Paulien van Dorp Denise Graafsma Idzard Hoekstra Geart Ludema

Windmills and Pumps in the Sahel, Burkina Faso

List of contents1.Preface...............................................................................................................................................4

2.Geographical research.......................................................................................................................5

2.1 Weather and climate...................................................................................................................5

2.2 Soil and vegetation......................................................................................................................5

2.3 Demographics..............................................................................................................................5

2.4 Economy......................................................................................................................................6

2.5 Language and religion..................................................................................................................6

2.6 Health..........................................................................................................................................6

2.7 Politics.........................................................................................................................................6

3. Wind turbines....................................................................................................................................7

3.1 Preface.........................................................................................................................................7

3.2 Theory behind the wind turbine..................................................................................................7

3.2 Different types of wind turbines..................................................................................................8

3.2.1 HAWT....................................................................................................................................8

3.2.2 VAWT....................................................................................................................................9

3.4 Design Bosman windmill.......................................................................................................12

4 The water pump..........................................................................................................................14

4.1 Properties of a water pump in the Sahel.............................................................................14

4.2 Different types of water pumps...........................................................................................14

4.2.1 Positive Displacement Pumps......................................................................................14

4.2.2 Impulse Pumps.............................................................................................................16

4.2.3 Velocity Pumps............................................................................................................16

4.2.4 Gravity Pumps..............................................................................................................16

4.2.5 Steam Pumps...............................................................................................................16

4.2.6 Valve less Pumps..........................................................................................................17

4.3 Comparison..........................................................................................................................17

4.4 Our choice............................................................................................................................17

4.5 Is it possible to produce electrical energy?..........................................................................18

5 Transmission................................................................................................................................19

5.1 Why a transmission?............................................................................................................19

5.2 Properties needed...............................................................................................................19

5.3 Calculations..........................................................................................................................19

5.3.1Maximum wind speed:........................................................................................................19

5.3.2Average oscillations per second of windmill:.......................................................................19

5.3.3Average rpm rope pump:.....................................................................................................19

5.3.4 Proportion:.........................................................................................................................20

5.4 Considerations and recommendations................................................................................20

Material.......................................................................................................................................20

Housing........................................................................................................................................20

How its driving the pump............................................................................................................20

6. Water storage..................................................................................................................................21

6.1 Preface.......................................................................................................................................21

6.2 Type...........................................................................................................................................21

6.3 A pond.......................................................................................................................................23

6.3.1 Problems.............................................................................................................................23

6.3.2 Other functions...................................................................................................................25

6.3.3 Others.................................................................................................................................25

6.4 A Tank........................................................................................................................................26

6.4.1 Features..............................................................................................................................26

6.4.2 An underground wooden tank compared to a wooden tank on the surface......................27

6.4.3 Which type of tank..............................................................................................................27

6.5 Time to choose between a pond and a tank on the surface......................................................27

6.6 An irrigation system...................................................................................................................27

6.7 Manual.......................................................................................................................................28

6.7.1 Platform or not...................................................................................................................28

6.7.2 How big...............................................................................................................................28

6.7.3. Collect materials................................................................................................................28

6.7.4. Build the tank.....................................................................................................................29

7.Sources.............................................................................................................................................30

7.1 Sources: Geographical research.................................................................................................30

7.2 Sources: The Wind Turbine........................................................................................................30

7.3 Sources: The water pump..........................................................................................................30

7.4 Sources: Transmission...............................................................................................................30

7.5 Sources: Water storage.............................................................................................................31

1.Preface

This is our first version of our worldschool report. In it are the things which we have been doing the past several months. It’s mainly focused on the theoretical side of the assignment. This because we decided not to take a leap in the dark and search out all the theory before possibly starting something practical.

It all started in July last year by picking out the right assignment; this would lead to the following:

M008: Windmills and pumps in the Sahel

After having lost two of our team members we started by dividing the tasks and making a schedule about which needed to be finished when. After that each started with its own research, yet keeping each other up to date about our succeedings and meeting at least once a week to discuss our succeedings and problems.

So this is the result of about four months searching, filtering and writing about all kinds of things which have to do with an irrigation system in Koupela, Burkina Faso. As said this is the first version, a couple of things need to be added. Probably the most important one of those is a manual in French so that the locals can understand all the things we made up for them.

Another thing which needs to be done is to inform our supervisors, Mr. Bijlsma and Ms. De Vries, more often. This is something that went wrong because of a miscommunication, we thought we had to come up with something first before discussing it with them. But as it turned out this was not the plan and from now on we are going to involve them more in our assignment.

Despite all this, here it is, our first version of our worldschool report: M008-Windmills and pumps in the Sahel.

2.Geographical research

Burkina Faso is a country in West Africa and is divided into thirteen regions and forty-five provinces. Our city, Koupela, is the capital city of the province Kouritenga. Burkina Faso is a member of the African Union, Community of Sahel-Saharan States, La Francophonie, Organisation of Islamic Cooperation and Economic Community of West African States.

Location Burkina Faso Location Koupela

2.1 Weather and climate

Koupela has a wet season; from July until the beginning of October. During this season, the soil is wet enough and people mainly breed sorghum. In October and November, there are still some puddles of water. After that, people have to use the wells until these also turn empty in April or May. The highest wind speeds occur before the monsoons during the wet season, but since or windmill doesn’t have to work during the wet season, the highest wind speeds we’ll have to deal with will be 8 Bft. During the dry season, when the wind is strong and the temperature is high, up to 2cm of water can evaporate per day.

2.2 Soil and vegetation The soil in the area of Koupela is very sandy. There is an urgent need of compost. During the dry season, the soil is very dry. Wells turn empty. In some places, water stays in the soil on a solid layer of rocks, about 40 to 70m meters below the surface. There might be underground water at about 320m below the surface (sea level). Vegetation in Burkina Faso is varied to a degree, although much of the country is dry and sparse, especially with a high deforestation rate in the country. The country is moderately forested with around 15% forest cover and an additional 34% of other wooded land, mainly gallery forests along rivers. Our pump will have to function during the dry season, when vegetables are bred. The water will be used for the vegetable garden and for young trees (these have to be sprinkled for 2 to 3 years).

