Catchword

Micro-Hydropower

In the utilization of water power, micro-hydropower (MHP) is at the lower end of the scale as regards technological sophistication and installed capacity per unit.

Micro-hydropower can be further subdivided into low-rpm waterwheels and medium to fast running turbines. It must be added here that waterwheel technology has been known for hundreds of years - also in many of the developing countries of today. 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.

Many developing countries with major water power resources, which often have only been developed to a minor degree, are attempting, or have attempted, to expand this potential to provide electricity for village communities as well, as a means of developing rural regions. However, these rural electrification programmes have often failed because the quantities of energy used in the villages were so low that the income from electricity bills did not even cover the cost of the meters.

Villagers only need power in the evenings, for electric light, radio, and perhaps television. Only the wealthiest family in the village can afford a refrigerator. Thus, the power consumption of 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) also failed to resolve this problem, because although it made investments for high-voltage transmission lines unnecessary, the investment costs per kilowatt of installed capacity increased. The costly regulating and control devices are hardly any cheaper for smaller units; in most countries this is the result of national legislation which lays down high quality standards- only slight deviations in voltage and frequency are permitted.

Designation	Installed capacity per unit	Energy utilization
Small hydropower	1000-10,000	electricity only
Mini-hydropower	50- 2,000	electricity only
Micro-hydropower	0- 100	mainly mechanical drives

Given these circumstances, it is only possible to build mini hydropower plants at a few locations - and over a country as a whole, only a few plants per year. Therefore, these plants have to be imported: national production of the machines does not appear economically viable. However, with imports, the well known problems associated with repairs crop up again: spare parts are expensive, they take a long time to arrive, and foreign fitters are far too expensive. (In the next page, table micro-hydropower and mini-hydropower are compared on the basis of certain criteria).

As micro-hydropower has more advantages to offer, GATE has decided - with the approval of the Federal Ministry of Economic Cooperation in Bonn - to exploit the wealth of experience of ITDG (UK), SKAT (Switzerland), FAKT (FRO) and other organizations, and to implement micro-hydropower projects of its own in various countries with suitable hydropower potential. This work is being coordinated with the Energy Section of the Deutsche Gesellschaft fur Technische Zusammenarbeit (GTZ) GmbH.