100 MPH wind turbine starts in 1 MPH winds

Pumping, Compression, Chilling, Electricity

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Introduction

Savonius turbines are well known for high torque, silent operation and robustness. This robust unit is designed around our high strength proprietary steel tube frame which makes it even stronger while providing optimal performance. 

This Savonius wind turbine incorporates  modern design based on airfoils  to maximize efficiency while a simplified mechanical model makes it strong enough to resist 100MPH winds without damage.    

This turbine self starts turning  in 1 MPH winds and provides high torque even in low winds. This makes it ideal for water pumping,  air pumping,  chilling and A2WH applications.  We originally designed it to use as part of our wind powered refrigerator and are making it available without the compressor or generator to use in your own application. 

If you are interested in wind energy you have seen pictures of turbines destroyed by high winds. There is a good reason for this since the amount of energy increases dramatically as wind speeds increase. There are a lot of design options to withstand the wind such as brakes and yokes.  This turbine uses an incredibly strong steel frame combined with impact resistant plastic skins. The skins are field replaceable. This avoids the need for complicated mechanisms which can malfunction and the worst time. In addition the efficiency of energy capture drops off as wind speeds exceed 30MPH which also helps avoid damage.   

Our test  unit installed in the mouth of a canyon. Our maximum recorded wind speed last year was 110 MPH which also happened on a day with -20F temperatures. If our unit withstood this without damage it is likely to withstand the worst mother nature will produce.    

Ultra Strong, Ultra Robust

heavy-duty-tubular-steel-turbine-frame.JPGThe strong steel frame is integrated into the turbine blade component and is covered by a modern high tech HDPE plastic which includes special additives to make it sun resistant.  The standard 1/16” skin material is strong enough to withstand considerable power and rigid enough to not flex in the wind which eliminates noise.  We demo this material by hitting it and watch it simply bounce back to shape. 1/8” or even ¼” are available at additional costs. ¼” may be justifiable in regular hurricane zones to help the unit withstand windblown debris but the base design will withstand over 100 MPH winds. If the skin is ever damaged it can be repaired with a hot air gun and replacement skins can be easily installed over the steel frame. 1/8” polycarbonate skins are available at additional costs which opens many options for artistic  fluorescent colors

This unit includes ball bearings support in UHMW support blocks top and bottom. The standard  ball bearings give the extremely low resistance which allows the unit to start turning at under 1.0 MPH. They will provide long life service and are easy to replace with standard components. Optional ceramic stainless bearings can be added. The ceramic bearings will likely last for the life of the unit and are immune to corrosion.

Due to the steel frame this turbine weighs more than many of the propeller based turbines.This gives the turbine a flywheel effect which stabilizes it’s energy  output.

This stored energy keeps the turbine turning at a more constant speed where the stored energy provides energy when wind energy drops off and then absorbs energy during wind bursts. The net result is stabilized rotation speeds and more smoothed energy output which is easier to regulate for storage or transmission. The stored energy also helps maintain rotational speed during short spikes of energy demand which would otherwise reduce rotation speed and cause more voltage fluctuation in the output.

The default support frame is made from 1.5” tubular steel with all joints welded. It is designed to come apart into three pieces for shipping in a flat box and is easily re-assembled by 1 person. It includes diagonal braces that hold the unit upright when installing.  

The mounting frame was shown is designed specifically to withstand high winds.  It has stood up in 30 MPH winds even without anchoring.

Design and Efficiency


This Savonius type turbines when airfoil optimized have demonstrated Coefficient of performance (CP) ranging from 0.2 to 0.35.    This unit is estimated to have a CP of between 0.25 and 0.30.   

There is a 1/2 inch threaded power takeoff at the top and the bottom of the frame. This two sided design allows sensors and small electric generation on the top while the main compressor or pump are hooked to the bottom. It also allows a smaller electric generator to be used on the top with a larger generator enabled by a centrifuge clutch that kicks in on the bottom when wind speeds increase.