2.3 Demographics The population of Burkina Faso was, in 2009, estimated around 15.7 million. In 2006 the population was 14,017,262. Most of Burkina's inhabitants live in the south and center of the country, sometimes exceeding 48 per square kilometer. The estimated population growth rate is 3.109%. In 2006, the town of Koupela had 19,980 inhabitants.

2.4 Economy Burkina Faso has a GDP per capita of $1,200. This is one of the lowest in the world. The total GDP was, in 2010, estimated around $19.992 billion. 32% of its gross domestic product consists of

agriculture. 80% of the working population works in the agricultural sector. It consists mostly of livestock but also, especially in the south and southwest, of growing sorghum, pearl millet, corn, peanuts, rice and cotton. A large part of the economic activity is made possible by international aid. Burkina Faso is part of the West African Monetary and Economic Union (UMEOA) and has adopted the CFA Franc. There is mining of copper, iron, manganese and gold. But most materials can be bought in the capital: Ouagadougou. In Koupela there are some small shops that can weld for the construction of our mill and pump.

2.5 Language and religion The official language of Burkina Faso is French. Other regional recognized languages are: Mòoré and Dioula. According to the Government of Burkina Faso’s census in 2006, 60.5% of the population practice Islam, and that the majority of this group belongs to the Sunni branch, while a growing minority adheres to the Shi'a branch. The Government also estimated that 23.2% are Christians (19% Roman Catholics and 4.2% Protestants), 15.3% follow Traditional indigenous beliefs, 0.6% has other religions. Among these different religions there is a large level of acceptance.

2.6 Health The average life expectancy was estimated at 52 for women and 50 for men (in 2004). The median age is 16.7. In 2009, it was estimated that there were only 10 physicians, 41 nurses, and 13 midwives per 100,000 people.

2.7 Politics The parliament of Burkina Faso consists of one chamber: the National Assembly which has 111 seats. Members are elected for a five year term. There is also a constitutional chamber with ten members, and an economic and social council whose roles are consultative. The current president is Blaise Compaoré who seized power in 1987. In 2010, he was reelected. Only 1,6 million inhabitants voted.

3. Wind turbines

3.1 PrefaceIn this chapter we will discuss a number of wind turbines. The choice of the particularly wind turbine will be mainly based on the simplicity of its design. Below a list of the criteria we have set up, ranking from most to least important:

Must have a simple design. Must be strong enough to withstand maximum wind speeds of 70 km/h Local shops must be able to produce the wind turbine Must be easy to build Must be easy to repair

3.2 Theory behind the wind turbineThe magic word is lift force. Lift force is the upwards pressure caused by the shape of the blade and the air that flows past the blade.

We take the wing of an airplane to explain what precisely lift force is. When we look at the wing to the below, you can see the flow of air above the wing has to cover a larger distance. We learned in physics class that air that has to cover more ground in the same amount of time has a higher speed. This is Bernoulli's principle. Furthermore, because the flow of air below the wing has a relatively smaller speed, the upwards pressure is higher than the downwards pressure. In the picture below F L

is the lift force and FW is the air resistance (drag force). Air resistance is a force that is caused by air, the force acts in the opposite direction to an object moving through the air. Because of this, the wing is lifted. The same theory applies at the blades of wind turbines and older windmills. For a blade of a windmill to be pushed up, the lift force has to be greater than the gravity.

3.2 Different types of wind turbinesI will categorize the wind turbines based on their axis position.

Position of the axisWhen looking at different types of rotors, we have the HAWT and the VAWT. Respectively the Horizontal Axis Wind Turbines and the Vertical Axis Wind turbines. As their names suggest the HAWT has a horizontal axis and the VAWT a vertical axis. Below I will further clarify what precisely the advantages and disadvantages are of both type of wind turbines.

3.2.1 HAWT Windmills with a horizontal axis have to be turned into the right direction. The propellers can have a constant as well as a variable thickness. Furthermore the gearbox has to be placed in the top of the shaft or can be installed on ground level with a special transmission. The HAWT has already been used in the same situations we want to use it, and proved to be very reliable. (http://www.youtube.com/watch?v=E1qIdvH1bvM&feature=player_embedded) & (http://www.youtube.com/watch?v=LM_1kCg9XWs&feature=related) Advantages of a horizontal axis wind turbine. A HAWT : Is easy to build Has a high rotational speed Is easy to repair Even with an easy and simple design, a HAWT can function. The tall tower base allows access to stronger wind in sites with wind shear. Wind shear is a

difference in wind speed and direction over a relatively short distance in the atmosphere. In some wind shear sites, every ten meters up, the wind speed can increase by 20% and the power output by 34%.

High efficiency, since the blades always move perpendicularly to the wind, receiving power through the whole rotation.

The rope pump the wind turbine has to power must not have a high circulation rate. Though he HAWT does have a high rotational speed, the speed can be transmitted to mechanical power with a gearbox.

3.2.1.1 Subtypes :American Wind turbineThe traditional, American "fan mill," is a well developed technology with very high reliability. It incorporates a step down transmission, so that pumping rate is a quarter to a third of the rotational speed of the rotor. This design is particularly suitable for relatively deep wells (greater than 30 meters). This wind turbine can be rotated into the right direction with a wind vane and can already operate at low wind speeds.

3.2.1.2 Subtypes: The BosmanWindmillThe Bosman windmill is a windmill based on the design of an American wind turbine, only the bosman windmill has a simpler design.It also has a wind vane to rotate the windmill into the right direction. Thenumber of blades can variate.

3.2.1.3 There are a lot more types of horizontal axis wind turbines. A short list of numerous wind turbines:

1-bladed wind turbine. – e.g. Monopteros. 2-bladed wind turbine – these are most of the time small wind turbines with high

rotational speeds. 3-bladed wind turbines – most used with the modern wind turbine.

