Salient White Elephant

April 25, 2009

Sustainable Skyscraper

A very tall building reserves some floors for producing energy. I guess you’d have to produce a heck of a lot of energy to generate as much revenue as you could get by leasing the space instead. I haven’t crunched any numbers or anything, but since the wind might be very strong at these altitudes, I’m guessing maybe it would work. Remember that the turbines would produce power 24 hours a day, and seven days a week. The office space would only be used for a fraction of that time:

Sustainable Skyscraper, Side View

Sustainable Skyscraper, Aerial View

Even more energy can be concentrated at the turbine if some of the wind from the non-turbine floors could also be collected. This might not be as difficult as it sounds:

Aerial View of Floor Used For Office Space Showing Flow Concentrating Windows, Sustainable Skyscraper

High pressure develops on the upwind side of the building in the cavity formed by the flow concentrating windows. Much of the air will simply escape around the outside edges of these upwind windows, but a lot of it will escape by flowing in the vertical directions (both up and down). Once this air escapes by moving either up or down, it will find itself at the entrance of the flow concentrating panels on one of the power producing floors. It thus augments the flow through the pie slice shaped flow concentrator. The same thing happens (but with opposite polarity) on the downwind side of the building. Note that these outside windows may span several floors of office space. In this case, we don’t have several levels of windows. Instead, just one tall window spans however many office floors are between the power producing floors.

It also might not be that difficult to think of ways to make sure no accidents happen. For example, the windows that can swing open are certainly designed so that there’s no way the wind could ever be strong enough to tear them from the building. But just to make sure, a cable could attach to the middle of the top and bottom of each window. The other end of the cable would be right above or below on one of the power generating floors, and it could attach either to the floor or the ceiling as the case may be. An alarm is activated if ever the window detaches from the building. Now there are 4 mechanisms that simultaneously guarantee the safety of the public:

  1. the windows are designed to be strong enough to withstand any weather conditions,
  2. the bottom of the window is tethered to the building in case the design proves to be flawed and the window tears away anyway,
  3. the top of the window is also tethered,
  4. an alarm notifies the authorities if ever a window becomes detached from the building (leaving it hanging from the 2 tethering cables). If the alarm is ever triggered, the streets below may be quickly evacuated.

Narrow Flow Concentrating Channels Variation

Here’s a variation that looks like it might make better use of real estate. (A mathematical analysis should be developed to verify whether this is indeed the case.) It is difficult for me to draw this variation, so let me first present a crude drawing that has some structures omitted, then I’ll explain how it works:

Aerial View, Sustainable Skyscraper with Narrow Flow Concentrating Channels

The panel in the center of the building yaws so as to separate the upwind flow concentrating channels from the downwind channels. The height of this panel is equal to the height of the building. High pressure air in the upwind channels is forced up to the roof of the building. This air is now drawn down from the roof of the building through the low pressure downwind channels. The turbine rotor and generator are on the roof. One side of the turbine rotor faces the high pressure air and the other side faces the low pressure air. In this way, a single turbine rotor and generator converts the wind to electricity. Alternatively, several (2 or 3) rotors are positioned (say) 10 stories apart, so that each turbine converts 10 stories worth of wind energy to electricity.

April 24, 2009

Super Honkin’ Counter-Rotating Water Cooler Cones

Tangential velocity is a function of radius. The radius of the vertex of a cone is zero, so this shows that if you get an empty paper cone from the water cooler and roll it across your desk, it will roll around in a circle. This is kind of nice, since a cone seems very close to the ideal flow accelerator. So if we put the vertices of two cones together, so that the open ends of the cones point in opposite directions, then roll the cones, their vertices will stay together, and the cones will “yaw” all the way around through a 360 degree arc and end up back where they started. So we roll the cones around so that one opens up in the direction of the wind and the other opens up in the downwind direction, put a HAWT rotor right in the middle of the two vertices, and we have a very powerful wind machine with all the important components at ground level. The only problem is that the cones smash all the corn in the field as they yaw around. But this is easy to fix. Just fit the mouths of the cones with a rim and the vertices with a rim, then separate the cones by the appropriate distance. The following diagram illustrates the general idea (it’s a terrible drawing… but I’m in a hurry):

Super Honkin' Counter-Rotating Water Cooler Cones

So now if we have two concrete roads, the cones can roll around and not smash all the corn in the field. Interestingly, it seems these shapes might be perfect for rolling around on top of a dome – like an enclosed baseball stadium or something like that.

Yawing Wind Dam

The diagram looks silly, but don’t dismiss this post too quickly – I think this is a terrific idea:

Yawing Wind Dam

There are many variations, but as we explore those variations, keep in mind the salient points of this machine:

  • direct drive
  • not only is the generator at ground level, the turbine rotor is on the ground as well!
  • incredibly scalable
  • low maintenance.

