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I'm not in the wind industry and am not a ME, but rather a EE, but why couldn't you build a big vertical-axis wind turbine and then couple that to multiple gene

I'm not in the wind industry and am not a ME, but rather a EE, but why couldn't you build a big vertical-axis wind turbine and then couple that to multiple generators, a big one and a small one, with gearing that lets the windmill drive either one? Then in low winds, you can drive the small generator at its optimal speed range, and then in high winds, you can switch over to the big generator and drive it at its optimal speed range (the small generator is decoupled in this mode). Obviously, this would be much more costly because of the additional big generator and the complication of the drivetrain. But it'd let you harvest a bunch of energy when it's really windy. And with a vertical-axis mill, not only would this be better for wildlife (lower overall speeds), the generators would be on the ground, not way up in the air, and driven by a shaft from the mill through its tower, so servicing would be easier and the weight and size of the generators and the drivetrain wouldn't be an issue.

iamgopal 10y ago
There is a very easy idea to achieve this, like the way tesla did to its induction motor, just use multiple windings.
brandmeyer 10y ago
I think you've misunderstood the innovation. The innovation in using a generator that is smaller than the blades and tower are capable of supporting isn't in the light-load efficiency of the generator. Its in the lower capital cost of the electrical system.
scblock 10y ago
For horizontal axis turbines two speed generators were historically a thing, usually with two sets of windings which were engaged at different speeds. This works, but is less efficient and mechanically more taxing on the machine than variable speed, variable pitch angle systems.
Bartweiss 10y ago
From a perspective a little closer to the industry, I think the answer is just "costs". This idea has higher turbine costs (and site profitability already ranges from impressive to deeply marginal), and the extra profit from the high end isn't excellent. Cringely overstates the money lost in high-wind conditions - most shutdowns are for low wind or to avoid damage in storm conditions, which are rather different than smooth, profitable high wind. Further, it might offer major operating-cost hits even with ground-based generators simply by being a major break with existing systems. Obviously that's surmountable, but it means that the system has to be better for a lot of sites to be worthwhile. That said, there are definitely vertical mill projects in the works, and I wouldn't be surprised if some of them have switchover generators.

iamgopal 10y ago

There is a very easy idea to achieve this, like the way tesla did to its induction motor, just use multiple windings.

brandmeyer 10y ago

I think you've misunderstood the innovation. The innovation in using a generator that is smaller than the blades and tower are capable of supporting isn't in the light-load efficiency of the generator. Its in the lower capital cost of the electrical system.

scblock 10y ago

For horizontal axis turbines two speed generators were historically a thing, usually with two sets of windings which were engaged at different speeds. This works, but is less efficient and mechanically more taxing on the machine than variable speed, variable pitch angle systems.

Bartweiss 10y ago

From a perspective a little closer to the industry, I think the answer is just "costs". This idea has higher turbine costs (and site profitability already ranges from impressive to deeply marginal), and the extra profit from the high end isn't excellent. Cringely overstates the money lost in high-wind conditions - most shutdowns are for low wind or to avoid damage in storm conditions, which are rather different than smooth, profitable high wind. Further, it might offer major operating-cost hits even with ground-based generators simply by being a major break with existing systems. Obviously that's surmountable, but it means that the system has to be better for a lot of sites to be worthwhile. That said, there are definitely vertical mill projects in the works, and I wouldn't be surprised if some of them have switchover generators.