Pico-hydropower is a viable technology that can be integrated into a decentralized, off-grid approach to
rural electrification in regions that currently have only limited access to electricity. The Turgo turbine is
classified as an impulse turbine, similar to the Pelton wheel, often used in pico-hydro systems. Both offer
high efficiency for a broad range of site conditions, but the primary difference is that the Turgo can
handle significantly higher water flow rates, allowing for efficient operation in lower head ranges and
thus potentially expanding the geographic viability. Published data on Turgo operating performance are
limited; despite the differences, discussion thereof in design manuals is generally lumped in with the
discussion of Pelton wheels. In this study, a laboratory-scale test fixture was constructed to test the
operating performance characteristics of impulse turbines. Tests were carried out to determine the effect
on turbine efficiency of variations in speed ratio and jet misalignment on two Turgo turbines. The results
were compared to similar tests in the same fixture on a Pelton turbine. Under the best conditions, the
Turgo turbine efficiency was observed to be over 80% at a speed ratio of approximately 0.46, which is
quite good for pico-hydro-scale turbines. Peak efficiencies for both the Pelton and the Turgo turbines
occurred at lower than theoretical ideal speed ratios based on a momentum balance; the reduction in
speed ratio at which peak efficiency occurs is likely caused by inefficiencies in the turbine. Tests of jet
misalignment showed that moving the jet to the inside or outside edge of the turbine blades caused
a drop in Turgo efficiency of 10e20% and reduced the optimal speed ratio by 0.03 (6.5%). Radial
misalignment had a significant adverse impact on both Turgo and Pelton turbines, however, angular
misalignment of the jet is more of a concern for the Turgo turbine. The results stress the importance of
proper system design and installation, and increase the knowledge base regarding Turgo turbine
performance that can lead to better practical implementation in pico-hydro systems.