Variations

Suppose we have five towers in the shape of a giant pentagon. Cables run between adjacent towers, and the shroud is attached to those cables. In this case, only the shroud is yawed:

Yawing Wind Dam, Only The Shroud, Turbine, and Generator are Yawed

Or it can look like this:

Aerial View of Yawing Wind Dam Only The Shroud, Turbine, and Generator are Yawed

Instead of making the shroud out of fabric like nylon, it can be solid. It would look kind of like the top half of a radar dish. In this case, it might be supported by a number of lattice structures on wheels.

Single Tall Tower Variation

Yet another variation would use a single very tall guyed tower. Because the bottom of the shroud is like a circular arc that sweeps through 180 degrees, the diameter of the arc at the lower end of the shroud can be made larger than the diameter of the anchor points for the guy wires. A long horizontal tube at the top of the tower supports the top part of the shroud. The turbine rotor and generator are on rails or wheels and trace out a circle as the machine is yawed through 360 degrees.

Alternatively, the guy wires are used not only to support a very tall tower – they also support the shroud. Suppose there are 5 guy wires. A cable connects the 5 guy wires so that an aerial view of it looks like a pentagon. There are several levels of these horizontal pentagonal cables, so that an aerial view of them looks like several pentagons of different sizes. The shroud is connected at each side to each of these cables, and rides these pentagonal cables as it yaws:

Yawing Wind Dam, Single Tower Variation

Tipi Variation

Just like the single tower variation just described, except now the entire surface traced out by the guy wires is covered with fabric. It looks like a giant American Indian tipi. Now all of the fabric that runs the circumference of the tent from an elevation of (say) 20 feet to 30 feet is separated from the rest of the fabric. It looks like a giant pentagonal wedding ring. This ring has two holes cut into opposite sides of it, and a fabric tube connects these two holes. The tube has the turbine rotor inside of it. The tube and the ring yaw, and the rest of the tent is stationary. The turbine is near the tower (or coaxial with the tower) so that it doesn’t have to move much when yawing.

April 23, 2009

Airborne Wind Dam

A blimp suspends a giant flow accelerator with a small high-power turbine in the middle of it. In other words, a blimp suspends a turbine that looks kind of like the one described in this earlier post:

Wind Turbine with Flow Accelerating Shroud

This rotor will spin at high rpm, so it is easy to make it a direct drive machine. As described in prior posts, the bottom of the flow accelerator can attach to the top of a supporting tube in order that the blimp doesn’t have to carry the entire gravity load of the shroud and turbine. The tube is on wheels and a control system causes it to follow the blimp around with changing wind speed and direction.

Here’s another variation:

Airborne Wind Dam

Airborne Wind Dam with Lattice Support

Blimp With a Hole Variation

In this variation, the blimp has a cylindrical hole right through the middle of it (running down its longitudinal dimension). The small high-speed direct drive turbine rotor is inside this cylinder. A large shroud like the ones depicted above encircles the blimp in order to further accelerate flow through the cylinder and direct drive turbine rotor.

Airborne Wind Dam, Cylindrical Hole in Blimp

Skyscraper Variation

In this variation, the blimp is moored to the top of a skyscraper. When the windspeed gets too high the blimp simply detaches from the building and flies to a nearby airport where it lands until the storm passes. I hate to make the next suggestion, because somebody might actually do it. The blimp could be moored to the top of a mountain. This would produce a lot of visual pollution, so I don’t think it’s a very good idea.

Lightweight Electrical Components Variation

The blimp is big and round. It has plenty of room for a ring generator. Of course, you don’t need a ring generator to make this machine direct drive, because the accelerated flow through the cylinder is already sufficient for making the turbine rotor spin at high rpm. But if the turbine drives a very large diameter ring generator, then electricity can be generated with high voltage. If voltage is high, then current is low, and the weight of electrical components such as the electrical cables is minimized. (I’m assuming insulation weighs less than copper.)

Structural Electrical Cable Variation

This option develops electrical cable technology that is suitable both for conducting electrical power and for carrying a tensile mechanical load. This minimizes the weight of the mooring cable, since the electrical cable simultaneously provides both mechanical and electrical functions.

Aerodynamic Transmission Variation

The diagram below is a little ridiculous, but I’m a terrible artist, and I’m using 2D software to create these diagrams, so for this diagram I decided to come up with something that just shows the general idea. And the general idea is to reduce the weight of airborne components by using a light-weight hollow tube to moor the blimps. The hollow tube transmits the high air pressure that accumulates at the center of the dam (shroud) to the ground. A small high-speed turbine rotor drives a generator at the ground level end of the tube. The turbine rotor is high speed, and so it doesn’t need a gearbox. The airborne system carries no electrical or mechanical devices, and so it is light in weight.

