This page is a collection of information concerning Energy Recovery from a Waterwheel.
Ideally a full scale system involves the use of a slow speed AC Motor, gearing from the wheel and Inverter Drives to recover the electrical energy, match the voltage to a usable level and return power to the local supply system via an individual building service. The cost of full scale systems can be difficult to justify below several tens of kW. The best choice of Motor is a Permanent Magnet synchronous machine, but this can be standard Induction motor at reduced efficiency.
Small low costs systems are possible, if they are only required to heat water or floor heating. Permanent magnet motors or brushless DC servo motors can be used to power three matching resistive loads directly, or rectified to supply a single heater. There is no electronic control over the current in this case and care should be taken with speeds, Voltages and current levels to keep well within the motor capabilities. PM motors can become de-magnetised, if current levels are too high or the unit is short circuited.
An over-shot wheel at full height will provide around 1.5 x the power capability of an Under-Shot wheel.
Some degree of control over electrical power and Voltage can be provided by water flow and height, if the facility exists.
Justifying the cost of an installation might be eased in the UK by the Government's commitment to increase the kWh payback rate for self generation systems with water-wheels and Wind Generators.
UK Planning Authorities might look more kindly on applications to convert dilapidated or redundant buildings, if the application includes a reasonable energy recovery system. We have heard of one Waterwheel installation that went ahead only on the basis it was a requirement of the Local Planning Authority for the building.