wind turbines on cars?

[Natorgator]

This is probably a stupid question, but is there any reason you couldn't put a small wind turbine on a car to power a battery? For some residential applications, rotors can be less than a meter in length and that's why I thought of this. Would the weight/efficiency of all the equipment make it unpractical?

[Admiral Valdemar]

You may as well strap a gerbil in a wheel to the thing. It's about as useful and a lot funnier.

[Natorgator]

So I take it either the technology doesn't scale down, or doesn't produce any net power?

[aerius]

Cars have alternators for a reason. A car mounted wind turbine will be far more inefficient and add a crapload of drag to the car and crap over its fuel efficiency.

[Beowulf]

It'd be insanely inefficient. Instead of going from engine to alternator to battery, it'd go from engine to wheels to airflow to turbine to alternator to battery. Every step you use introduces inefficiencies, sapping power.

[Sea Skimmer]

Umm, when is this turbine supposed to generate a net gain of energy? When the car is moving it will create an enormous amount of drag, it MUST in ordered to function, so you sure aren’t making any then. You’re making things much worse. A turbine could only begin to try to gain you energy in a moving car if the wind speed was higher then your speed of travel.

When the car is stationary you have a small turbine low to the ground that wont do jack crap; it would make way more sense to put a bigger turbine on a much taller poll in your backyard and continuously charge up a whole bank of batteries. Then if you have a hybrid you can use those batteries to charge it up at night. If you don’t have a hybrid, then your car was never going to gain anything from the turbine to start with because charging up a cars normal starter battery takes a pretty irrelevant amount of energy.

[The Duchess of Zeon]

Here's a suggestion. We just build, gasp diesel hybrids, which unlike the current stupid and largely worthless hybrids would have all-electric motors with no connection between the engine and the wheels, the engine is just hooked up to the generator. You put a battery pack in it which gives it a range of about 100 miles (possible with a light car, the extremely newest of technology, etc), and then the tiny diesel engine built for max efficiency runs at constant speed (where diesels are at their most extremely efficient) recharging the batteries as necessary. This car can be easily fitted with a connection which allows its batteries to be recharged from your house, from your office, from the roadside diner you stop at, etc. So, say, you stop for lunch at Denny's and you just pull out your power cord, plug your car in, and pay like a flat two bucks or something on top of your tab (or the place will offer it complimentarily to draw in new customers) to recharge for an hour while you eat. The car would of course have regenerative braking to also recharge the batteries.

Performance would be shit, but the efficiency level would be extremely high. Now, the next step is to limit the size of these cars; the largest would only have the same internal space as, say, a Toyota Corolla, and the same weight or maybe a little bit more to reflect the batteries. All other vehicles larger than this would be banned from production unless they're so large that they warrant a commercial driver's license anyway. The vehicles could also easily be fueled with grease or bio-diesel (which is worthless, but, eh, it isn't going away anytime soon), and they would now be the only vehicles which could be legally produced and sold in the United States. It would now be illegal to sell any older vehicle, except as a trade-in to the government, which would recycle it, though older vehicles could be converted by the owner to a similar setup. A high tax on gas for those people who continue to use gasoline-operated vehicles would fund this, along with extensive buybacks of older vehicles to help low income families into the new, efficient vehicles.

Now, again, performance would be very bad on a vehicle of that design, but people would just have to deal with it. They should be quite thankful they'd have a car at all. If they couldn't afford one, or the conversion for their existing vehicle, a programme could be set up to help people in the same neighbourhood pool together to buy a single such vehicle and share it.

Now, is this going far enough in terms of staving off Peak Oil? No, but it would be something that could conceivably happen to mitigate it, and would be, well, a nice start.

[His Divine Shadow]

Why not go even further and replace the diesel with a turbine? Aren't they even more optimized for that kind of work and more fuel efficient and will run on practically anything?

[Aaron]

Why not go even further and replace the diesel with a turbine? Aren't they even more optimized for that kind of work and more fuel efficient and will run on practically anything?

A diesel will already burn pratically anything. You just have to change the filters and I believe the fuel pump. Military diesels (alot of them the same Cat engine that's in a big rig) are referred to as multi-fuels for that reason. You can use kerosene for example.

[Sea Skimmer]

The need for a different fuel pump depends on just what you want to burn; the real key of the whole thing is to have a fuel preheater. Once you have one of those and a way of priming it you can use just about anything gas or liquid that burns. You can go further then this though, and make a turbine or diesel engine combine cycle, in which the waste heat from exhaust and radiator is used to power a steam turbine. Mercedes Benz already has adapted this technology to gasoline powered cars, with two different steam turbines, one for the radiator and one for the exhaust heat running at different pressures for optimal efficiency gain. Course, that’s also really expensive; but this proposed car will already be expensive as hell. I’m not sure though if you could get any real gain from a combined cycle if the engine only runs in bursts.

