-The power required to carry out an activity e.g. diesel, electricity, etc.
Sources of Energy
-Classified into 2 types: renewable and non-renewable sources of energy.
Renewable Sources of Energy
-Which can be regenerated and used over and over again.
Types of Renewable sources of Energy
- Water (geothermal, hydro power, tides and waves).
- Biomass (wood, biogas)
Energy from the sun is called solar energy.
The sun is the primary source of all types of energy.
Solar radiation can be converted into 2 types of energy.
HeatSolar panels are used to tap solar energy which is then used to heat water in coiled pipes which are inside which are painted black.
Mirrors are used to converge rays of the sun on one spot which are then used to heat water or cook food in a pot.
Suns rays are reflected and focused on crops to dry them.
ElectricityPhoto- voltaic cells are used which when sunlight shines on them they generate electricity which is then stored in batteries.
Advantages of Solar Energy
- Cheap because it’s obtained from sunlight which isn’t paid for.
- Requires minimal maintenance once tapping equipment has been installed.
- It doesn’t pollute the environment like fossil fuels (environmentally friendly)
- Can be stored in batteries and used when there is no sunlight.
- It’s inexhaustible i.e. available as long as the sun continues to shine.
- Available in all parts of the world.
- Can’t be used to run heavy machinery.
- Tapping equipment e.g. solar panels are expensive to buy.
- The batteries which it’s stored in are cumbersome to carry around.
- It fluctuates in various seasons throughout the year.
- Large numbers of solar panels are required to produce useful amounts of energy.
Wind energy is mainly used in arid and semi-arid areas where wind flow isn’t obstructed by vegetation.
- Wind is harvested using wind mills and converted into mechanical energy which is used for pumping water, grinding grain and generating electricity.
- Wind energy is also used to propel ocean going vessels e.g. dhows.
- It is an inexhaustible source of energy.
- It doesn’t pollute the environment.
- Land between the windmills can be used for other purposes.
- Can be produced on small scale basis for local consumers.
- Wind mills for harvesting it are expensive to buy and install.
- The equipment for harvesting is relatively expensive to maintain.
- Many windmills are required to provide a significant amount of electrical energy.
- It fluctuates when the strength and direction of wind changes.
- The large tracts of land it requires (wind farms) alter the environment beauty.
- It’s not available in many areas except in open areas.
Steam from underground is heated when in contact with hot rocks.
The steam finds its way to the surface through fissures or cracks.
The steam is tapped and used to turn turbines and thus generate electricity e.g. at Olkaria in Kenya.
- Cheaper as no fuel is required to turn turbines.
- It is Continuous.
- It’s inexhaustible unlike hydro-power which depends on water levels.
- The cost of operating geothermal power station is low compared to hydro-power station.
- A good supplement for other sources of energy.
- Causes noise pollution from generation plant.
- Not available in many areas where there aren’t hot springs and geysers.
- Gases released with steam may pollute the environment e.g. sulphur dioxide, hydrogen sulphide, methane, ammonia, etc.
- Its exploration is expensive because it requires expensive technology.
-Power obtained from falling water.
-Most widely used renewable source of energy.
-Used to generate electricity (HEP) when falling water is directed to turn turbines connected to generators to produce electricity.
- It doesn’t pollute the environment.
- It’s inexhaustible.
- Hydroelectric power can be transmitted over long distances using cables.
- Dams for HEP generation create lakes which can be used for recreation, irrigation and fishing.
- HEP can be used for many purposes e.g. transport, cooking, etc.
- It’s reliable because significant levels of energy are produced.
- Affected by fluctuation of water levels in reservoirs.
- Construction of HEP generation dams displaces many people.
- It causes inconvenience to migratory species of fish.
- The cost of constructing and running hydro-power plants is high.
- Dams may break and destroy a lot of property and lives downstream.
- Not available throughout the world.
Tides and Waves
-Dams are built across an estuary.
-Incoming and outgoing tides rotate turbines and electricity is generated in similar way as hydro-power.
-All forms of energy released by plants and animal wastes.
