numbers of batteries of 140Ah capacity. As cost of this battery bank is very high an alternative method was to be suggested. It was to store the water requirement for three days in a tank and store only electricity requirement for household electrification in battery bank. Then the batter bank size could be reduced by three fourth (3/4) and cost came down to 60450USD (775 batteries). However the water storage method was not to construct storage tanks, but to use the existing paddy fields as they have that capacity and

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increasing of water level up to that height is not harmful for the crop. A small storage tank (40m3) was proposed to construct.

9. Conclusions As a conclusion it is worthwhile that a system presented here be implemented in the application of irrigation water pumping because of several reasons. First it is more economical than the use of present low efficient, old water pumps. Secondly as it is a renewable based system, it helps to reduce the GHG emission. Thirdly it has the capacity of supplying a large amount of water than individual pumps and hence in addition to the present agricultural lands, further number of unutilized lands can be used for farming. (Since the water demand varies and the system has been designed for the highest water demand, during less water consuming month’s excess energy can be used for pumping water for any other crops such as vegetable and large numbers of unutilized lands are available in this area.) The system can generate 39.9kW of electricity at rated wind speed (9.5 m/S) and it is sufficient (even the power generated at lower wind speeds than the rated one, as per our calculations) to fulfill the demand of household electrification (15 kW peak, and 147 kWh per day) and the electricity required to drive the electric irrigation pumps. In the economic point of view, supply of electricity for household lighting through the proposed system is not attractive; however the government’s policy of providing electricity to the rural community and hence achieving 100% household electrification will diminish the importance of this cost factor. Government has only the other option for household electrification in this region is solar PV installation as no use of extending the national grid to this area due to its high cost associated with the long distance. Solar PV system is also very expensive comparatively and therefore the installed wind turbine for irrigation purpose is more economical than other sources. On the other hand the cost of electricity unit gets much higher in our system because of the cost of battery bank. The battery bank size was determined so large in order to supply a more reliable and uninterrupted service by storing energy sufficient for three days. This is by considering a worst case where consecutive three days with a very low wind speed and hence zero is assumed. And also the Depth of Discharge (DOD) of the battery was set to 50% and it can be set to 80% that reduces the size of the battery bank. If at the worst case the DOD is set to 80%, the cost of electricity generated will decrease to 27.93 LKR, which is in our range.

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10. References

Aeolos Wind Turbine Company http://www.windturbinestar.com, accessed in 2014 Agriculture and Agrifood, Canada www1.agric.gov.ab.ca/$department/deptdocs.nsf/.../$FILE/wind.pdf accessed in 2014 Barkley Centrifugal pumps, Product Catalogue http://www.berkeleypumps.com/resources/images/302.pdf, accessed in 2014 Bergey, M., Small Wind Systems For Rural Energy Supply, Village Power 2000, Washington,

DC, USA, 2000 Vick B.D, Neal B.A, and Clark R.N., Performance of a small wind powered water pumping system, accessed in 2008 Central Bank of Sri Lanka, http://www.cbsl.gov.lk, accessed in2015 Ceylon Electricity Board, http://www.ceb.lk, accessed in2015 Elliott D., Schwartz M., Scott G., Haymes S., Heimiller D., George R. National Renewable Energy Laboratory (August 2003), Wind Energy Resource Atlas of Sri Lanka and the Maldives, http://www.nrel.gov/wind/pdfs/34518.pdf, accessed in 2014 Email, Aimee John aimee@windturbinestar.com, November 10, 2014 Email, Aimee John aimee@windturbinestar.com, November 18, 2014 Facility Dynamic Engineering (https://av8rdas.wordpress.com/2010/12/18/variable-frequence-drive-system-efficiency, accessed in 2014 Google, https://earth.google.com,accessed in 2014 Grundfos (2013) The Centrifugal Pumps, pp 14-29 https://manpreet159.files.wordpress.com/2013/09/the_centrifugal_pump.pdf,accessed in2014 International Renewable Energy Agency (June 2012), Renewable Energy Technologies Cost analysis Series, Volume 1: Power Sector, issue 5/5, wind Power, https://www.irena.org/DocumentDownloads/Publications/RE_Technologies_Cost_Analysis-WIND_POWER.pdf, accessed in 2014 Ironman Wind Mills Company. http://www.ironmanwindmill.com ,accessed in 2014 J. Howell (1982), Water Pumping Windmills (Page 14-40) http://www.fastonline.org/CD3WD_40/JF/427/Waterpumping%20Windmill%20%20Book%20-%20NAI%201982.pdf,accessed in 2014 Ministry of Power and Energy Sri Lanka ,October 2006, National Energy Policy and Strategies of Sri Lanka, http://worldfuturecouncil.org/fileadmin/user_upload/PACT/Laws/Sri_Lanka_Energy_Policy_2006.pdf, accessed in 2014

