The document provides an introduction to energy management concepts including: - Different forms of energy including potential (chemical, nuclear, gravitational, elastic) and kinetic (mechanical, electrical, thermal, radiant, sound) energy. - Energy transformations are never 100% efficient and energy is conserved by changing forms but not being created or destroyed. - Examples of energy transformations include burning fuel, solar panels generating electricity, photosynthesis, and cars gaining thermal energy from motion.

1. EE 40403 – Energy Management
Energy Management
Rantharu Attanayake
BSc. (Eng) , MSc, MBA
Email : rantharu@gmail.com
Mobile : 0773630002

2. Introduction to Energy
Types and Forms
EE 40403 – Energy Management

3. Objectives
• Explain what energy enables us to do.
• Differentiate between forms and sources of energy.
• Demonstrate how energy is stored in the major energy sources.
EE 40403 – Energy Management

4. Energy
• Energy exists in many forms.
• Energy can be moved from one object to
another.
• Energy can be changed from one form to
another.
• Energy cannot be created or destroyed.

5. Energy in two Forms
Potential Energy and Kinetic Energy
Potential
Potential Energy has 4 forms:
1.Chemical energy
2.Nuclear energy
3.Gravitational energy
4.Elastic energy
The energy in matter due to its position or the arrangement of its
parts
One of the most common equations for potential energy can be used to
determine the energy of an object with respect to its height above a base:
E = mgh ( Joule)

6. Energy in two Forms
Kinetic
Kinetic Energy has 5 forms:
1.Mechanical energy
2.Electrical energy
3.Thermal energy
4.Radiant energy
5.Sound energy
The energy of a moving object
A common formula for kinetic energy is
for a moving mass:
KE = 1/2 mv2 (Joule)

7. Law of Conservation of Energy
With every transformation, some energy is converted to less useful forms. Energy
conversions are not 100% efficient. The energy output for the intended purpose is
seldom the same as the energy we put in.
100 J electricity in
95 J heat out
5 J light out
While energy can change forms, it is conserved. In other words, the total
energy of a system is a constant value. This is often written in terms of kinetic
(KE) and potential energy (PE):
KE + PE = Constant

8. Gravitational Energy
The energy an object or
substance has because
of its position; anything
“up high”
Potential Energy

9. Stored Mechanical Energy
Energy stored in an object by
the application of force
Must push or pull on an object
Potential Energy

10. Potential Energy
Nuclear Energy
Energy contained in the
nucleus of an atom
Nuclear energy is
released when nuclei
are split apart into
several pieces, or when
they are combined to
form a single, larger
nucleus

11. Chemical Energy
Energy released by a chemical
reaction
The food you eat contains
chemical energy that is released
when you digest your meal
Wood, coal, gasoline, and natural
gas are fuels that contain
chemical energy
Potential Energy

12. Mechanical Energy
(Motion)
 Energy that moves objects
from place to place
 You use mechanical energy
when you kick a ball or turn
the pedals of a bicycle
 Other examples include water
flowing in a stream, tires
rolling down a road
Kinetic Energy

13. Electrical Energy
 Energy that comes from the
electrons within atoms
 It can be generated at a power
plant or inside a battery and can
power everything from remote-
controlled cars to refrigerators
 Lightning and static electricity
are also forms of electrical
energy
Kinetic Energy

14. Sound Energy
Movement of
energy through
substances in the
form of longitudinal
(compression)
waves
Kinetic Energy

15. Radiant Energy
 Electromagnetic energy that
travels in transverse waves
 Energy that can move through
empty space
 The sun and stars are
powerful sources of radiant
energy
 The light given off by light
bulbs and campfires are also
forms of radiant energy
Kinetic Energy

16. Kinetic Energy
Thermal Energy
Internal energy of a
substance due to the
vibration of atoms and
molecules making up the
substance

17. Elastic energy
Mechanical energy

18. • Striking a match
• Photovoltaic cell
• Photosynthesis
• Interior temperature
increase of a car
Describe the
Energy
Transformations

19. Transition: Forms to Sources
chemical
chemical
chemical
chemical
chemical
nuclear
motion
motion
thermal
radiant

20. Transition:
Forms to Sources
86%
9%
5%
1%
1%
89%
11%

21. Potential Energy and Kinetic Energy Examples
PE =m g h
=2 kg × 9.8 m/s2 × 0.4 m
=7.84 kg m2/s2
=7.84 J
Example: This 2 kg hammer is 0.4 m up. What is it's PE?

22. Potential Energy and Kinetic Energy Examples
KE = ½ m v2
KE = ½ × 1500 kg × (14 m/s)2
KE = 147,000 kg m2/s2
KE = 147 kJ
Example: What is the KE of a 1500 kg car going at suburban speed of 14
m/s (about 50 km/h or 30 mph)?

23. Potential Energy and Kinetic Energy Examples
KE = ½ m v2
KE = ½ × 1500 kg × (28 m/s)2
KE = 588,000 kg m2/s2
KE = 588 kJ
Example: The same car is now going at highway speed of 28 m/s (about
100 km/h or 60 mph)?

24. Potential Energy and Kinetic Energy Examples
KE = ½ m v2
KE = ½ × 1 kg × (11,000 m/s)2
KE = 60,500,000 J
KE = 60.5 MJ
A 1 kg meteorite strikes the Moon at 11 km/s. How much KE is that?

25. Potential Energy and Kinetic Energy Examples
At 1 m above the ground it's Potential Energy is
PE = m g h
PE = 0.1 kg × 9.8 m/s2 × 1 m
PE = 0.98 kg m2/s2
Ignoring air resistance (which is small for this little drop anyway) that PE gets converted into KE:
KE = ½ m v2
Swap sides and rearrange:
½ m v2 = KE
v2 = 2 × KE / m
v = √( 2 × KE / m )
Now put PE into KE and we get:
v = √( 2 × 0.98 kg m2/s2 / 0.1 kg )
v = √( 19.6 m2/s2 )
v = 4.427... m/s
Example: We drop this 0.1 kg apple 1 m. What speed does it hit the
ground with?