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wind generation?

6297 Views 55 Replies 17 Participants Last post by  rfhendrix, 
R
i was thinking the other day. what if we put a wind powered generator in the grill where the rad would normally go to help keep the batteries charged while driving. i think something like this would really help highway driving?

just a thought, wondering if anyone would have any in put in making it happen?
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Qer
  1. If you'd bothered to search the forum you'd find out that that "idea" has been shot down already numerous of times.
  2. If it had been possible it'd mean that you in a specific case could create more energy than consumed which would undoubtedly had lead to this to happen somewhere, sometimes in the universe and the universe would already have exploded and disintegrated in a cloud of uncontrolled blast of energy.

So, the mere fact that we're all still alive pretty much means that it's impossible to create energy for free. Thankfully.
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R
i know you cant make more or even as much power as you are using. but just to add maybe 10-20% to the total range. i don't think that would be too hard. that would only be highway use. it wouldn't work for city of course.
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T
The basic problem is that it takes more energy to drive the wind turbine that the energy it can produce, just one of those things that happens. If the vehicle was stationary and the wind was blowing hard enough then some energy can be extracted in the form of electricity via a wind turbine. To try and create the same amount of wind energy by pushing the vehicle through the air would use a lot more energy that the wind turbine can collect, it's all in the inefficiencies. If the air is simply allowed to flow through far less drag is created so less energy is required to push the vehicle through the air.
There is a reason wind turbines have such solid mounting poles, there is a lot of energy pushing against the blade faces to make them spin.

T1 Terry
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R
ok that makes a little more scene. thanks
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Woodsmith
If you lived in a particularly windy area then it may be worth looking at a static mounted wind generator to charge your batteries at home.

This would be good if your electricity supplier also bought the electricity for a fair rate when you were not using it yourself.
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G
If the car is stationary and pointed into the wind, then the wind turbine will generate power. Likewise if you are driving into a head-wind, you will have a net gain of energy. If you are driving with a tail-wind, you will lose energy.

Since we tend to drive in all directions, the overall energy from the car-mounted turbine will be negative (ie it is a loss). As was explained, the turbine pushes back on the car, so you need to use even more energy to move forward.

As suggested, a turbine fixed on your home/garage would be a better bet (larger blades then what you can fit on a car, more energy).

One interesting mind game - imagine a full-sized wind turbine mounted on the roof of your car. Some of the wind energy will move the car back, but since the blades are angled, some of that energy will produce a rotational torque (on the generator shaft) - this will tend to push the car sideways (you would probably have bad tire-wear). If you were driving into a strong wind, then hit a big bump in the road, you may land with the car on its side!

A bonus points math question - under what conditions could you hit a bump/ramp, get airborne, do a full rotation, and land back on your wheels?
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dtbaker
rabbithazen said:
i was thinking the other day. what if we put a wind powered generator in the grill where the rad would normally go to help keep the batteries charged while driving. i think something like this would really help highway driving?

just a thought, wondering if anyone would have any in put in making it happen?
Click to expand...

...back to physics 101 for you!

- available frontal area is pretty small, even if you could perfectly duct all of the normal grill area. Figuring the available sq feet at your average urban speed of 35mph, doesn't give much air mass to generate much power even if you had a 'perfect' duct and 100% efficient turbine. If you engage the generator at steady state speed, it would act as a brake, which you motor would have to OVERCOME to keep steady speed.... and since nothing is perfect, you'd lose whatever the in-efficiency % is in the systems to heat.

- it MIGHT be useful if you could let it 'freewheel' when driving, and apply generation load only when you are braking; but even under best circumstances I doubt the power generated versus cost to install would be anywhere near worth doing. Additionally, if you use it as a brake, your speed is dropping, and power drops as a square of wind speed....
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I
Wow, you guys are quick to jump on things sometimes. The air going in the grill will hit something anyways, whether it's the engine or the firewall. Putting a win generator there might increase turbulance, therefore increasing drag a tiny, tiny amount, but it will generate enough electricity to compensate for it. Nevertheless as dtbaker pointed out, the frontal area of a car is small and energy generation even at 70mph would be very small.