Airborne Wind Dam With Aerodynamic Transmission

This idea suggests an interesting question – what happens to the Betz Limit when de-energized air doesn’t flow away from the turbine on the downwind side of the turbine “rotor”?

Of course, the aerodynamic transmission may also be applied to more convention turbine designs. Perhaps a shroud is positioned at the top of a conventional wind turbine tower, and the tower itself is used to route the high pressure air to a turbine rotor and generator on the ground.

Pressure Differential Aerodynamic Transmission Variation

A wall is added to the inside of the aerodynamic transmission tube. This separates the tube into two halves, just as though there were two tubes instead of one. One half of the tube opens on the high pressure side of the shroud, and the other half opens on the low pressure side. This pressure differential is carried to the ground where one side of a high-speed turbine rotor encounters the high pressure, and the other side of the rotor encounters the low pressure. Air thus flows through the rotor and turns an electric generator.

Cross-Section of Aerodynamic Transmission Tube Showing Transmission of Pressure Differential

Rotating Drive Shaft Variation

Hollow, light-weight, rotating tubes are connected end-to-end through universal joints. The tubes are attached to the mooring cable and so are suspended beneath the mooring cable. A high-speed rotor at the top transmits power to the ground through the rotating drive shaft tubes. The spins at high rpm so drive shaft torque is low.

April 10, 2009

Biplane Wind Turbine Rotor

Biplane Wind Turbine Rotor

Now suppose that the struts that connect the two layers of blades are themselves airfoils. Would they act like the concentric rings in the Wind Turbine Concentric Rings Flow Accelerating Shroud? And if so, would the fact that each end of each strut is terminated at a turbine blade result in minimal energy loss due to vortices created by the short “concentric ring imitating” airfoil struts?

Biplane Wind Turbine Rotor, Imitating Concentric Rings Shroud

March 27, 2009

Wind Turbine With Flow Accelerating Shroud

Everyone knows that a smaller wind turbine rotor may be used if a shroud accelerates flow in its direction. Most people who know much about the design of utility scale wind turbines don’t take this idea seriously, and I confess I never took it seriously either. It just seems like an idea that cannot be applied to a large wind machine. But here are some ideas for light-weight shrouds that can be easily retracted during storm wind conditions:

Wind Turbine With Flow Accelerating Shroud

The idea is to provide a shroud that is made from some flexible material (nylon or whatever… I don’t know anything about materials). The shroud is shaped like a giant cone with its large end opening in the downwind direction (colored aqua in the diagram). But the cone is flexible… how will it be supported? It is supported by attaching its large opening to the small opening of another conically shaped shroud (colored purple in the diagram). The large end of the purple shroud opens in the upwind direction. The two upwind openings of these shrouds are each supported by a rigid ring – sort of like bending a couple of giant coat hangers into circles:

Downwind View Wind Turbine With Flow Accelerating Shroud

In order to help the shrouds hold their proper shapes, some kind of minimally designed light-weight rigid supports may be added:

light-weight ribs may be sewn into fabric of shroud to help maintain proper shape

Now we get to the second big problem with shrouds – their terrible storm wind drag profile. But since the shrouds are nothing but flexible fabric, they can easily be designed to fold into a shape that has a low drag profile! In fact, if the shrouds were well designed, it seems like maybe this machine would have even a much improved storm wind drag profile as compared with a traditional design with the same rated power output.

Giant Spoked Annular Wheel Variation

Here’s an interesting variation on this idea. This shroud sits on the ground or on a small post with bearings for yawing:

Wind Turbine With Spoked Annular Shroud, Downwind View

One interesting feature of this idea is that it makes use of all of the energy in the wind all the way down to the ground!

Wind Turbine With Spoked Annular Shroud, Side View

The following diagram shows how the shroud looks like a doughnut sliced in half (the doughnut slice and the cross section slice are in different planes):

Cross Section of Side View of Fabric Part of Shroud

The next diagram shows how the shroud may be deployed or retracted much like opening and closing drapes:

Wind Turbine With Spoked Flow Accelerating Shroud, Deploying the Shroud

Partial Cross Section of How Shroud is Deployed or Retracted Like Opening and Closing Drapes

Of course, another way to reduce the storm wind drag profile is to just lay the whole turbine down on the ground. Can’t get a much better drag profile than that!

Linear Turbine Variation

Here’s a variation that resembles the Direct Drive Linear Turbine With Yawing Oblong Track:

Shrouded Linear Turbine With Elongated Oblong Track

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