watermill to microhydropower_ethiopia
DESCRIPTION
Micro-hydropower systems are relatively small power sources that are appropriate in most cases for individual users or groups of users who are independent of the electricity supply grid.1 In Ethiopia, where the national elec-tricity supply is still on the development stage to satisfy the increasing energy demand, off-grid small scale hy-dropower plays a major role for rural and remote communities’ energy consumption. The remote, highlands and river rich areas of Ethiopia have been an attractive site for small scale hydropower generation.The rural communities mostly from Ethiopian highlands have begun using watermills instead of hand mills (pounding) for grain-milling industry, in private as well as cooperative basis, back to mid-19th century.2 The analogy of watermills and micro hydropower is quite apparent as they both exploit the head potential and volume of water for their respective specific purpose; watermills use the potential for rotating a locally-made turbine, in turn wheeling the grinding-disks to grind grains, whereas Hydropower advances the system to produce electricity. A lot of studies have been attempted to upgrade the traditional system of watermills to a multipurpose micro hydropower schemes.GIZ (Deutsche Gesellschaft für Internationale Zusammenarbeit) by its Energy Coordination Office in Ethiopia have made an effort to develop and execute two or three pilot projects for small scale hydropower in cooperation with Jimma University and other local organizations. Jimma University Institute of Technology has undergone an investigation and up gradation of feasible watermills sites for electricity generation in 2008/9.This presentation discusses the Desk study, Reconnaissance visit, Pre-feasibility study & Feasibility study that have been performed to select best 2 potential watermill sites for Micro-hydropower production from the 7 pro-posed sites in Southwestern Ethiopia. It illustrates the generalTRANSCRIPT
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!