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Pacific Gas & Electric Company,http://www.2jbs.com/windturbines/pgeenergie3550kw.html, accessed in 2014 Polaris America http://www.polarisamerica.com/turbines/39-9kw-wind-turbines, accessed in 2014 Project Management Institution, PMBOK Guide, Fifth Edition,pp 105 -190, & pp 393-413 Public Utility Commission of Sri Lanka http://www.pucsl.gov.lk/english/information-centre/tariff-revision-2013, 2012 Sri Lanka Sustainable Energy Authority, Sri Lanka Energy Balance 2012, http://www.info.energy.gov.lk/content/pdf3/2012%20Energy%20Balance.pdf, accessed in 2013 Sustainable Productivity, http://sustainableproductivity.blogspot.com/2013/08/how-over-sized-equipment-can-be-drain.html, accessed in 2014 U.S. Department of Energy, Renewable Energy Data Book 2012 (Page 40-53) http://www.nrel.gov/docs/fy14osti/60197.pdf, accessed in 2014 Wikipedia, https://en.wikipedia.org/wiki/Premium_efficiency,2014 Agriculture and Agri food, Canada, accessed in 2014 Zawawi M.A.M., Mustapha S., and Puasa Z. , (2010), Determination of Water Requirement in a Paddy Fieldat Seberang Perak Rice Cultivation Area http://dspace.unimap.edu.my/dspace/bitstream/123456789/13717/1/032-041Determination%20of%20Water%206pp.pdf, accessed in 2014

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Annexes

Annex A- Pump Performance Curves

A1- Type 1 – 4 X 5 X 10

Pump Performance curves (Barkley centrifugal pumps, 2014)

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A2: Type 1 - 4 X 5 X 9.5 BH

Pump Performance curves (Barkley centrifugal pumps, 2014)

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A3: Type 1- 4 X 5 X 12 BH

Pump Performance curves (Barkley centrifugal pumps, 2014)

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A4: Type 1- 4 X 5 X 13 BH

Pump Performance curves (Barkley centrifugal pumps, 2014)

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A5: Type 2 – 5 X 6 X 10H

Pump Performance curves (Barkley centrifugal pumps, 2014)

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A6: Type 3- 6 X 8 X 13BL

Pump Performance curves (Barkley centrifugal pumps, 2014)

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A7: Type 3- 6 X 8 X 9L

Pump Performance curves (Barkley centrifugal pumps, 2014)

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A8: Type 3- 6 X 8 X 13 BM

Pump Performance curves (Barkley centrifugal pumps, 2014)

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A 9: Type 1 - 2.5 X 3 X 6M

Pump Performance curves (Barkley centrifugal pumps, 2014)

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A10: Type 3 X 4 X 6M

Pump Performance curves (Barkley centrifugal pumps, 2014)

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Annex B – Total Electrical Power Requirement for Selected Pumps

Pu

mp

Typ

e

Pu

mp

Siz

e

Pu

mp

Bra

ke P

ow

er (

kW)

Effi

cien

cy

Mo

tor

Size

(kW

)

Pu

mp

Bra

ke P

ow

er a

s a

Per

cen

tage

o

f M

oto

r Fu

ll Lo

ad (

%)

Mo

tor

Effi

cien

cy (

%)

Mo

tor

Ru

nn

ing

Po

we

r (k

W)

Mo

tor

Ru

nn

ing

Po

we

r as

a

Per

cen

tage

of

VSD

Siz

e (%

)

VSD

Eff

icie

ncy

(%

)

Ove

rall

Effi

cien

cy o

f El

ectr

ical

Co

mp

on

ents

(%

)

Tota

l Ele

ctri

cal p

ow

er D

raw

n (

kW)

Full

Load

Eff

icie

ncy

(%

)

Effi

cien

cy a

s a

Per

cen

tage

of

Fu

ll

Load

Ove

rall

Mo

tor

Effi

cien

cy (

%)

