Pico-and Micro-Hydropower Turbine Selection 

Pico and micro-hydropower turbines are often selected based upon hydraulic head and flow rate, as this has been found to be their best operating performance. However, there is often no physical reason why they cannot be used outside the standard ranges. Quantitative criteria, such as efficiency and size, can be combined with qualitative criteria, such as maintainability, serviceability and installation environment requirements, to ensure the most suitable turbine is chosen for a system specification. For example, using this methodology for a specification in a remote community with a low head system that required modular design, a single-jet Turgo turbine was shown to be appropriate, ahead of the typical axial-flow turbine solution.

‌Turgo Turbine Modelling and Testing

Turgo turbines are impulse turbines, using the change in momentum of a jet of water that impacts a turbine runner to create a mechanical torque on a shaft. Modelling the turbine over a range of heads and flow rates, alongside experimental validation, enables the performance for different environmental conditions to be determined. We have developed an analytical model for a low head Turgo turbine, and verified the model through a scaled experimental testing regime. Using a design of experiments method, we improved the operating water-to-shaft efficiency to 90%. We are working with partners in Nepal to co-develop improvements that can be made in design of the Turgo turbine runner to make it suitable for local workshop manufacture, and measure the performance implication of these design changes.

Barriers to Good Plant Performance

We have surveyed of micro-hydropower sites in Nepal to understand the key technical, social and economic issues that lead to poor performance of the plants. This included site assessments, interviews with operators, managers and consumers and discussions with manufacturers. This will lead to the development of methods to address these issues through planning and process changes throughout the design, manufacture, implementation and operation of the system.