Coastal Wind Characteristics

[KBwind]

Hello Otherpower,
I have just finished a 4 pole 7 footer HAWT for a heads up comparison with my Venecia VAWT design. Both are installed at a beach on the Pacific literally 20 ft from the high tide. The VAWT has a hub height of 8 ft - the HAWT is mounted on a 20 ft tower. The other day when we raised the tower the winds were blowing off the ocean at about 4 m/s as measured by a hand held anemometer at ground level.
The VAWT was really cranking, spinning about 100 rpm loaded putting out about an amp (both turbines are 12 volt) but the HAWT was just barely self starting with no load.
I was very confused since I expected the HAWT to at least keep up to my VAWT since it's such a tried a true design - then my local apprentice said it's because the winds were stronger closer to the ground and that the turbine would do better at half the height. Ofcourse this makes no sense and goes against conventional knowledge and so I wanted to ask the folks here. Has anyone experienced a situation where winds were higher closer to the ground in a coastal environment? Also - what sort of performance should I expect out of a 7 footer in 4-5 m/s winds. The blades were carved according to the otherpower design and the alt has six coils of 130 turns each (about 1 inch airgap).
Thanks in advance for any input. I will be posting a detailed performance comparison of the turbines once I am confident the haw is running properly.

[Jerry]

Hello Otherpower,
I have just finished a 4 pole 7 footer HAWT for a heads up comparison with my Venecia VAWT design. Both are installed at a beach on the Pacific literally 20 ft from the high tide. The VAWT has a hub height of 8 ft - the HAWT is mounted on a 20 ft tower. The other day when we raised the tower the winds were blowing off the ocean at about 4 m/s as measured by a hand held anemometer at ground level.
The VAWT was really cranking, spinning about 100 rpm loaded putting out about an amp (both turbines are 12 volt) but the HAWT was just barely self starting with no load.
I was very confused since I expected the HAWT to at least keep up to my VAWT since it's such a tried a true design - then my local apprentice said it's because the winds were stronger closer to the ground and that the turbine would do better at half the height. Ofcourse this makes no sense and goes against conventional knowledge and so I wanted to ask the folks here. Has anyone experienced a situation where winds were higher closer to the ground in a coastal environment? Also - what sort of performance should I expect out of a 7 footer in 4-5 m/s winds. The blades were carved according to the otherpower design and the alt has six coils of 130 turns each (about 1 inch airgap).
Thanks in advance for any input. I will be posting a detailed performance comparison of the turbines once I am confident the haw is running properly.

KBwind.

Could you convert the 4-5 m/s winds to mph? I for one can relate to mph easyer the m/s. Others here with similar machines may find it easyer to relate to mph also.

This may help them respond to your question. To me at first glance and without more info, your alternator sounds to small for the 7ft blades. It may need more rpm then the 7ft blades offer?

Jerry

[just-doug]

I'm not familiar with this particular alternator,but typical 12 volt machines use 30 to 40 turns per coil.at 130 turns per coil sounds more like a 48 volt winding.machine is probably in bad stall,try opening up the air gap.just my first thought.good luck Doug

[Flux]

Far too many unknowns to answer this properly. I suspect the wind is not very different at 20ft or 8ft on the coast, short of mounting the anemometer on a stick and reading it with binoculars you won't know.

You say a 4 pole machine, that to me makes me suspect it is iron cored, possibly a motor conversion. I have no idea of your blades but there is not a lot of energy at 4m/s and if they are fast low torque blades you may not even be able to start an iron cored alternator against the core loss at that wind speed.

It may be as someone else suggested that you are actually hitting cut in and stalling your blades ( prove this by disconnecting the battery).

If you have the same sort of alternator for both then it may far better suit the high torque of the VAWt if it a drag device and may not suit a fast HAWT prop.

See what happens when the wind gets over 5m/s and if the HAWT doesn't get away then and get performing then there is a real problem. It is in this low wind region that the air gap ironless alternator really does come into its own.

See what happens in higher winds and if things don't make sense then come back with much more details.

Flux

[KBwind]

Hi again, sorry for my lack of details - was writing that post on a bus that would make anyone laugh. Ok, it's a dual rotor axial flux 4 pole, no core. The turbine was open circuit so it wasn't stalled. The turns for the stator were based on my experience building four pole alts - with 130 turns it should make 12 volt at around 160 rpm. The VAWT uses the same basic alt with 160 turns per coil and a 2:1 chain drive transmission.
The wind did change direction later in the day and the HAWT did self start and pick up pretty well. I saw it really go for a few minutes but by the time I got the voltmeter hooked up it was back down to about 60 rpm putting out 4 volts open circuit. Mind you in this same wind the VAWT was kicking at about 150 rpm and 2 amps. The winds might have been 5 or 6 m/s.
I do feel better hearing that 5 m/s is still in the very low range for real power output. I suppose it could be one of those "no wind but I just got this thing done and want to see some power" kinda deals.