Firewood, charcoal and saw dust which are used for cooking and heating.
It can be exhausted if its cut at a higher rate than they are being replaced. so it requires management if it has to be sustained.
Advantages of Wood
- It’s a cheap source of energy.
- Available almost throughout the world.
- No maintenance cost is needed.
- Ashes from burned firewood can be used for plastering houses and as a fertilizer.
- Dirty because when burning it gives off smoke and soot.
- Pollutes environment through the gases it emits.
- Requires a big storage area.
- Its overexploitation leads to deforestation leading to problems of soil erosion, global warming and shortage of water.
Agricultural wastes e.g. straw, molasses and cassava are fermented to produce power alcohol which is directly used to heat or blended with gasoline to run machines.
Human and animal wastes are used to produce methane (biogas) through fermentation which is used for cooking and lighting.
Advantages of Biomass
- An inexhaustible source of energy.
- Fuels are efficient and relatively clean.
- Cheap because it makes use of waste products.
- Production of biogas is cheap as it doesn’t require advanced technology.
- Biogas gives twice as much heat as natural gas.
- Slurry left behind when biogas is being made can be used as fertilizer.
- Available throughout the world.
- Biogas digesters require a lot of space and can’t be set in congested areas.
- Can’t be transported to distant places.
- Contributes to pollution which causes global warming.
Examples of Animals and Their Uses
- Oxen for ploughing and pulling carts.
- Horses for transporting by riding on their backs.
- Donkey for transporting of goods on their backs or by pulling carts.
- Camel for transporting goods and people on their backs.
- Elephant in Burma and India for transporting logs from forests
- Inexhaustible because animals keep multiplying as a result of production.
- Available in all parts of the world.
- Cheep to maintain as they only require food and water.
- Animals are flexible because they are able go through forests and narrow paths unlike motor vehicles.
- Some are slaughtered for meat when they outlive their usefulness e.g. oxen, camels etc.
- They are prone to diseases and fatigue.
- They can die as a result of too much work.
- Their use is restricted only to rural areas.
- They can only transport small loads.
- They can only do limited work because they tire easily.
Non-renewable Sources of Energy
-Sources of energy which are exhaustible if they aren’t well managed.
-They include petroleum, coal and uranium.
-A black or brown rock made of carbon.
- Mud, sand and other materials are deposited over vegetative matter such as tree trunks and branches.
- Deposited material prevents decomposition and also exerts pressure on it causing great heat.
- Peat layers are formed which gradually change into coal.
Usage of coal has declined due to:
- Discovery of other forms of energy such as petroleum.
- Exhaustion of old accessible mines.
- High cost of mining coal.
Advantages of Coal
- More efficient in thermal generation of electricity than oil.
- Most suitable in the smelting of iron.
- It leaves a lot of dirt on any surface it touches.
- It leads to formation of smog and smoke which is a health hazard.
- Its mining leads to environmental degradation.
- Consists of gaseous and liquid hydrocarbons from animal and vegetation matter laid on sedimentary rocks.
- Natural gas and petroleum are extracted from the same oil wells.
- Petroleum is refined to get by-products such as motor oil, diesel, kerosene, gasoline, jet fuel, lubricants, liquid and petroleum gas.
- Natural gas occurs alone or is found on the upper layers of crude oil.
- It’s a mixture of hydrocarbons with methane making about 90% and other gases such as propane, ethane and butane.
- It’s used for domestic purposes, generation of thermal electricity and for industrial activities.
- A clean source of energy to use.
- Cheap to transport by pipes to distant areas.
- Transport and maintenance costs are low.
- Easy to use as one needs only switches and burners.
- Free of the effects of weather changes.
- An exhaustible source of energy.
- Accidental fires can occur incase the gas leaks or the pipe is damaged.
- It can greatly pollute the environment incase of accidental fires occurrence.
- Expensive for low income groups.
-A naturally occurring radioactive material used to produce nuclear energy in fusion and fission in reactors.
A lot of heat is produced and the water used to cool the heat producing core is heated and turns into steam used to generate electricity.