3.2.2 VAWT

Advantages: VAWT’s can be packed close together, but this is only an advantages when you want the

have a wind farm VAWT’s are quiet and do not have to be pointed into the wind, because they are omni-

directional. Less stress on the support system Do not require as much wind to generate power, therefore can be installed closer to the

ground. The gearbox can be placed at ground level, therefore easier to maintain.

Disadvantages: As mentioned before VAWT’s are installed closer to the ground, this because VAWT’s

cannot function well with very high wind speeds. VAWT’s have dynamic stability problems. The blades of a VAWT get worn out as the blade spins around the central axis. The

vertically oriented blades used in early models twisted and bent as they rotated in the wind. This caused the blades to flex and crack. Over time the blades broke apart and sometimes leading to catastrophic failure. Because of these problem, Vertical axis wind turbines have proven less reliable than horizontal-axis wind turbines (HAWTs).

The key disadvantages include the low rotational speed, and the higher torque.

It’s difficult to model the wind flow accurately and therefore it’s challenging to design the rotor and the rotor is more difficult to produce.

3.2.2.1 Subtypes : Darrieus wind turbineThe darrieus wind turbine is efficient, but produces large torque and stress on the main shaft, and is therefore not very reliable.

3.2.2.2 Subtypes : Savonius turbines

Savonius Turbines are used whenever cost or reliability is much more important than efficiency. Savonius is good at pumping water and other high torque, low rotational speed applications and are not usually connected to electric power grids. They can sometimes have long helical scoops, to give smooth torque.

3.2.2.3 Subtypes : Twisted SavoniusTwisted Savonius is a modified savonius, with long helical scoops to give a smooth torque, this is mostly used as roof windturbine or on some boats.

Twised Savonius turbine Savonius wind turbine Darrieus wind turbine

3.3 Comparison and decision

Although the VAWT has quite some advantages, Vertical axis machines, such as the Savonius rotor, have usually been less successful in practice. (said by James F. Manwell, a VITA Volunteer at the University of Massachusetts who researched the build of pumps driven by wind mills in third world countries. )Therefore the VAWT is in any case not suitable for our purpose. When we look at the requirements we defined earlier it is clear the American wind turbine and the Bosman mills are the most suitable options left. They both have proven themselves in similar situations we want to use them, and next to that they can be turned into the right direction, are strong and are fairly easy to build. The difference between the two are the blades. Because of its many blades the American wind turbine has a low starting speed, but the bosman wind mill can function better under circumstances with high wind speeds. We have chosen for a compromise.The bosman wind mill is mostly build with 4 blades. We want to have some more blades on our design, so the wind Bosman windmillturbine can pump up water even at lower wind speeds, but not so much as on a American wind turbine. This also is an advantage when building the wind turbine. Because of its many blades the American wind turbine also requires more material and is more difficult to build. Therefore we want to base the design mostly on the bosman windmill, but we will later on discuss the exact number of blades it will have and so in further chapters we will refer to the chosen type of windmill as a bosman wind turbine.

Below some links to videos of examples where the Bosman wind turbine or American wind mill has been used to pump water to the surface.

LINKS: http://www.youtube.com/watch?v=dkf8rjTaymY&feature=related

http://www.youtube.com/watch?v=E1qIdvH1bvM&feature=player_embedded

http://www.youtube.com/watch?v=LM_1kCg9XWs&feature=related

3.4 Design Bosman windmillNow we have chosen the type of wind turbine we want to base our design on, it is time to talk about the more specific things. Like the number of blades the wind turbine should have and the length of

the blades. Furthermore we will discuss the vane and the material the wind turbine should be made

of. We will also discuss the design of the main shaft.

3.4.1 The number of blades

There exist wind turbines with only one blade, but they put repeatedly a lot of pressure on the same point of the axis. Two-bladed wind turbines have the advantage of saving the cost of one rotor blade and its weight, of course. However, they need a higher rotational speed to yield the same energy output. Because of this the wind turbine will produce a lot more noise. Next to this two- and one-bladed turbines require a more complex design with a hinged rotor. The rotor has to be able to tilt in order to avoid too heavy shocks to the turbine when a rotor blades passes the main shaft. Modern wind turbines are most of the time build with three blades. By adding more blades the starting speed can be lowered, but as the wind speeds in the area we want to use the wind turbine are relatively high, adding a lot of blades will only cost more and can be dangerous. This is because there is an upper limit to how fast a blade should turn, if it turns much faster, it would act like a solid surface and stresses will be enormous on the wind turbine. This maximum speed a blade should turn depends on the number of blades the wind turbine has. The more blades, the lower the maximum speed. Technically speaking 3 blades are the optimum, between the amount of needed material, and the equal pressure on the axis.

3.4.2 Length of the bladesYet to be researched.

3.4.3 The vane

The vane on the bosman wind turbine allows the axis to turn into the right direction. There are other alternatives for a vane. See the left picture below. But this design is more difficult to build and therefore we will stick to a traditionally vane like the right one below.

3.4.4 Main shaft

We are going to research this more thoroughly, but the main shaft will probably be around 10 meters high. This is the most used height for the somewhat smaller wind turbines.

3.4.5 MaterialStill needs to be done:

- First a list of possible materials that the windmill can be made of. - A list of available local materials.- At last a list of the materials the wind mill can be made of.

4 The water pump

4.1 Properties of a water pump in the SahelA water pump in the Sahel needs to have the following properties, listed in order of decreasing importance:

Reliable Easy to repair Efficient Be able to work with a covered well

The first three points speak for themselves, but the last one might need some explanation. An open well is easily infected by bacteria and germs. A covered well greatly reduces this risk. The other three properties include that an easy repairable pump greatly reduces aftersales costs and for a pump to be socially acceptable it needs to work better than the common bucket on a rope. A pump also needs to pump up a certain amount of water, the deeper a well, the more difficult this gets.

4.2 Different types of water pumps

There are a multitude of pumps, all with their advantages and their inherent disadvantages. They will be discussed below, and in this way to deduct the best pump for this application.