Low wind speed operation

The turbine regularly turns in winds under 1MPH which shows that with our low resistance design our high mass turbine requires less than 0.05 watts of wind energy to begin turning.   

Most wind turbines specify their rated for production in  26 to 30 MPH winds. We feel this is misleading because most areas can not provide consistent 26 MPH winds. This turbine is designed to do useful work in as little as 10MPH winds so here are the calculations for production at various wind speeds. Your output may be different due to wind direction changes and gustiness.   

Bird Friendly

One advantage of the relatively large Savonius turbines is that they turn slower than their horizontal axis propeller based relatives.  Even in high winds the unit is turning slow enough to avoid injuring a bird.

Low noise

axle-bearing-supportaxle-bearing-support-small.JPG.JPGWind turbine farms have a terrible reputation for noise. Part of this is caused by the lift based designs of the propellers which turn the propellers at speeds substantially higher than wind speed.      

This unit is nearly silent.   In 20MPH winds I could hear no noise at all from the unit. At 30MPH there is a slight sound of rushing air as it blows through the center cavity since it is accelerated like a Venturi through that area.  

Our motion conversion  bearings used to convert rotary motion to reciprocal motion when running our piston compressor are completely silent. Even when running the compressor the loudest noise is the air getting sucked into the intake.







Power and Torque

These measurements use a CP of 0.25 although our design may be a bit higher.  It uses a assumption of a electric generator which is 85% efficient and that the bearings and gears are 95% efficient. Calc Wind Speed MPH calc speed meter per sec Power out in watts Amps @ 12V.

Turbine Power Output Calculated  from Wind speed
Wind speed MPH Watts Harvested
8.0 MPH 8.8 watts
10.0 MPH 17.1 watts
12.0 MPH 29.6 watts
14.0 MPH 46.9 watts
16.0 MPH 70.1 watts
18.0 MPH 99.8 watts
20.0 MPH 136.8 watts
22.0 MPH 182.1 watts
24.0 MPH 236.5 watts
26.0 MPH 300.6 watts
28.0 MPH 375.5 watts
30.0 MPH 461.8 watts
32.0 MPH 560.5 watts
34.0 MPH 672.3 watts
36.0 MPH 798.0 watts
38.0 MPH 938.5 watts
40.0 MPH 1,094.watts
42.0 MPH 1,267.2 watts
44.0 MPH 1,457.0 watts

At speeds above 40MPH the efficiency drops off which is part of the design to help protect the unit from damage in high wind speeds. As a result calculations for wind speeds above 40MPH would be inaccurate. These estimates are based on a university formula not empirical test results. A CP of 0.25 was used with a 85% efficient generator and 95% efficient bearings.

University and private laboratory tests have shown that Lift enabled Savonius turbines are capable of reach CP of up to 0.35.   We use a CP of 0.25 to be conservative but have expectations that when laboratory tests are completed our system will exceed a CP of 0.295.

As the blade spins up momentum is stored in the blade which would give it momentarily a torque hundreds of times higher than the stall torque so please do not let the blade hit you when moving  at high speeds because there is a lot of stored momentum.

Why is starting to spin in 1 MPH winds important

The wind does not deliver very much energy at low speeds. Our calculations show that at 1 MPH total wind energy only contains 0.086 watts with 0.017 watts delivered to the axle. Since our turbine starts turning reliably in less than 1 MPH winds the total energy needed to overcome initial blade mass and bearing resistance is less than 0.017 watts.

The turbine may or may not start at 1MPH when a load is added but it will consistently start at a lower wind speed than most other turbine designs give the same starting torque requirements.  

Many lift based turbines have a difficult time self starting due to low initial energy input . Some of these have so much problem starting that they must be spun up to speed using an electric motor before they can reach sufficient lift.

