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Hydropower retrofitted onto existing water infrastructure assets Marco van Dijk
Lecturer and Principal Researcher
University of Pretoria / Water Research Commission
South Africa
Presentation Layout
• How to identify assets with hydropower opportunity?
• Aspects of importance in development of water infrastructure assets.
• Integration of the hydropower with the main function of the water infrastructure asset.
Presentation Layout
• Introduction
• Classification/groupings of hydropower
• Elements (Civil, Mechanical and Electrical/Electronic)
• Assets with hydropower opportunities
• Examples of opportunities
• Policy and regulation
• Integration of assets (water & hydro)
• Summary
Introduction
• Water storage and supply schemes in SA provide an exciting opportunity for hydropower development. As of the rest of the world.
• These assets worth billions in monetary value have been constructed over decades as the country developed and expanded.
Introduction
These assets onto which hydropower can be retrofitted however have various owners:
– Government (DWS)
– Water Boards
– Irrigation Boards
– ESKOM
– Municipalities (all levels)
– Privately owned
– Mines, etc.
Introduction
• Recently DWS compiled a draft policy document which aims to allow for the sustainable development of their infrastructure (dams, weirs, canals, pipelines etc.) by hydropower developers.
• This will open up numerous opportunities in the hydropower field.
Introduction
• What is hydropower?
Hydropower is often referred to as water power. The simplest definition of hydropower would be the power that derives from the force of energy of the moving water.
• Available WRC studies KV238/10 - A High Level Scoping Investigation into the Potential of
Energy Saving and Production/Generation in the Supply of Water Through Pressurized Conduits
TT596/14 - Conduit Hydropower Pilot Plants
TT597/14 - Conduit Hydropower Development Guide
KV323/13 - Scoping study: Energy generation using low head hydro technologies
Hydropower classification
Hydropower
category
Capacity in
power output
Potential hydropower use either as a single source or in a hybrid
configuration with other sources of renewable energy
Pico Up to 20kW 10kW network to supply a few domestic dwellings
Micro 20kW to 100kW 100kW network to supply small community or building with
commercial/manufacturing enterprises
Mini 100kW to 1MW 1MW to 10MW network– electrical distribution will be at
medium voltage ranging from 11 to 33kV and transformers are
normally needed. The generation must be synchronised with the
grid frequencies (typically to 50 or 60 Hertz). Small 1MW to 10MW
NB: All installations above 10MW are classified as macro (or large) hydropower plants
Hydropower classification
• Conventional hydropower Dams, run-of-river and pump storage
• Unconventional hydropower Anything else
Linked to:
Different application
New technology
Size
Hydropower classification
http://hydro4africa.net/
Elements
Head H (variable) Depends on: • Intake location • Powerhouse location • Pipe length • Pipe diameter Flow Q (variable) Depends on: Hydrology • Catchment • Rainfall • Storage • Geology • Surface cover • Flow duration curves
Hydraulics • Demand pattern • System layout • Reservoir capacities • Flow duration curves
Q H
Elements
Diversion Channel
Intake
Pipeline
Tailrace
Powerhouse
Power Line
Elements – Civil Works
Conventional hydropower schemes consist of a number of structures or combinations of structures, depending on the type and layout of the scheme. • Impoundments/dams/weirs • Intake structures • Trash rack and sediment trap • Canals and tunnels • Penstock • Powerhouse • Tailrace All these components are not always necessary
Elements – Civil Works Impoundments/dams/weirs/reservoirs
Elements – Civil Works Intake structures
Elements – Civil Works
Trash rack and sediment trap
Elements – Civil Works
Trash rack and sediment trap
Elements – Civil Works Canals and tunnels
Elements – Civil Works Penstock
Elements – Civil Works Powerhouse
Elements – Civil Works Powerhouse
5kW 80kW 2.5MW 100MW
Elements – Civil Works Tailrace
2.5MW 500kW 5kW
Elements
• Mechanical Works – Turbine
– Valves
– Pipework
• Electrical/Electronic – Generator
– Transformers & switchgear
– Controls
– Grid connection
Assets with hydropower opportunities
Assets with hydropower opportunities
Assets with hydropower opportunities
Assets with hydropower opportunities
Due to SA having a semi-arid climate, we have a vast network of large dams and water distribution infrastructure (according to SANCOLD > 4500 registered dams)
Assets with hydropower opportunities
We also have a vast network of rivers - Opportunities
Assets with hydropower opportunities
Assets with hydropower opportunities
Assets with hydropower opportunities
Operational category Type Purpose
Conveyance
Open channel
Convey fluid from one point to another
Tunnel / conduit
Aqueduct
Drops (vertical and chutes)
Culverts
Water distribution systems
Bulk sewer lines
Regulatory and diversions
Sluice gates Control water level upstream side of structure.