4.2.1 Positive Displacement Pumps

This type of pump works by trapping a certain quantity of (in this case) water, and then by mechanical movement, forces this to the output of the pump. There are several ways in which this can be achieved, all discussed below.

4.2.1.1 Rotary Positive Displacement Pumps

These pumps work on the principle of rotation. They create a vacuum by transporting up the air and thus the water is transported through the pump. The advantage of this system is that there’s no need to manually remove the air, since this is removed by the system itself. Air in the system makes the pump work inefficient and therefore it has to be seen to that as less as air as possible is contained within the system. Disadvantages of this system is that the clearing between the rotating part and the stationary part should be near zero, without ever touching each other, because this would lead to unwanted friction. This also means the pump can’t operate very fast, since this would wear out the pump fast, which is both for logistical and economic reasons unwanted.

Generally, these pumps require a lot of building materials, so they’re only convenient for small height differences. The more advanced systems are also quite complicated and therefore unfit for widespread use in the third world, since repair costs would be off the charts.

There are several examples of these types, and they can be divided into three groups:

- Gear pumps: The liquid is pushed between two gears.

- Screw pumps: One or more screws turning inside a closed compartment cause a fluid to move into the direction of the movement of the screw(s).

- Rotary vane pumps: This type of pump utilizes two eccentrically mounted circles, with the center circle pierced lengthwise. Two vanes connected with a pushing spring are placed inside this cavity. The force of the spring makes sure the vanes are always in contact with the outer circle. The decreasing area on the one side pushes the water out and the increasing area on the other side causes the water to flow into the pump, making it available to be pushed further.

4.2.1.2 Reciprocating Positive Displacement PumpsUtilizing one or more pistons, plungers or membranes. These move up and in the fluid and with help of several valves they force the fluid upwards. A common found example is the plunger pump:

The fact that these pumps depend on valves for their job makes them quite repair intensive. They’re also quite complicated and they do not have a nice constant flow rate. Furthermore they’re quite difficult to install since the plunger and the valves need to be in the well, at water level. This also means that a long shaft needs to be made that transfers this action to the valve.

4.2.1.3Linear Positive Displacement PumpsThis type of pump relies on a loose hanging rope (or chain) which is lowered down into a well and drawn up through a long pipe with the

bottom immersed in water. On the rope, round disks or knots matching the diameter of the pipe are attached which pull the water to the surface.

4.2.2 Impulse PumpsThese pumps work on the principle of pressure. A gas is pressurized and then fed through the liquid, hereby forcing the liquid upwards. The disadvantage of this system is that one needs a high efficiency compressor for pressurizing the air. This could possibly lead to high maintenance costs or high educational costs. Therefore we shall not discuss this type further, since our main goal is for the third world to achieve self sustainability.

4.2.3 Velocity PumpsThese type of pumps gives kinetic energy to the water and accelerates the water into a certain direction.

4.2.3.1Centrifugal pumpsUtilizing a rotating impeller to increase pressure and speed within the piping. These are not applicable in our system, since they may not have enough power and also need to be a perfect fit in the tubing, otherwise efficiency will tumble down.

4.2.3.2Eductor-jet pumps

These pumps use pressurized gas to accelerate the water. This involves highly sophisticated technology, which might prove to vulnerable in the dusty area of the Sahel. Since we want maintenance costs to be as low as possible, we should not take the risk of burnt out engines in the compressor.

4.2.4 Gravity PumpsThese type of pumps rely on gravity, letting water flow from high to low. Since we want the water to go up and there being no sufficient sources of water on ground level this is type of pump is inapplicable in the Sahel.

4.2.5 Steam PumpsThese types work by creating an under pressurized region and the water is sucked into this region. This is accomplished by using steam power, which will most likely come from a steam engine. Since this design use water to create steam, and water being already scarce, the high evaporation rate of this pump is not to be neglected.

4.2.6 Valve less PumpsMost pumping systems need valves to regulate the flow of water but these systems function without. An advantage of this is that the flow of water is more constant, but today’s solutions are still quite delicate and therefore unfit for the rough conditions in the Sahel.

4.3 Comparison

The table beneath shows the different models (on a global scale) compared with each other:

type reliability ease of construction

Type Reliability Construction Applicability Repair Efficiency ScorePositive Displacement + +/- ++ + ++ +Impulse +/- -- - -- + --Velocity + +/- +/- - + +/-Gravity ++ + -- - ++ -Steam + +/- -- - + -Valveless ++ -- -- -- ++ -

The main reason why a lot of designs receive a negative score is that they employ highly sophisticated technology. This is too difficult to repair by a villager and therefore unfit, since these countries need to stand on their own legs.

Now let us compare the different Positive displacement pumps, since there’s a great diversity within this section:Type Reliability Construction Applicability Repair Efficiency ScoreLinear ++ ++ ++ ++ + ++Reciprocating + +/- + + ++ +Rotating + +/- + +/- ++ +/-

This diagram makes clear that a rope or chain pump (since these are of the linear type) would be the best solution. A chain pump is impractical since this would mean a very rugged structure needs to be built and this increases build and repair complexity.

4.4 Our choicewe set out for a quest to find the most reliable water pump. We believe this to be the rope pump for the following reasons:

Reliability

The pump can withstand a lot of sand before the pump stops working. It can pump water even when there’s only 10 cm’s of water in the well. Other types of pumps have their water inlet placed higher above the floor of the well, in order to stop the pump from getting clogged.

Ease of construction

Since the main construction is just a rope running around a bicycle wheel with some knots and washers, albeit in reality this is a little bit different of course. The main principle is however a very logical construction. There’s also little to no fuss with difficult

Ease of repair

The ease of construction means that this system is simple for anyone to comprehend and therefore problems are easily solved locally.

