Would wind turbines be more effective if they came in packs of 4?

[LargeDeflections]

The questions sounds funny but as a structural engineer interested in renewable energy, I understand that one of the challenges of wind turbine construction is the resolution of large bending moments in a cantilever frame and foundation.

Maybe I'm thinking too simplistically but what if you took the standard wind turbine design and connected 4 of them together into a tower frame with a vertical truss design?

I perceive the following benefits:
1) dramatically simpler foundation
2) smaller structural elements (cheaper/simpler fabrication, transportation and erection)
3) higher operating speeds because of the structure's ability to absorb higher wind loads

Now maybe there's some wind current issues that would prohibit this style design, but that's why I'm proposing the question.

 

[GregLocock]

The immediate issue is that you are doubling the excitation from the air hitting the structure, and the downstream rotor will be in the exhaust of the upstream one. Having said that, yes the idea of spreading the foundation out seems like a great move.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[itsmoked]

Maybe I'm not picturing things correctly but wouldn't anything connecting the towers together prevent the sweep of the blades when the heads try to rotate to follow the winds?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[rb1957]

would the 4 pivot on one axis ?

i don't like the idea. A pair makes more sense, but the downstream one is probably less efficient/effective.

another day in paradise, or is paradise one day closer ?

 

[TugboatEng]

Contra-rotating propellers are efficient. Perhaps the same can be applied to turbines? With synchronous generator sets no mechanical linkage would be required.

 

[GregLocock]

Single bladed propellers are the most efficient. However, engineering efficiency (in terms of power generated per unit area in a given windspeed) is not the important metric for wind turbines. Power per amortized dollar is the overriding consideration. If you could build a larger but cheaper turbine for a given condition, that's what you'd do.

Here's a paper on the effect of global installation of wind turbines on wind speed, which is more interesting than relevant

https://www.pnas.org/doi/10.1073/pnas.1602253113

And here's one on wind farms slowing each other down

https://www.sciencedaily.com/releases/2021/06/210603171247.htm

And finally Figure 7 in this shows the velocity profile near a single turbine.

https://link.springer.com/article/10.1007/s10546-019-00473-0

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

Power per amortized dollar is the overriding consideration.

Actually here in Ontario the most important consideration was how much of $7B and associated jobs we could donate to a foreign company (Samsung), as well as socializing it with farmers as badly as possible. We're still recovering from that exercise 10 years ago (and don't even mention relocated gas plants please).

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."