Our turbine's high torque at low speeds means that it can effectively spin up under loads that would prevent other turbines from ever starting. As a result it does not need a spin up motor or the clutches which are typically used to allow a turbine to spin up before placing them under load.

RPM at wind speeds

RPM Increases as wind speeds increase. Every increase of 2MPH increase in wind speed roughly doubles available power. This power is represented as both torque and faster RPM.

Savonius turbines are drag based and receive a majority of their energy from wind impacting the turbine blade.  In contrast, common propeller based turbines transfer energy by using aerodynamic lift similar to that used by airplane wings. The lift based designs actually spin faster than than wind speed but provide less torque and are subject to stall. A characteristic of Savonius turbines is that they never spin faster than the wind is blowing but they provide more torque and the torque increases when loads cause the turbine to spin slower than the wind. The CorrectEnergySolutions turbine is fundamentally a drag based design but it uses lift to increase speed and efficiency.  
These speeds are measured from the unit with no power take off so it is spinning pretty much as fast as possible with no resistance.   Under normal conditions the speed will be lower due to the load imposed by the power take off or generator.
 
RPM Measured from wind Speed
Measured speed MPH RPM by counting 10 revolutions with timer Notes
7.2 to 8.4 38 Wind was very Erratic
. . .

Measured torque

The torque is measured as a function of maximum pull at a given wind speed with the blade held at a stationary point. The power take off lever used to measure the torque was 2” long. When the blade is turning at wind speed the torque will be lower because there is less wind resistance. When operating with a load the blade will typically be moving at a speed slower than wind speed and when operating in this condition it will present higher torque than than when turning freely at wind speed.

As the blade spins up momentum is stored in the blade which would give it momentarily a torque hundreds of times higher than the stall torque if delivered all at once to a stationary object. This normally works to our advantage especially when powering reciprocal processes because many of these reciprocal processes have portions of each cycle where more work must must be used such as when a piston pump has maximum pressure near the end of each stroke.

The flywheel effect of the turbine allows it to speed up slightly during the easy part of the stroke and this extra energy is used to push the turbine on through the hard part of the stroke even if gross wind speed would normally have not been adequate to provide that level of torque.

 Do not let the blade hit you when moving because there is a lot of stored inertia. I have reached out and stopped the blade at 20MPH without any problem however as wind speeds go up here is more inertia and it could be dangerous.

Torque from wind Speed
Measured speed MPH Measured torque pounds measured from 2" lever from axle Notes
7.2 to 8.4 . .

. .

Power Conversion radial motion Reciprocal motion 

Our motion conversion bearings convert rotary motion to reciprocal motion. This is
typically necessary for driving pistons, diaphragm type pumps and some types of saws.

When running our piston compressor it is completely silent except for the slight noise of air getting sucked into the intake

The reciprocal motion shown here is 4" versus a 48" blade providing a effective 12 to 1 ratio.

The reciprocal conversion gears and pumps are normally covered in a weather tight housing which has been removed to show the motion.

Play Video of reciprocal pumping.
Additional Videos




Installation

  1. mounting-frame.JPGThe support frame is re-assembled and bolted together.  
  2. The support frame is stood up and supported by the diagonal braces.    (two people make this step easier)
  3. The support posts and the diagonal braces are fastened to their ground support
  4. The two turbine halves are bolted together. (Two people make this step easier)
  5. Then the main  axle brackets are inserted into the top and bottom holes.
  6. The main turbine is then set in place temporarily resting on the main axle braces.
  7. One person must hold the top axle bracket in place until the top of the main turbine can be slid into place by the second person.  Once the main turbine is in place it will support the axle bracket.   This step should be done in winds less than 8MPH or the wind acting on the turbine can make it difficult to hold the turbine in place.
  8. The bolt holes for  in the turbine are aligned with the main axle brackets and bolted in place.
  9. Insert top shims if necessary to force top axle bracket bearing holder over top axle.
  10. Tighten bolts for axle brackets
  11. The turbine will start turning if there is any wind.
  12. Hook your wind appliance, pump, generator, etc to the ½” power takeoff.
  13. Paint all bolts where tightened with corrosion resistant paint to help prevent corrosion and match the bolts to the rest of the frame.

