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1. Wachemo University
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College of Engineering and Technology
Department of Mechanical Engineering
Lecture note of Alternate technology for Energy Sources
Compiled by
Abraham M.(M.Sc. Energy technology )

2. Contents
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CHAPTER ONE
 Introduction
 Energy Sources
 Classification of Energy Sources
 Advantage and Disadvantage of conventional Energy
Sources
 Current tends of RE application in Ethiopia

3. Introduction
 Energy has been an important component to meet the day to day
need of human beings.
 The degree of civilization is measured by the energy utilization for
human advancement or needs.
 The word ‘energy’ itself is derived from the Greek word‘en- ergon’, which means
‘in-work’ or ‘workcontent’.
 Energy has been defined as the capacity to do work or capability
to produce an effort.
 Energy is one of the major inputs for the economic
development of any country.
 In the case of the developing countries, the energy sector assumes a critical
importance in view of ever-increasing energy needs requiring huge
investments to meet them.
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4. Sources of Energy
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The main sources of energy includes;



Sun
Geothermal
Ocean tides
Wind
Biogas
Water, fuels and radio- active substances.
 Water (30%), Fuels (64%) and Radio- active substances (5%) are
the most commonly used sources for generation of energy and
they are usually called Conventional Sources of energy.
 The other sources are also valuable but in comparisons with the
quantum of energy produced by the three main sources, their
contribution is negligible and they are often called
Unconventional Sources.

5. Classification of Energy Sources
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 Energy can be classified into several types based on
the following criteria:
– Primary and Secondary energy
– Commercial and Non-commercial energy
– Renewable and Non-Renewable energy
– Conventional and Non-conventional energy
FORMS OF ENERGY
The various forms of
energy are as follows
1.Electrical energy
2.Chemical energy
3.Mechanical energy
 Potential energy
 Kinetic energy
 Thermal energy
4.Nuclear energy
5.Electromagnetic
energy
6. Transitional energy
7.Capital energy
8.Celestial energy
9.Stored energy

6. Sources of Energy
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Primary energy
•
•
They are found or stored in nature.
Common primary energy sources are ; coal, oil, natural gas, biomass
(such as wood), nuclear energy from radioactive substances, thermal
energy stored in earth's interior, and potential energy due to earth's
gravity.
Primary energy sources are costly converted in industrial utilities into
secondary energy sources; for example, coal, oil or gas converted into
steam and electricity.
Primary energy can also be used directly.
•
•

7. Commercial and Non-commercial Energy
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The energy sources that are not available in the commercial market
for a price are classified as non-commercial energy.
•
•
• They includes fuels such as firewood, cattle dung and agricultural
wastes, which are traditionally gathered, and not bought at a price
used especially in rural households.
They are also called traditional fuels.
Non-commercial energy is often ignored in energy accounting.
Example: Firewood, agro waste in rural areas; solar energy for
water heating, electricity generation, for drying grain, fish and
fruits; animal power for transport, threshing, lifting water for
irrigation, crushing sugarcane; wind energy for lifting water and
electricity generation.

8. The energy sources that are available in the
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commercial market for a definite price are classified as commercial
energy.
 By far the most important forms of commercial energy are;


Electricity,
Coal and refined petroleum products.
Commercial energy forms the basis of industrial,agricultural,
transport and commercial development in the modern world.
In the industrialized countries, commercialized fuels are
predominant source not only for economic production, but also for
many household tasks of general population.
Examples: Electricity, lignite, coal, oil, natural gas etc.

9. Renewable and Non-Renewable Energy
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Renewable energy is energy obtained from sources that are
essentially inexhaustible.
 are those which are continuously restored by nature
 These include wind power, solar power, geothermal energy, tidal
power and hydroelectric power
 The most important feature of renewable energy is that, it can be
harnessed without the release of harmful pollutants.
 Non-renewable energy is the conventional fossil fuels such as coal,
oil and gas, which are likely to be deplete with time.

10. ADVANTAGES DISADVANTAGE OF RENEWABLE ENERGY SOURCES
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ADVANTAGES
1. The renewable energy sources are non-exhaustible.
2. Renewable energy sources can be matched in scale to the need and
also can deliver the energy required for a specific task.
3. Some of the renewable energy conversion systems can be built on
or close to the site where energy is required.
4. The diversity and technologies of renewable energy conversion
systems offer more flexibility in designing the conversion systems
compared to the conventional energy conversion systems.
5. The local or regional self-sufficiency can be achieved by harnessing
locally available renewable energy, which otherwise would be left
unutilized.
6. Except biomass energy, all other renewable energy sources offer
pollution-free environment and maintain ecological balance. .

11. DISADVANTAGE
1 Some of the energy sources are intermittently available (i.e. not
continuously available). E.g. solar energy, tidal energy, wind energy
etc.
2 There is a limit to the rate at which solar energy is received at the
Earth.
3 Renewable energy sources like wind energy, tidal energy etc. are
concentrated only in certain regions.
4 State-of-the-art technology in harnessing the renewable sources is
yet to be developed to meet the present day energy requirements.
5 Solar cells, automatic tracking systems for solar energy etc. require
advanced technologies, which are sophisticated and costly.
6 Application of renewable energy sources in transportation sector is
not viable as of today .
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13. Conventional and Non-conventional energy resources
1. Conventional:-
 . The term "Conventional" means "not unusual or extreme or ordinary."
Conventional energy sources are the traditional sources of energy.
 The sources of energy which provide a net supply of energy are
called conventional sources of energy, and are useful for mass
generation of power. Conventional energy resources are (fossil fuel,
nuclear and hydro resources)
 Natural energy sources present in limited quantity but used for a
long period of time and deplete.
2. Non-conventional :-
o The sources of energy which provide energy in a dilute form are
called non-conventional sources of energy.
o useful for generating power in lesser magnitude. are called non-
conventional energy sources, e.g., solar, wind, biomass, etc.
o They are easily replenished (Replaced in natural process)
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14. Advantage & Disadvantage of
Conventional energy sources
Thermal Power (Fuels) plant
 Converts heat energy into
electricity
Advantages
 Fuel used is cheaper.
 Less space required in setup
in comparison hydroelectric power plant.
 They can be located conveniently near the
load Centre.
 A portion of steam generated can be used
as a process steam in different industries
 As these plants can be set up near
industries, therefore the transmission
costs are reduced.
Disadvantages
 Maintenance & operating costs are
high.
 Cost of plant increases with
increase in temperature &
pressure.
 Long time required for erection &
putting into action.
 Greatly difficulty experienced in
cool handling.
 Presence of troubles due to smoke &
heat in the plant.
 Smoke & gaseous emission
cause pollution in the
environment. 14

