COAL GENERATION OPTION- EXPLOITING THE
RICH POTENTIALS OF NIGERIAN COAL
DEPOSITS FOR ATTAINING ADEQUATE AND
STABLE POWER IN NIGERIA
PRESENTED BY
By Engr. C. C. Ohakwe
Assistant General Manager (Thermal)
Generation, Operations Sector,
PHCN CHQ, Maitama, Abuja
@ NSE Meeting, Thursday, 14th July 2011, PHCN , CHQ, Maitama, Abuja
1
CONTENT
- Introduction
- Basic Electricity
- Coal
- Coal and Electricity
- Typical Coal Fired Power Plant
- Efficiencies
- Recommendations & Conclusions
2
Introduction
NEPA as was previously called was set up by a decree in
in1973
In 2004, NEPA was unbundled into Generation,
Transmission and Distribution.
On 11th March 2005, the Electricity Power Sector Reform
(EPRS) bill was signed into law
On May 5th 2005, NEPA was Transformed to PHCN Plc.
In 18th October 2005, The Nigerian Electricity
Regulatory Commission (NERC) was set up as the
sector regulator
In November 2005, The successor companies were
incorporated
- Six (6) Generation, - One (1) Transmission
- Eleven (11) Distribution
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Introduction cont’d
Three (3) more have since been incorporated via
Geregu, Papalanto and Omotosho.
Market rules to guide sales of electricity have been
put in place.
NERC has put in place needed market codes (Grid,
Distribution, Performance, Metering etc)
NELMCO, a Special Purpose Entity to manage
stranded liabilities & pension liabilities has been
incorporated.
(xi) On 1st July, 2006, greater operational
autonomy was granted the successor companies
with the transfer of Assets, Liabilities and Staff of
PHCN were transferred to them.
The processes of procuring a management
contractor for TCN is in progress.
4
Existing Generation (Thermal)
S/N Station No. of Installed Ave. Actual
Units Cap (MW) Gen. as at 6.00
HRS 11/07/11
1 Egbin 6 1,320 992
2 Delta 18 972 183
3 Afam 20 986 60
4 Sapele 10 1,020 75
5 Ijora 2 40 nil
6 Geregu 3 414 279
7 Olorunsogo 8 303 52.7
8 Olorunsogu II 4GT 2ST 675 112.1
9 O/tosho 8 303 nil
Total 81 6,033 1,753.8 MW
5
Existing Generation (Hydro)
S/ Stations No. of Installed Ave. Actual Gen. as
N units Cap. (MW) at 13/07/11
(MW)
1 Kainji 8 760 91
2 Jebba 6 578 171
3 Shiroro 4 600 250
Total 18 1938 512
6
Existing Generation (JV/IPP’s)
S/N Stations Installed No. of units Ave. Actual
capacity Gen. as at
(MW) 13/07/11
(MW)
1 Okpai 480 3 409
2 Omoku 150 2 30.3
3 AES 360 9 142.5
3 Ajaokuta 110 2 nil
4 Afam VI 650 5 295
(Shell)
Total 1,750 21 876.8
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NATIONAL INTEGRATED
POWER PROJECTS (NIPP)
S/N NAME INSTALLED
CAPACITY (MW)
1 Calabar 563
2 Ebgema 338
3 Ihovbor 450
4 Gbarain 225
5 Sapele 450
6 Omoku 250
7 Alaoji 961
9 Papalanto 676
9 Omotosho 451
10 Geregu 440
TOTAL 4805
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Existing Energy Mix
Stations Total Ave. Actual % of
Installed Gen. as at Energy Mix
Capacity 11/07/11
(MW) (MW)
Hydros 1,938 512 19.94
Thermal 6,033 1,753.8 62.06
(PHCN)
Thermal 1,750 876.8 18.00
(JV/IPP)
Total 9,721 3,142.60 100.00
80.06% of the total installed capacity is thermal. The availability of
these stations depend on Adequate Supply of Gas.
