Electricity
•  Generator consists of:
magnets
coil
split rings
•  Permanent magnets
or electromagnets
produce
magnetic field
•  Ends of coil wires are
connected to two rings =
split rings
•  Electric current
flows from coil wires
to external circuit
by means of brushes
which come into contact
with the split rings
Faraday’s Discovery (1831)
Power
distribution
network
throughout SA
and
neighbouring
countries
Electricity Generation Mix:
Coal Nuclear Hydro Gas Other
90%
Ref. CRSES 2008
5%
2%
1%
2%
Coal – a Fossil Fuel
Low quality =
Low heat value,
High ash content
Abundant Source
Inexpensive
= Prosperity
Electricity Demand Pattern
•  The instantaneous
amount being fed
into the grid must
always match what
the consumers are
taking out
•  This varies not only
from day to day, but
from minute to
minute
•  As the demand
increases, more
stations must be
brought online
Supply vs Demand
The Energy Balance Problem
Electricity:
For a 220 W computer
used 365 days per year
•  Generated as needed
•  Consistent and reliable
938kg of coal =
One ton Bakkie load
Alternatives to
Fossil Fuels:
Sun
Biomass
Wind
Hydro/Water
Ocean
Wave
Geothermic
Comparison of Energy Technologies (2010)
Non Renewable
Renewable
Coal
Nuclear Gas Turbines
Wind Solar Solar Solar Biomass
Central Receiver Forestry residue (FR)/
Hydro
InstallaCon cost
Rand per MW
R17m to R20m
R26m to R33m/MW
R4m (OC)
R6m (CC)
R14m to
R17m
R28m to R36m
R27.5m (0hr) R51m (9hr)
R27m (3hr) R40m (14hr)
R33m (FR) R67m (MSW)
R1m/MW excluding the dam
Power Reliability (Availability/Capacity factor)
92%
(85%)
92 – 95%
(High)
89% (10 – 50%) (Used for peak loads only) 94 – 97%
(29 – 41%) 98%
(19%)
(Depending on loca6on)
95%
(25 – 44%) (Depending on storage size) 92% (29 – 47%) (Depending on storage size) 90% (85%)
High
(10 – 50%)
(Used for peak loads only) CO2 emissions
930kg/MWh
Low
622kg/MWh (OC) 376kg/MWh (CC)
Low
Low
Low
Low
1287kg/MWh (FR) 1607kg/MWh (MSW)
Medium (dams release methane)
Water usage
33 -­‐ 230L/MWh
For cooling:
6 000L/MWh Sea water
19.8L/MWh (OC)
12.8L/MWh (CC)
None
245 -­‐ 270L/
MWh
280 -­‐ 316L/MWh
200 -­‐ 210L/MWh
For storage, same water is pumped back to be reused during peak 6mes.
OperaCng & maintenance costs
Fixed
(Variable)
R350 – R500/kW-­‐ N/A yr (R95 -­‐ R125/MWh)
(R36 – R44/MWh)
R70/kW-­‐yr (OC)
R148/kW-­‐yr (CC)
(Zero for both)
R266 – R312/kW-­‐yr
(N/A) For washing mirrors & PV panels:
45 000L/MW per year
R402/kW-­‐yr
(N/A)
R424 – R635/kW-­‐yr
(N/A) R490 – R700/kW-­‐yr
(N/A)
R972/kW-­‐yr (R31/
MWh)(FR) R2579/kW-­‐yr (R38/
MWh)(MSW)
N/A
(R40 – R150/MWh)
Fuel cost esCmates
R15/GigaJoule (GJ)
R6.25/GJ
R42/GJ (Depending on fuel prices!)
R19.5/GJ (FR) Zero (MSW)
Note that water needs to be pumped back up, thus there are some electricity costs.
Economic life
30 years
60 years
30 years
20 years
25 years
30 years
30 years
30 years
50 years
Period for installaCon 5 – 9 years in years
1 Unit – 6 years
6 Units – 16 years 2 – 3 years 2 – 6 years 1 – 2 years 4 years
4 years
4 years
Site dependent 3 – 6 years Base load / Peak power
Base
Peak
Intermifent
Intermifent
Intermifent
Intermifent
Base
Peak in SA
Pulverized coal without/with flue gas desulphuriza6on
Base
Open cycle (OC)/ Combined cycle (CC)
Grid connected PV (CdTe)
Parabolic with no storage Grid connected Trough
with no storage With various storage 6me
Typically used for With various storage Municipal Solid Waste energy storage, (MSW)
included for 6me
completeness only
*All data (except Hydro) from EPRI Member Specific Final Report, July 2010 – contact crses@sun.ac.za for more informa6on. The Choice!
•  Are we going to invest in
renewable energy
systems?
•  Or will we continue to
burn fossil fuels •  and suffer the
consequences
of releasing more and
more COշ into the
atmosphere?
European Union Energy Policy:
•  Targeted 20% Renewable Energy Consumption in EU by 2020
EU Member State
2005
Figure
2020
Target
% To
cover:
1 United Kingdom
1.3%
15%
13.7%
2 Denmark
17%
30%
13%
3 Ireland
3.1%
16%
12.9%
4 France
10.3%
23%
12.7%
5 Germany
5.8%
18%
12.2%
6 Italy
5.2%
17%
11.8%
7 Netherlands
2.4%
14%
11.6%
8.5%
20%
11.5%
EU
Ref. http://www.energy.eu/#renewable
Practical Assignment:
•  SA energy mainly generated by burning fossil fuels (e.g. coal).
•  Releases greenhouse gases such as CO2.
•  Excessive greenhouse gases cause global warming, resulting in climate change.
Electricity generated by burning coal causes ± 0.915 kg/kWh of CO2 to be released.
Select any 10 appliances in your home. Complete table below over a period of 5 days:
Power
Kilowatt
(kW)
Usage time
per day in
hour
(h)
Energy
consumption
per day in
kWh
No. of
days
Total Energy
consumption in
kWh
Electrical Appliance
Qty
Watt
(W)
Light bulb
1
100
100
1000 = 0,1
30min
60min = 0,5h
0,1kW x 0,5h
= 0,05kWh
5
0,05kWh x 5days
= 0,25kWh
Kettle
1
1600
1600
1000 = 1,6
48min
60min = 0,8h
1,6kW x 0,8h
= 1,28kWh
5
1,28kWh x 5days
= 6,4kWh