So is it worth it? Definately not as space is more valuable than 1% range improvement as you're better off buying an extra battery. But does it break the laws of physics? Come on now...
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dtbaker
icec0o1 said:
The air going in the grill will hit something anyways, whether it's the engine or the firewall. Putting a win generator there might increase turbulance, therefore increasing drag a tiny, tiny amount, but it will generate enough electricity to compensate for it. ...does it break the laws of physics?
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uuuhhhh, yeah if you expect the generation to overcome the additional drag when it is 'working'. The thing that this concept seems to boggle people on is that the more work the turbine does, the more effective drag it creates... that work has to come from somewhere.... increased work to push the car thru the air! (this is the Laws of Physics part)

Hence it would ONLY be useful when braking and you WANT more drag, all other times it would add effective drag even if free-wheeling because of the tiny increase in aero drag even in a perfect duct.
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G
No, it won't work even if you have some drag anyway. It takes energy to drive that generator and that energy is coming from your batteries. You will get less range with it on than if you turned it off.
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T
How about a pop up wind turbine from the boot lid for braking :p just kidding folks.
If anyone is seriously interested in building a home made wind generator there is a lot of very good info here at a site called The Back Shed. A wind turbine charging the used battery pack from the EV and recharging the new batteries in the EV when you get home, now there is a wind generation plan that would work.

T1 Terry
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I
dtbaker said:
uuuhhhh, yeah if you expect the generation to overcome the additional drag when it is 'working'. The thing that this concept seems to boggle people on is that the more work the turbine does, the more effective drag it creates... that work has to come from somewhere.... increased work to push the car thru the air! (this is the Laws of Physics part)

Hence it would ONLY be useful when braking and you WANT more drag, all other times it would add effective drag even if free-wheeling because of the tiny increase in aero drag even in a perfect duct.
Click to expand...
This turbine won't be on the roof of the car... it'll be right in front of the engine/batteries/firewall. The air is either going to hit them and do no work or hit a turbine and do some work. Either way the air's slowing the car down but in one case you get some energy out of it.
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G
No, It won't work. You create drag with it. The drag is not coming from the item in the air stream. It is electrical drag from energizing your generator. As soon as it's activated it will cause drag to create that electricity putting a drain on your battery pack as well as driving your vehicle and you will not put back into the pack more than you have put in. You only have X amount of power in your pack. You will not get more no matter what you do. You may not use as much over the course of time but you don't get more. Energize your generator and put power back in the battery will not work as it takes more out of the battery to produce that power you putting in and you will lessen the distance you can drive. It just does not work.

Regen does not give you more either. It only allows you to use your power over a longer time. Not much either.

A generator and motor running at the same time just does not work. Sure I can have a generator running to maybe run some lights but it is a drain on the main pack. I'd be better off using my original pack to pull power from DC DC to run my lights than to run a generator to do the same job. Using the generator will use more power from the pack.

Same reason I prefer to use a DC DC to an alternator.
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Woodsmith
icec0o1 said:
This turbine won't be on the roof of the car... it'll be right in front of the engine/batteries/firewall. The air is either going to hit them and do no work or hit a turbine and do some work. Either way the air's slowing the car down but in one case you get some energy out of it.
Click to expand...
Yes it will give you something back but at the cost of increasing your drag.

The air that currently hits the front of the car causes some drag, smoothing out the airflow but blocking the grille, filling in gaps, etc. will make the car more efficient by reducing the drag created at the front. Opening it up and adding a turbine blade adds drag. It is the drag that will generate electricity in the turbine generator. But the drag the turbine causes will be more then the car has without the turbine and also will not provide enough energy to overcome the drag in the first place.

It would be like asking the car to do $10 extra work for a return of $2. Sure you will get the $2 but at the loss of $8 plus the cost of the turbine generator.
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alvin
A wind turbine to fit the grill is about 1 ft diameter and will produce about 47 watts in 20mph wind.
alvin
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I
So a quick theoretical question then:

You're in a moving car and open the window to extrude a square foot metal sheet facing the front as to create maximum drag. Then right next to it, you stick out the same square foot metal sheet except that it has a second 2" by 2" plate right in the middle offset forward about an inch.

Would the second metal sheet have more drag?
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Duncan
So a quick theoretical question then:

You're in a moving car and open the window to extrude a square foot metal sheet facing the front as to create maximum drag. Then right next to it, you stick out the same square foot metal sheet except that it has a second 2" by 2" plate right in the middle offset forward about an inch.

Would the second metal sheet have more drag?

Yes
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T
This might give you an idea of the amount of drag a wing can create. This is the strand windmill in Townsville. Have a look at the wing area and the size on the pole and mounting foot. That's a lot of drag, this was not in the immediate path of the cyclone.

T1 Terry
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Ziggythewiz
T1 Terry said:
How about a pop up wind turbine from the boot lid for braking :p just kidding folks.
T1 Terry
Click to expand...
Wind braking is a great idea (for those with no sense of economics, but really want some wind power in their car) as an alternative to standard regen. Another way to do it would be to have a couple wind turbines behind a grill that is typically closed, but opens when the brakes are pressed.

Did anyone else read about the australian car that used a kite to pull them along the highway? I think they got < 10% of their range from the kite (which would be far more efficient than using the wind to make electricity) which would make the value of the added expense questionable, but brings new meaning to the phrase "drive by wire".
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