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Wind to recharge batteries

This question if for any of the Tesla designers... Has there been any thought about using the wind while driving to recharge the batteries? Initially I was thinking of using a paddle (like on a riverboat) right behind the front gill allowing the wind to spin the paddle thereby charging the batteries?

I answered this in "Questions". Please don't post the same thing in multiple places. We read all the posts. No need to read the same thing again.

I think the fact that any downhill motion in the Model S will help re-charge the batteries (or so I am told), defeats a need for such.

Laws of physics defeats a need for such.

You can't collect much energy from such a small amount of wind Rbeninati1, however the Tesla will capture power when coasting, or going downhill. The process is called regeneration.

As the driver, the best enery saving solution is to find a commuting route from your house to your destination that is mostly downhill, capturing energy through regeneration. On your return home, avoid your origional route, instead selecting a different path that is also downhill.

Topological maps specifc to your area that can assist in your trip planning can be ordered from the MC Escher company, which you should be able to find on the internet.

I doubt if you can make a trip that is downhill BOTH ways.

My dad walked to school uphill in the snow..both ways
; )

Brant,

I used to go to school with your dad. We didn't even have shoes, but in the winter we used to wrap our feet with barbed wire for traction.

Headwind both ways too, but that's more possible.

@jbunn
/chuckle "MC Escher company"

It'll be easy in the 'S'; if you have air shocks, just raise the rear and lower the front.

Timo said:

>Laws of physics defeats a need for such.

Well said, Timo!

Timo said:

>Laws of physics defeats a need for such.

----

For the benefit of anyone who needs further explanation:

Regenerative braking works because we already want to remove kinetic energy (motion energy) from the car anyways. When you hit the accelerator and then let go of the pedal (but don't hit the brakes), your car will roll for some amount of distance, right? That motion represents gas that you already burned to make the car continue to roll, even though you're not pressing the pedal anymore. When you want to stop in a car, it means you want to remove kinetic energy from the car. In a normal car the brakes just use friction and the kinetic energy is dissipated as heat. You already fed enough gas into the engine to go farther, but you want to stop sooner. In a sense, whenever you use the brakes on your (normal) car you're wasting gas. In the case of an electric car, it's easier to convert that energy (that would normally be wasted anyways) and store it in a form of energy that can be used for driving later.

rbeninati1's idea is to use rushing air and a paddle to turn a turbine to generate electricity while the car is driving. The problem with this is that the rushing air is caused by the car moving forward. The car is moving forward because the electric motor is propelling the wheels. So the actual effect is that the eletric motor will be used both to propel the wheels and to turn a paddle. That the paddle feeds back into the motor means that you're wasting energy because the most energy that could be theoretically recovered is 100% of the portion of the motor's energy that is used to turn the paddle. So at best, you accomplish nothing. That's not physically possible though has you'll lose a bunch of energy converting rushing air back to electricity. So you'll actually waste more energy.

There ain't no such thing as as free watt-hour.

typo: There ain't no such thing as a free watt-hour.

That depends a bit how you define "free". I know that that is famous quote that is meant to illustrate that there is always losses in energy generation and you can't generate energy from "nothing", but how about generating energy from something?

We have three main "free" sources of energy: Sun, nuclear and heat from Earth core. All of those are already in use in several ways. Fossil fuels are just chemical energy stored in the thing and it originates from Sun.

What makes it free? Well, nothing comes without effort, not even energy from nothing if there would be such a thing. You would always need to build some sort of capturing device. Well, that's exactly what we are doing with power plants.

What matters is energy put in building such capturing device & maintaining it versus energy you gain from it. With that definition any and all power plants that actually generate energy are "free energy" generating devices.

This brings to my mind a definition of "peak oil" that doesn't mean end of oil: You use more energy in finding, extracting, refining and transporting it than you gain from using it. In that definition peak oil is very close, if not already past it.

Peak oil is still 40 years away, and always will be. That's the de facto chosen buffer period for the industry.

Fusion is just 5 years away, and always will be. :-P

Fisker Karma delivery date is always 2 months away...

Free beer tomorrow...

VB;
The standard quote is "50 yrs". This is a different technology, and actually I'm padding the number; it's probably more like 1-2 years for demonstration of feasibility, 3-4 for first commercial prototype. I said "5" to allow some slack. (It had already been set back a year by the underperformance of commercial switches, which couldn't actually handle the advertised 45kV, and had to be replaced with in-house designs.)
One of the items that had to be upgraded, the trigger core rod:
http://1.bp.blogspot.com/_VyTCyizqrHs/TUu4X6JOKOI/AAAAAAAAKQM/4KFxJv0tY0...

Yeah I know. And earth is flat. You are a lucky guy, live must be easy and fun with so many simple certainties.

Edit: "life" or "living", of course, not "live".

Easy mistake since you guys pronounce it the same. :D

I'd say peak oil and usable fusion happen in same time. At that point oil becomes obsolete (as energy source), and finding, extracting, refining etc. definitely costs more in energy count than you get from it.

LPP experiment is very promising considering how miniscule budged they run that experiment. They have already achieved fusion, but not yet break-even. It is close however. WAY WAY closer to actual usable fusion than any Tokamak ever made with teeny weeny fraction of the cost. I think Brian H is a bit optimistic, these kind of projects tend to take a bit longer than anticipated just for tiny engineering things, like Roadster got because of original two-gear transmission. Science behind that however seems to be OK, so it can't be very far in future.

Because cost, size and safety of that power plant, if it can get aneutronic fusion with target 5MW power, it revolutionizes our entire electricity production. Every ocean-worthy ship after that will be fusion-powered. Overhead wires for electric trains disappear. Long transfer line grid becomes obsolete, electricity can be produced on site. Big apartments can produce their own power.

And Timo,
I don't know the power requirements for large planes, but the size/weight of the 5MW (or about 6700 horsepower)units would probably make electric planes really practical. The would just need normal fuel for emergency situations.

About 2 tons/unit. Much of that is water shielding and capacitors. The latter may shrink with future tech.

I remember one meter water shield, which makes that a lot more than two tons. 4/3Pir^3 is the minimum volume if you need to shield it from all sides. Because one ton = roughly one cubic meter of water that makes this very easy calculation 4/3 * pi ~= 4.2 tons from water alone.

If you don't need to shield it from all sides it makes this highly variable number.

I don't think you allowed for the size of the reactor inside the shield, but assumed a minimum size of zero. So the weight would be a bit higher.

Reactor itself is really tiny. It would fit into a passenger car without any trouble. The actual reaction chamber is small enough to fit into lawnmower. Most of it is capacitors and that shielding.

It would be a bit bigger than that absolute minimum because of structure needed, maybe five tons. Water is heavy. People rarely realize how heavy it is.


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