Yorkshire Water were aiming to generate electricity from the discharge flows from its Esholt sewage treatment plant.
In the first project of its type in the UK, Yorkshire Water used screw generators from Spaans Babcock.
The equipment supplied comprised two 2.6m diameter screw generators, each compact in design and weighing more than 20 tonnes. The generators were to be installed in a series, with 2678 l/s flowing sequentially through the two screws over a total fall of around 10m. Approximately 180kW of energy was generated (90kW per screw generator).
The electricity generated was transferred back into the mains grid.
Benefits of screw generators include:
- Low maintenance
- No pre-screening required
- Flat efficiency curve
- Simple control
- No cleaning required