We suggest that the center posts be bolted to 1.5” galvanized steel tube that is embedded in at a cement pillar similar to what is used to install outdoor basketball poles.   Local contractors can give guidance on the depth of amount of cement needed to support outdoor basketball poles and our turbine will require a similar amount.    
We have installed our demonstration systems with simple 4 foot tall green field fence posts driven into the ground on each side of the main support legs.  These fence posts are driven at least 3 foot into the ground and then bolted to the main supports.   In this configuration the test units have withstood 75MPH winds.    This configuration is not recommended unless the unit will be moved relatively often.

Each of the diagonal braces is ideally tied to the ground wither with a cement post or a pound in fend post or twist in stake.     
For our demonstration systems we either leave these unanchored or pound in 3 foot fence posts 2 foot into the ground and bolt to each diagonal support.

The amount of strength holding the unit to the ground will directly affect how the unit survives in high winds.    In hurricane strength winds the strength of the ground anchor is particularly important.

Disclaimer & Conditions


FAQ

Can you freeze water with your turbine?
Yes we can freeze water with this turbine. It requires a heat pump which converts the rotational energy to chilling energy.  CorrectEnergySolutions offers an optional compressive / vacuum pump which can extract heat out of water. This can be done either by directly exposing the water to vacuum which accelerates evaporation enough to cause freezing or the compressor pump can be used in a standard vapor compression cycle with the resulting cold being used to freeze the water.  
Can you stack rotors to get more power?
You can add multiple segments to the vertical aspect of each rotor but these must be specified at the time the order is placed.

It is technically feasible to add 30 to 50 foot of vertical height but it would require increasing the strength of some components to withstand the additional wind sheer stress. For larger installations this  is one of the most cost effective ways to increase system output while using limited amounts of land. It  will obviously require stronger mounting pillars to support the taller unit.

You can combine multiple turbines by feeding the compressed gas output into multiple rotors into the compressed gas delivery channel which simplifies the plumbing of the system. The compressed gas sheds heat in transit so we can allow the turbines to be up to a mile away from the point where the chilling is needed, provided here is a 1 inch supply line.  

To reach the maximum COP a 1" return line must also be provided. Smaller lines can be used for shorter distances. Larger lines are needed for larger buildings. In this mode the buried pipe actually acts as part of our heat sink and improves system performance. It is actually cheaper to deliver cold energy this way than it is to carry DC power a similar distance.
Can you use this turbine to deliver space cooling (air conditioning)?
You may have seen the commercial installations that freeze water, when energy is lower priced, and then use the ice for cooling during the hot daytime. Like for office buildings. The wind turbine when combined with the optional compressor / vacuum pump can chill water using free wind energy.  

When the wind energy is available during the same hours when cooling is needed it can be used immediately. Otherwise it can be stored in the cold water or ice and used the next day.  

One interesting aspect of this application is that it would allow the turbines to be installed over a mile away from the structure where the cold is used. this makes it particularly appealing when the turbines can be placed up on a ridge where there is more wind.
Can the turbine be used for pumping water?
Yes the turbine can be used to pump water. The CorrectEnergySolutions compressor pump can pump water and will supply up to 24 foot of vacuum for self priming and over 20 PSI of head on the uphill side. The CorrectEnergySolutions pump should be protected by a 400 mesh input filter to prevent sand from interfering with the check valves.  

There are also diaphragm pump and roller pump options which can be powered directly from the turbine.
How many turbines are needed per ton of air conditioning?
This is a very complex question. In general modern air conditioners plan about 900 watts per ton of delivered cooling. Normally this is delivered in the form of electricity.  As the EER goes up the number of watts required per ton of delivered cooling goes down.  EER 10 requires 1,000 watts per ton.  