- It’s a long lasting supply of raw material.
- It produces large amounts of energy.
- It doesn’t produce green house gases.
- It’s expensive to construct a nuclear reactor.
- Wastes from a nuclear power station are difficult to dispose because they are radioactive for 100 years.
- It is an exhaustible source of energy.
HEP Projects in Kenya
Factors Favouring Development of HEP
- A large and constant volume of water such as R. Tana and its tributaries.
- Can be located on areas with falling water such as on rapids, water falls, and Knick points.
- Deep and narrow valley. Deep to ensure a large capacity for the reservoir and narrow to minimize the cost of constructing the dam.
- Hard basement rocks to reduce the amount of infiltration and also to provide a strong foundation for the dam.
- Area for dam and reservoir construction should be sparsely populated to minimize the cost of relocating people.
- There should be presence of industries and urban areas to provide market for electricity to make the project economically viable or bring a profit.
- Construction of an HEP station requires adequate capital because it’s expensive to construct a dam, to maintain it, to transmit power and to compensate the displaced people. Kenya is financed from external source e.g. Sondu Miriu which is financed by Japanese government.
Development of HEP in Kenya
By the dawn of independence there was few industries and hence low demand for electricity.
Few HEP stations available were set up to supply power for agricultural processing.
The earliest stations were Mesco on R. Maragua, Ndula on R. Thika and Sagana on R. Sagana.
The rest of power supply came from diesel plants in Kipevu.
There was power which was being imported from Uganda which was connected in 1955.
Demand for electricity increased as more industries were established.
The country opted to use her water resources to provide electricity and reduce her reliance on power from Uganda.
- Tana was identified as the one with the largest potential.
Seven sites appearing as a cascade were identified along the river where the Seven Forks Scheme was launched.
- Kindaruma was the first project to be established which was completed in 1968.
- Kamburu followed which was completed in 1974.
- Gitaru was next which got completed in 1978.
- Masinga which is a multipurpose project was completed in 1981. It has the largest lake. It’s a reservoir for the rest of the dams downstream and the water is also used to provide water for irrigation.
- Kiambere was the last station downstream completed in 1988.
- The other proposed power stations to complete the Seven Forks project are Mutonga and Grand Falls.
- The other HEP stations are Turkwel Gorge on R. Turkwel which was completed in 1991 and Sondu- Miriu which was expected to be completed in 2008.
It’s the main source of electricity accounting for 72% of power production.
The stations are maintained by Ken Gen which sells power to KPLC which distributes it to consumers at a fee.
Benefits of Tana River Projects
- The reservoirs provide power for irrigation and domestic use.
- The dams promote transport by serving as bridges across the rivers.
- The dams are a tourist attraction e.g. Masinga tourist lodge provides recreational facilities.
- The dams provide fresh water fisheries.
- The projects have generated employment to people thus raising their standard of living.
Problems Facing the Tana River Projects
- Shortage of capital to purchase spare parts which has interfered with maintenance of machinery in the power house.
- Fluctuation of the water levels of R. Tana due to drought in the catchment areas and evaporation due to flowing through the dry Nyika region which affects power generation.
- Siltation of dams which occasionally blocks the tail race tunnels leading to a low volume of water and dredging is required which is expensive.
- Inadequate skills and technology which causes failure to maximise on power production.
HEP Projects in Uganda
It has the largest renewable fresh water resources in E. Africa.
It is endowed with numerous rivers and lakes with high potential of electricity generation.
The country receives an average of 1000mm of rain throughout the year.
- Nile which flows out of L. Victoria has the highest potential.
Where it flows out it has provided a natural water fall.
Owen Falls Dam was built on the site in 1954.
It’s the Africa’s largest storage dam.
It supplies most of Uganda’s electricity (162MW) and exports 30MW to Kenya.
The presence of power was a catalyst to industrial development e.g. Njinja town a few metres from the dam became a scene of several industries to use the cheap electricity nearby.
The country is developing another power station below the Owen Falls.