Hydroelectric Power Systems

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hyro electric dam
Hydro electric dam

Hydroelectric power plants convert potential and kinetic energy of water into electricity.

In hydroelectric production, potential energy of water is created by the construction of large dams. The dams hold the water at a greater height than the water level at the turbines.

Water is the greatest contributor of renewable energy to the world electricity generating system.

The common unit of measurement used to indicate the installed capacity of a hydroelectric power station is Megawatts.

Types of hydroelectric power plants

Based of design, hydro electric power plants are broadly divided into 2 types;

  1. Impoundment power plant
  2. Diversion power plant.

In the impoundment type of power plant, All water coming into the plant is dammed. The dammed water creates the head needed to power the hydro plant.

Impoundment type of Hydro dam
Impoundment type of Hydro dam

In the diversion type, the water coming to the plant is partially dammed, some water is allowed to flow back into the river immediately while the rest is used to power the hydro plant.

Head and tail water

 In a hydro power plant system, the dammed water upstream is known as Head water and the water on the other side of the dam is known as Tail water. The difference between the top of the head water and that of the tail water is called pressure head.

Components of hydroelectric power plant

Trash rack; when water is coming fresh from the dam it needs to be cleared of big debris such as wood , plastic bags etc. the duty of the trash rack is to remove these.

Inlet gate; after water have been processed to remove debris, it then passed through the inlet gate. The inlet gate is used to regulate water flow into the turbines

Water conductors; water conductors are equipment used to convey water within the hydo electric power system. Example include; penstock, draft tube, scroll case, spill way, canals etc.

Penstock; the main pipe that conveys water to the turbine is known as penstock. It is a pressurized water conductor.

Spill way;  a spillway is a water conductor used to prevent overflow of dammed water

Runner; the runner is part of the turbine system and it rotates as water from the penstock passes through it at high pressure

Power house; the power house houses the turbine, electric generators, transformers and other electric generating equipment

Open air switch yard; when the electrical transmission equipment is installed in open air, it is called an open air switch yard.

How a hydroelectric turbine works

Water with high pressure head on the upstream side of the dam is lead through large penstock pipe. Before the water get to the turbine it passes through a scroll case. The scroll case is a large curved pipe that helps the flowing water to efficiently rotate the turbine. The turbine is connected to the generator through a shaft. so  as the turbine rotates, the connected generator also rotates  producing electricity.

Advantages of hydroelectric power plant.

  1. It is a completely green process
  2. It is a very efficient way of generating electricity.

Disadvantages of hydroelectric power plant

1. It is always necessary for settlement around the dammed area relocate. This is because water required to run hydroelectric plants is extremely large and dammed water will cause flooding of the settlement.

2. It is capital intensive. This is because the hydro dams constructed are extremely large.

Types of hydro power plants

  1. Impoundment type power plant. This type of power plant utilizes a dam to impound large amount of flowing river water. The dammed water is the potential energy necessary to power the hydro plant. The different type of dams that could be used include; gravity, reinforced concrete, buttress, rock filled or earth dams.
  2. Diversion type power plant( run of the river). In this case, the river water is partially dammed, only part of the flowing water is utilized to produce electricity.
  3. Tidal water plant. This process works based on tidal action of water. it helps create a height difference on either side of the turbine, this pressure difference cause water to flow through the turbine rotating it.
  4. Pumped storage power plant. This type of plant basically consists of very large reservoir of water held at a very high level. The stored water is then made to flow downwards through a penstock pipe to run the turbine and generate electricity. After reservoir is depleted, the water is pumped back again and the whole process is repeated. Pumped storage power plant is a type of standby power generator.Its acts as a supplement and is usually made available to the national grid during peak hours

Types of turbines

Broadly of two types;

  1. Reaction turbine
  2. Impulse turbine

The reaction turbine are pressure turbines. When water flow through this turbine, it creates a pressure differential which causes the turbine to rotate.

Impulse turbine are pressure-less turbines. It rotates due to the kinetic energy given to it by a jet of water as its hits the blades.

Types of turbine runners

There are many types of turbine runners, however, the 3 most commonly used are;

  1. Kaplan runner
  2. Francis runner
  3. Pelton runner

Kaplan runners are types of turbine runners that can operate with medium to high water flows and efficient at low pressure heads. Kaplan runners are reaction  runners because the pressure difference of the water flowing through the blades causes it to rotate.

Kaplan runner
Kaplan runner

Francis runners  are reaction runners and can operate within a wider range of pressure heads than the Kaplan runners.

