Technology Status - NET Nowak Energie & Technologie AG

Head [m]
1000
100
10
Figure 8
Small Hydropower Turbine Selection Chart
1
10 0 kW 100 kW 500 kW
0.01 0.1 1
Flow [m
10 100
3 3/s]
Generators
Today, generators commonly have efficiency rates of 98-99%. Two main
types of generators are used in the small hydropower industry: synchronous
and asynchronous generators. Synchronous generators typically have higher
efficiency but are more expensive. Control of their rotor excitation also
requires a more complex and more expensive regulating device. Both
generator types are very well known throughout the industry and have been
steadily improved to meet the needs and demands of the hydropower sector.
The efficiency of small hydropower depends mainly on the performance of
the turbine, since generator efficiencies are close to 100%. As a general rule,
larger and newer plants have higher efficiencies of up to 90%. Average
performance is typically in the range of 70% to 85%. Efficiency can be as low
as 60% for old and smaller plants.
2
SMALL HYDROPOWER
35
10000 1 kW
5000 kW
1000
kW
Sources: NET Ltd., Switzerland; RETScreen International; MhyLAb. Turbine graphics courtesy of European Small
Hydro Association