Post on 28-Jan-2018
Identification and study of feasible watermill sites for
Micro Hydropower Generation in Jimma Area
Seminar Presentation Frezer Seid Awol
30.10.2012
Watermills
• Constructed by diverting water from river to hit a wheel which is connected to a mill
• Water driven mills used to grind grains • History in Ethiopia traced back to mid 19th century • Distributed in rural areas where electricity and diesel not reached • Privat or public Substitute hand-driven mills Small scale industry Multipurpose use of river X Slow operation X Flooded in rainy seasons X Inefficient water use
Hence, upgrading to small hydropower scheme was advocated and requested.
Classification of Hydropower
By capacity
Large >100 MW
Medium 15-100 MW
Small 1-15 MW
Mini 100 KW – 1 MW
Micro 5 – 100 KW
Pico <5 KW
By design head
Low-head <15 m
Medium-head 15-50 m
High-head >50 m
By grid type
Off-grid
In-grid
By design type
Run-of-river
Pumped-Storage
Storage
Tidal
By Power supply system (Ethiopian context)
Inter-Connected System (ICS)
Self-Contained System (SCS)
The investigation sites are off-grid, low to medium head, micro, self-contained system run-of-river hydropower plants.
• Memorandum of Understanding signed between Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH and Jimma University : – To actively involve stakeholders in hydropower development secter – To select and implement 2 joint pilot projects in Jimma area from proposed 6 sites for
demonstration and know how transfer – To establish a center of Excelence for research and capacity building
MoU for Rural Electrification
• BMZ and BMF • Since 1964 in Ethiopia • Energy Coordination
Office • Policy & stategy advice • Energy efficient
technology promotion • Rural electrification • Pilot projects evaluation • Funding
• 2nd largest University • Started as a college in
1952 • Institute of
Technology • Courses & Researchs • Proposal on
hydropower projects • Feasibility study for
pilot projects • Jimma Hydropower
Center of Excelence
• Hydro – Scout • Consultancy and support • Customized training and lectures • Feasibility study and design • Research and thesis • 2 Pilot projects design and execution
Jimma Hydropower Center of Excelence
• Concept note and proposal • Awareness and promotions • Community setup • Supervision • Documentation
Source: Abera Melese, JHPCE, July 2010
Feasibility Study - The final decision for or against the
recommended sites - Best 2 pilot projects selection and re-
assessment - Design of civil and electromechanical structures - Socio economic analysis
Detail Design - Preparation of the detailed layout of the Civil &
Electro Mechanical scheme - Cost-Benefit analysis
Pre feasibility study - Available flow at dry season - Available head - Topographic maps - Access to project site - Availability of local construction material at project
sites - To determine which sites are most attractive - Development options , conclusions and
recommendations are made
Desk Study - To be familiar with hydrologic and topographic profile
of the project sites - To be aware of rough location (distance) &
accessibility Reconnaissance visit
- Short Visit to the proposed sites - Identify if there is watermills at the sites & which are
functional or not - Identifying ownership & social structures - Nominate contact persons
Activities
• Desk study • Reconnaissance Visit • Pre – feasibility study • Feasibility study • Detailed design
Team assigned to select 2 most technically & socio-economically attractive watermills sites from the proposed 6 sites and design the HP scheme
Proposed sites
Site Name: Kersa-1 Distance (From Jimma): 23km GPS location: N 07o44’05.2’’ E 37o0’51.62’’ Elevation: 1760masl
Proposed sites
Watermills: 1 traditional Discharge: 120-160l/s Head: 11m Accessibility: Good Power Potential: 11 KW Remark: Attractive
Proposed sites
Site Name: Kersa 2 Distance (From Jimma): 26km GPS location: N 07o 44’ 53.9’’ E 36o 57’ 41.8’’ Elevation: 1750masl
Watermills: NO Discharge: 200l/s Head: 4-5m Power potential : 5.5-6.9KW Accessibility: Bad Remark: Not Attractive for
MHP
Proposed sites
Site Name: Kelecha Distance (From Jimma): 25km GPS location: N 7°39'30.40" E 37° 1'50.71“ Elevation: 1702masl
Watermills: 1 Not functional Discharge: 100 l/s Head: 5m Power output: 3.4KW Accessibility: Medium Remark: Not Attractive for
MHP
Proposed sites
Site Name: Melka Qiltu Distance (From Jimma): 24km GPS location: 7°46'30.71"N 36°38'35.16"E Elevation: 1930masl
Watermills: 1 Not functional Discharge: 80 l/s Head: 15m Power output: 8.24KW Accessibility: Medium Remark: Not Attractive for MHP
Proposed sites
Site Name: Fechie Distance (From Jimma): 23km GPS location: 7°44'8.11"N 36°40'49.06"E Elevation: 2017masl