Francis runner
Francis runner

Pelton runners are only adequate for very high flows and operates within a narrower range compared to the Kaplan and Francis runners.

pelton runner
Pelton runner

Some basic terminologies in Geography Part 1

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Easting and Northings  

With reference to a point, the line or axes running from north to south are known as Eastings. Eastings indicate the distance east of the referenced point. Similarly, the line running from east to west are known as Northings because they indicate the distance north of the referenced point.

Contour lines

contour lines
contour lines

Contour lines are imaginary lines joining places of equal height above mean sea level. Contour lines make it possible to read areas of hills, valleys and level land on a map.

Contour lines that are very close together on a map indicate very steep slope. When these lines are far apart on a map, it indicate gentle slope. The absence of contour lines on the map indicate very flat land.

Plateau

Plateau

The top of a plateau is flat, characterized by very few contours while the sides are often steep which is characterized by contours close together.

Bench marks

Bench marks are basically fixed heights above mean sea level. They are indicated by the sign

    Bench marks are chiseled into stonework or walls of buildings.

Photographic maps

Photographic map

There are two types of photographic maps, Vertical; which is picture taken from an airplane and looking down vertically (90 degrees) and Oblique; taken at any position except vertical.

Scales

Scales can be represented in two ways on maps;

  1. As a statement scale such as ½ inch to 1 mile or
  2. Representative fraction (R.F), for example, 1: 253440, which means 1 inch to 253440 inches.  In R.F, the scale unit and what it represents are the same.

Gradient

Gradient

Gradient is the means of defining the slope of a land. It is calculated by measuring the horizontal distance between two points and dividing by vertical difference in height between the 2 points.

Direction

Can be defined as angular bearing measured from north in a clockwise direction.

Human geography

This is defined as the activity of man on the landscape for building settlement, farming, making routes, etc. to achieve the best results, man is usually guided by natural conditions of land and terrain.

How to Make Millet Starch at Home

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Millet . two types of grains shown
Millet

Millet starch is produced from millet. It is a very cheap good food for children, particularly toddlers. You can make it at home if you have a blender.

Items you need prepare millet starch;

  1. Millet ( at least 1kg)
  2. Blender
  3. Clean buckets, bowls or container. (large enough to store and soak the millet grains)
  4. Water
  5. Sieving cloth bag

Processing;

  1. Soak the millet with water inside a container for about 4 days. This is to soften the grains and make it easier to blend.
  2. Blend the millet grains. Using water, blend grains into a smooth paste as much as possible.
  3. Get ready clean water in a bucket or container up to half its capacity, and while holding the sieving cloth bag inside the bucket, pour the blended millet paste into it.
  4. You can use your left hand to seal the top of the sieve bag, and with the filled bottom part of the bag in water, wash and squeeze out the starch content into the water.
  5. Remove the shaft residue in the sieve bag.

You should sieve the blended millet paste little by little. You can even blend and then sieve, and repeat process until all millet grains is processed.

  • Wait a day for the starch to settle
  • Your millet starch is ready.
millet starch

How to make Palm Kernel Seed Oil at home

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Palm kernel seed oil
Palm Kernel Seed Oil

Items you will need to make palm kernel seed oil

  1. Palm kernel seeds. To extract substantial quantity you will need up to 1 congo or seeds weighting about 1.5kg
  2. An old cooking pot
  3. A metal cooking spoon for stirring
  4. A cooking device, for example a camp gas or an electric cooker

Caution

This process generates a lot of white smoke, its safest doing this out doors at the backyard of your home.

Processing of palm seed oil

  1. The first step is to crush the palm kernel shells to remove the seeds. To extract a substantial amount of oil you will need up to 1.5kg of seeds.
  2. Put the seeds into a clean dry cooking pot and place on your activated cooking device. The process will generate a lot of smoke so put on your nose marks if necessary.
  3. Start stirring the seeds with a metal spoon. This is to distribute the cooking heat evenly across the seeds. Stirring should be done intermittently say every 30sec to 1min intervals.
  4. Keep stirring intermittently until. Smoke begin to form. This indicates oil is beginning to extract from the heated seeds.
  5. Keep on stirring, After substantial amount of oil is extracted you can pour into a metal bowl
  6. Continue the previous process until all oil in the seeds is extracted.
  7. When all oil in the seeds have been extracted the seed will look burnt inside out
  8. Finally let the oil cool down and pour into a clean plastic Bottle.
  9. You can extract over 250ml of oil from 1.5kg of seeds.

