[ntucker86]

There isn't a large amount of energy stored in the tether catenary or elasticity. Any hardware to recoup it probably wouldn't pay for itself.

Offshore, there can be a lot of energy stored in buoy motion, and utilizing this can help, but probably in a resonant way that doesn't require additional hardware.

"Rigid" is a relative term. The tether already utilized a carbon fiber core. It doesn't get much stiffer, short of going to exotic fibers or more of them, both of which degrade performance in other ways.

The optimum is going to be closer to a strength limited tether than an overly stiff one.