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Existing Transmission Network
Status
Currently the Grid consists of:
o There are 24no 330/132 kV Transmissions
Stations with a transmissions capacity of
7688 MVA
o There are 128no 132/33kv Transmissions
Stations with a transmissions capacity of
9130 MVA
o About 5,515.35km of 330kV lines
o About 6,801.49km of 132kV lines
10
Existing Distribution Network
Capacity (2008)
Total Number of Injection Sub-Stations (33/11kV) 1,078
Total Capacity of Injection Sub-Stations 10,988.29MVA
Total Number of Distribution Sub-Stations
(11/0.415kV) 41,477
Total Capacity of Distribution Sub-Stations 17,044.29MVA
Total Length of 33kV Network 46,481.68KM
Total Length of 11kV Network 31,784.76KM
Total Length of 0.415kV Network 193,822.01KM
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PROJECTED LOAD DEMAND
Peak Demand Forecast = 10,400MW
Average Installed Available Capacity =
4,800MW
Av Daily Generation = 3,024.25MW
Generation gap required to be
met = 7,375.75MW
This gap is growing 6000MW plus
in 2008
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BASIC ELECTRICITY
We have heard of electrons and their movements in
conductors. But they need to be driven by potential.
Basic physics tell us that when a coil, a conductor
rotates in a magnetic field, cutting the magnetic
flux, current is induced in that coil or conductor.
This can be tapped out via carbon brushes, slip rings
etc. Remember the old bicycle dynamo.
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Basic Electricity con’d
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BICYCLE DYNAMO
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COAL
The question is what is coal?
Fossil fuel, the altered remains of
prehistoric vegetation originally
accumulated in swamps and buried.
Quality of coal is dependent on
-Vegetation type
-Depth of burial
-Temperature and pressure of depth
-Duration the coal has been forming.
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Coal Continued
Coalsification
- Is the degree of change of maturity of coal. This has
to do with both the physical and chemical
properties.
Types of Coal
Lignite
Sub-bituminous
Bituminous
Anthracite
Coal Quality
Sulphur 0.40-0.93%
Ash 6.40-11.2%
Moisture 7.60-13.5%
Heating Value 5520-6610Kcal/kg
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Source: Coal, Power for Progress - World Coal Institute
Coal Continued
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Coal cont’d
Coal Analysis
Comprise Carbon, Hydrogen, Oxygen, Nitrogen and
Sulphur.
High Rank Coal More Carbon, low in hydrogen and
oxygen
Low Rank Coal Less Carbon, high in hydrogen and
oxygen.
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Coal cont’d
Coal Statistics
- Coal provides 27% of global
primary energy needs and
generates 41% of the world's
electricity
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COAL STATISTICS cont’d
21
Coal cont’d
Top Ten Hard Coal Producers (2009e)
PR China; 2971Mt
South Africa; 247Mt
USA; 919Mt
Russia; 229Mt
India; 526Mt
Kazakhstan; 96Mt
Australia; 335Mt
Poland ;78Mt
Indonesia; 263Mt
Colombia; 73Mt
Nigeria; Nil
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Coal in Electricity Generation
Coal is the major fuel used for generating electricity
worldwide - countries heavily dependent on coal for
electricity include (2008):
-South Africa; 93%: -Kazakhstan; 70%
-Morocco; 55%: -Poland; 92%
-India; 69%: -Greece;52%
-PR China,79%: -Israel,63%
-USA, 49%: -Australia, 77%
-Czech Rep, 60%: -Germany46%
-Nigeria, 0%
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COAL AND ELECTRICITY
- Life today, especially modern life would be absolutely
meaningless and frustrating in the absence of
electric power. Think of lighting in houses, streets,
heating for those in temperate regions, offices
machineries and factories. Provision of electricity
and increasing access to it is critical to poverty
reduction.
- Utilization of Coal for Power Generation is a world
phenomenon.
- Nigeria is yet to key in to this.
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Continental Coal Reserves
25
Existing Potential Coal Mines
Sites with Reserves in Nigeria
BOREHOLE DATA ANALYSIS
2.7 billion tonnes inferred.