High efficiency with minimum technological complexity

Although simple it is hugely more productive than a rope and bucket type of pump. Add this to the fact that a rope can extract more water from a well than any other solution and we have a winner. Furthermore the pump has an efficiency of about 80 to 85 percent, depending on the depth of the well and the

Covered well

A covered well means less chance of a dangerous disease gets into water. This will of course greatly improve the standards of living.

4.5 Is it possible to produce electrical energy?One way of generating energy is using a pump that is installed on a small platform approximately 2 meters above the water container’s maximum level. It is then possible to use the kinetic energy of the falling water to drive a water wheel. It might also be possible to mount a generator directly on one of the gears, but this should not interfere too much with the pump itself. Of course it makes no sense to provide electrical energy when there are no apparatus in the village or town that need power.

5 Transmission

5.1 Why a transmission?Nothing is more changeable than the wind. Therefore we need some way of regulating the high speed that the wind every now and then reaches, as these velocities would probably ruin the water pump. A transmission can also transfer speed into power or vice-versa. This is an important aspect of our construction, since a windmill is probably not strong enough, but can supply enough speed. This would also greatly simplify a breaking system.

5.2 Properties neededOur transmission needs to be both rugged and durable. It doesn’t need to be super precise or highly sophisticated, it simply needs to work.

5.3 Calculations

5.3.1Maximum wind speed:

8 Bft = 74 km/h = 20,5 m/s

5.3.2Average oscillations per second of windmill:

?????

5.3.3Average rpm rope pump: 

When we take into consideration the average depth of a well, the diameter of the pumping pipe and the average speed of one person pumping water, one can calculate the velocity of the rope pump.

Average depth: 35 m = 3500 cmDiameter pipe: ½ inch = 1,27 cmDiameter wheel: 29 inch = 73,66 cm

First we’ve got to calculate the volume of the pipe. As this is a cylinder, the next formula applies:Volume = Height * Area(circular face)

Area is calculated as followed:Area = π * r2 ( r = 0,5 * diameter)

And now it’s only a matter of completing the calculation: Volume = 3500 * π * (0,5 *1,27)2 = 4433 cm3 = 4,4 L

The average adult is able to pump about 12 Liters a minute (1). Assuming our pump is a bit faster and can achieve a higher velocity, say 13 Liters a minute. That’s a total of three pipe lengths as 4,4 multiplied with 3 is approximately 13. This means that the rope has to travel three times the distance of the pipe, 35 meters. Velocity is only one step away:

Velocity = Distance : Time = (35*3) : 60 = 1,75 ms-1

Next stop, the circumference of the guiding wheel:

Circumference = π * diameter = *73,66 =231 cm = 2,31 m

Now we only have to make two calculations and we know the rpm:One round = Circ. : Velocity = 2,31 : 1,75 = 1,32 s per roundAll rotations in a minute = 60 : 1,32 = 45,5 revolutions per minute.

5.3.4 Proportion:

??

5.4 Considerations and recommendations

MaterialWood or metal?

Since wood is very scarce in the Sahel this would need to be imported. As this is financially unpractical, the most practical material would be metal, to be specific, iron. This is a common resource (it’s the fourth most common element in the earth’s crust). It’s also very strong and highly durable, especially when it’s properly maintained.

HousingAn enclosed water pump / gear mechanism would be preferable since this would protect the mechanism from dust. This way the installation becomes more durable and also more cost effective. This might seem counter-intuitive, but the most expensive parts are the gears, since these cost a lot of time to make and are the most fragile elements of the construction.

How its driving the pumpThe easiest and most cost-effective way of connecting the windmill to the pump is by means of two sets of gears and a shaft between these two mechanisms. This has the least moving parts (no difficult transmissions with parts made of unobtanium or stuff sealed in third party designs).

6. Water storage

6.1 PrefaceOur goal is to pump up water in order to use it for irrigation. The people in Burkina Faso do need an irrigation system for food production. Worldwide irrigated lands yield a 3.6 times bigger harvest than not irrigated land. And the crops grown on irrigated land are of a better quality than crops grown on not-irrigated land, this makes that people worldwide can ask a 6.6 timer higher price for crops grown on irrigated land. So the main reason why they need an irrigation system is to feed all the people in Koupela, this is a problem now but it should partly be solved by this irrigation system.

The water pumped up for irrigation has to be stored somewhere so that it can be used on a later moment. This water storage can be done in different ways, each with their different advantages and disadvantages. These have to be compared to each other and in the end a choice has to be made about the type of water storage.

6.2 TypeFirst we had to decide which type of water storage we were going to apply. There were a couple of options, listed below:

A pond A tank, which can be made of different materials like wood, plastic, concrete, clay. The tank

can as well be made above the ground as in the ground. An aquifer, which is a ground layer in which you can store water. In order to store water in an

aquifer you first have to drill a borehole to get to the exact ground layer. Natural wetland, you can store the water in one of those, at least if there is one. Soil moisture, storing water in soil, this can be done if the ground particles are able to hold

water. With this we first made an overview of the advantages and disadvantages of the different water storage types. We did this on several features:

The price, so how expensive is this type of water storage. Pathogens, how many pathogens will there be more with this type of water storage

compared to no water storage at all. This includes pathogens from water contamination and disease vectors like malaria or schistosomiasis.

Other health risks, if there are other health risks to the type of water storage than pathogens. E.g. drowning risks in a pond.

Evaporation, how many water is lost to evaporation. Water loss, other than evaporation there are more types of water loss, e.g. if there is a

leak in a tank. Irrigation: the water pumped up from the ground will be used for irrigation so the

water storage has to be suitable for this. This depends mainly on how expensive the system will become with this type of water storage.

Maintenance, is there a lot of maintenance to be done, and is it hard to do?

Additional functions, are there other functions possible other than just storing water. Capacity, how much water can be stored. Enlargement, how easy can this type of water storage be enlarged. Feasibility, is this type of water storage possible, taking local conditions into

consideration. With these features we made an overview, which is seen below. If the type of water storage does good on that feature it gets a +, if it does bad it gets a -, and if it’s in between there’s a ±.

