C. Alatorre Frenk & T. H. Thomas (1996)
For micro hydropower systems, say under 100 kW, there has been a growing interest in using turbines having no hydraulic controls. The financial savings from omitting control gear is substantial and further savings are possible if 'pumps', mass-produced in country, are used instead of individually designed turbines, often imported.
There are three system/operation designs we might use in this context. The simplest way of operating is to employ a single turbine that runs only when river flow exceeds turbine rated flow. A second option is to employ several small turbines operating in parallel: the number in use is varied to match the variation in river flow. A third option is to intermittently operate a single turbine fed from a small reservoir (e.g holding only 15 minutes flow). It is the purpose of this paper to compare these three alternatives and to show that the third has apparent economic advantages over the others. All three alternatives can give higher economic returns in many semi-industrialised countries where, power for power, turbines cost over four times more than pumps.
Note: scan of the original document.