Watermills: 1 Not functional Discharge: 90 l/s Head: 14m Power output: 8.65KW Accessibility: Bad Remark: Not Attractive for MHP
Proposed sites
Site Name: Wanja Distance (From Jimma): 38km GPS location: N 07o52’02.5’’ E 36o42’03.8’’ Elevation: 1520masl
Watermills: 1 traditional Discharge: 250l/s Head: 35m Accessibility: Good Remark: Irrigation scheme is being
constructed on the river without affecting the watermill, attractive
Site Name Distance (km)
Discharge (m³/s)
Head (m)
Power output (KW)
Accessibility Existing Watermills
Social status
1 Kersa 1 23 0,14 12 11,5 Accessible 1 Operational Active
2 Kersa 2 26,03 0,2 4 5,5 Not accessible None Passive
3 Wanja 38 0,25 35 60,1 Accessible 1 Operational Active
4 Kelecha 25 0,1 5 3,4 Mostly Accessible 1 Abandoned Passive
5 Melka Qiltu 24 0,08 15 8,24 Accessible 1 Abandoned Passive
6 Fechie 23 0,09 14 8,65 Not accessible 1 Abandoned Passive
Proposed sites Summary
Selection Criteria
Technically attractive sites fulfills ideally most of the following criteria • Available flow and head are substantial. • Topography is favorable. • Ratio of water head to canal length is 10% or better. • Firm capacity is more than demand estimate. • Low degree of difficulties / risks. • Distance of powerhouse to load center is less than 1 km per 100 kW
installed capacity. • Consumer density is greater than 30 connections per 1Km of
transmission and distribution lines.
Technically attractive projects are not necessarily promising projects and vise-versa!
Source: GIZ guide lines, MHP assessment standards
Selection Criteria
Non-technical aspects should be considered equally. • Synergies with other projects or installations e.g. irrigation, water supply… • Large part of the equipment can be manufactured & maintained locally. • Limited number of technically critical parts. • Country's feed-in-tariff policy is encouraging. • Substantial equity contribution to project cost is available. • Broad political support at all relevant levels can be secured. • No social conflicts due to project implementation expected. • No major adverse environmental impacts to be expected.
Kersa-1 and Wanja sites are selected.
Source: GIZ guide lines, MHP assessment books, JU Civil Eng’g student thesis
Kersa-1 • 124 households • Power Consumption: 45.276 KWh/household/month • Good access for transportation • Local construction material • Village out of gird line • Traditional weir of 6m length at 40o CCW • Main river 160 l/s, diverted canal 120l/s • 1200m earth canal
Selected sites
Kersa-1 • Development option Option 1. At the existing watermill- To modify the existing site to get 11m
head and upgrade the trash-rack, forebay, penstock and powerhause Option 2. 50m upstream of the watermill- To construct new Civil and
Electro-mechanical structures, • Diverting water completely and using T-14 cross flow turbine(η = 70%),
has power potential of: Power = ηγQH = 0.7*9810 N/m*0.14 m³/s*12 m = 11.5 KW
Selected sites
Wanja • 688 households • Power Consumption: 99.176 KWh/household/month • Site is easily accessible for transportation • Community is in remote area • Head - 35m • Discharge - 250 l/s • Ratio of water head to canal length about 16% • Synergy with Irrigation scheme • Local construction materials available • Power potential = 60 KW • the most attractive & promising feasible site
Selected sites
Wanja
Kersa 1
Rough layout
Hydraulic design Wanja Site
Intake structure – Weir
Hydraulic design Wanja Site
Penstock
Forbay tank
Diversion canal
Length – 220m
Hydraulic design Wanja Site
Penstock – Slide block
• Length = 67m • Type - Welded steel • Internal Diameter = 0.35m • Wall thickness = 6 mm • Anchor block size = 2.34 m3 • Slide block spacing = 8m
Slide block
Hydraulic design Kersa-1 Site
Intake structure – Weir • Type – Diagonal Ogee-crested weir @ 40o
• Calculation according to USACE and Chow, 1959
• HQ50 = 58 m³/s • Length – 7.5m • Upstream height – 1m • Downstream height – 1.66m • Bottom Width – 2.66m
Hydraulic design Kersa-1 Site
Diversion Canal • Modify the traditional canal • Length = 1150 m • Type - unlined earth • Total depth = 0.5m • Base width = 0.7m • Channel bed slope = 0.002 m/m
T-15 Crossflow turbine is selected for both plants
Hydraulic design Turbine Selection
• Design head 36.47m • Design discharge 230 l/sec • Diameter of the runner 0.3m • Calculated width of the runner = bo = 159mm • Calculated turbine speed = 765 rpm • Run away speed = 1377 rpm • Specific speed = 24.7 • Generator, belt and transmission efficiency = 85 % • Electrical power output = 54.28 KW
Hydraulic design Turbine sizing – Wanja site
Locally manufactured T-15 turbine @ Ererte site, a GIZ project
Thank you!