4 ms·
On the other other hand they seem mechanically simpler because the entire turbine doesn't have to be mounted to pivot depending on the direction of the wind, an
by Pxtl 6y ago
On the other other hand they seem mechanically simpler because the entire turbine doesn't have to be mounted to pivot depending on the direction of the wind, and the column that holds up the turbine and blades is much shorter.
- JulianMorrison 6y agoAlso the generator can be at ground level, rather than having to perch at the top.
- tobtoh 6y agoDon't quote me on this, but I recall reading that there is a layer of air at ground level that is very turbulent/choppy due to it's interaction with the ground which makes it terrible for wind power generation.
- lippel82 6y agoOnly the generator is at the bottom, the power still comes from the upper part of the structure and is transferred mechanically, I would assume.
- Pxtl 6y agoWhat the parent-post means is that the machinery of the generator is positioned at the bottom below the blades instead at the top of a tall column behind the blades. Presumably this creates some savings in terms of construction and maintenance.
- bigfudge 6y agoperhaps also aerodynamics relative to a big generator blob right at the top?
- throwaway316943 6y agoVAWTs do ok in turbulent conditions. HAWTs don’t like it because they need a consistent stream of air flowing in one direction.
- 8note 6y agoGeneral fluid speed is ~0 at any surface and has some gradient to the proper wind speed as you get some distance away from the surface.
- brudgers 6y agoGenerally, turbine farms are built where the wind mostly comes from one direction. When the wind is not in a favorable direction the turbines are idle.
- ahartmetz 6y agoWhy would they be idle? They can pivot for a reason and I haven't seen turbines very close together in any direction. Sometimes they are indeed arranged in a long row, but even then, why not use all the wind energy they can get? I could imagine problems with turbulence and mechanical wear close to maximum design wind speed and yeah, they might shut down then.
- dylan604 6y ago>Why would they be idle? Sometimes they are idle not because of the lack of wind, but because of the lack of need for the electricity. When power demand is low, the wind turbines are the first things to be stopped. In fact, they use an electrical braking system to keep them from turning. The power companies say that it is much easier to stop/start wind turbines than lower/raise the output of gas/nuclear/coal power plants.
- avianlyric 6y agoGP is asking why the turbines would be idle if the wind isn’t coming from a particular directions. They’re not asking for a list of unrelated reasons for why a turbine might be idle. > When the wind is not in a favorable direction the turbines are idle.
- dylan604 6y agoActually: >Why would they be idle? They can pivot for a reason It seems to me you are reading into the post something not there. The person I replied to, quoted above, did not ask what you asked, and actually stipulated that HAWTs do pivot to turn into the more favorable direction.
- 6y ago
- blake1 6y agoThe short height is a serious problem. I think we can make some conclusions about the power output for a given material input. Based on the the images, my assumptions are: 100m mast and 80m blades; for the vertical turbines, a radius of 50m. The blades look to be lighter weight, but the mast looks heaver weight, so say the two styles use similar amounts of materials. Also, windspeed is logarithmic with height. Wind power goes as the cube of wind velocity over the swept area. With my assumptions, the vertical turbine outputs about 2.7MW, while the horizontal turbine outputs about 8.4MW. The reason is height: it helps to have the blades sweep more higher altitudes wind, where it's faster. These might be easier to pack tightly into a windfarm, where the metric that matters is W/m^2. But most of us care about W/kg because that is proportional to W/$: the winner looks to be horizontal turbines because they reach higher. A hybrid of horizontal behind vertical might be interesting. There are diminishing returns to how "deep" you can make your windfarm: the trailing edge suffers from turbulence from leading edge, and these could work better in turbulence.
- mc32 6y agoHowever the variability of physical forces on the blades as they rotate means the materials have to have properties that make them less brittle or prone to fatigue due to these conditions. Those materials I think are mor expensive than those on traditional blades.