A solution for inefficient wind power?The Saphonian is a wind energy device like no other. Saphon Energy CEO Hassine Labaied discusses his company’s radically new concept.
My partner Anis Aouini is the brains behind this innovation. He was inspired by the way sailboats capture the kinetic energy of wind and convert it to mechanical energy.
The concept was a new way of harnessing wind without using rotating blades because the rotation of the blades is behind most of the problems with the existing technology, which has very poor efficiency levels of 30 to 35 percent.
What’s the problem with rotating blades?
Only the wind energy in contact with the surface of the blades and creating lift will be captured; any wind energy travelling between the blades will continue on its way and be lost.
The Betz Limit is a law of aerodynamics which explains theoretically why rotating blades like windmills can’t capture more than 59 percent of the initial kinetic energy of the wind. If you then factor in extra losses like mechanical and electrical losses the final average efficiency level is 30 to 35 percent.
How does your technology work?
The idea was to capture wind using a sail in a stationary device. There is a sail-shaped body like a large dish that captures the wind. Behind this body is a series of pistons activated by the movement of the dish. The wind pushes the dish in different directions and the pistons are activated.
The Saphonian harnesses a combination of two movements: one back and forth, and one rotational, and this creates a movement like a big figure of eight, as if the dish is dancing back and forth and also up and down.
Three-blade turbines only move in two dimensions. This dish is moving in three dimensions. So the wind captured is about two to three times more than with three blades.
What is the sail made from?
It could be fabric or plastic or could be the same fabric used by sail boats. The sailing industry can get world class materials in terms of resistance and weight.
How does it generate electricity?
The pistons are part of a hydraulic system. They are connected to a pipe containing oil or any other liquid to be compressed. When the piston pushes the liquid this creates hydraulic pressure which can either be stored in a hydraulic accumulator or used to spin a hydraulic motor which can be connected to a generator.
We are not reinventing the wheel; we are just using a system which has been adopted for years, which is the hydraulic accumulator. At any point in time you can take that hydraulic pressure and use it to activate your motors.
Instead of going all the way to electricity and then trying to store electricity (a big headache and expensive) we can stop and store the hydraulic energy. Storing the pressure is very simple and affordable.
What efficiency levels have you achieved with your prototype?
There is the theory and then there are the empirical tests. In terms of theory we claim we are about three times more efficient than the current three-blade turbines: that means from 35 percent we can go up to 90 to 95 percent.
We have to compare apples to apples; that means comparing our dish with the wind’s kinetic energy captured from the entire area swept by the blades, the “swept area”. We compared our lab-scale prototype to a three-blade turbine with same swept area.
After the empirical tests we did we are about 2.3 to 2.5 times more efficient than the three-blade turbine, capturing about 60 to 70 percent of the wind’s kinetic energy.
How much electricity could be generated from the Saphonian?
In terms of power this prototype generates about 300 to 500 Watts, although it depends on the wind speed and other parameters. The best comparable three-blade turbine of the same size on the market generates about 150 Watts.
When will you have a commercial device for sale?
We have two lab-scale prototypes and are in the process of developing a third, perhaps by the end of the year. Ideally we don’t want to take this innovation from the lab to market ourselves. We want to partner with a big player to manufacture and deploy.
They could be bigger. Why? Firstly because the sail fabric is very light. Secondly, with rotating blades you have to produce electricity instantly at the turbine level so you need all the components at height: hub, gearbox and generator. This is heavy.
In our case we don’t need to put anything at height. Once you create the pressure it goes all the way down the piston pipes so you have all your other components on the ground. At the top you just have the sail shell body, the pistons and pipes. In our case the weight would be reduced dramatically.
As would the production costs?
We cannot have accurate costs unless we are in the manufacturing phase. However, if we are removing the most expensive components—gearbox, blades and hub—that equates to about 50 percent of the cost of a three-blade turbine. We can say comfortably that we can reduce the cost by at least 45 to 50 percent.
And if you scale it up into a wind farm you can centralize everything on the ground. You just generate pressure and instead of having many hydraulic motors and generators for each device you just have one, which would be much more convenient and affordable.
Where would be the best locations for Saphonians?
The choice of sites for three-blade turbines is extremely important because they are very sensitive to turbulence created by obstacles like buildings and forests. So they go offshore and into remote areas.
The Saphonian is not sensitive to turbulence because it is moving in different planes. In some cases turbulence might even be helpful.
So we are not obliged to go into very remote areas, and can even use it in urban areas without suffering from a drop in efficiency. And as it doesn’t rotate, we could even use Saphonians as advertising billboards.