When our compressive pump energy is used to extract head directly from the storage fluid we can achieve efficiency similar to the modern air conditioners but we still need to plan on at least 700 watts of input energy per ton of delivered cold.

Using an estimate of 700 watts per ton of consumed mechanical energy it would require the following at 8 hours per day of wind per day the number of turbines are needed delivered ton hour. This must be multiplied  by  the number of hours the normal HVAC system runs per day.  Most homes in zone 3 should plan on approximately 30 ton hour per per 1,000 square foot. Local HVAC contractors can supply estimates based on the heat load for a given structure. 
10 MPH - 5.10 turbines per ton hour
12 MPH - 2.90 turbines per ton hour
14 MPH -  1.83 turbines per ton hour
16 MPH - 1.23 turbines per ton hour
18 MPH - 0.86 turbines per ton hour
20 MPH - 0.63 turbines per ton hour
22 MPH - 0.47 turbines per ton hour
24 MPH - 0.37 turbines per ton hour
26 MPH - 0.19 turbines per ton hour
If there are more or less than 8 hours of wind  the calculations can be scaled linearly. A few hours of faster wind can have can deliver a lot of energy and should be accommodated.

Can you use this turbine for Generating electricity
Yes this turbine can be used to generate electricity however it is somewhat more complex to implement than with horizontal turbine systems. The primary issue is that the turbine turns slower which is problematic for many motors when being converted to generators or alternators. This can be overcome by gearing the system up to a higher speed. It is also possible to build alternators specifically designed for operation at lower RPM and when designed for this purpose these alternators can exceed 90% efficiency.

CorrectEnergySolutions  offers a belt driven gearing system that is coupled to a DC motor and routed through a AC rectifier to ensure a consistent polarity output. Our preferred motor is a Brushless Dayton DC motor which has proven to deliver a very high reliability but tops out at about 10 amps. The shaft output is geared up to the 1750 RPM recommended for this motor. The gear ratio is chosen to reach the requested RPM at the customer specified wind speed. CorrectEnergySolutions also offers a special charge controller that decouples the motor from the charging circuit lower speeds to allow spin up.

There are power take off shafts with 1/2 inch at the top and bottom which allows the compressor or pump and the electric generation to be driven.

How many turbines are needed to deliver 100 watts
Watts needed per turbine
Wind Speed Watts delivered per turbine turbines needed for 100 watt output
6 3.7 27.0
8 8.8 11.5
10 17.1 6.0
12 29.6 3.4
14 46.9 2.2
16 70.1 1.5
18 99.8 1.0
20 136.8 0.7
22 182.1 0.6
24 236.5 0.4
 
Is your turbine better than other turbines?
Defining better can be difficult. Our turbine is optimized for specific conditions which we believe are more widely available and which make it ideally suited for applications which can tolerate lower RPM in exchange for higher torque.   

Our root CP will never reach the better computer controlled pitch based propeller systems being deployed in major wind farms for use in large scale utilities. On the other hand our turbine is more usable in many other applications.  

Our root toughness would be impossible to match at anywhere near the same price point. Our design can be installed close to the ground because it is immune to the turbulence that can destroy propeller based systems and negatively effects Darrieus efficiency.

We designed our turbine to be ground based or at least within 10 foot of ground. This is important because we wanted to maximize the locations where they could be installed without violating local ordinances. Our system is designed to do real work in the 10 to 12MPH range which we felt could be more consistently delivered.   
 
Isn't there a big advantage to installing wind turbines farther off ground?
There is normally a wind speed advantage which increases as much as 2MPH per 60 foot off the ground. Each 2MPH speed increase can nearly double delivered energy.

Our  turbine can be installed on top of a tower or pole but it designed from the assertion that additional installation and maintenance costs associated with elevated installation can make it better to consider installation  closer to ground installations especially in the hurricane zones we consider one of our primary markets.  