639 Million tonnes proven in 22 locations in 15
States of the Federation (Adamawa, Anambra,
Bauchi, Benue, Cross-River, Eboyi, Edo, Enugu,
Gombe, Imo, Kogi, Kwara, Nassarawa, Ondo,
Plateau)
BEHRE DOLBEAR
Three main coal districts identified in the Anambra
Basin:- Kogi, Owukpa-Ezimo and Enugu
JORC CLASSIFICATION
Demonstrated 396 Million tonnes
Inferred 1,091 Million tonnes
Total Coal resource 1,487 tonnes
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Typical Coal Fired Power Plant 2
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Typical Coal Fired Power Plant
1. Cooling tower, 2. Cooling water pump
3. Transmission line (3-phase), 4. Unit transformer
(3-phase) 5. Electric generator (3-phase),
6. Low pressure turbine 7. Boiler feed pump, 8.
Condenser 9. Intermediate pressure turbine 10.
Steam governor valve, 11. High pressure turbine ,
12. Deaerator, 13. Feed heater, 14. Coal conveyor ,
15. Coal hopper, 16. Pulverized fuel mill, 17. Boiler
drum, 18. Ash hopper,19. Superheater, 20. Forced
draught fan, 21. Reheater, 22. Air intake, 23.
Economizer, 24. Air preheater, 25. Precipitator
26. Induced draught fan, 27. Chimney Stack
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Typical Coal Fired Power Plant cont’d
Description
A typical coal-fired thermal power plant.
Coal is conveyed (14) from an external stack and
ground to a very fine powder by large metal spheres
in the pulverized fuel mill (16).
There it is mixed with preheated air (24) driven by
the forced draught fan (20).
The hot air-fuel mixture is forced at high pressure
into the boiler where it rapidly ignites.
Water of a high purity flows vertically up the tube-
lined walls of the boiler, where it turns into steam,
and is passed to the boiler drum, where steam is
separated from any remaining water.
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Typical Coal Fired Power Plant cont’d
The steam passes through a manifold in the roof of
the drum into the pendant superheater (19) where
its temperature and pressure increase rapidly to
around 200 bar and 570°C, sufficient to make the
tube walls glow a dull red.
The steam is piped to the high-pressure turbine
(11), the first of a three-stage turbine process.
A steam governor valve (10) allows for both manual
control of the turbine and automatic set point
following.
The steam is exhausted from the high-pressure
turbine, and reduced in both pressure and
temperature, is returned to the boiler reheater (21).
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Typical Coal Fired Power Plant cont’d
The reheated steam is then passed to the
intermediate pressure turbine (9), and from there
passed directly to the low pressure turbine set (6).
The exiting steam, now a little above its boiling
point, is brought into thermal contact with cold
water (pumped in from the cooling tower) in the
condenser (8), where it condenses rapidly back into
water, creating near vacuum-like conditions inside
the condenser chest.
The condensed water is then passed by a feed pump
(7) through a deaerator (12), and pre-warmed, first
in a feed heater (13) powered by steam drawn from
the high pressure set, and then in the economiser
(23), before being returned to the boiler drum.
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Typical Coal Fired Power Plant
cont’d
The cooling water from the condenser is sprayed
inside a cooling tower (1), creating a highly visible
plume of water vapor, before being pumped back to
the condenser (8) in cooling water cycle.
The three turbine sets are coupled on the same
shaft as the three-phase electrical generator (5)
which generates an intermediate level voltage
(typically 16 kV).
This is stepped up by the unit transformer (4) to a
voltage more suitable for transmission (typically
132/330 kV) and is sent out onto the three-phase
transmission system (3).
Exhaust gas from the boiler is drawn by the induced
draft fan (26) through an electrostatic precipitator
(25) and is then vented through the chimney stack
(27). Source: Wikipedia 32
TYPICAL SCHEMATIC 1
33
Typical Coal Fired Power Plant cont’d
Mine the Coal
Coal is mined from Mines. It is a complete
occupation of its own with its hazards- Recall recent
Chilean drilling experience.
