Author Topic: Enlil Vertical Axis Turbine  (Read 556 times)

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Offline EEVblog

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Enlil Vertical Axis Turbine
« on: July 02, 2019, 12:21:26 pm »
I think these have been discussed on here before (maybe not this brand, I think there is more than one group doing this), using a wind turbine next to motorways to harvest energy.
The immediate answer that pops into ones head is that there is no free lunch here and the energy must come the increased drag on the cars.
But how much in this case?
Just running this through my head now and I'm not so sure it's going to add much to the drag of the vehicle, as the vehicle has already expended the energy against it's surface area. A turbine a meter away isn't likely to add much?
So if the car has already expended the energy, harvesting that energy usually lost to the environment could be beneficial?

Take for example when the turbine is initially not moving, the vehicle moves past and the tail wind vortex (for want of a better term) turns the turbine, thus for the first car though it surely hasn't added any meaningful extra drag?

For subsequent cars I'd image that the turbine is creating some air turbulence that might add on the drag, but again, how much?

What am I not seeing?

BTW, I'm not concerned in this discussion with the powering 20,000 homes part, just how much impact it will have on the vehicles.

« Last Edit: July 02, 2019, 01:11:04 pm by EEVblog »
 

Online Kleinstein

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Re: Enlil Vertical Axis Turbine
« Reply #1 on: July 02, 2019, 01:11:42 pm »
The wind turbines don't seem to have a lot of power: They claim 1 KW per hour, and the day has 24 hours - so just a little more than 40 W for a day. I very much doubt the units could produce 1 kW of power excepts for storm force wind short of breaking the units. So 40 W may actually be a realistic value.

With many small units, cabling and maintenance will be quite some effort.
Another point is mechanical safety.

The towers close to the street would add to the drag - it may not be much for a single unit, but it would add up. It's especially bad when hitting them head on.
 

Offline EEVblog

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Re: Enlil Vertical Axis Turbine
« Reply #2 on: July 02, 2019, 01:23:25 pm »
The wind turbines don't seem to have a lot of power: They claim 1 KW per hour, and the day has 24 hours - so just a little more than 40 W for a day. I very much doubt the units could produce 1 kW of power excepts for storm force wind short of breaking the units. So 40 W may actually be a realistic value.

Yes, they say kW/h and not kWh, but then the voiceover says that's the daily energy needs of two households so they are implying kWh  :palm: which would indeed be about two households worth a day.
But anyway, what I'm really interested in is if they actually drag (pun intended) that extra energy from the vehicles in drag, or if it's actually harvested from mostly already expended energy. I'm not sure how to run the calcs on this, I suspect some sort of advanced modelling may be required.
 

Offline EEVblog

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Re: Enlil Vertical Axis Turbine
« Reply #3 on: July 02, 2019, 01:30:11 pm »
Again, kW/h
And says if it runs for 6 hours it can light a house for a day (not run a house)
 

Offline EEVblog

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Re: Enlil Vertical Axis Turbine
« Reply #4 on: July 02, 2019, 01:38:16 pm »
No mention of power produced in this pitch, I wonder why...
Although they mention the price, so I guess you could back calculate.

 

Offline GregDunn

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Re: Enlil Vertical Axis Turbine
« Reply #5 on: July 02, 2019, 07:14:13 pm »
If there's no turbine in that spot, there will still be drag because the vortex from the vehicles is interacting with still air, or even the building - which both cause turbulence and add some drag.  The thing is that the force exerted won't be very large, so the turbine will have to be very easy to spin - which means it won't be able to take much of a load in the way of a generator.

I think it's likely just to be very inefficient, and not a significant source of drag.
 

Offline voltsandjolts

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Re: Enlil Vertical Axis Turbine
« Reply #6 on: July 02, 2019, 07:20:37 pm »
Don't bolt them to the ground, bolt them to all the cars. Much more efficient that way.
 
