# Using Hydraulics to generate electricty

## Main Question or Discussion Point

I was wondering if someone could help me here. I would like to understand how hydraulic cylinders can be used to convert mechanical movement (say the up and down motion of something for example) into electricty. I understand you probably need a motor and a genertor but I can't seem to find any information about how to set up the system or how the individual componenets work. Any help would be appreciated!

Thanks

Related Mechanical Engineering News on Phys.org
russ_watters
Mentor
Well, hydraulic fluid is a fluid, so you'd just use a turbine and a generator. I don't really know what you have in mind, but if you have an oscillation that the cylinder would be absorbing, you'd probably want to have some valving to make the fluid always travel through the turbine in the same direction.

Danger
Gold Member
I believe that this was one of the methods that they looked at for harnessing wave power, before settling on air compression instead. On a small scale, I think that using an engine oil pump, power steering pump or a hydraulic gear motor with mechanical drive would be more effective than a turbine (and definitely cheaper). Matching the fluid to the tolerances of the seals can be a problem if using auto parts, though.

fluid pushes the piston-piston reciprocates-reciprocation is converted into rotory(by oscillatory or crank mechanism)-fed to generator-electricity comes out.

drankin
I don't know of any way a linear actuator (cylinder) could be used to directly generate electricity. At some point it would have to be converted to a rotary motion from which a traditional generator (electic motor) would be used to create electricity. I believe most large wind turbine generators rotate a passive hydrostatic (hydraulic closed loop pump-to-motor) arrangement. In short, mechanicl rotary motion to hydraulic rotary motion to rotating shaft of a generator.

I don't believe converting rotary motion to a linear reciprocating motion and then back to rotary motion of a generator shaft would be as efficient due to losses in the mechanical gearing involved. Certainly do-able but not the easiest way to go about it.