Case Study: Dŵr Uisce
Measuring Pump-as-Turbine (PAT) Efficiency in Micro Hydropower (MHP) with Torque Sensors
The Client
Dŵr Uisce
Dŵr Uisce was a collaborative research project funded by the Ireland-Wales 2014-2020 ETC programme dedicated to improving water distribution efficiency in Ireland and Wales.
Led by academic staff and researchers from Trinity College Dublin and Bangor University, its goal was to improve water distribution efficiency and reduce carbon emissions by developing smart, low-cost technologies for energy recovery in water networks.
The project addressed challenges such as rising energy demand, climate change impacts, and water scarcity by exploring innovative solutions like micro-hydropower (MHP) systems.
The Challenge
Among the many proposed strategies to reduce the energy consumption and carbon intensity of the water sector, a prominent one is the adoption of micro hydro turbines to recover the excess energy along the water distribution lines.
Due to the reduced size and residual pressure requirement, a standard hydro turbine is often impractical or too expensive to install in such locations. Therefore the researchers decided to investigate the use of Pumps as Turbines (PAT), also known as pumps in reverse, as low cost and easily maintained solutions for distributed energy generation within water networks.
Following the first phase of desk studies, theoretical modelling, and small-scale testing, the researchers sought to build a large-scale hydraulic test rig at Trinity College Dublin. To evaluate a pump’s efficiency and working point, they needed to measure torque delivered by the turbine under realistic conditions, at different regimes, accurately, and in real-time.
Instead of a costly ordinary hydro turbine, the team proposed two low-cost micro-hydro systems, using centrifugal pumps working in reverse as turbines, referred to as Pumps as Turbines (PATs).
The Solution
Following thorough market research, the team decided to acquire a Datum Electronics M425 Torque Transducer to sit at the heart of the test rig, providing highly accurate (±0.1% FSD) torque data, while also measuring shaft speed (RPM), eliminating the need for an additional, dedicated sensor.
When installed axially into the driveline, connecting the hydraulic turbine to the generator, the torque sensor measured the mechanical power produced by the former and transfers the real-time readings to a data logging PC for further analysis.
The Outcome
With their dedicated hydraulic test rig, the Trinity College Dublin team measured a peak mechanical efficiency of 72%, compared to the manufacturer’s stated range of 52-56% depending on setup.
This finding highlighted the importance of experimental validation and suggests that PATs are a highly viable, low-cost alternative to conventional turbines for energy recovery in water networks.
Learn more about the Dŵr Uisce project and its successor venture, DWR at dwr-uisce.eu.
To read more about the Datum Electronics M425 Torque Transducer – click the button below:
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