Wind Powered Car... Sometimes I despair

[The Wookie]

http://www.whynot.net/ideas/720

Eight year... EIGHT YEARS of people trying to argue that it's not a stupid idea

Take note boys and girls, just because your opinion is different to the status quo, doesn't mean it's remotely sensible.

[wolves_wanderer]

http://www.youtube.com/watch?v=Xy0UBpagsu8

[Roman]

I suppose you could have a small portable or integrated folding wind turbine on top of an electric car when parked up to help recharge the batteries.

The small turbines frequently used on yachts are designed to generate 200-400 watts.

[The Wookie]

Roman said:

I suppose you could have a small portable or integrated folding wind turbine on top of an electric car when parked up to help recharge the batteries.

The small turbines frequently used on yachts are designed to generate 200-400 watts.

Unfortunately it's really not worthwhile, the extra weight of the turbine and the battery capacity required to store enough energy to run the car's electronics for a significant period of time would more than negate any fuel consumption advantage. It's the same reason why Solar panels haven't been used beyond gymcrack parcel shelf ones from Argos for people who are too tight to sort out an electrical fault or buy a new battery.

Plus it's more windy at sea, and when you're in a vehicle powered solely by the wind then using it to provide electrical power is the only viable option (excluding Solar, but I doubt you'd get enough juice out of it).

But that's not what these people are on about, these people are on proper 'fans attached to the front of the car to produce electricity while its driving along'.

It seems to break down into these categories:

'but if you improved the aerodynamics to suit it...' no, because if you did that then the car would still be more aerodynamic without the fans

'but you could use it only during braking...' a bit like regenerative braking then, only less efficient

'free thinkers have changed the way people see things in the past...' but they haven't defied the laws of physics as far as I'm aware

'the second law of thermodynamics doesn't apply here...' yes it does, it applies to absolutely everything in the universe

[4Q]

Surely the most 'sustainable' method of producing electricity is the cat/toast dynamo?



Although the weight increase of such a device might negate the power produced...

[Mr Will]

This one makes my brain doubly hurt:

moron said:

...direct current which could therefore power other parts such as the exhaust...

[Hugo a Gogo]

I thought you meant this

http://www.wired.com/autopia/2010/06/downwind-fast...

hard to get your head around

[grgrgray]

What next...A wind powered boat????

[CampDavid]

doogz said:

"Perpetual motion is great and all, but not cost effective"

LOL.

That's technically true. Close to impossible is costly, it follows that impossible should be sodding expensive

[The Wookie]

doogz said:

"Perpetual motion is great and all, but not cost effective"

LOL.

That was my personal favourite, along with a similar thread elsewhere on the site that said something along the lines of "Everyone has a downer on thermodynamics, why doesn't someone just use another theory?"

[Mr Gear]

The sad thing is, the very first response he got was correct:

"The laws of thermodynamics would prevent a wind generator from ever recovering more than a small fraction of the energy spent to accelerate and keep the car moving. Adding a wind generator to a car would only be adding to its drag."

[The Wookie]

Hugo a Gogo said:

I thought you meant this

http://www.wired.com/autopia/2010/06/downwind-fast...

hard to get your head around

That is hard to get your head around! The best analogy I could come up with is that it's a way of 'gearing up' the power of the wind

[Roman]

The Wookie said:

Unfortunately it's really not worthwhile, the extra weight of the turbine and the battery capacity required to store enough energy to run the car's electronics for a significant period of time would more than negate any fuel consumption advantage. It's the same reason why Solar panels haven't been used beyond gymcrack parcel shelf ones from Argos for people who are too tight to sort out an electrical fault or buy a new battery.

Plus it's more windy at sea, and when you're in a vehicle powered solely by the wind then using it to provide electrical power is the only viable option (excluding Solar, but I doubt you'd get enough juice out of it).

But that's not what these people are on about, these people are on proper 'fans attached to the front of the car to produce electricity while its driving along'.

It seems to break down into these categories:

'but if you improved the aerodynamics to suit it...' no, because if you did that then the car would still be more aerodynamic without the fans

'but you could use it only during braking...' a bit like regenerative braking then, only less efficient

'free thinkers have changed the way people see things in the past...' but they haven't defied the laws of physics as far as I'm aware

'the second law of thermodynamics doesn't apply here...' yes it does, it applies to absolutely everything in the universe

Yes some of the ideas on that site are utterly flawed and unrealistic!

