1. Energy Environment
ENVE 411
Energy Fundamentals

2. Lecture Outline Introduction Why Do We Use So Much Energy?
Energy Basics
Units of Energy
The Principle of Energy Conservation
Transformation of Energy from One Form to Another
Renewable and Nonrenewable Energy Sources

3. Energy Fundamentals
Why Do We Use So Much Energy?
We don’t use our energy resource as efficiently as we could.
Figure 1.1, illustrates per capita Gross Domestic Product (GDP) and per capita Energy use for several countries of the world.
There is no relation between GDP per capita and the standard of living but both are related to the use of energy.

4. Energy Fundamentals
Figure 1.1

5. Energy Fundamentals
A citizen of developing country might use the energy equivalent of less than one barrel of oil per year compared to an annual energy equivalent of 20 to 60 barrel of oil per capita for the most industrialized countries.

6. Energy Basics Background What energy is ? What form it can take?
Energy define as the capacity to do work.
Definition as quantitative analysis, we can define the energy as:
the product of force times the distance through which the force acts.
Work has the unit of (N.m) force times distance.
So the metric unit of energy is Joule define as
1 j=1N.m.

7. Energy Basics
The work done on an object is equal to the energy gained by the object.
The work comes out to be zero if the pushed object doesn’t move through some distance. (pushing wall).
Work being done also comes out to be zero if an object moves through a distance but with no force being exerted on it in the direction of the motion.

8. Energy Basics
An example to gain a feeling for magnitudes and units of work and energy:
Imagine that you slowly lift a 10 pound sack of sugar up-ward 10 foot. So the force is 10 pounds and the distance is 10 foot, the work you done on sack of sugar is 10 ft-Ib. the energy to do that work would come from the food you ate.
1 ft-Ib = 1.36 joules.
So , the 10 ft-Ib is equal to 13.6 joules.

9. Energy Basics
Example 1
A force of 50 pounds pushes a box along a floor a distance of 100 feet. How much work has been done? How much energy has been expended?
Solution
Work = force x distance
= 50 Ib x 100 ft= 5000 ft-Ib.
Energy expended= work done
= 5000 ft-Ib x 1.36
= joules.

10. Energy Basics Forms of Energy
a) Chemical Energy: is the energy stored in certain chemicals or materials that can be realesed by chemical reactions, often combustion. Burning of wood, paper, coal, natural gas, or oil releases chemically stored energy in the form of heat energy.
Other chemical energy sources are hydrogen, charge electrical batteries and food in the stomach.
Chemical reactions release this energy for our use.

11. Energy Basics
b) Heat Energy: is the energy associated with random molecular motions within any medium.
Increase of heat energy contained in any substance result in a temperature increase.
Decrease of heat energy produces a decrease of temperature.
The term thermal energy is interchangeable with heat energy.

12. Energy Basics
c) Mass Energy: Einstein state that there is an equivalence between mass and energy. Einstein formula is :
E=mC2
C: speed of light ( m/sec.)= 3x108 m/sec.
The most dramatic example of this equivalence is in nuclear reactors. The mass that is lost in the reaction appears as energy according to the Einstein formula:
∆E= ∆mC2

13. Energy Basics Where : ∆m is the missing mass
C is the speed of light (m/sec.)
The energy that appears ∆E, is in joules if ∆m in kg & C in m/sec..
Because C is such a very large number of 3x108, a small loss of mass results in a large release of energy.
According to the Einstein formula, any reaction of any type chemical or nuclear which releases energy does so in a association with a loss of mass between the inputs and outputs.

14. Energy Basics d) Kinetic Energy: is a form of mechanical energy.
An object of mass m moving in a straight line with velocity v, has kinetic energy given by:
KE= 0.5 mv 2
Speeding car must do work in being brought to rest.
Work done on the accelerating car is drived from the fuel.
Work done by the stopping car will appear mainly as a heat energy in the brakes.
Rotating an object around an axis has kinetic energy associated with the rotation.

15. Energy Basics
e) Potential Energy: is associated with position in a force field.
An example is an object having weight w and height h above the earths surface, it will have potential energy :
PE= wxh
If the same object released and let it fall down, it will loss the potential energy but gain kinetic energy in the same amount.

16. Energy Basics
Another example of potential energy is hydroelectric dam.
The water hitting the blades of the turbine kinetic energy equal to the potential energy it would have had at the top of the reservoir surface.
Potential energy in this example is measured relative to the turbines location.
The kinetic energy of water becomes electric energy as the turbine spins the generator.

