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!