Marco van DijkLecturer

University of Pretoria

South Africa

The first conduit hydropower installation in a city ’s water distribution system in South Africa

Do you know how an electrician tells if he's working with AC or DC power?If it's AC, his teeth chatter when he grabs the conductors. If it's DC, they just clamp together.

What's the difference between a woman and a battery?A battery has a positive side.

• What is conduit hydropower?

• Research project

• Description

• Identifying potential sites

• Potential sites in Tshwane

• Identified projects

• PvRCHP

• Feasibility

• Way forward

The first conduit hydropower installation in a city ’s water distribution system in South Africa

• Conduit hydropower is where excess energy available in pressurised conduits (pumping or gravity) is transformed into clean, renewable hydroelectric energy by means of a turbine.

• The excess energy is normally dissipated by means of pressure control valves but by conveying it through a parallel dissipating system, the water turbine, the pressure head and flow is utilized to generate hydroelectric power.

What is conduit hydropower?

What is conduit hydropower?Uitkijk reservoir

Brandkop reservoir

1 400

1 420

1 440

1 460

1 480

1 500

1 520

1 540

1 560

1 580

0 10 000 20 000 30 000 40 000 50 000 60 000

Chainage (m)

Ele

va

tio

n (

m)

Longitudinal profile

HGL static conditions

HGL maximum flow

∆Hmax = 83.2 m, Qmin = 0 m³/s

Qmax = 1.42 m³/s, ∆Hmin = 15 m

∆H

What is conduit hydropower?Uitkijk reservoir

Brandkop reservoir

1 400

1 420

1 440

1 460

1 480

1 500

1 520

1 540

1 560

1 580

0 10 000 20 000 30 000 40 000 50 000 60 000

Chainage (m)

Ele

va

tio

n (

m)

Longitudinal profile

HGL static conditions

HGL maximum flow

When flowing at 70% of design capacity ∆H70% = 47.1 m, Q70% = 1.0 m³/s

Research project

Title: Energy generation from distribution systems

Period: 2 years

Funding: Water Research Commission with a number of collaborating organisations

• To prove feasibility and technically possible

• Development of guidelines to identify potential hydropower locations

• Development of an assessment model including a cost benefit tool

• Development of optimization tool

• Demonstration using full scale pilot plants

• To illustrate benefits and complications

• Provide educational material

Research project aims

“Conduit hydropower” – energy generated from pressurised conduits

Description

Drivers for a municipality to consider “conduit hydropower”:

• Renewable energy source

• Rising energy costs

• Reduced revenues

• Financial incentives

• Public perception

• Job creation

• Extending the operational life of control valves

• Remote power (alarms, communications etc.)

Description

• Q, H, generation time and assurance of supply

• Accessible?

• Reservoir storage to accommodate fluctuating demands

• Generated electricity consumption?

• Bypass alternative

• Safety mechanisms

• Feasibility

Identifying potential sites

Potential sites in Tshwane

Geographically speaking the City of Tshwane has a lower elevation then the bulk service Reservoirs of Rand Water which is the main water supply. Water is then distributed through a large water system that includes 160 reservoirs, 42 water towers, 10677 km of pipes and more than 260 pressure reducing installations (PRV’s) that operates at pressures of up to 250 m.

Potential sites in Tshwane

Potential sites in Tshwane

Reservoirs TWL(m.asl)

Capacity(kl)

Pressure(m)

Flow(l/s)

YearlyPotential power

generation (kWh) #

Garsfontein 1 508.4 60 000 165 1850 3 278 980

Wonderboom 1 351.8 22 750 256 470 1 292 471

Heights LL 1 469.6 55 050 154 510 843 673

Heights HL 1 506.9 92 000 204 340 745 062

Soshanguve DD 1 249.5 40 000 168 400 721 859

Waverley HL 1 383.2 4 550 133 505 721 483

Akasia 1 413.8 15 000 190 340 693 930

Clifton 1 506.4 27 866 196 315 663 208

Magalies 1 438.0 51 700 166 350 624 107

Montana 1 387.6 28 000 82 463 407 829

Total calculated yearly power generation in Tshwane from Total calculated yearly power generation in Tshwane from 10 reservoirs 10 reservoirs -- (Nearest 10 000 kWh)(Nearest 10 000 kWh) 10 000 00010 000 000

• Pilot plants by collaborating organisations

• City of Tshwane Metropolitan Municipality (various)

• Queenswood Reservoir (PaT)

• Pierre van Ryneveld Reservoir

• Ethekwini Municipality (various)

• Sea Cow Lake, Kwa Mashu 2, Aloes, Phoenix 1, Phoenix 2 and Umhlanga 2 Reservoirs

• Bloem Water (0.6 MW)

• Uitkijk and Brandkop reservoirs

• Rand Water (13MW)

• Zoekfontein, Klipfontein, Brakfontein and Hartebeeshoek

Identified projects

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Supply line

Isolating valve

Cross flow turbine

“ballast tank”

Control panel

“pinch valve”

Guide vane control

15kW

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower PlantPierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Pierre van Ryneveld Conduit Hydropower Plant

Feasibility (PvRCHP)

Payback period

•The preliminary cost for the pilot plant totalled R550 000.

•This was for the turbine and generator, electrical work, pipework, valve chamber, enclosure/plant housing, monitoring system and

data logging and communication system.

•Annual income could be in the order of R130 000 for electricity generated based on 100 c/kwh.

•Assuming a discount rate of 10% and a very optimistic energy escalation rate of only 8% results in a payback period of ±5 years

(IRR = 28% for 20 year design life).

Payback period

•The preliminary cost for the pilot plant totalled R550 000.

•This was for the turbine and generator, electrical work, pipework, valve chamber, enclosure/plant housing, monitoring system and

data logging and communication system.

•Annual income could be in the order of R130 000 for electricity generated based on 100 c/kwh.

•Assuming a discount rate of 10% and a very optimistic energy escalation rate of only 8% results in a payback period of ±5 years

(IRR = 28% for 20 year design life).

• Why develop large hydropower?

• Economically feasible – Garsfontein #1 and others

• Why develop smaller conduit hydropower schemes?

• On site use of electricity

• Upliftment of community• Free internet access for an area?

• Free electricity for a school?

• Mass lighting?

• Improved operational control of WDS• Telemetry

• Security/Alarm system

• Site lighting

• Identification and development of other water infrastructure with hydropower potential

Way forward

Way forward - Example

Way forward - Example

Potential this past week = 82 097 kwhAnnual potential = 4 280 000 kwh

Way forward - Options

Energy generation from distribution systems P1-

THANK YOU!