1. Module 2 Energy and the Environment

2. It exists in several forms
 According to the law of conservation of energy total
energy of a system remains constant although the
energy can be transferred into another form.

3. Type of Energy
 The names of energy are related to:
a) The way the energy is perceived e.g. mechanical,
electrical, light.
b) The way the energy is transported e.g. thermal
c) The origin of the energy e.g. nuclear, solar, wind.

4.  Since energy can neither be created nor destroyed, the
sum of energies which enter a process must be equal to
the sum of energies resulting from this process.

5. Names of energy
 Potential energy aka Stored energy
 Kinetic energy aka Energy of motion
 Chemical energy
 Mechanical energy
 Thermal Energy aka heat energy
 Solar energy
 Light energy
 Electromagnetic Energy (EMR)

6. Names of Energy con’t
 Electrical Energy
 Nuclear energy aka Atomic energy

7. The basic use of energy measurement is the Joule (J)
Symbol
name
Value in Joules
Equivalent
KJ
Kilojoules
1000 J (103 J)
Maximum amt of
solar radiation
received by 1sq of
earth in one
seemed
MJ
mega joules
1000,000 J( 106 J)
Kinetic energy of
one tonne vehicle
moving out at 160
Km/h
GJ
Giga joules
1000,000,000 J
(109 J)
6GJ is about the
amount of
potential chemical
energy in a barrel
of oil when it is
combusted.

8. The Basic use of energy
measurement is the joule (J)
Symbol
Name
Value in Joules
Equivalent
TJ
Tera joule
1,000,000,000,000
J (1012 J)
60 Tj were released
by the atomic
bomb which was
droppedon
Hiroshima.

9. Work
 The deffinition of work says nothing about the time
taken during which work was done.
 E.g a person does the same amt of work when he
carries something up a flight of stairs, whether he runs
or not, But, he is more tired when ge runs. Therefore,
to distinguish these cases, the concept of power was
introduced.

10. Power
 Is defined as the rate of doing work .
 Power= work done/time taken
 The unit of power measurement is Watt (W)

11. Watt (W)
Symbol
Name
Value in watts
Equivalent
KW
Kilowatts
1,000 W (103 W)
Largest industrial
light bulb of 1.8
house power
MW
Megawatt
1,000.000 W
(106 W)
Enough to play a
night game at a
stadium- 1300hp
GW
Gigawatt
1,000,000,000W
(109W)
Enough to power a
major city for a
day.

12. Energy Conversions
 Example
 Heating water with a burner
 Photosynthesis
 Internal combustion Energine
 Power station
 Nuclear Power

13. Non renewable energy Sources
 Fossil Fuels e.g coal, oil,natural gas. Peat(from
waterlogged marshland)
 Carbon Dioxide (CO2)
 Sulphur Dioxide (SO2)
 Nitrogen Oxide (NO)

14. Non Renewable energy sources
cont’d
 Major fossil fuels
Coal
OIL
Natural gas
Peat

15. Nuclear Power
 There are two types of nuclear reactions
 1) nuclear fission
 2)nuclear fusion
 Nuclear fission
Nuclei of atoms are split, releasing energy. This
process occurs in a)atomic bombs nuclear
reactons.
b) Nuclear reactions.

16. Nuclear Fusion
 Nuclei of atoms joined or fused together This
happends under very hot conditions . The sun like all
other stars creates heat and light , through nuclear
fusion. In the sun, hydrogen nuclei fuse to form
helium.

17. Nuclear Fission
 Uranium is the main fuel used in nuclear fission
because it splits easily when bombarded by neutrons
once a uranium molecule is split, multiple neutrons
are released.
 The “free” neutrons are used to split other uranium
molecules. This is called a chain reaction.

18. Functioning of a nuclear Power
plant.
Enriched uranium is formed into 2.5cm pellets
2. Pellets are arranged into long, hollow, metal rods.
3. Rods are collected together into bundles.
4. Rods are submerged in water inside a pressure vessel(
the water acts as a coolant)
1.

19. Outside a Nuclear Power Plant
 Due to harmful radiation extra precautions are
required in the construction design of nuclear power
plants.
1. Hence there is an outer steeled vessel which houses
the reactor core, all the equipment used to fuel +
maintain the reactor. This steal barrier serves as a
barrier to prevent leakage of any radioactive gases or
fluids from the plant.

20. Reactor Types
Boiling water reactors/BWR
2. High temperature gas cooled reactor/ HTGCR
3. Process Inherent Ultimate Safety reactor PLUS
4. Pressurised Water reactors
1.

21. Uranium conversation+ enrichment
 Uranium oxide is a raw mined product which cannot
be used as fuel for a nuched reactor.
 Additional processing is required. Only ).7% of
naturally-occuring uranium is “fissile” (capable of
undergoing fission. This fissile isotype form is called
Uranium 235 (U-235). The rest of the deposit is made
up of U-138 most reactors need the concentration of
U-235 to be above 3.5-5%. This is achieved by a process
call Enrichment which requires uranium to be
gaseous.

