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close this bookGATE - 2/88 - 10 years GATE (GTZ GATE; 1988; 44 pages)
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Micro-Hydropower

Due to an oversight the table referred to in our last "Catchword" (gate 1/ 88, p. 11) has unfortunately been omitted. Here it is; we have also decided to reprint the "Catchword" text as an aid to interpreting the table. - Ed.

Micro-hydropower (MHP) is one of the less sophisticated technologies to harness waterpower and as a relatively low installed capacity per unit.

Micro-hydropower can be further subdivided into low-rpm water-wheels and medium or fast running turbines. It should be added here that waterwheel technology has been known to man for hundreds of years in many parts of the world which are today classed as developing countries. The crossflow (or Mitchell-Banki) turbine, which is widely used in micro-hydropower installations, features elements of both the waterwheel and large-scale water-power installations.

In many developing countries with major water power resources which have often only been marginally developed efforts are being or have been made to put this potential to better use. Water power is being harnessed to provide electricity for village communities as well as towns and is thus an important instrument of regional rural development.

Designation per unit

Installed capacity utilization

Energy

Small hydropower

1000-10,000

electricity only

Mini-hydropower

50-2,000

electricity only

Micro-hydropower drives

0-100

mainly mechanical

These rural electrification programmes have, however, often failed because the quantities of energy used in the villages were so minimal that the receipts from sale of electricity were not even sufficient to cover the costs of the meter.

Villagers only need power in the evenings for electric light, radio, and perhaps television. Only the most wealthy families in the village can afford a refrigerator. In this way the total electricity consumed by a village household rarely exceeds ten or fifteen kilowatt hours in three months.

Changing over to smaller water power units, such as small and mini hydropower units, also failed to resolve this problem. Although this did not entail investment in high-voltage transmission lines the investment costs per installed capacity rose. The costly governing and control devices are only marginally cheaper for smaller units. In most countries this is the result of national legislation which lays down high quality standards and permits only slight deviations in voltage and frequency.

In this circumstances mini-hydropower plants can only be built at a few locations and only a few plants can be built per annum in any given country. These plants therefore have to be imported since local production does not appear economically viable. Importing machinery, however, entails the well-known problems when repairs are necessary: spare parts are expensive, delivery times long and the costs of employing foreign fitters astronomical. The table overleaf is a comparison of micro-hydropower and mini hydropower.

Since micro-hydropower is more attractive, GATE has decided with the approval of the German Federal Ministry for Economic Co-operation to use the wealth of experience available at organizations such as ITDG in the United Kingdom, SKAT in Switzerland and FAKT in the Federal Republic of Germany in implementing micro-hydropower projects of its own in various countries with suitable hydropower potential. This work is being co-ordinated by the Energy Section of the Deutsche Gesellschaft fur Technische Zusammenarbeit (GTZ), GmbH.

Comparison of Mini-Hydropower and Micro-Hydropower

Criterion

Mini-hydropower

Micro-hydropower

End form of energy

usually electricity

usually mechanical, shaft power,

electricity generation possible,

but problematic

 

Level of technology required

medium or high

low to medium

     

Machinery manufacturer

foreign (imported)

local (engineering or mechanical workshop)

     

Governor

necessary and costly

not necessary

     

Investment cost per kW

high

low

     

Type of realization

only individual plants

production and dissemination

     
 

programme possible

       

Spare parts supply

complicated, involves delay,

easy, fast, cheap

     

costly (imported)

(produced locally)

       

Major repairs to be flown in

manufacturer's mechanic has

can be done locally

     

Energy consumption

low, irregular; in rural regions

unproblematic;

     

only in the evenings

important that simple

machinery is available

     

Lighting, radio, TV in evenings

unproblematic

possible, but problematic

     

Technology transfer from industrialized to developing country

very difficult and time-consuming

simple or moderately difficult

     

Partner organizations

Electricity Corporations

village millers, artisans, workshops,

(national or communal)

small and medium-scale industries

 

Operation and maintenance

costly, if electricity corp.

done by miller in his spare time

of plants

requires own staff

 

Intake construction

often costly reinforced concrete

simple, cheap, has to be renewed

construction, flood damage

annually after flooding

sometimes irreparable

Connection to national grid

possible

not possible

     
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