Crush, Pulverize, Gasify the Coal
Various Coal Handling systems. Rope way. Conveyor
Belt system etc.
Mined Coal is conveyed to power plant site or where
it is to be crushed, pulverized, gasified.
Transportation issues.
The pulverized Coal is blown to the combusting
chamber where it mixes with a good quantity of air
(oxygen) to burn at very high temperature over
500oC. A lot of ash is generated and this must be
evacuated and disposed. Ash handling issues.
Typical Coal Fired Power Plant cont’d
HEAT GENERATOR OR BOILER
The heat produced by this action, heats up water in
the boiler tubes linning the boiler, into steam and
dry steam in the superheat chamber. Boiler water is
a sensitive issue. It is specially prepared and
monitored continuously.
A well equipped Laboratory and qualified staff
monitor water quality to ensure safety of the Boiler.
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Typical Coal Fired Power Plant cont’d
TURBINE
The hot (over 500oC) and high pressure steam 200
bars is passed to the turbine, that contains rows of
propeller like blades causing the blades to rotate at
very high speeds – up to 3000 rpm.
GENERATOR
Usually, a Generator is mounted at the end of the
turbine shaft. Because of this high speed of
rotation, usually of the rotor, (status coils don’t
rotate), electrical current is induced in the coil and
can be tapped out.
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Typical Coal Fired Power Plant cont’d
TRANSFORMER
POWER Electricity produced (in our system, big
generations – 16kv) is transformed to 330kv for
onward HV transmission to long distances where it is
stepped down to appropriate voltages for required
purposes.
Subsequent transformations 132kV and 66kV
Transmissions purposes.
And then 33kV and below for Distribution purposes
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Typical Coal Fired Power Plant cont’d
CHIMNEY/EXHAUST STACK
The waste product of combustion is discharged to
the atmosphere via the Exhaust Stack or chimney.
There is a lot going on in the bid to reduce green
house gases. There is also a lot of modern
technology inputs in terms of monitoring discharges
into the atmosphere and meeting environmental
regulations that is becoming more stringent by the
day.
There is also a lot of utilization of exhaust gases.
This include pre heating of both coal and water used
in the boiler to improve on efficiency and reduce
waste.
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Typical Coal Fired Power Plant cont’d
CONDENSER & COOLING TOWERS
Used Steam is Condensed back to water and re-
circulated. Make up water is added to compensate for
losses.
A condenser must have adequate source of water to
cool the large amount of s team. LTS is located near
the lagoon in Lagos. Oji River Power Station near Oji
River.
Power Station location is carefully planned. Very
relevant factors must be considered in any type of
Power Station – Gas Turbine, Hydro Turbine, Solar
energy, Wind. Name it.
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Typical Coal Fired Power Plant cont’d
Condenser/Cooling tower cont’d
Where there is no water or limited water, Cooling
Tower is employed. The purpose is to create a large
surface for better and effective cooling.
There is the issue of having enough vacuum in the
condenser for effectiveness.
Power plants are complex and have a whole lot of
subsystems. There are lots of developments and R
& Ds going on.
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A simple model
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OJI RIVER POWER STATION
It is a coal fired Power Station
located in the East, between Enugu
and Onitsha.
Sited near the Oji River - used for
water supply, cooling system, feed
water system.
It was commissioned in Feb 1956
Output is 30MW
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OJI RIVER POWER STN con’d
Cooling Towers were built but were
never commissioned.
Mechanical coal feed system
operated to provide fuel supply.
Consisted a coal handling system
including transporting coal 27 km
from the Mines, Overhead cable
ropeway with intermediate winding
gear. Other trappings of a P/Station.
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EFFICIENCIES OF SOME POWER PLANTS
“Energy can neither be created nor destroyed” First
Law of Thermodynamics.... Mayer.
Electricity generation converts of energy from different
forms to Electricity which is the most convenient form of
energy. How efficiently does this conversion take place?
Coal Fired Power Plants
Ranges from 32 % to 42 %.