Feature Type

Pond Tank Aquifer Wetland Soil moisture

Price + ± - + +

Pathogens - ± + - -

Other health risks - - + - +

Evaporation - + + - ±

Water loss ± - ± ± ±

Irrigation ± + - ± -

Maintenance + - - + +

Additional function + ± - - -

Capacity + + ± ± -

Enlargement + ± - - +

Feasibility + ± - - -

As you can see the pond does quite good, but it has problems: There is a lot of water lost because of evaporation, and the biggest problem is that it attracts a lot of pathogens.

The tank has much better results on the pathogens and evaporation losses. But its maintenance is difficult and the additional functions are limited. This makes that the tank is less easy to attain. But a tank is very suitable for an irrigation system.

The results of the aquifer are the weakest, it is expensive, has got no additional functions, and the biggest problem is that a borehole cannot be made in Koupela (Burkina Faso), at least not by the local people. So if you did want to make a borehole in order to reach the aquifer in which you want to store the water, you have to get equipment from somewhere else.

The wetland is a cheap option, but only if there is a natural wetland in the neighbourhood. Next to that the wetland does very bad on health risks, as well as on the pathogens as on the other health risks which mainly is the risk of a flood if you store more water in it than usual. But the biggest problem is the feasibility because there isn’t a wetland in the neighbourhood of Koupela

Soil moisture doesn’t do very good, this mainly on pathogens, irrigation, additional function, capacity and feasibility. The capacity and the feasibility are the two biggest problems, this is because the soil in Koupela is quite sandy so the ability to hold water is quite small.

Taking the table with all the advantages and disadvantages into consideration we decided to drop the aquifer, the natural wetland and the soil moisture as options for water storage in Koupela, Burkina Faso. This is because for an aquifer you need a borehole in order to reach it and store water in it. But this borehole cannot be drilled by the local people because they do not have a the equipment. This means that you would have to get equipment and people who can handle the equipment from somewhere else. This makes the aquifer very expensive, last but not least the aquifer is not suitable for an irrigation system because than you would have to pump up the water twice.

For the natural wetland, you need a natural wetland and there isn’t a natural wetland in the neighbourhood of Koupela. So this option is not possible.

And for soil moisture you need to have soil which has the ability to hold water, this isn’t possible in Koupela because the soil there is sandy.

Taking all this into consideration we decided to focus on the pond and the tank for further investigation.

6.3 A pond

6.3.1 Problems

6.3.1.1 FeaturesThe pond is a low priced option. Just dig a hole and make it a little watertight and you can store water in it. But there are some problems with water:

There are high evaporation losses; a lot of water is just lost. There is a high risk of diseases spreading caused by a pond. There is a high risk of people drowning in a pond.

Here the problems are discussed more thorough.

6.3.1.2 Evaporation losses:Evaporation losses in Burkina Faso are very high, if there are strong winds and the temperature is high the evaporation is up to 2 centimeters a day. The evaporation loss has to be compared with the rainfall because the Gross evaporation subtracted by the rainfall is the net evaporation. The following table shows the annual evaporation and rainfall.

Annual rainfall and evaporation in Koupela, Burkina FasoMonth Rainfall (mm) Potential evaporationJanuary 0 172February 2 173March 10 209April 22 201May 68 197June 109 163

July 171 145August 222 129September 142 129October 30 157November 1 158December 1 160Year 778 1994Source of data: FAO Web LocClim.

From the table you can conclude that the net evaporation is 1994-778=1216mm per year. This is the amount of water which will evaporate from a pond in Koupela. With a diameter of four meters which is about needed for 10m³ of water, the total surface would be π*2²=12.6 m². Which means that the total evaporation is 12.6*1216=15280mm per year. This would be more than 15000 liters a year, if the pond is refilled.

6.3.1.3 Diseases:There are several ways of diseases spreading through a pond. The categories are listed below:

Water-borne diseases: caused by water being contaminated by people or animals. Water-based diseases: caused by aquatic organisms, which spread part of their life in water

and part as parasites. Water-related vector diseases: caused by vector-insects or other animals transmitting the

diseases.Below you see the categories with the diseases belonging to them. The causes and the symptoms of the diseases are mentioned as well.

Group Diseases Cause SymptomsWater-borne diseases Cholera Bacteria Diarrhoea,

vomiting, dehydration. Leads to death.

Typhoid Bacteria Diarrhoea, dehydration, bloody nose, high fever,.

Bacillary Dysentery Bacteria, Viruses, Protozoa

Diarrhoea, dehydration.

Infectious hepatitis (hepatitis A)

Virus Fatigue, fever, abdominal pain, nausea, loss of appetite, jaundice.

Giardiasis Protozoa Diarrhoea, vomiting, fever, loss of appetite, fatigue.

Water-based diseases Schistosomiasis Worm Abdominal pain, diarrhoea, fever, fatigue, skin symptoms.

Dracunculiasis Worm Fever, nausea,

vomiting, intense pain.

Threadworm Worm Itching.Water-related vector diseases

Yellow fever Virus Fever, nausea. Can cause liver damage and lead to death.

Dengue fever Virus Fever, chills, pain in joints and muscles, skin rash. Can develop into dengue haemorrhagic fever which is life threatening.

Malaria Protozoa Fever, headache, liver and nerves are destroyed. Can lead to coma or death.

Onchocerciasis Worm Itching, swelling and imflammation of the skin. Causes blindness.

Filariasis Worm Damage and swelling in lymphatic vessels.

6.3.1.4 Other risks:A pond has other risks next to the spreading of diseases. The biggest risk is people, especially children, drowning in the pond. This of course you do not want. To overcome this you could place a fence around the pond but this costs money and there is not a lot of that in Koupela.

6.3.2 Other functionsA pond can have other functions than for irrigation. You could e.g. breed fish in the pond but than you need to have a pond which is big enough. This because of the evaporation loss, especially in summer, so this fish will die unless there is enough water. For irrigation system finally we only need 10m³ of water. This means that you would get a very small pond so that fish breeding is not a possibility in this case.

