The wind is faster at higher altitudes and wind power is directly proportional to wind velocity cubed. But mounting a turbine up high makes it more expensive to install and maintain, and requires a stronger tower to support such a top-heavy structure. Engineers at SheerWind have a solution: “scoop” the air from up high and bring it down low to drive a ground-level turbine. Oh, and while they’re at it, how about amplifying the wind speed too?
SheerWind coined the term INVELOX - INcreasing the VELOcity of wind - to describe its innovative design. Using a giant omni-directional funnel whose mouths are mounted at the top of a tower, INVELOX brings the wind down to ground level and sends it out through a narrow neck, which increases the wind speed, much like putting your thumb over the end of a garden hose and leaving a tiny opening will increase the water velocity. This makes the turbine smaller, decreasing its cost. And because the turbine is on the ground, routine maintenance doesn’t require climbing a tall tower. Funnel mouths facing all directions eliminates the need for the turbine to rotate towards the wind, resulting in fewer moving parts, less complexity, and increased reliability.
Since traditional turbines have relatively high start-up speeds (8 MPH or 3.6 m/s is typical), they can’t generate electricity at lower speeds. Because the INVELOX design increases the speed of the wind before it reaches the turbine, it allows the system to generate power at wind speeds as low as 2 MPH (0.9 m/s).
If you’re thinking that reducing the diameter of the turbine will decrease the power, you’re correct. Wind power is proportional to the square of the diameter of the turbine. However, power is also proportional to the cube of the wind speed. So let’s say you cut the diameter in half and at the same time you double the wind velocity. The result: twice as much power.
Field testing showed that the INVELOX design did, in fact, increase the velocity of the wind reaching the turbine. More importantly, over an eight-day test, it generated an average of three times more electricity than the same generator mounted at the top of a tower in a conventional system. SheerWind's field testing demonstrated that the INVELOX turbine generates electricity at $0.01 per kWh.
Here’s a short video showing how it works:
Images and video: SheerWind