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Kariba South Extension Project
Janus Basson
Introduction
• Client: The Zimbabwe Power Company
(ZPC)
• Consultant: Hatch Africa (Pty) Ltd
• Hydro Project: Kariba South Extension
Project (KSEP)
– 2 x 150 MW
• Thermal Project: Hwange Expansion
Project
– 2 x 300 MW
Background
• Present peak power demand of 2500 MW
• Existing power stations (Installed capacity)
– Kariba South (Hydro) – 750 MW
– Hwange (Thermal) – 920 MW
– Other (Small Thermal) - 250 MW
• Available capacity of less than 1 500 MW
• Also imports from SAPP
Project Phasing
• Phase 1: Evaluation
• Phase 2: Engineering
• Phase 3: Construction and Commissioning
• Phase 4: Warranty
Location
5
Kariba Dam
6
Kariba Dam (2)
Dam Height 128 m
Crest Length 617 m
Spillway Gates 6 x 8.8 m wide and 9 m high
Spillway Discharge Capacity 9 500 m³/s
Full Supply Level El 488.5 m
Minimum Operating Level El 475.5 m
Total Storage 180.6 x10⁹ m³
Live Storage 64.8 x10⁹m³
Lake Area 5 580 km2
Kariba Complex
Kariba North
Kariba South
Kariba South Power Station
Kariba South Power Station (2)
Type of powerhouse Underground
Number of units 6
Type of turbine Vertical Shaft Francis
Capacity of each unit 125 MW
Speed 166.7 RPM
Rated Head 86 m
Generation voltage 18 kV
Generator Transformer
(common for two units)
3x80 MVA, 18/330 kV
(single phase transformers)
Kariba South Extension Project
Project Operation Peaking Power
Design Head 89.0 m
Design Flow 376 m3/s total, (188 m3/s per unit)
Intake Headwork’s A conventional submerged intake with trash
racks and bulkhead gate slots
Low-Pressure
Tunnels
Two 7 m diameter concrete-lined low-pressure
tunnels
Inclined/ Vertical
Shafts
Two 7 m diameters inclined or vertical shafts
Power Tunnels Two 6.5 m diameter concrete lined tunnels
Penstocks Two 6.5 m diameter steel-lined penstock
sections
Powerhouse Underground powerhouse cavern
approximately 24 m wide x 36 m high x 94 m
long
Kariba South Extension Project
Surge Chamber The surge chamber is an 25 m diameter by 60
m high vertical shaft excavation
Turbine Two vertical-axis Francis units with a capacity
of 150 MW each unit.
Turbine Speed 150 rpm
Generator Direct-coupled synchronous type, each
generator rated at 180 MVA, 50 Hz, 0.85 pf,
18.0 kV
Tailrace Tunnel Single 12 m diameter
Step-Up
Transformers
Two three phase step-up transformers
General Layout
Long Section
Powerhouse Layout
Layout at Centre Line of Units
Section - Powerhouse
Transformer Platform
Contracting Strategy
• Competitive Bid
• FIDIC Silver Book (EPC/Turnkey Projects)
• Expression of Interest (EOI)
• EPC Tender Documents to be issued to
between 3 and 5 short-listed bidders
• Technical and Financing bids to be
evaluated
Current Project Status
• EPC Tender Documents were issued for
Client Review
• Expression of Interest closed on 13
September 2011
• EPC Tender Documents to be issued to the
short-listed bidders during November 2011
• 4 month bid period