6.3.3 OthersThe pond is a low cost option. Its maintenance is quite easy to do and if you want to enlarge it, this will not be a very hard job. This means the capacity of the pond can vary from very small to very big depending on the amount of water you need. In this case only 10m³ of water is needed so that you would only need a fairly small pond. But you can easily make o bigger pond if necessary.

All these things added up means that the feasibility of a pond is quite high.

6.4 A Tank

6.4.1 FeaturesA tank isn’t a very expensive, depending on the form you choose, option to store water. There are a couple of different forms:

An underground lake, made of e.g. wood or concrete. A tank made of wood, concrete or steel just on the ground.

The two options compared divided into the different materials. We have chosen for the materials wood and concrete for an underground lake (no steel because of quick erosion) and wood, concrete and steel for a tank on the surface.

Characteristic Type

Underground lake Tank on the surface

Wood Concrete Wood Concrete Steel

Price + ± + ± -

Pathogens + + + + +

Other health risks ± ± ± ± ±

Evaporation + + ± ± ±

Water loss ± ± ± ± ±

Irrigation ± ± + + +

Maintenance - - ± ± ±

Additional function

- - - - -

Capacity ± ± ± ± ±

Enlargement - - - - -

Feasibility + ± + ± ±

As you can see there are a couple of differences between the underground lake and the tank on the surface. The first thing is that an underground is harder to make. The biggest problem of an underground tank is the maintenance, but in an underground tank is less evaporation than in a tank on the surface. The difference in price is between the materials, of course concrete is more expensive than wood and steel is even more expensive. Both options do average on other health risks (people could drown in a tank), water loss (a leak in the tank means water loss) and the capacity (you can’t make a very large tank). Other problems of a tank are: the additional function, this is hardly possible (only possible if the tank is very big), and the enlargement (it is not very easy to make the tank bigger once built). Another difference between an underground tank and a tank on the surface is the suitability for irrigation, this is because with a tank on the surface you can use gravity to get the water to the fields an with an underground tank you need an extra pump.

As you can see the both tanks made of wood have the highest feasibility. This is because wood is not a very expensive material, and it´s found in the neighbourhood of Koupela. So from now on we are going to focus on the wooden tanks.

6.4.2 An underground wooden tank compared to a wooden tank on the surfaceThe differences between these two are: evaporation, maintenance and irrigation.

Evaporation because with an underground tank there is less evaporation because the sun does not reach the tank.

Maintenance because with an underground tank the maintenance is much harder than with a tank on the surface.

Irrigation because if you have a tank on the surface you can use gravity to transport the water to the fields, whereas with an underground tank you need an extra pump.

Next to that a tank on the surface is easier to make in the first place, because you do not have to dig a hole, make it watertight etc.

6.4.3 Which type of tank Taking all of the above into consideration we have chosen the tank on the surface. This because of that the maintenance with an underground tank is very hard to do and this is more easy if you have a tank on the surface. And the biggest advantage of the tank on the surface is that it is very suitable for an irrigation system because you can use gravity to get the water to the fields. This is because the tank is on the surface and if you make a connection between the bottom of the tank and the irrigation system you get a kind of low pressure pipe line.

6.5 Time to choose between a pond and a tank on the surface.To choose between a pond and a tank isn’t as easy as it looks. You can’t compare the two very well. The pond does better on price, maintenance and things like the additional function and after all the feasibility. But the tank does better on pathogens, evaporation loss and irrigation. So the main question is which are the most import features.

We have chosen irrigation as the most important feature because the water stored eventually has to be used for irrigation. So that’s the reason why we have chosen for the tank on the surface. The tank on the surface can easily be used for irrigation because there is already some pressure in a tank. Because of the water pressure you do not need an extra pump to get the water to the place where it’s needed, you would have needed a pump with a pond because you cannot use the waterpower with a pond because it’s already below surface.

With this choice made, the water storage system does not have an additional function. This because of the tank being closed, so that you could not e.g. breed fish in it because they would need sunlight in order to survive. So because our main goal is to create a working irrigation system, we decided to chosen the tank over the pond.

6.6 An irrigation systemWater stored in the tank is going to be used for irrigation. This is not very hard if you have the tank on the surface because you can use gravity for this. The gravity provides you with water head, so

that there is pressure in the tank. So with small canals and pipes the water can be transported from the tank to the fields where it is needed. Because you have already got water head in the tank you do not need an extra pump for this. And it there is not enough water head to get the water from the tank to the fields if the tank is on the surface you could easily put the tank on a platform to get more pressure on the pipes leading to the fields.

This all makes the total system the cheapest so the most likely to be reached.

6.7 Manual

6.7.1 Platform or notFirst there has to be decided if the water tank is going to be built on the surface or on a platform. This depends on how you are going to transport the water to the fields, when this is going to be done by a pipeline you would possibly need a platform, if this is not done by pipelines you do not need a platform.

If you decide to transport the water to the fields by pipeline it depends on the altitude of the place where the tank is going to be built compared to the altitude of the fields whether you need a platform or not. If the altitude does not differ a lot or if the place where you are going to put up the tank is lower than the fields you need a platform to create enough water head in order to transport the water to the fields.

6.7.2 How big This depends on the amount of water which has to be stored, which depends on the total amount of water which is going to be pumped up. We have calculated this is going to be approximatel 20,000 liters per day, which is 20 m³. So if you want to store water for five days you would need a tank of 100 m³.

The volume of a tank can be calculated through the following function:

Volume= π*h*r2 (r=radius, h=height)

This means that you can vary the height and the radius and still have the same volume. The best thing to do in this case is to make a tank which is quite high to get more pressure.

As example we are going to take a tank of 100 m³. With a radius of 2 meter you need a height of 8 meters to get to the 100 m³; π x 8 x 2²= 100.5 m³, so that’s about the dimensions which you would need.