That suggestion about the anemometer on a pole and look at it with binoculars is clever. I will give that a try next time we get winds off the ocean. I was thinking that the main reason wind varies with height is due to the "surface roughness" of the land with all the trees, brush obstructions etc. In our coastal case there are literally zero obstructions along the pacific until Japan so there should be very little practical difference in a difference of 12 feet.
Thanks everyone for the help

[Watt]

Could you explain the 6 coils and 4 poles a bit further.  What kind of magnets and magnet size are you using?

[TomW]

You could tie streamers (ribbons) to a long pole at various heights to get a visual on differences in wind if any. very low tech but a valid one to one comparison in real time.

Just thinking into the keypad

Tom

[KBwind]

I'm using 2x1x0.5 N42 mags. 8 mags per  10 inch disc. Stator wire is 18 AWG. The original 4 pole design was published by Mr.
Piggot for a project in Peru I believe - I just modified it for Neos and my desired cut in. I guess I've done 5 of these alts now so I've got a good idea of how many turns I need for a certain cut in and power output.

Yes, I think having some streamers placed strategically would help me visualize the flow field in my area.

[Watt]

KBwind

Is this the HAWT? You have an 8 pole 3 phase alternator then instead of 4 pole?  2 coils in series each coil having 130 turns?  Or 4 poles, two magnets 1 per coil three phase.  Or do I have the VAWT mixed in?

Not questioning your abilities or comparing anyone else to this thread.  Just try to get an better idea of your build differences between the VAWT and the HAWT.  That's all.  

[KBwind]

Hi Watt,
Both turbines have the same basic alt - the VAWT with 160 turns and a transmission - the HAWT with 130 turns direct drive. Here's a link to the document http://practicalaction.org/docs/energy/pmg_manual.pdf for the original alt design.
Two coils in series per phase - wired in wye.

[Watt]

Hi Watt,
Both turbines have the same basic alt - the VAWT with 160 turns and a transmission - the HAWT with 130 turns direct drive. Here's a link to the document http://practicalaction.org/docs/energy/pmg_manual.pdf for the original alt design.
Two coils in series per phase - wired in wye.

Thank you for the link, now I have better understanding.  With the stronger magnets, you should have higher voltage for sure.  More turns of wire should have also given you more voltage.  Is there a chance that your coils are connected back to front or is there a chance the magnets are back to front in a place or two.  If by chance the coils are back to front, this could have been a reason the turbine was thought to be in stall by someone even open circuit.

Is this wye ( star ) or delta wired? 

[KBwind]

Hmmm..
I was very careful in ensuring the coils were connected correctly - but I didn't know that having them mixed could make the turbine act like that open circuit. Good to know for the future. These little alts are rather strong - but way too much stator resistance for a VAWT direct drive and thus the transmission. It should be interesting to see how they compare once I get them dialed in. Even then the comparison will be taken with a grain of salt - I have 7 operational VAWTs under my belt and this is my first HAWT so I have some learning to do in that area. It's a whole other animal with different challenges and difficulties. I do like the carved blades and here in Nicaragua I can get good pine cheap. In the end the blades cost about 2$ each for materials.
I also enjoy seeing both turbines operating side by side - it really highlights the essential differences of the machines in form and function.

[CaptainPatent]

It is true that coastal wind patters are a bit different. If you look at the wiki page about prevailing winds: http://en.wikipedia.org/wiki/Prevailing_winds and scroll down to the "Sea and land breezes" section you can see how and why they form.

With that in mind, at low altitudes you have air moving the opposite of air at mid-altitudes generally. I wasn't initially under the impression that the wind direction started dying off at such a low altitude but it may depend on your site and they may be lower than I imagined. I think Tom had a great idea with the streamers though.

[Watt]

Hmmm..
I was very careful in ensuring the coils were connected correctly - but I didn't know that having them mixed could make the turbine act like that open circuit. Good to know for the future. These little alts are rather strong - but way too much stator resistance for a VAWT direct drive and thus the transmission. It should be interesting to see how they compare once I get them dialed in. Even then the comparison will be taken with a grain of salt - I have 7 operational VAWTs under my belt and this is my first HAWT so I have some learning to do in that area. It's a whole other animal with different challenges and difficulties. I do like the carved blades and here in Nicaragua I can get good pine cheap. In the end the blades cost about 2$ each for materials.
I also enjoy seeing both turbines operating side by side - it really highlights the essential differences of the machines in form and function.