Overall a combined cycle gas turbine can reach 60% efficiency, which is 10% more then the best (read biggest, like 100,000hp ship engines) diesel can reach. The diesel engines normally used in trucks can hit perhaps 45%, I’m not sure how much of a gain a steam turbine would add.

Note that running the engine in bursts will greatly increase emissions because the catalytic converter wont stay hot enough to do its job. This is why most hybrids cars now sold in America don’t have electric only modes.

[The Duchess of Zeon]

The need for a different fuel pump depends on just what you want to burn; the real key of the whole thing is to have a fuel preheater. Once you have one of those and a way of priming it you can use just about anything gas or liquid that burns. You can go further then this though, and make a turbine or diesel engine combine cycle, in which the waste heat from exhaust and radiator is used to power a steam turbine. Mercedes Benz already has adapted this technology to gasoline powered cars, with two different steam turbines, one for the radiator and one for the exhaust heat running at different pressures for optimal efficiency gain. Course, that’s also really expensive; but this proposed car will already be expensive as hell. I’m not sure though if you could get any real gain from a combined cycle if the engine only runs in bursts.

Overall a combined cycle gas turbine can reach 60% efficiency, which is 10% more then the best (read biggest, like 100,000hp ship engines) diesel can reach. The diesel engines normally used in trucks can hit perhaps 45%, I’m not sure how much of a gain a steam turbine would add.

Note that running the engine in bursts will greatly increase emissions because the catalytic converter wont stay hot enough to do its job. This is why most hybrids cars now sold in America don’t have electric only modes.

The engine would still produce a lot of waste heat, couldn't we tap that to insulate the catalytic converter? If that's impractical, well, couldn't we arrange the drive cycle so that the batteries always get drawn down first and then the diesel simply runs continuously until they're fully recharged? (With the driver choosing when to initiate its operation after starting, so the charge from stopping somewhere and plugging in will be favoured first.) Braking would still be contributing to the recharge of the batteries as well.

[Sea Skimmer]

The engine would still produce a lot of waste heat, couldn't we tap that to insulate the catalytic converter?

Well if the engine is making waste heat, then it’s already heating up the converter, no point to adding a system to externally heat it. Insulation would be a tricky proposition given the variance in the US climate, because while too little heat means the converter doesn’t function, too much heat even once will ruin it. I really doubt insulation could be effective anyway, unless the engine only pulses off for a minute or two. The heating and cooling of those things is pretty rapid.

The temperature range we are talking about is about 500 degrees for any functionality, about 1,200 degrees for optimal effectiveness, and when you start to approach 2,000 degrees you start getting damage. Overheating can occur very quickly despite requiring such a high temperature, a standard emission dyno test lasts only 240 seconds, plus maybe 30 seconds preheating, and that’s enough time for it to happen if you have a serious problem.

If that's impractical, well, couldn't we arrange the drive cycle so that the batteries always get drawn down first and then the diesel simply runs continuously until they're fully recharged? (With the driver choosing when to initiate its operation after starting, so the charge from stopping somewhere and plugging in will be favoured first.) Braking would still be contributing to the recharge of the batteries as well.

Running the engine only for significant periods of time would help an awful lot, and the batteries will prefer a trickle charge to high powered pulses too.

Overall though this would not be a particularly bad issue, because if everyone is driving way less then emissions will go way down overall, even if each car pollutes worse. But just to give you an idea of how bad things can be, a 20cc lawnmower engine with no converter can pollute worse then a 1.8 liter car engine that has one. Because of this many communities are now banning all forms of gasoline powered yard equipment; it’s not really practical to fit a converter onto anything less then a riding mower because of how hot and expensive they are.

Also, if you actually run this proposed multi fuel vehicle on multiple different fuels without adjustments, it’s going to run dirty as hell no matter what technology it has. But then this is hardly an insurmountable problem either. Aside from different fuel injectors the changes would be mainly electronic, and it might be possible to simply program them in and have a fuel type switch in the fuse box.

Anyway, just some practical issues to think about

[Ryan Thunder]

You folks are thinking waay too far into this. What the OP is suggesting is a perpetual motion machine, unless I've misunderstood it.

Obviously, this is impossible. [/thread]

[Sea Skimmer]

You folks are thinking waay too far into this.

Not really, I’ll soon have access to an automotive shop my friends are opening, and while it’s pretty unlikely to be a priority, we may end up building our own hybrid.

[Aaron]

You folks are thinking waay too far into this. What the OP is suggesting is a perpetual motion machine, unless I've misunderstood it.

Obviously, this is impossible. [/thread]

Not really. Assuming it's just a car with a battery driving an electric motor with a turbine on top, you'd still have to put energy in at some point. Think about it, the turbine charges the battery but how do you get the car moving if the batteries aren't charged? You'd have to charge them up by plugging it into an outlet. Then once you got going the turbine would charge the batteries, only as others have pointed out that's not enough power. So you'd still have to charge it up at home.