15. Nuclear Power Plant
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Converts nuclear energy into electrical energy.
Advantages
 It avoids the wide variety of environmental problems
arising from burning fossil fuels - coal, oil, and gas.
 It is possible to generate a high amount of electrical energy in
one single plant using small amount of fuel.
 Nuclear power is reliable. This technology is readily a
available.
 Produces small amounts of waste.
 Nuclear power is also not so expensive as compare to
power from coal.

16. Disadvantages
 The problem of radioactive waste is still an unsolved one.
• High risks: It is technically impossible to build a plant
with 100% security.
• The energy source for nuclear energy is Uranium.
Uranium is a scarce resource;
• Its supply is estimated to last only for the next 30 to 60 years
depending on the actual demand.
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17. Hydropower
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• Hydropower generation is much better suited to meet
demands for peak load.
The ability to start quickly and adjust to rapid changes
in load adjustments makes hydroelectric plants
particularly suitable for responding to peak loads.
•
• Operating hydropower plants emit minimal amounts of
airborne pollutants.
As countries grapple with reducing emissions of
greenhouse gases, hydropower can provide a significant
energy alternative and displace other.
•

18. MERITS OF HYDROPOWER
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•
•
•
Economical source of power
Non-polluting and hence environment friendly
Reliable energy source with approximately
availability
Low generation cost compared with other energy
Use of water but do not consume it
Storage based plants are often has a benefits of;
flood control
Irrigation
Public water supply
navigation, fishing, tourism etc.
90 percent
•
•
•

19. MERITS OF HYDROPOWER
Provide employment opportunities being labour intensive
Lead to development of remote areas
Technically more reliable than many thermal plants.
Plant equipment is simple and less
Low operation and maintenance cost,
Can be matched with load requirements.
•
•
•
•
•
•
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20. DEMERITS OF
HYDROPOWER
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•
•
•
•
Susceptible to vagaries of nature such as drought
Longer construction period
High initial cost
Long term flow data is essential for proper assessmentof
irrigation and power benefits
Loss of large land due to submergencein the reservoir so
created and displacement of large population from reservoir
Non-availability of suitable sites for the construction of dam,
Environmental aspect; reservoir vs. river ecology, and
High cost of transmission system for remote sites.
•
•
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•

21. Current trends of RE application in Ethiopia
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1.Hydropower: It is estimated that Ethiopia's hydropower potential with up to
45,000 MW is the 2nd highest in Africa (only DR Congo has a higher potential).
Approximately 30,000 MW are estimated to be economically feasible .
2.Solar Power: Ethiopia receives a solar irradiation of 5000 – 7000 kWh/m²
according to region and season and thus has great potential for the use of solar
energy.
3.Wind Energy: Ethiopia has good wind resources with velocities ranging from
7 to 9 m/s. Its wind energy potential is estimated to be 10,000 MW. Areas with
high wind velocities of up to 10 m/s are distributed throughout the Eastern
half of the country, including the western escarpment of the Rift Valley.

22. 4. Geothermal Energy
• Ethiopia’s geothermal resources are estimated to be 5 GW
of which 700 MW are suitable for electric power
generation.
• Geothermal resources are primarily located in the Rift
Valley area, where temperatures of 50 – 300°C prevail in
a depth of 1,300–2,500 m.
.
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23. Ethiopian Energy Policy
Rationales of Energy Policy
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• To develop and utilize the country's energy resources on the basis of
Ethiopia’s overall development strategy
• To assist other economic sectors to meet their development objectives
by putting in place a clearly defined energy policy
• To save scarce foreign exchange resources and to ensure that energy is
efficiently utilized
• To ensure reliable and secure energy supplies to cushion economy from
external and internal disruptions of supply as well as price fluctuations;

24. • To ensure that development of energy prices and to ensure
economic profitability;
• To ascertain what energy technologies and equipment are
appropriate for and compatible with the country’s economic
development needs, and
• To raise the efficiency of the energy sector and develop the
necessary institutional and man power capabilities to undertake
energy development programs.
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25. Objectives of Energy Policy
• T
o provide guidelines and strategies for the faster
development and supply of energy;
 To ensure a reliable supply of energy at the right time and
affordable price;
 To give priority to the development of indigenous energy
resources;
 To increase energy utilization efficiency and reduce energy waste;
and
 To ensure that the development and utilization of energy is
benign to the environment.
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• To ensure sustainable (reliable, affordable and long lasting)
supply of energy;
• To remove bottlenecks inherent to energy resource
development and utilization;

26. Energy Policy
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Energy Resource Development Policy
•
•
Traditional Fuels
Modern energy resource
development
• Alternative energy resources
development
Energy Supply
 Household Energy
policy
 Transport Energy
Policyll
 Agricultural Energy
Policy

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