6.7.3. Collect materialsThe materials needed are:

Wood for the tank If necessary: wood for a platform Metal plates for the roof Metal pipelines Metal rings to hold the wood

The wood can probably be cut in the woods surrounding Koupela. The rest of the materials has to be bought somewhere else, probably in the capital city of Burkina Faso, Ouagadougou.

6.7.4. Build the tankIf you need a platform (see 6.7.1) you need to build that first. This can be done quite easily, see the picture besides.

After that you can build the tank of which a picture is shown here. You start with the bottom in which you put the beams, make sure the wood used is dry. Around the

beams you put the metal rings to make sure the whole thing does not collapse when you put water inside. Then you install two pipes, one at the bottom which leads to the fields, and one at the top which is connected to the pump. The last thing you do is making a roof so that the water does not get contaminated by e.g. birds, insects, rainwater etc. The last thing is to put two pipelines in the tank. One at the top which is connected to the pump and one at the bottom which leads to the fields.

When the tank is finished you can pump water in it. The first couple of days the tank will leak but this will change later on because the wood expands when it gets wet. Make sure the pipe at the botom of the tank is closed until the tank does not leak anymore

7.Sources

7.1 Sources: Geographical research Wikipedia Information from our contact person; Huib Povel. WHO Country Offices in the WHO African Region. WHO; Regional Office for Africa. Comité national du recensement (july 2008). “Recensement general de la population et de

l’habitation de 2006”. Conseil national de la statistique. (20-01-2011) International Religious Freedom Report 2010: Burkina Faso. United States Bureau of

Democracy, Human Rights and Labor. “Burkina Faso’s Blaise Compaore sacks his government”, BBC News, 15 April 2011.

7.2 Sources: The Wind Turbine http://www.victordanilochkin.org/research/turbine/papers/HAWT%20versus.pdf http://www.debroek.info/molen.html http://www.dagroengedoe.be/Ontwerp%20van%20een%20windmolen.pdf http://nl.wikipedia.org/wiki/Schaal_van_Beaufort http://www.aesturbines.com/ht/h_typesofwindturbines.php http://sleekfreak.ath.cx:81/3wdev/VITAHTML/SUBLEV/EN1/WINDWTRP.HTM http://www.flapturbine.com/how_many_blade.html http://en.wikipedia.org/wiki/Drag_(physics)

7.3 Sources: The water pump http://www.hydraulic-design.com/wp-content/uploads/2011/01/external-gear-pump.jpg

(3-11-11) http://www.google.nl/imgres?

q=archimedes+pump&um=1&hl=nl&biw=1280&bih=827&tbm=isch&tbnid=BJXjhNPg-QfM9M:&imgrefurl=http://wdict.net/word/archimedes%27%2Bscrew/&docid=86o0EKxXzPmmFM&imgurl=http://wdict.net/img/archimedes%2527%252Bscrew.jpg&w=509&h=696&ei=G8G7TtqnLseE-wbKpvSXCA&zoom=1&iact=rc&dur=156&sig=111391078330684670577&page=3&tbnh=138&tbnw=101&start=44&ndsp=24&ved=1t:429,r:20,s:44&tx=59&ty=46 (10-11-11)

http://www.pfeiffer-vacuum.com/know-how/vacuum-generation/rotary-vane-vacuum-pumps/technology.action?chapter=tec2.2 (10-11-11)

http://en.wikipedia.org/wiki/File:Pump-tah.jpg (13-11-11)

7.4 Sources: Transmission http://www.ropepump.com/ BINAS, 5th edition

7.5 Sources: Water storage IWMI Working Paper 142: Typology of Irrigation Systems in Ghana. By: Regassa E. Namara;

Leah Horowitz; Shashidhara Kolavalli; Gordana Kranjac-Berisavljevic, Busia Nambu Dawuni; Boubacar Barry and Mark Giordano.

IWMI Working Paper 140: Inventory of Water Storage Types in the Blue Nile and Volta River Basins. By: Robyn Johnston and Matthew McCartney. With contributions from (in alphabetical order): Barnabas Amisigo, Felix Asante, Seleshi Awulachew, Fiseha Behulu, Samuel Dagalo, Fikadu Fetene, Gerald Forkour, Eric Sarpong Owusu, Kassa Tadele, Tarekegn Tadesse and Wondmagegn Yazea.

IWMI Working Paper 136: Health Impacts of Small Reservoirs in Burkina Faso. By: Eline Boelee, Philippe Cecchi and André Koné.

Rainwater harvesting and shallow groundwater solutions in Budunbuto, Somalia. SamSamWater. By: Sander de Haas

Blue paper: Water Storage in an Era of Climate Change: Addressing the Challenge of Increasing Rainfall Variability. By: Matthew McCartney and Vladimir Smakhtin.

Waterborne and Vector diseases, by LMAS district health department. From the website: http://lmasdhd.org/uploads/PDF/Water_VectorFS08.pdf (10-10-2011)

Water related diseases, by House of Water and Environment (HWE). From the website: http://www.hwe.org.ps/Projects/Training/Training%20Municipality/course1/material/Water%20Related%20Diseases%20-%20Asia%20Issa.pdf (13-10-2011)

SamSamWater Climate Tool, annual Precipitation and Potential Evotranspiration. From the website:

http://www.samsamwater.com/climate/climatedata.php?lat=12.00000&lng=-0.31250&alt=284&loc=Koup%E9la%2c+Burkina+Faso (30-10-2011)

Local Monthly Climate Estimater, by the Food and Agriculture Organization of the United Nations (FAO) . From the website: http://www.fao.org/sd/locclim/srv/locclim.home (24-11-2011)

Integrated irrigation and Aquaculture in West Africa, concepts, practices and potentials, from the Food and Agriculture Organization of the United Nations (FAO). By Matthias Halwart (Fishery Resources Officer, FAO Fisheries Department, Rome Italy) and Anne A. van Dam (Senior Lecturer, Department of Environmental Resources, UNESCO-IHE Institute for Water Education, Delft the Netherlands).

Statistics about irrigation: http://nl.wikipedia.org/wiki/Statistieken_over_irrigatie (12-01-2012)