We figure that the savings in near ground installation pay for the difference in larger numbers of turbines especially in areas with dangerously high wind speeds.

There are times where elevated installation is mandatory such as when the wind is being blocked by fences, walls or trees. Our turbine is compatible with this.

One of the main uses of our turbines is the use of the compressor pump to drive chilling and this can allow the feed lines to be extended for over a mile. This flexibility can allow cheaper options such as ridge line installation.
 
Are Savonius turbines less efficient?
There is always a trade off for Savonius based designs where drag can never exceed wind speed. Even if extra lift portions of the cycle tried to push the blade to exceed wind speed then other portions of the blade would eventually introduce extra drag and slow it back down.     

This means the blade operates slower but the total power delivered is similar due the higher torque. The primary disadvantage for the Savonius design is caused by the impact of the wind on the trailing edge of the blade. We  have provided curves optimized to minimize this loss but it still has an impact on total performance.

 Some credible wind tunnel tests have shown CP as high at .35 but these are closer to Darrieus designs by the time they are fully optimized so they loose their tolerance for turbulence and chaotic flow which we felt was an important design criteria. Many propeller based designs claim CP of .35  with the leading edge computer feathered blade systems reaching as high as 0.50. We expect our turbine to ultimately reach a CP of 0.30 which is competitive with most fixed blade propeller systems and there are other strengths.    

In general the lift based systems will provide speeds that are more ideal for electricity generation without gearing changes however the custom alternators can supply similar efficiency while providing some additional advantages.

The amount of lift we gain helps push us above the CP of .25 for simple Savonius systems because it converts the first 10 to 15% of the trailing pass into a suck forward rather than  resistance. It also helps accelerate the first 20% as the blade is moving the scoop into drag position.  Our Venturi shaped funnel in the center helps accelerate that post blade push a little bit but the real strength of the design is in it's great inherent strength and ease of manufacturing.
 
How does your extra blade weight affect performance system?
The bearing energy loss is pretty low with the overhead and bottom paired ball bearings even with our current weight. To put this in perspective the turbine starts turning with no load at 0.8MPH winds. 1MPH calculates at .085 watts total wind power for a turbine of this size or 0.017 watts with a CP of .25. The bearings must be providing less than 0.017 watts base resistance.    

 The bearings used are way overrated and good to 10K RPM and 15 times the weight of the turbine so they should last the life of the unit. They are also easy to replace. The one challenge this design is larger axial loads where the turbine is pushing sideways on the bearing  but since we have the top and bottom bearings the axial load is a simple sideways push rather than a twist  and in this configuration the bearings are rated to over 200 times the turbine weight.
 
We actually use the mass in the blade as a type of flywheel to better average the energy input versus energy curve. In our compressive pump system not all stages of the cycle provide the same resistance. At the top of every cycle as the piston is moving in it starts from basically 1ATM of pressure and by the end of the cycle can reach 2 ATM which means the piston is working harder as it approaches the bottom of each cycle. The same thing works in reverse when it starts from the residual overpressure in the head and quickly becomes increasing vacuum as the piston is pulled back out. The weight of the turbine time momentum equals the inertia to carry the unit through the last 20% of each stroke which is much harder than the first 20%.
What artistic options are available?
We have quite a bit of flexibility on skin color but the black and off white shown in the picture will last the longest due to specialized UV packages. The skin we are using is so slick that most paints can not stick to it.   

We also have some flexibility on shape tall versus wide. Big curves versus small. Helical designs are beyond our fabrication ability. 

We can  use 1/8" polycarbonate for the skin which gives us a incredible range from clear through fluorescent. 
     

 

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All illustrations and documentation shown in these pages is subject to change as CorrectEnergySolutions adds new capabilities to the product, releases new versions and tests new materials.    All financial estimates are the best we can make with currently available information and resources.  There are many variables such as the plastic, aluminum, steel, oil, electricity, weather patterns and economic upturns and downturns that could substantially change the answers.