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Offline Nominal Animal

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Re: Enlil Vertical Axis Turbine
« Reply #7 on: July 02, 2019, 08:51:24 pm »
Make buses more aerodynamic, reducing drag and any air movement generated, instead.  If you also make vehicles' surfaces dimpled (like golf balls), you not only get better aerodynamics, but also less glare from sun or street lights, possibly reducing traffic accidents; plus small bumps and bruises won't show up so badly, so savings on panelwork repairs might be statistically significant, too.

What?  Non-boxy buses don't look "busey" enough?  A car must look like a face on a dildo to sell?  Oh well, better build fucking windmills next to roads then, I guess.
 

Offline dunkemhigh

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Re: Enlil Vertical Axis Turbine
« Reply #8 on: July 04, 2019, 05:25:17 pm »
Quote
Make buses more aerodynamic

Do you have an idea to share on how that might be achieved?

Quote
Non-boxy buses don't look "busey" enough?

Doubt if it's looks, more that there isn't the space to have pointy bits.
 

Offline Nominal Animal

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Re: Enlil Vertical Axis Turbine
« Reply #9 on: July 04, 2019, 06:22:42 pm »
Quote
Make buses more aerodynamic
Do you have an idea to share on how that might be achieved?
Dimpled surface, nose cone, and fins/protrusions at the rear end to control the vortices.  But, fluid dynamics is not exactly my forte; I'm just extrapolating from what little I know similar R&D been done in the last few decades for actually aerodynamic stuff to reduce drag.

Doubt if it's looks, more that there isn't the space to have pointy bits.
Why not?  You need, what, a meter or two added length, maybe a half meter of ducting on top.  Should not even affect cornering radius.  These are also completely in the crumple zones, so would add minimal weight.  You could do stuff like directed vents in front to aid in maneuverability (which is the main reason buses fronts are currently flat).  It's just that there are very few people doing such basic research today; it ain't sexy enough.  But green wind energy, now there's a sexy subject you can get a grant in, even if it makes no long-term sense at all.

All that said, roads tend to be in open areas, so sticking a bunch of few-meter-high VAWTs along the roads should work just fine, especially along highways and rural areas.  Not in the sense of harvesting energy from passing cars, but harvesting energy from naturally occurring wind.  Haven't done any calculations, but I bet it makes more sense than solar roadways...
 

Online Kleinstein

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Re: Enlil Vertical Axis Turbine
« Reply #10 on: July 04, 2019, 06:57:43 pm »
With wind turbines it makes a lot of sense to have them well higher than the typical obstacles (e.g .trees). The wind speed goes up with altitude quite a bit for the first 10 m. The power goes up as the third power - so twice the wind speed 10 m up is a big plus.

There is also not much wind left behind a fence to keep dogs and children out of the rotor. So the middle of a very busy highway maybe the only place where they could get away without a fence.  :-DD
 

Offline Nominal Animal

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Re: Enlil Vertical Axis Turbine
« Reply #11 on: July 04, 2019, 07:21:05 pm »
The power goes up as the third power - so twice the wind speed 10 m up is a big plus.
Right -- so putting smallish VAWTs on top of highway light poles might make sense, I guess?

Oops, there goes my million dollar idea.  Oh well...  8)
 

Online Kleinstein

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Re: Enlil Vertical Axis Turbine
« Reply #12 on: July 04, 2019, 07:23:54 pm »
Putting them on top of poles makes more sense - though it would need stronger poles and one still has the wiring problem - maybe if the wires are there for lights anyway.
 

Offline Brutte

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Re: Enlil Vertical Axis Turbine
« Reply #13 on: July 05, 2019, 09:34:42 am »
WRT obstacles in the proximity of a vehicle, I believe the aerodynamic drag is a monotonic function of the clearance. If you provide 0 clearance (you won't allow any air to pass the bus, like piston and cylinder) then the drag will have its maximum value. When you allow the clearnce to be (theoretically) infinite then the drag will be at minimum (approximately rho*S*Cx*V^2/2). Within all the cases in between the relation of drag=f(clearance) is monotonic.

So the energy provided to that turbine could be free only if drag=f(clearance) had extremum(minimum) and putting an obstacle in the proximity of the road would shift the equlibrium into that minimum region, harvesting on the difference that was gained.
 


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