Hydrokinetic Turbines for Moderate Sized Rivers
Summary: The paper argues that for HKTs(hydro kinetic turbine) to genuinely serve rural off-grid
communities, they must be affordable, reliable, and deployable at many ordinary river sites not just
exceptional deep, fast-water locations. The paper focuses specifically on villages in high-rainfall
tropical regions where solar, wind, and conventional micro-hydro are all inadequate. The paper
identifies these issues with HKTs: high capital cost, low capacity factor, low power density from slow
river flow, shallow water, rocky beds, boat passage requirements, floating debris, log damage, flash
flood loading, and difficult deployment/retrieval.At the end this paper also give a solution on this
issue, The modified New Energetics "orthogonal" turbine (a multi-blade Darrieus variant) is identified
as the most promising: simple, potentially low-cost, buildable in developing countries, and capable
of high blockage in wide shallow rivers.
Research Gap:
The paper identifies several key research gaps for hydrokinetic turbines (HKTs) in moderate-sized
rivers, especially for off-grid power in developing countries:
Most rivers have low flow velocities, leading to low power density and poor capacity factors for
existing HKT. Innovative turbine designs are needed that can efficiently extract power from lowvelocity flows, or strategies to enhance flow velocity at the turbine site.
Current HKTs are too expensive and difficult to deploy and maintain locally. Development of
lower-cost HKTs and more realistic performance assessments based on typical river flow conditions
are crucial. This includes exploring designs that can generate meaningful power at lower flow
velocities
Turbines need to be designed to operate efficiently in shallow depths and handle challenging
riverbed conditions.
Further research is needed to safely and effectively utilize channel blockage to enhance power
output.
Specific Turbine Design Refinements:
•
Darrieus Turbines: Need improvements in starting torque, torque ripple, and efficiency,
especially for fixed-pitch and variable-pitch designs.
•
Helical Turbines: Starting torque remains an issue, and commercial viability is unclear.
•
Savonius Rotors: Require efficiency improvements and structural development for larger
scales.
•
Waterwheels: Need design innovations to increase RPM and power output for electricity
generation.
•
Belt Turbines: Face challenges with high internal loads.