Type 3

4 X 5 X 10 BM

23.35 82% 93.20 25.06% 95.50% 68.00% 0.65 35.96 38.59% 78.00% 50.65% 46.11

4 X 5 X 9.5 BM

21.06 75% 55.90 37.67% 94.50% 87.00% 0.82 25.61 45.82% 85.00% 69.88% 30.13

4 X 5 X 12 BH

26.33 78% 93.20 28.25% 95.50% 77.00% 0.74 35.80 38.42% 77.00% 56.62% 46.50

4 X 5 X 13 BH

26.00 79% 111.90 23.23% 95.50% 63.00% 0.60 43.21 38.61% 78.00% 46.93% 55.39

4 X 5 X 13 BH

25.35 80% 111.90 22.66% 95.50% 62.00% 0.59 42.82 38.26% 77.00% 45.59% 55.61

Type 4

5 X 6 X 10 H 17.97 80% 74.60 24.09% 94.50% 69.00% 0.65 27.56 36.94% 75.00% 48.90% 36.74

5 X 6 X 10H 16.40 78% 74.60 21.98% 94.50% 60.00% 0.57 28.92 38.77% 78.00% 44.23% 37.08

Type 5

6 X 8 X 13BL 18.05 72% 111.90 16.13% 95.50% 52.00% 0.50 36.34 32.48% 66.00% 32.78% 55.06

6 X 8 X 9L 22.64 48% 37.30 60.71% 94.00% 100.00% 0.94 24.09 64.58% 95.00% 89.30% 25.36

6 X 8 X 13BM

20.91 83% 111.90 18.68% 95.50% 58.00% 0.55 37.74 33.73% 70.00% 38.77% 53.92

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Annex C - Turbine Power Curves

C1- WT1

Wind turbine power curves (Aelos Wind Turbine Company, November 10, 2014)

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C2- WT2

Wind turbine power curves (Aelos Wind Turbine Company, November 10, 2014)

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C3- WT3

Wind turbine power curves (Aelos Wind Turbine Company, November 10, 2014)

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C4 – WT4

Wind turbine power curves (Aelos Wind Turbine Company, November 10, 2014)

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C5 – WT6

Wind Turbine Power Curves (Pacific Gas & Electric Company, 2014)

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C7- WT7

Wind Turbine Power Curves (Polaris America,2015)

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Annex D – Turbine Prices

Wind Turbine Prices (Aelos Wind Turbine Company, November 18, 2014)

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Wind Turbine Prices (Aelos Wind Turbine Company, November 18, 2014)

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Annex E – Estimate for the Construction and Installation

of Power System

Item Description Unit Local Component Foreign Component (CIF to Colombo Port))

Total

Rate (USD)

Quantity Amount (USD)

Rate (USD) Quantity Amount (USD)

1 Construction of Foundation for Wind Turbine

1.1 Excavation & Earth work

m3 6.00 20 120.00 120.00

1.2 Screed 50mm thick with Grade 15 concrete

m2 4.00 12 48.00 48.00

1.3 Reinforcement kg 1.50 410 615.00 615.00

1.4 Shuttering m2 16.00 39 624.00 624.00

1.5 Concreting ( Grade 30)

m3 140.00 15 2,100.00 2,100.00

2 Installation of Wind Turbine

2.1 Cost of Turbine Including Auxiliary (Tower, Control Panel, Generator, Inverter etc.)

NoS 44,600.00 1 44,600.00 104,000.00 1 104,000.00 148,600.00

2.2 Cost of Turbine Installation & Wiring

Item 10,000.00 10,000.00

Battery Bank NoS 25,180.00 78.00 775 60,450.00 85,630.00

3 Construction of Pump House and Control Room

m2 400.00 13.5 5,400.00 5,400.00

4 Pumping System Installation

4.1 Cost of Pump including Auxiliaries ( Motor, VFD, Controllers )

NoS 1,490.00 2 2,980.00 3100 2 6,200.00 9,180.00

4.2 Cost of Pump Installation and Wiring of Control System

Item 300.00 0.00 300.00

4.3 Pipeline Installation

m 58.00 115.00 6,670.00 0.00 6,670.00

5 Construction of Water Storage Tank (10 X 2 X 2 m3 )

5.1 Excavation & Earth work

m3 6.00 15 90.00 0.00 90.00

5.2 Screed 50mm thick with Grade 15 concrete

m3 4.00 25 100.00 0.00 100.00

5.3 Reinforcement kg 1.50 1450 2,175.00 0.00 2,175.00

5.4 Shuttering m2 16.00 136 2,176.00 0.00 2,176.00

5.5 Concreting ( Grade 30)

m3 140.00 14.2 1,988.00 0.00 1,988.00

5.6 Water proofing m2 68 0.00 0.00 0.00

5.7 Plaster finish/Rendering

m2 2.00 136 272.00 0.00 272.00

TOTAL 276,088.00

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Annex F – Analysis of Unit Cost