If you were having coil issues, can you lower the turbine and see if you have a warm stator or section of the stator.  This will be warm open circuit.  Good luck with your tests. 

[KBwind]

That's a fantastic reference list - thanks very much. I now finally understand why the wind changes direction consistently at 12:30pm each day. That must be the time of day when the air above the land becomes of greater temperature than air above the ocean  causing the land air to rise more amd create a low pressure zone. We also have an interesting situation since we are sandwiched on a peninsula between the ocean and an estuary about a kilometer away. We are also at low elevation- basically at sea level - both turbine towers are 2 foot deep in the ocean at the highest tides in June. Could I be the only one on this forum with what could loosely be considered an off-shore turbine?

[Watt]

That's a fantastic reference list - thanks very much. I now finally understand why the wind changes direction consistently at 12:30pm each day. That must be the time of day when the air above the land becomes of greater temperature than air above the ocean  causing the land air to rise more amd create a low pressure zone. We also have an interesting situation since we are sandwiched on a peninsula between the ocean and an estuary about a kilometer away. We are also at low elevation- basically at sea level - both turbine towers are 2 foot deep in the ocean at the highest tides in June. Could I be the only one on this forum with what could loosely be considered an off-shore turbine?

Hmmm...  I wonder how those tidal wive water tubines could be tested there?  Ideas?

[CaptainPatent]

That's a fantastic reference list - thanks very much. I now finally understand why the wind changes direction consistently at 12:30pm each day. That must be the time of day when the air above the land becomes of greater temperature than air above the ocean  causing the land air to rise more amd create a low pressure zone.

No problems. I was absolutely intrigued when I learned about how prevailing winds work myself (originally for aviation purposes) That would be precisely why the winds change though, and it may be the one reason your site will fly in the face of the "taller is better" logic.

both turbine towers are 2 foot deep in the ocean at the highest tides in June. Could I be the only one on this forum with what could loosely be considered an off-shore turbine?

Haha - I think on that technicality, you may just be!

[KBwind]

Every morning I wake up and think - why am I messing with this wind when that ocean is raging with waves 24 hrs a day. I literally have the perfect site to develop small scale wave turbines. We live on a 40 km stretch of completely undeveloped beach and there certainly aren't any city inspectors or permits to worry about. Hey, if anyone is interested I can offer accomidations and a decent shop for developing an open source wave turbine!

[CaptainPatent]

The problem is you have a very low head situation if you want to routinely be able to harness electricity from waves or tide. With waves, you may be able to do some sort of splash-over mechanism but I can only envision getting a couple gallons per minute and with a 3 to 5 foot drop we're talking a maximum of MAYBE 3 watts.

I'll even work through a best-case scenario:

Even if you routinely get huge waves - say 15 feet - and you manage a trough style intake that can grab 100 gallons of water from each and every wave and each wave is 4 seconds apart...

Your flow rate would be around 1500 gallons per minute and you'd have a drop of about 7-10 feet (keep in mind the water flows back to equilibrium and not to the wave-minimum. That setup would produce a respectable 1500 watts maximum (assuming 10 feet) but then you have to look at how realistic that would be.

If you can only get 3 feet of drop,  your power cuts all the way down to 450 watts. If you can only pull in 50 gallons, it gets cut in half again.

Plus you have to deal with the wear and tear that saltwater will do to your components.

Because you have such a reliable and constant wind source on the coast, it will probably be better to stick with that.

I'm not saying that it isn't possible, and there actually is a monstrous amount of power in a 100 foot section of a 3 foot ocean wave, it's just very difficult to reliably harness.

[Larsmartinxt]

On a show aired on National Geographic called Planet Mechanics they had an idea on how to make wavepower work without to much wear and tear on the turbine. This because they use the waves to pump air trough a turbine so it doesn't get in direct contact with salt water.
http://www.youtube.com/watch?v=pAxBzI6DEkA

[KBwind]

Thanks for the input and that link. I will watch it a little later when I have some time. Wave energy certainly wont be easy. I was thinking more along the lines of extracting energy from the kinetic motion of the water and not actually the change in elevation. It could be very similar to my VAWT - with the bottom half of the blades submersed - sort of like a vertically mounted cross-flow turbine. There are some very strong under water currents which are more consistent than the waves - that would keep the thing moving between waves. Then waves will hit the top half kind of like a gust.
There are definitely some 15 ft plus waves- it's just a matter of how far off shore (surfing is a hobby of mine and the real nice breakers are always a little further out than I want to go by myself) and how to find the correct location of the turbine considering the difference of as much as 200 feet between high tide and low tide. Perhaps I will build small scale model and see how it moves - that would definitely help me visualize the flow and think of how it can be harnessed.

