Hydropower retrofitted onto existing water infrastructure assets

Transcription

1 Hydropower retrofitted onto existing water infrastructure assets Marco van Dijk Lecturer and Principal Researcher University of Pretoria / Water Research Commission South Africa

2 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.

3 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

4 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.

5 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.

6 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.

7 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

8 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 Small 100kW to 1MW 1MW to 10MW 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). NB: All installations above 10MW are classified as macro (or large) hydropower plants

9 Hydropower classification Conventional hydropower Dams, run-of-river and pump storage Unconventional hydropower Anything else Linked to: Different application New technology Size

10 Hydropower classification

11 Elements Head H (variable) Depends on: Intake location Powerhouse location Pipe length Pipe diameter Q H 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

12 Elements Diversion Channel Intake Pipeline Power Line Powerhouse Tailrace

13 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

14 Elements Civil Works Impoundments/dams/weirs/reservoirs

15 Elements Civil Works Intake structures

16 Elements Civil Works Trash rack and sediment trap

17 Elements Civil Works Trash rack and sediment trap

18 Elements Civil Works Canals and tunnels

19 Elements Civil Works Penstock

20 Elements Civil Works Powerhouse

21 Elements Civil Works Powerhouse 5kW 80kW 2.5MW 100MW

22 Elements Civil Works Tailrace 2.5MW 500kW 5kW

23 Elements Mechanical Works Turbine Valves Pipework Electrical/Electronic Generator Transformers & switchgear Controls Grid connection

24 Assets with hydropower opportunities

25 Assets with hydropower opportunities

26 Assets with hydropower opportunities

27 Assets with hydropower opportunities

28 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)

29 Assets with hydropower opportunities We also have a vast network of rivers - Opportunities

30 Assets with hydropower opportunities

31 Assets with hydropower opportunities

32 Assets with hydropower opportunities Operational category Type Purpose Open channel Conveyance Tunnel / conduit Aqueduct Drops (vertical and chutes) Culverts Water distribution systems Bulk sewer lines Convey fluid from one point to another Regulatory and diversions Sluice gates Control water level upstream side of structure. Weirs Navigation, Storage, Hydro. Barrages Parshall flume Flow measurement Crump weir Broad crested weir Sharp crested weir Measure flow Dams Outlet works Reserve flow releases, domestic or irrigation releases, spill/overtopping flows Water treatment works Inlet works Treatment facility with specific opportunities at Outlet works both in- and outlet Waste water treatment works Inlet works Treatment facility with specific opportunities at Outlet works both in- and outlet Energy dissipation Drop structure Dissipate energy associated with big elevation Kinetic structure change, or velocity head Industrial flows Conduits and channels Water utilized in industrial activities/processes

33 Examples of 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)

34 Example Household supply 10 W potential Pico hydropower unit

35 Example - Zeekoegat WWTW

36 Example - Zeekoegat WWTW 20 kw potential

37 Example - Zeekoegat WWTW 5 kw developed

38 Example Boegoeberg Irrigation Canal 15 kw potential (specific site)

39 Example Boegoeberg Irrigation Canal

40 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 m 3 /s

41 Example Bulk water supply line (Bloemwater) 96 kw developed (350 kw potential)

42 Example Transfer scheme (Teebus)

43 Example Transfer scheme (Teebus) Irrigation tunnel (5.3 m diameter, 82.8 km long)

44 Example Transfer scheme (Teebus) Potential: ±10 MW

45 Example Control structure (Teebus) Tunnel outlet

46 Example Control structure (Teebus) Potential ±1.3MW 11 months a year 24 h/day

47 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

48 Example Dam (Hartebeespoort)

49 Policy and Regulation SUSTAINABLE HYDROPOWER POLICY POSITIONS Draft for internal consultation and discussion - Version 1 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

50 Integration of assets (water and hydro) 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

51 Integration of assets (water and hydro) Objective function 1: maximize the income from the hydropower generation system F j = max T ρgh t,j Q t,j η t,j C t,j t=1 Constraints Reservoir storage limits Pipe system discharge limits Hydropower station power generation limits Hydropower station discharge limits Water balance equation

52 Integration of assets (water and hydro) Similar to cascading reservoirs/dams

53 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). R i = min T i=1 Reservoir operating risk evaluation Pipeline operating risk evaluation α t,i β t,i P t,i I t,i

54 Elevation (m) Integration of assets (water and hydro) De Hoek reservoir Uitkijk reservoir Brandkop reservoir Uitkijk - Brandkop profile De Hoek - Uitkijk profile HGL maximum flow Chainage (m)

55 Integration of assets (water and hydro) CHOT analyses provides Paretooptimal trade-off curve 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.

56 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

57 In summary 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

58 The authors wish to thank the Water Research Commission of South Africa for funding the various research projects