How Does Reciprocating Motion Affect Alternator Efficiency?

[JJ21]

Hi guys,

Currently just looking through a few concepts for wave energy converters and I noticed that a few designs use bi-directional rotating turbines (or linear action) meaning the alternator has to continuously keep rotating in one direction, stopping, rotating in the other direction, stopping etc etc. I would have thought that this continuous stop start would severely affect the alternator's efficiency and the power generated? If anyone knows of any papers on this or it would be much appreciated.

Thanks

 

[sophiecentaur]

There are many examples of machines with reciprocating motion. There is no inherent energy loss involved (as in a pendulum) although slippage and friction could be factors which could reduce efficiency.
The cyclic nature of these systems would mean that less energy would be available than for a system where water is, for instance, falling all the time from a height. But you 'take what you can get', surely and you are probably talking about something like a 1/√2 reduction factor (best case) which isn't too bad.