F1- Method 1

Water Pumping System Item Description USD LKR Time of

Lasting (years)

Pumping System 16,150.00 2,147,950.00 10 Pump house 5,400.00 718,200.00 20 Storage Tank 6,801.00 904,533.00 20 Turbine 162,107.00 21,560,231.00 10 Battery Bank 85,630.00 11,388,790.00 5

Description Turbine Pumping

System Storage Tank Pump House &

Control Room Total

Initial Investment 16,170,173.25 2,147,950.00 904,533.00 628,425.00 19,851,081.25

Depreciation per year

1,617,017.33 214,795.00 45,226.65 31,421.25 1,908,460.23

O&M cost (5%) 808,508.66 107,397.50 45,226.65 31,421.25 992,554.06

Total cost per year 2,425,525.99 322,192.50 90,453.30 62,842.50 2,901,014.29

Electricity units utilized for pumping (kWh) 110,730.00

Cost to generate 1kWh 26.20

Power Generation System Description Turbine Pump House

& Control Room

Battery Bank Total

Initial Investment 5,390,057.75 89,775.00 11,388,790.00 16,868,622.75 Depreciation per year

539,005.78 4,488.75 2,277,758.00 2,821,252.53

O&M cost (5%) 269,502.89 4,488.75 0 273,991.64 Total cost per year 808,508.66 8,977.50 2,277,758.00 3,095,244.16

Electricity units utilized for household electrification 50,981

Cost to generate 1kWh 60.71

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Water Pumping System

Item Description USD LKR Time of

Lasting (years)

Pumping System 16,150.00 2,147,950.00 10 Pump house 5,400.00 718,200.00 20 Storage Tank 6,801.00 904,533.00 20 Turbine 162,107.00 21,560,231.00 10 Battery Bank 85,630.00 11,388,790.00 5

F2- Method 2

Description Turbine Pumping System

Storage Tank Pump House & Control Room

Total

Initial Investment 21,560,231.00 2,147,950.00 904,533.00 718,200.00 25,330,914.00

Depreciation per year

2,156,023.10 214,795.00 45,226.65 35,910.00 2,451,954.75

O&M cost (5%) 1,078,011.55 107,397.50 45,226.65 35,910.00 1,266,545.70

Total cost per year 3,234,034.65 322,192.50 90,453.30 71,820.00 3,718,500.45

Electricity units utilized for pumping (kWh) 110,730.00

Cost to generate 1kWh 33.58

Power Generation System Description Turbine Pump House

& Control Room

Battery Bank Total

Initial Investment 11,388,790.00 11,388,790.00 Depreciation per year

2,277,758.00 2,277,758.00

O&M cost (5%) 0 0.00 Total cost per year 2,277,758.00 2,277,758.00

Electricity units utilized for household electrification 50,981

Cost to generate 1kWh 44.68

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Annex G - Electricity Rates in Sri Lanka

If the consumption is between 0-60 kWh per month the following tariffs will be applicable

Monthly Consumption kWh

Unit Charge (Rs./kWh)

Fixed Charge (Rs./month)

0-30 2.50 30.00

31-60 4.85 60.00

If the consumption is above 60 kWh per month the following tariffs will be applicable

Monthly Consumption kWh Unit charge (Rs/kWh)

Fixed charge (Rs/month)

0-60 7.85 N/A

61-90 10.00 90.00

91-120 27.75 480.00

121-180 32.00 480.00

>180 45.00 540.00

Electricity Tariff Rates of Sri Lanka, (Ceylon Electricity Board (CEB), 2012)

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Annex H – Feed in Tariff Paid by CEB for Private Power

Producers

Feed in Tariff for Private Power Producers, (Ceylon Electricity Board, 2012)

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Annex I – Equivalent Lengths of Pipe Fittings