Understanding the Wire Colours connected to Electrical Appliances

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Wire Colours connected to Electrical Appliances
wire colours

All electronic appliances comes attached with a power cable for connecting to electricity outlet in your house.The power cable may contain 2 or 3 wires. A power cable with 2 wire colours are in RED and BLUE. A power cable with 3 wires have the colours GREEN, RED and BLUE.

Meaning of the wire colours

The Wire colours have their meanings and It is briefly explained below;

Red colour : Live wire

Brown or Black colour : Live wire

Blue or White colour: Neural wire

Green or Yellow colour: Earth wire

In some places, the live wire is black in colour and the neutral wire is white.

The red or brown wire is “LIVE” as the name implies, electric current flows through this wire. The live wire supplies electric current to the appliance. You should take care when you handle this kind of wire. It can cause an electric shock

The blue wire is “NEUTRAL” . This wire do not give a shock upon touching it or show a red light through a tester. In reality it carries electric current back to the power source. It is the neutral wire that allows the current to alternate. Neutral wire is an integral component of an AC power system.

The green wire is “EARTH” . The purpose of this wire is to remove excess electric charges that might be on the connected appliance and drive them into the earth. It is good practice to earthen electrical appliances to prevent any form of electric shock upon contact. The Earth wire is usually connected to a metal rod driven into the ground.

Some electrical appliance come with just the live and neutral wire. This is Ok. But you are always at a risk of receiving electric shock from contact with the appliance when connected to electricity. This usually happens when the electrical appliance is faulty.

The live wire supplies current to the appliance, the neutral wire carries it back and the earth wire is to serve as protection from electric shock.

How to estimate the number of Blocks required for wall construction

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On a construction site it may become necessary to estimate the number of blocks required for the construction of a wall. To do it correctly you will need to read the construction plan or building plan and section drawing. From the building plan you will need to know;

  1. The length of the wall
  2. The height of the wall
  3. The thickness of the wall
  4. Window or door spaces within the wall unit.

In most cases, the thickness of the wall is not required unless the wall thickness is greater than the width or thickness of the block.

How to estimate the number of blocks using AREA METHOD

This method requires that you know the number of blocks required to construct 1m2 of wall. For a normal block size of length 450mm, height 225mm, and width 225mm, with thickness of wall the same as the block, there is approximately 8 blocks per 1m2. Simply put; 8 blocks per m2 

The above result was obtained practically, however other calculations report a value of between 8-10 blocks per m2 .

How to practically obtain the number of blocks per unit area

calculating the no of blocks per square meter

You can obtain the result practically, look for an already constructed wall of similar type you want to build. The wall should still show the exposed block work, or is not yet rendered. Then with a builders square or builder’s level, draw a square of 1m dimension on the wall using a chalk or erasable material. The square you draw should have an area of 1m2 .Next, count the number of blocks that fall within the square. The result you get is the number of blocks per square meter. This method works for any size of block or brick.

Now that you have the amount of blocks per m2 , look at the building and section plan then calculate the area of the wall using the area formula of length x height .  From this wall area, deduct any area of door and window spaces. Finally multiply the wall area by number of blocks per unit area or per m2 . (note the unit)

Formula for number of blocks required = (Area of wall) X (no. of blocks per unit area)

Simple example;

length and height of wall to calculate area

A wall of length 5m and height 3m will have an area of

5m X 3m = 15m2

Therefore number of blocks = 15m2 X 8 = 120 Blocks.

How to estimate the number of blocks using DIMENSION METHOD

This method involve using the block dimensions to estimate the number of blocks required for a wall construction.

Lets assume you are required to estimate the number of blocks in foundation required to fence a plot of land. Block will be laid in stretcher bond. The height of wall in foundation being about 450mm. and we are to use block size of length 450mm, height 225mm, and width 225mm. The dimensions of the plot of land being 30m by 15m. Here is what you do;

Perimeter of plot of land;

2 X (30+15)m = 90m

Since the wall will be constructed in stretcher bond, you will just divide the perimeter of the plot of land by the length of the block;

90m / 0.45m = 200 blocks          ( note; 450mm is converted to m by dividing it by 1000)

This 200 blocks is the approximate number of blocks required for the 1st layer in foundation.

Since the height of wall in foundation is 450mm, it means we will have 2 layers of blocks in foundation i.e. 450mm / 225mm (height of block) = 2

Hence total blocks required for foundation is 200 blocks X 2 = 400 blocks