The large power plants operate at steam pressures of 170
bar and 570 °C Superheat, and 570 ° C reheat
temperatures. The efficiencies of these plants range from
35 % to 38 %. Super critical power plants operating at
220 bar and 600/600 °C can achieve efficiencies of 42 %.
Ultra super critical pressure power plants at 300 bar and
600/600 °C can achieve efficiencies in the range of 45%
to 48 % efficiency.
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EFFICIENCY OF SOME POWER PLANTS cont’d
Natural Gas Fired Power Plants
Have an efficiency of 32 % to 38 %.
In the combined cycle mode, the new "H class" Gas
turbines with a triple pressure HRSG and steam turbine
can run at 60 % efficiency at ISO conditions. This is by far
the highest efficiency in the thermal power field.
Renewables
Hydro turbines is in the range of 85 to 90 %.
The oldest and the most commonly used renewable
energy source, have the highest efficient of all power
conversion process. The potential head of water is
available right next to the turbine, so there are no energy
conversion losses, only the mechanical and copper losses
in the turbine and generator and the tail end loss.
Wind turbines have an overall conversion efficiency of 30
% to 45 %.
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Recommendations/Conclusions
We have seen that Nigeria has proven coal reserves
of 639 tonnes in about 22 locations in 15 States of
the Federation.
There is need to include coal fired plants in our
generation mix for its numerous advantages. Thus
diversification is imperative for a more stable
electric power regime.
There is need for government to muster political will
and courage to exploit coal for power and reap the
ripple effect which includes stable electrical power
(Base load operation) and poverty reduction.
Environmental issues should not stupefy us to
inaction since we have not started.
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Recommendations/Conclusions
cont’d
It is to be noted that gap between demand and supply is increasing 6000
MW plus in 2008, now it is 7000 MW plus.
The Power Sector cannot operate at 100% efficiency when other
supporting infrastructures are operating at less. Our roads, schools,
factories etc.
Federal Government should continue to fund the power sector for now till
when private investors are comfortable with investing in power.
Federal Government should run the present PHCN as a business entity
pending when there will be full privitisation.
The mode of running it now is a fertile ground for inefficiency and
corruption. If run like a business, lapses would become so obvious. South
African Power System we refer to is run that way. There are many State
run Companies that run as a business entity.
For now, the only real addition to the Power System is NIPP. It is not
keeping the expected pace for both Generation and Transmission. National
Assembly delayed the project for 2 years and we paid heavily for it.
Remember that NIPP is Obasanjo’s brain child which he initiated in the
twilight of his admin. Ya’ardua’s first 4 years is gone. Jonathan’s 4 years
is now on.
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Recommendations/Conclusions
cont’d
Electric Power is technology based. Even if we buy all the Turbo-
Generators and dump in Nigeria, we must be able to sustain them. Shell
said just one of the Gas Turbine Inspections in their Afam Plant will cost
them a whooping $7m. OEMs LTSA are very expensive. When all the units
are in private hands, the public must pay to sustain them. All these
monies principally goes to the OEM and would leave the shores of Nigeria.
As a result, I submit that Nigeria cannot sustain its power need except
there is a deliberate policy thrust to industrialize.
We cannot make 20:20:20 except we industrialize. We are so close to
20:20 that I find it difficult to see how we can make it.
For this I suggest the Federal Government to set up a Think Tank on
industrialization. The Think Tank should find practical solutions on:
Why we could not run Ajaokuta Steel Company till date.
Why Osogbo Machine Tool Industry is dead.
Why the Osogbo, Alaja and Katsina Steel Rolling Mills operating optimally.
Why we could not sell NITEL till date and the infrastructure left to decay.
Telecommunication was only commercialized.
The Think Tank must prefer solutions and come up with a workable blue
print for industrialization.
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Recommendations/Conclusions cont’d
We must be ready to shut our doors and eat mostly the food we
produce and ride the cars we make. India did it. China did it.
Are we ready to do it?
That is only when we can put our teaming population to work and
create wealth for ourselves.
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