[SCRawl]

You folks are thinking waay too far into this. What the OP is suggesting is a perpetual motion machine, unless I've misunderstood it.

Obviously, this is impossible. [/thread]

Not really. Assuming it's just a car with a battery driving an electric motor with a turbine on top, you'd still have to put energy in at some point. Think about it, the turbine charges the battery but how do you get the car moving if the batteries aren't charged? You'd have to charge them up by plugging it into an outlet. Then once you got going the turbine would charge the batteries, only as others have pointed out that's not enough power. So you'd still have to charge it up at home.

The reason it's impossible is because turning that turbine to generate electricity while the car is moving will cost more energy (in the form of drag) than you'll ever get out of it. Hence the comparison to a perpetual motion machine.

[Aaron]

The reason it's impossible is because turning that turbine to generate electricity while the car is moving will cost more energy (in the form of drag) than you'll ever get out of it. Hence the comparison to a perpetual motion machine.

Seen.

[Enola Straight]

If the car was parked and the wind turbine was being used to trickle charge the batteries using ambient wind conditions, then yes it would work...but you would have to guard against theft/vandalism of the turbine unit.

[Chardok]

But could the turbine itself slow down the rate of discharge, thus increasing the range of the vehicle from one that did not carry a supplemental charge system?

(Incedentally, I'm a big fan of all-electric cars with multiple recharge mediums, so this interests me.)

I envision a car that harnesses it's own static electricity somehow. Dragging thin metallic strings along the road underneath it.

I envision a car that uses the same principles as that there faraday charger dealy in those little LED flashlights generating a trickle of electricity.

I envision a car with solar cells on it's roof, trunk, and hood.

I envision a car with a plug-in

I envision a car with a compressed air storage tank that runs a small generator for emergency charges

I envision a car that carries a tiny 2 cylinder gas engine it can use to run the generator for extended range and for emergency recharges.



I envision a car that has three or more of these ideas built into one platform that uses only a tiny fraction of the amount of energy todays cars use.

[SCRawl]

But could the turbine itself slow down the rate of discharge, thus increasing the range of the vehicle from one that did not carry a supplemental charge system?

As mentioned before, such a system would cost more energy in drag than it would produce in electricity. The only way it would work is if it were a selectively deployable device. In other words, if you had one operating while you were stopped (which would rely solely on the prevailing wind), while you were going downhill, or while you were slowing down, it would add something to the charge of your battery while taking nothing away. As a full-time device, it can't help but lose.

[Starglider]

Note that running the engine in bursts will greatly increase emissions because the catalytic converter wont stay hot enough to do its job. This is why most hybrids cars now sold in America don’t have electric only modes.

Is there any good reason why you can't just electrically preheat the catalytic convertor prior to starting the engine? By my rough calculation even 1000 degrees F from cold will take less than a kilowatt hour, and heating elements (even high temperature ones) are dirt cheap.

[Sam Or I]

In the current hybrids, the exhaust gas drive a turbine which generates the electricity. The exhaust gas is much higher pressure than you can obtain from the wind around the car.

Slightly off subject BMW was experimenting with steam hybrid. Using the heat from the exhaust to help drive the wheels.

[Sam Or I]

Maybe I should have read through the posts instead of skimming.

[Sea Skimmer]

In the current hybrids, the exhaust gas drive a turbine which generates the electricity. The exhaust gas is much higher pressure than you can obtain from the wind around the car.

No actually, no production hybrid that I’m aware of uses turbo compounding, which would be used to put energy back into the crankshaft in any case. A handful of big truck engines do use that technology, but they aren't hybrids Turbo compounding overall suffers from numerous technological limitations.

Hybrid cars use the direct drive of the engine crankshaft to turn a generator. Typically the engine retains the ability to directly drive the wheels, but some purely electric drive models do exist.

Is there any good reason why you can't just electrically preheat the catalytic convertor prior to starting the engine? By my rough calculation even 1000 degrees F from cold will take less than a kilowatt hour, and heating elements (even high temperature ones) are dirt cheap.

Well since you have a big battery pack already, you could do some preheating, but I wouldn’t risk trying to bring it all the way up to operating temperature. The inside of a cat is a pretty delicate honeycomb structure that’s meant to be evenly heated; you’d need to use a number of heating elements with temperature sensors to avoid any risk of damage. Its really pretty amazing that the things last as long and well as they do already.

[Illuminatus Primus]

This is probably a stupid question, but is there any reason you couldn't put a small wind turbine on a car to power a battery? For some residential applications, rotors can be less than a meter in length and that's why I thought of this. Would the weight/efficiency of all the equipment make it unpractical?

The only reason you have apparent wind on a car is because of the energy you expended to acceleration through some air. You're simply increasing the car's drag and therefore making it take more gas milage, and not ever reclaiming all that much by means of the wind turbine.