[DamonHD]

Sounds like you may be talking about "tidal flow turbines".

Have a look here: http://www.emec.org.uk/

Rgds

Damon

[wooferhound]

This was my idea on how to get power from the waves


After thinking about it some more . . . I would pot a big Float on top of the waveplate.

[KBwind]

Some great resources in this post thanks all. This will certainly give me lots to think about when I find myself staring off out to sea. I suppose it may be a little while before I get to building something like this. When I do I will be sure to start a new topic where we can share observations and ideas. My first hydro project will be development of an open source cross-flow turbine DIY style. I could just take the unshrouded rotor out to sea one day to see how she does.
Woofer- cool idea thanks-  not sure I completely understand it yet but it certainly opened my eyes to an out of the box solution.

[TomW]

Long long ago in a galaxy far far away...

I forgot the details but they used a simple PVC based pump similar to a sucker rod pump mounted in the water with an arm that rode the waves to operate the pump that pushed water through crude turbine generator on shore yes, an automotive generator from a truck I believe.  A bit Rube Goldberg but was built from common items at least the pump was. A smart guy could make it pump on both strokes?

Raise a large weighted car on rails on the tide then use it to drive a generator on up and down travel on the rails. Tides can lift an enormous weight a long ways you know.

Good luck and don't sprain yer brain trying too hard to figure it out.

Tom

[Larsmartinxt]

There has been done a lot of research on wave power over the years and what happens is that people underestimate the shear power of a storm with the constant bashing of waves. Resulting in a wrecked structure. I've seen huge boulders been thrown over a concrete pier from the power of waves.
 
This is (as far as I know) the only concept that works because you can keep the mechanical parts out of the water.

[bob golding]

there are a few of those in various sites around the uk. seem to have been pretty reliable as far as i know.

[CaptainPatent]

There has been done a lot of research on wave power over the years and what happens is that people underestimate the shear power of a storm with the constant bashing of waves. Resulting in a wrecked structure. I've seen huge boulders been thrown over a concrete pier from the power of waves.
 
This is (as far as I know) the only concept that works because you can keep the mechanical parts out of the water.

Nice - Now THAT'S an implementation that would work fairly well. If you make sure your intake is huge (several feet around) and several feet deep in the water at low tide to make sure the air is properly preasurized and taper it off to a very long & narrower, high-pressure tubing system, you could probably get some serious power out of it! It would work even better if you made rubber valves so air only came in in one direction and only came out in the other and both the intake and outtake worked with the turbine to turn it the same direction.

I wonder what the efficiency would be though since air is fairly compressible though.

[TomW]

Being inland and a landlubber is this last idea essentially a "blow hole" that you capture air flow in and out to drive a turbine?

[CaptainPatent]

Being inland and a landlubber is this last idea essentially a "blow hole" that you capture air flow in and out to drive a turbine?

*Points to nose*

You could get some serious pressures too. The larger the size of the intake in relation to the size of the air feed hose to the turbine, the higher your resulting PSI and the more your blowhole blows!

[Larsmartinxt]

Nice - Now THAT'S an implementation that would work fairly well. If you make sure your intake is huge (several feet around) and several feet deep in the water at low tide to make sure the air is properly preasurized and taper it off to a very long & narrower, high-pressure tubing system, you could probably get some serious power out of it! It would work even better if you made rubber valves so air only came in in one direction and only came out in the other and both the intake and outtake worked with the turbine to turn it the same direction.

I wonder what the efficiency would be though since air is fairly compressible though.

I think they use "wells turbines" that rotates the same way independent on direction of airflow.
http://en.wikipedia.org/wiki/Wells_turbine

[CaptainPatent]

I think they use "wells turbines" that rotates the same way independent on direction of airflow.
http://en.wikipedia.org/wiki/Wells_turbine

Hmm, interesting. I hadn't heard of a Wells Turbine until now. I'm having a little trouble wrapping my mind around the aerodynamics, but it looks like it's a drag-only device at startup and then the apparent pitch of the moving device gives it additional lift. Very cool and interesting.

[just-doug]

the Piggot design that you refer to calls for ceramic mags and 100 turns on the coils.you changed the design to n42 mags ,much stronger mags.should probably took 30 turns off the coils insted of adding 30 turns.piggot is on here from time to time,I'm  sure  with his vast experience he will have a more exact answer.