However, at 400w over a 20 hour period a turbine produces around 28.75 million joules or around 8000 watt hours. A Prius running in electric mode consumes 260 watt hours per mile then a 20hour charge could give a range of around up to 30 miles.

Certainly not worth it simply to recharge the batteries on a conventional petrol car but A small 400w turbine won't add that much weight to an electric car which already has batteries and I'm sure they will only become more efficient than the current Prius.

In reality of course inconsistent inshore winds would generate much less energy over the same period, as you say. It would make more sense to simply recharge from a bigger wind turbine sited higher at your home or work place if either are in a suitable location.

May be worth considering for 15-30 miles worth of free energy per day for some people though considering current (and future) fuel prices!

[Gargamel]

Thing is though, my office has an underground car park

[The Wookie]

Roman said:

However, at 400w over a 20 hour period a turbine produces around 28.75 million joules or around 8000 watt hours. A Prius running in electric mode consumes 260 watt hours per mile then a 20hour charge could give a range of around up to 30 miles.

Not really relevant but I'll say it anyway, Toyota probably claim that 260Wh/mile, but that's probably european drivecycle, and at least 300 watt hours per kilometer is more likely real world in an EV. 8kWh is unlikely to get you further than about 15 miles.

Roman said:

Certainly not worth it simply to recharge the batteries on a conventional petrol car but A small 400w turbine won't add that much weight to an electric car which already has batteries and I'm sure they will only become more efficient than the current Prius.

Unfortunately, if a car is getting most or all of the electrical energy to power its systems during braking (which is increasingly common) then it negates the need for the turbine entirely at no weight penalty. Also, a quick look at 400W turbines suggests that they're over a meter in diameter, so not exactly easy to slot back into the car when you're not using it

Roman said:

In reality of course inconsistent inshore winds would generate much less energy over the same period, as you say. It would make more sense to simply recharge from a bigger wind turbine sited higher at your home or work place if either are in a suitable location.

May be worth considering for 15-30 miles worth of free energy per day for some people though considering current (and future) fuel prices!

THAT is the answer, but again EV's need to be more cost effective first. Whether that means ridiculously expensive petrol or better and cheaper batteries I don't know. Probably a combination of the two.

[Roman]

Gargamel said:

Thing is though, my office has an underground car park

Ahh, in that case, several hundred of these - if you can find enough rats underground to power them!:

http://www.youtube.com/watch?v=YqzNMxyILbY

[Roman]

The Wookie said:

THAT is the answer, but again EV's need to be more cost effective first. Whether that means ridiculously expensive petrol or better and cheaper batteries I don't know. Probably a combination of the two.

[thinfourth2]

i thought this might of been the story where some british students went along to the world championship of wind powered cars.

The rules stiplulated very strictly the size of the wind turbine and its max hieght etc to ensure everyone had the same amount of power. However the brits read the rules carefully and no where did it state how many turbines they could use.

So they turned up with two

http://www.bbc.co.uk/news/technology-11694911

[BarnatosGhost]

A thought:

Would mounting a small wind turbine in a grille at the front of a car (a BMW nostril, for example?) be a way of recovering some energy? The air passing over it is going into the car anyway.

How much energy could a 4" fan capture at 70mph? and would its additional drag (however much it would be) negate the energy it captured?

What would be the consequence of the fan slowing the passage of air onto the radiator? Would it only be applicable in instances where the full cooling capacity of the radiator was not required? Could it be swung out of the way at those times?

And most importantly of all - if it was yellow, would it look cool?

[The Wookie]

BarnatosGhost said:

Would mounting a small wind turbine in a grille at the front of a car (a BMW nostril, for example?) be a way of recovering some energy? The air passing over it is going into the car anyway.

No because the car would always be more aerodynamic without it being there. If the fan is doing work then it is by definition increasing aerodynamic drag, and if it's increasing aerodynamic drag then it's increasing the power demand from the engine

It doesn't matter if it's a 4 inch fan or a 4 foot fan, the principle is the same

Edited by The Wookie on Thursday 17th February 13:22