Salter's duck

The wave impact induces rotation of gyroscopes located inside a pear-shaped "duck", and an electrical generator converts this rotation into electricity with an overall efficiency of up to 90%.

The Salter's duck was invented by Stephen Salter in response to the oil shortage in the 1970s and was one of the earliest generator designs proposed to the Wave Energy programme in the United Kingdom.

The funding for the project was cut off in the early 1980s after oil supplies rebounded and the UK government moved away from alternative energy sources.

As a result of the 1973 oil crisis, Salter set about creating a source of alternative energy.

The idea for creating Salter's duck came about from his studies on a lavatory cistern while at the University of Edinburgh.

[2] He invented Salter's duck in 1974 and attempted to make it the main device of choice for the Wave Energy programme in the United Kingdom.

A prototype attempt to use the device was constructed in 1976 off Dores Beach.

Cost considerations based on the findings were among the main factors in the ducks not being put into widespread production under the Wave Energy programme in the late 1970s.

This causes four gyroscopes inside to move back and forth, creating hydraulic energy that is transferred to a turbine or generator.

[8] In order to determine the efficiency of energy output from Salter's duck, in 1975, scientist Swift-Hook and others ran a series of tests.

They also had to test for the incidence energy (R) given off by a submerged surface (s), the formula of which is,

With this, they were able to then use the final formula that tested for the absorption efficiency, eta (n),

In varying types of realistic conditions, the efficiency of the duck varies wildly and often drops to around 50%, as ducks are more often used in rough weather in order to convert enough wave power.