22. Fuel Fabrication
 Generally available in the form of ceramic pallets
encased in metal tubes called rods.

23. Functioning of a nuclear power
plant.
 Used Fuel
Made up of approximately: 94% U-238, 1% U-235, 1%
Plutonium,4% fission particles.
 In a reprocessing facility, used fuel is separated into 3
components namely: uranium forms, plutonium,
waste.

24. Important nuclear terms
 Critical mass-averge one free neutron hits another U-
235 nucleus, then the masss of the uranium is said to
be critical and exist at stable temperature.
 Sub-critical mass – Less than one of the free neutrons
hits another U-235. Eventually fission will end and
source power stops.
 Super-critical mass- more than one of the free
neutrons hits another U-235 nucleus. This causes the
reactor to heat up.

25. Nuclear Power Issues
 Transportation
 Reactor safety
 Terrorism
 Worker+ publia Exposure to radiation
 Contamination
 Radioactive waste disposal
 Thermal pollution
 Decommissioning

26. Renewable energy
 Biomass
 Hydroelectric
 Wind energy
 Solar energy
 Geothermal energy
 Tidal Energy

27. Biomass
Biomass
– includes all biological waste and there are several
sources of biomass
1. Fuel wood
2. Municipal waste and industrial waste
3. Agricultural crop residue and animal waste.
4. energy plantations.
N.B Anaerobic disasters produces biomass which consist
of methane and carbon dioxide.

28. Environmental issues of Biomass as
an energy source
•Air pollution
•Habitat and Biodiversity Loss
•Carbon dioxide and global warming
•Effects on food Production
•Crop residues and Animal waste

29. Hydroelectric power/ Hydropower
Hydropower – flowing water creates energy that can be
captured and turned into electricity.
Sources include
a) Darms > most common method
b) Streams> Store areas of the world
c) Canals
N.B Development potential of Hydropower is best in
mountainous areas + large rivers valleys. Use of
hydropower is expected to increase.

30. Environmental Issues of
hydropower as an energy source.
•Fish migration
•Loss of Natural Habitats and reduction in fish species
Diversity
•Volume of water
•Sediment Deposits

31. Solar Power
The sun provides a supply of energy which far exceeds the worlds
demands
There are 3 main methods of utilising solar energy as follows:
1. Passive Heating System> suns energy converted directly to heat.
E.g drying clothes.
2.Active solar systems > heat is transferred from the collection site to
the place of use, requirements include; solar collector, Pump, Pipe
System for transfer.
3.Solar generating electricity.
E.g domestic water heating

32. Solar Power continued
>Photo Volture Cells PV
These are solid state semi – conducter devices which convert light directly into
electricity.
Characteristics:
•Usually made of silicon with some trace elements.
•Once installed, a PV system needs little to no maintenance, just cleaning most PV
systems come with storage better (Os)
• Produce no pollutants

33. Environmental issues of Solar
Power as an Energy Source
1. Supply
2. Land Use
3. Manufactor, Installation and disposal

34. Environmental issues of wind
Power as an energy source
•Location of wind fields
•Supply
•Land use
•Noise and Visual Pollution
•Wildlife

35. Geothermal Energy
Defined as heat contained below the earths surface
Geothermal energy can be contained in 2 ways
•Geologically active areas: where hot magma reaches
the earths surface
•Geologically in active areas: in these spots,
geothermal pumps are used to extract heat from the
earths and transfer it to buildings.

36. Environmental issues of
Geothermal Power as an energy
source
•Air Pollutions
•Water Pollution
•Chemicals
•Safe Disposal of Hazadous Waste
•Location of plant
•Land Subsidence

37. Tidal Power
There are Two high and two low
tides everyday. Certain coastal
areas (bays + inlets) experience
higher tides than others because
of their geographical features.

38. Environmental issues of Tidal
Power as an energy source
Environmental.
Construction of dam across a bay or
estuary causes negative impacts on
•Aquatic and shoreline Ecosystems
•Navigation
•Recreation

39. Limiting Factors Affecting Energy
Use
1. Technology
2. Geographical
3. Reliability of Supply
4. Cost of Production
5. Energy Policy of a Country
6. Social Factors

40. Factors affecting electrical
generating capacity and demand.
Generating Rates
Demand Patterns
Load Patterns + supply characteristics
Intermittent Energy Sources
Although hydroelectric power is seasonable predictable and controllable, solar and
wind power are only available when whether permits.

41. Methods of supply meeting
Demand
•
Load levelling. This involves moving demand from peak periods to times
when the demand is low. This is done by:
1. Peak shaving
2. Smart Grid
3. Energy Storage