Navigation, Storage, Hydro. Weirs
Barrages
Flow measurement
Parshall flume
Measure flow Crump weir
Broad crested weir
Sharp crested weir
Dams Outlet works Reserve flow releases, domestic or irrigation
releases, spill/overtopping flows
Water treatment works Inlet works Treatment facility with specific opportunities at
both in- and outlet Outlet works
Waste water treatment works Inlet works Treatment facility with specific opportunities at
both in- and outlet Outlet works
Energy dissipation Drop structure Dissipate energy associated with big elevation
change, or velocity head Kinetic structure
Industrial flows Conduits and channels Water utilized in industrial activities/processes
Assets with hydropower opportunities
Examples of retrofitting existing assets with hydropower
• Household supply (<1 kW)
• Waste Water Treatment Works outflow (20 kW)
• Irrigation canal (15 kW)
• Bulk water supply line (96 kW)
• Water Treatment Works inflow (
• Transfers scheme (10 MW)
• Hydraulic control structure (1.3 MW)
• Dam (? MW)
Examples of opportunities
Example – Household supply
Pico hydropower unit
10 W potential
Example - Zeekoegat WWTW
Example - Zeekoegat WWTW
20 kW potential
Example - Zeekoegat WWTW
5 kW developed
Example – Boegoeberg Irrigation Canal
15 kW potential (specific site)
Example – Boegoeberg Irrigation Canal
Example – Bulk water supply line (Bloemwater)
Pipeline Distance 105 km
Pipeline Diameter 1170 mm
Avg. Pressure Head 46.5 m
Avg. Flow rate 1.05 m3/s
Example – Bulk water supply line (Bloemwater)
96 kW developed (350 kW potential)
Example – Transfer scheme (Teebus)
Irrigation tunnel (5.3 m diameter, 82.8 km long)
Example – Transfer scheme (Teebus)
Potential: ±10 MW
Example – Transfer scheme (Teebus)
Tunnel outlet
Example – Control structure (Teebus)
Potential ±1.3MW 11 months a year 24 h/day
Example – Control structure (Teebus)
Example – Dam (Hartebeespoort)
Opportunity to generate 134 kW on a continuous basis. Site has greater potential, up to 5.7 MW, when utilizing the water released for irrigation, domestic and industrial consumption as well as excess yield available due to increasing inflows from WWTW
Example – Dam (Hartebeespoort)
Policy and Regulation
• The policy is at a very advanced stage now.
• Top Management categorised it as a Strategic Policy
• In other words there is support for the first draft
• Next step is to go through relevant governance structures approval process
• At the Ministers office, for approval to gazette and obtain public comments
• Start public consultations
SUSTAINABLE HYDROPOWER POLICY POSITIONS
Draft for internal consultation and
discussion - Version 1
• WDS analysis is governed by complex, non-linear, non-convex and discontinuous hydraulic equations.
• Adding to this complex network, the hydropower plant from which maximum benefit needs to be extracted requires a systematic procedure to evaluate the interrelationships
• A procedure could be using a multi-objective genetic algorithm, maximizing electricity generation and hence revenue and minimizing the risk of non-supply.
• Objective function: maximize the net annual income from the hydropower generation system whilst still operating the water supply system within acceptable reliability regimes
Integration of assets (water and hydro)
• Objective function 1: maximize the income from the hydropower generation system
Fj = max ρgHt,jQt,jηt,jCt,j
T
t=1
Constraints Reservoir storage limits Pipe system discharge limits Hydropower station power generation limits Hydropower station discharge limits Water balance equation
Integration of assets (water and hydro)
Similar to cascading reservoirs/dams
Integration of assets (water and hydro)
• Objective function 2: Minimize the risk of non-supply i.e. associated risk when reservoir levels are low, or operating scenarios which could compromise the system integrity (maximizing the reliability).
Ri = min αt,iβt,iPt,iIt,i
T
i=1
Reservoir operating risk evaluation Pipeline operating risk evaluation
Integration of assets (water and hydro)
Uitkijk reservoir
Brandkop reservoir
De Hoek reservoir
1 400
1 450
1 500
1 550
1 600
1 650
0 20 000 40 000 60 000 80 000 100 000
Chainage (m)
Ele
va
tio
n (
m)
Uitkijk - Brandkop profile
De Hoek - Uitkijk profile
HGL maximum flow
Integration of assets (water and hydro)
The peak rates for electricity are significantly higher than standard and off-peak rates and therefore the maximum income in this case is not generated when the total maximum power is generated for the week but rather generating maximum power during peak periods.
CHOT analyses provides Pareto-optimal trade-off curve
Integration of assets (water and hydro)
In summary
• The development of these hydropower schemes will require a management strategy to integrate the operation of the hydropower and the main function of the asset, which could be water supply, measuring of flow, treatment of water, etc.).
• Similarly the maintenance should be incorporated in a sustainable way with that of the asset
• It is believed that there are water assets in South Africa and elsewhere where hydro power opportunities exist
• Feasible and sustainable solutions without subsidies
• Require more successful working plants
• Require some legislative changes
In summary
The authors wish to thank the Water Research Commission of South Africa for funding the various research projects
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