Modular turbine systems

Worldwide there are literally hundreds of thousands of micro-hydropower sites (up to 100 kW) that could be developed to supply environmentally friendly renewable energy. Two factors limit how many of these sites are developed; cost and local technical knowledge.

At present micro-hydropower systems are basically scaled-down versions of large-scale systems, and are bespoke designed for a specific site. The turbines themselves are fabricated in steel at great expense in materials and skilled labour time. This makes the current technology prohibitively expensive for many potential sites.

Our water turbine is based around a polymer moulded rotor and stator unit. The complex geometrical shapes typical of any turbine are ideal for polymer moulding. We can produce a finished turbine rotor or stator relatively quickly, using low-cost materials. The turbine itself is a ‘back-to-back reaction turbine’. The water enters at the centre of the rotor and is discharged in equal quantities from the two ends. This means that there is zero net axial thrust on the rotor which minimises bearing wear. The flexible but tough material used for the rotor and stator also absorb the energy of waterborne particles (they effectively ‘bounce off’), minimising erosion. The whole design is ‘modular’ which reduces the amount of site-specific design work that has to done, and the level of local expertise required.

The other system components are similarly innovative, including a fibreglass volute casing and a modular chassis system. The whole system is weatherproof so there is no need for an expensive turbine house. The overriding factors that have driven the design are low cost, ease of installation and minimal, simple, maintenance requirements. We can manufacture four rotor sizes; 200, 300, 400 and 600 mm. The power outputs for the operating range of heads and flows are shown below:

We are working on mating our water turbines to a permanent magnet synchronous generator with power electronic power conditioning. This will enable the turbine to operate as a variable speed machine, optimising efficiency over a wider flow and head range and allowing local power conditioning, such as varying the amount of reactive power generated. This flexibility will make integrating the system in local electricity distribution networks more straightforward, especially in developing countries. The water turbine can also be operated as a standalone system with resistive dump load to dissipate excess energy.