MULTIPURPOSE MINI / MICRO HYDRO PROJECT PLANNING AND

MANAGEMENTPRJ 002

NYAKINDA WALTERF17/10476/2003

SUPERVISOR: MR. WALKADEEXAMINER: DR. MANG’OLI

INTRODUCTION

Category Size

Pico-hydro < 5kWMicro -hydro 5 kW–100kWMini-hydro 100kW-1000kWSmall -hydro 1MW – 15MWMedium-hydro 15 MW- 100 MWLarge- hydro More than 100 MW

PROJECT OBJECTIVE

The objective of this project is to investigate the feasibility of multipurpose mini/micro hydro projects on a co-operative or self help basis

Mini/micro hydro projects can be divided into three categories based on their specific utilisation:

n Milling projectn Add-on electrification projectsn Stand-alone electrification

Benefits of MHP schemen They require considerably less funding and a shorter

time to implementn They permit the local population participation in all

activitiesn Since the site is usually next to the load centre,

transmission distances are shortn Decentralised nature of these schemes coincide with

the dispersed nature of rural populationn The interference with the environment is minimaln They do not require elaborate civil works and the

power generating equipment is relatively simple and can be locally manufactured

Project FeasibilityA list of studies that should be undertaken:-• Topography and geomorphology of the site. • Evaluation of the water resource and its generating

potential • Site selection and basic layout • Hydraulic turbines and generators & their control • Environmental impact assessment and mitigation

measures • Economic evaluation of the project and financing

potential • Institutional framework and administrative procedures

to attain the necessary consents

Components of a mini / micro hydro power scheme

Lateral Intake

Sediment Trap

Losses

Power produced can be calculated as follows:

P= ρ Q g H η

Where:n ρ = specific water density [kg/m3] n Q = Discharge [m3/s] n H = "net head" [m] n g = acceleration due to gravity [m/s2] n H g = specific hydraulic energy of machine [J/kg]n η = turbine efficiency

Turbine Selection based on Head and Discharge

Cross-flow turbine

Synchronous generators

n The synchronous speed is given by:Nsync = 120 f

PWhere: f = frequency

p = number of poles

Asynchronous generators

n These are simple squirrel-cage induction motors running at a speed directly related to system frequency.

n The generator is accelerated to a speed above synchronous speed.

n For stand-alone plants the generator must be supplied with reactive power. This is achieved by adding a bank of capacitors across the machine terminals.

Slip is given by:S = Nsync – Nm

Nsync

Where: Nsync = synchronous speedNm = motor speed

Nm = 120 f (1 - s) P

The generating speed (Ng) is given by:Ng = 120 f (1 + s)

P

Typical efficiencies of small generators

Rated power [kW] Best efficiency 10 0.910 50 0.940

100 0.950 250 0.955500 0.960

1000 0.970

Community ownershipØ Programmes promoting the use of micro-hydro

power in developing countries have concentrated on the social, as well as the technical and economic aspects of this energy source.

Ø Technology transfer and capacity building programmes have enabled local design and manufacture to be adopted.

Ø Local management, ownership and community participation has meant that many schemes are under the control of local people who own, run and maintain them.

CASE STUDY - TUNGU-KABIRI MHP PROJECT

n The site selected for the project case study was on River Tungu about 200Km north of Nairobi, and 12Km from Chuka town, close to Mbuiru village.

n About 200 members of this community came together and formed a commercial enterprise to own, operate and maintain the micro hydropower plant.

n Each individual bought a share in the company, with a maximum share value of about US$50.

n The members also contributed labour, dedicating every Tuesday for over a year to the construction work

n The day-to-day operations of the plant are managed by a 10-member community power committee

n The electricity is currently used mainly for micro-enterprises such as a welding unit, a battery-charging station, a beauty salon, a barber shop, photographic studio, video hall and some retail outlets.

n The scheme now distributes electricity over an area of 3 square kilometres.

n The canal length is 250mn The penstock length is 20mn Head height is 13.5m n The facility is rated at 18 kW; it produces 18kW

mechanical power or 14 kWe.n Flow rate in canal is 200 l/s with an effective 180 l/s

running a T12 cross-flow turbine. n The cross flow turbine is connected to a 40 kW

synchronous generator that produces 3-phase AC power.

MHP in Kenya

CONCLUSION

n So far only a few mini hydro schemes have been realised, either as part of the national grid supply or as stand-alone systems for agro-industrial establishments or missionary facilities.

n Only few examples of community-based installations are known.

FURTHER WORK

n It is expected that the recent liberalisation of the Kenyan power market will facilitate the engagement of private project developers and independent power producers in areas presently not sufficiently served by the national grid.

n The Ministry and the Kenya Bureau of Standards is preparing standards and code of practice to govern the installation and operation of SHP, this steps are expected to encourage the development of community based mini/micro hydro power initiatives

END

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