Techno-economic Analysis of an Off-grid MicroHydrokinetic River System for Remote Rural
Electrification
Central University of Technology
Energy Postgraduate Conference 2013
Presentation outline
• Introduction
• Hydropower situation in South Africa
• Hydrokinetic
• System modeling and simulation
• Results and discussion
• Conclusion
Introduction
• Currently over 90% of South Africa's electricity comes from coal power.
• Government target: 10 000 GWh renewable energy contribution (biomass, wind,
solar and small-scale hydropower ),
• Approximately 6000 to 8000 potential sites for traditional micro hydropower.
• The Use of Hydrokinetic power for river applications in South Africa.
Objective of this study
• To investigate the
possibility of using and developing hydrokinetic power for
electricity supplies for rural and remote loads in South Africa.
• Simulation (HOMER): Compare the use of Hydrokinetic with other supply
options.
Hydropower situation in South Africa
Size
Type
Installed capacity Estimated potential
(MW)
(MW)
Macro hydropower (Larger (i) Imported
1 450
36 400
than 10MW)
(ii) Pumped storage for peak
1 580
10 400
supply
(iii) Diversion fed
5 200
(iv) Dam storage regulated
662
1 520
head
(v) Run of river
270
Small hydropower (from As above (iv) and (v)
29.4
113
few kW to 10 MW)
Water transfer
0.6
38
Refurbishment of existing plants
8.0
16
Gravity water carrier
0.3
80
Sub-total for all types
3 730.3
53 837
Excluding imported from abroad
2 280.3
17 437
Excluding pump storages using coal based energy
700.3
7 237
Total “green” hydro energy potential available within the border of South Africa
7 237
No significant development of hydropower in the country has been noted for 30 years
Hydrokinetic
Technology
3
1
P


A



V
 Cp
• Operation principle similar to wind turbine, a
2
• Potential energy available almost 1000 time more energy from the hydrokinetic
than wind.
Advantages compared to the traditional hydropower:
• No dam,
• No destruction of nearby land,
• No change in the river flow regime,
• Reduction of flora and fauna destruction.
Theoretically, a greater number of
potential sites for hydrokinetic power
can be identified.
System modeling and simulation
HOMER: Hybrid Optimisation Model for Electric Renewable
Problem: Unfortunately, HOMER is not equipped
1.0
with a hydrokinetic power module considered in
0.8
Proposed
solution:
-The
wind
turbine
components has been used with hydrokinetic input
rather than wind-related information.
-The wind turbine power-
Power Output (kW)
this study.
0.6
0.4
0.2
curve has been replaced with the hydrokinetic.
0.0
-The wind speed information
with the river current velocity.
0
1
2
Wind Speed (m/s)
3
4
Load estimation (rural household)
Resources
Velocity Clearness
index
(m/s)
January
0.627
5.31
February
0.646
7.25
March
0.639
6.09
April
0.638
1.81
May
0.698
2.67
June
0.758
2.18
July
0.743
1.84
August
0.641
1.54
September
0.690
1.41
October
0.607
1.69
November
0.561
2.83
December
0.553
5.27
Average
0.638
Water
velocity3.32
in the worst
month:
Month
The daily
energy
consumption
(9.5kWh) The peak load at 3.4
kW
Daily
radiation
(kWh/m2/d)
7.404
7.178
6.274
5.200
4.663
4.522
4.663
4.804
6.302
6.443
6.500
6.613
5.873
1.41
m/s, Viable depth: 1,8m, Width: 5,2m,
Cross sectional area: 9.36m2
Pa= 1,075 kW
Costs
Components
HKP
PV
Battery (6V,
360Ah)
Inverter
Diesel
Generator
3.4 kW
Investment
costs
$9170/kW
Replacement
costs
$9170/kW
O&M costs
Lifetime
Lubricant
25yr
Diesel
price
-
$20/yr
$4100/kW
$175
$3500/kW
$150
$105/yr
$3/yr
20yr
10yr
-
-
$800/kW
$2830
$800/kW
$2830
$10/yr
$0.5/h
15yr
10yr
$1.25/L
$1.30/L
-
Simulation results and discussion
The architectures and costs of
different
supply
options
found
feasible by Homer are presented
below:
Simulation results summary
Costs
HKP
PV
DG
Capital ($)
11 475
7 880
2 830
Replacement ($)
4 697
9 344
20,300
O&M ($)
831
2 337
55 991
Systems
HKP
PV
DG
Fuel ($)
0
0
75 971
Size (kW)
1
6
4.5
Salvage ($)
-290
-967
-264
Number of
7
12
0
16 713 18 495
154 829
Battery
Inverter (kW)
3.5
3.5
0
Rectifier (kW)
3.5
3.5
0
Total NPC ($)
COE ($/kWh)
Grid extension
distance (km)
0.387
0.416
3.475
0.911
1.07
13.1
Conclusion
This paper aimed to investigate the possibility of using hydrokinetic power suitable
to supply electricity to rural and isolated loads in South Africa where reasonable water
resource is available. Simulations of the hydrokinetic power have been performed with
HOMER software.
The results have been compared with those of a diesel generator and PV while they
are supplying the same load. The hydrokinetic system (composed of 1kW turbine,
3.5kW converter, and 7 batteries) has an initial capital cost of $11 475, a Net Present
Cost of $16 713, and energy production cost of 0.387 $/kWh.
The results of this study have led to the following further study recommendations:
• Identify sites and assess potential energy available,
• Develop policies supporting the development of hydrokinetic power in South Africa.