17. Energy Basics
Power: energy expressed in the units of joules or foot –pounds as an amount.
The rate of use of energy will be in terms of joule per second.
We commonly discuss our wages in Rials per hour (as a rate) as well as in Rials ( as an amount), these two quantities are related but different.
So power is the time rate of using or delivering energy.

18. Energy Basics Power unit is Watt, where: 1 W= 1J/sec.
British system power unit is horsepower, where : 1 horsepower=550 ft-Ib.
If power plant operating at a steady power P has run for a time t, then the energy produced is:
E=p x t
One kilowatt – hour = 3.6 x 106 joules.
Because one watt = one joule per second and there are 3600 seconds per an hour.

19. Units of Energy
The Joule: metric unit of energy, one metric unit of force ( the Newton) acting through one metric unit of distance (the meter) is equal to one joule of energy.
The kinetic energy of tennis ball moving at 14 miles per hour is about one joule.
The British Thermal Unit: the amount of heat energy required to raise the temperature of one pound of water by one degree Fahrenheit.
BTU is a relatively large amount of energy, it is the same as 1055 joules.

20. Units of Energy
The Calorie: is the amount of energy required to raise the temperature of one gram of water by one degree Celsius.
Celsius = 1.8 Fahrenheit
1 BTU= 252 calories.
Food Calories= 1000 calorie in physics or chemistry
One food Calorie is equal to about 4 BTU.

21. Units of Energy The Foot Pound: useful unit for energy. 1BTU=778 ft-Ib
Or what it would be take to lift a one pound weight to a height of 778 feet.

22. Units of Energy Example 2
The mass of pencil is 10 grams. What is the equivalent mass energy in joules?
Solution :
E (joules)=m (kg) x c2 (m/s)2
E= 10 x x (3x108)2 = 9 x 1014 Joules.

23. Units of Energy Example 3
The temperature of 15 pounds of water in a tank has been raised by 10 degrees Fahrenheit. How many BTU of energy was added to the water? What is this energy in joules?
Solution:
Energy (BTU)= Weight (Ib) x ∆T (oF)
= 15 x 10= 150 BTU
Energy (joule)= 150 BTU x 1055 joule/BTU
= 158,250 joules

24. The Principle of Energy Conservation
law of physics states that the total energy in isolated region cannot change.
So the energy can neither enter nor escape that region, even though it may be transformed from one form of energy to another ,the total energy in the region is conserved.
Energy cannot be created or destroyed, that is the principles of energy conservation. Its different from reducing the waste of energy.

25. The Principle of Energy Conservation
An example of energy conservation , the installing of better insulation in the walls of a house in order to allow one to maintain the interior at a comfortable level on a cold winter day with the use of less fuel in the furnace.
In the battery connected to the lightblub by wires. When connection is made, a current flows and the chemical energy inside the battery becomes electric energy and heats up the filament in the lightblub.

26. The Principle of Energy Conservation
After the wires are disconnected, the amount of heat energy tha has been added will be exactly equal to the chemical energy taken from the battery.
This chemical energy in the battery could use powering a motor, sounding a horn and so on.
None of these things can be done with heat energy finally stored in the box, eventhough the number of joules is the same. The energy has been conserved.

27. Transformation of Energy from One Form to Another
Let consider coal that was mined to fuel the boilers of an electric utility plant.
The chemical energy in the coal is transformed through the process burning into heat energy.

28. Transformation of Energy from One Form to Another
Heat energy will boil the water into high pressure steam to drive the turbine.
The mechanical energy of the rotated turbine will transformed into electrical energy by generator.
The electrical energy then transmitted to the final users.
Energy is conserved in each time transformation.

29. Renewable and Non-renewable Energy Sources
Nonrenewable sources are those that could be exhausted within a short time.
An example would be fossil fuel ( coal, oil, natural gas, shale oil, tar sands) .
It takes hundred million years for natural process to produce useful amounts of petroleum, natural gas, or coal.

30. Renewable and Non-renewable Energy Sources
Renewable sources are those that could never be consumed to completion.
Three sources of renewable energy,: solar energy.
Wherever solar energy source we put into use will continue to be available.
The more renewable energy we use , the cheaper it will be.

31. Renewable and Non-renewable Energy Sources
Because of concerns over resource depletion and environmental damage, the use of renewable energy preferred much than nonrenewable one.
In US 2003, only 6.3% or 6.15 QBTU* of total 98 QBTU came from renewable sources.
* quadrillion is a number represented in the U.S. by followed by 15 zeros, and in Great Britain by 1 followed by 24 zeros.