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Wind to recharge batteries

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?

EdG | December 8, 2011

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.

TikiMan | December 8, 2011

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.

Timo | December 8, 2011

Laws of physics defeats a need for such.

jbunn | December 9, 2011

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.

stephen.kamichik | December 9, 2011

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

Brant | December 9, 2011

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

jbunn | December 9, 2011

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.

David70 | December 9, 2011

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

brianman | December 10, 2011

@jbunn
/chuckle "MC Escher company"

Brian H | December 11, 2011

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

Ron5 | December 12, 2011

Timo said:

>Laws of physics defeats a need for such.

Well said, Timo!

olanmills | December 13, 2011

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.

Brian H | December 13, 2011

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

Brian H | December 13, 2011

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

Timo | December 14, 2011

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.

Brian H | December 15, 2011

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

Volker.Berlin | December 16, 2011

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

Robert.Boston | December 16, 2011

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

jbunn | December 16, 2011

Free beer tomorrow...

Brian H | December 16, 2011

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...

Volker.Berlin | December 16, 2011

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

Volker.Berlin | December 16, 2011

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

Mycroft | December 16, 2011

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

Timo | December 16, 2011

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.

David70 | December 16, 2011

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.

Brian H | December 17, 2011

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

Timo | December 17, 2011

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.

EdG | December 17, 2011

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.

Timo | December 17, 2011

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.

David70 | December 17, 2011

Timo,

So the one meter size is radius rather than diameter? And the geometry is spherical?

EdG | December 17, 2011

If the reactor could fit in a 1 meter diameter sphere (1/2 meter radius), then the water for a 1 meter water shield (using Timo's assumptions) would be

4/3 Pi (1.5)^3 - 4/3 Pi (.5)^3 + the weight of the reactor (assume small)

Again, using Timo's numbers, that would be 13.6 tons of water.

EdG | December 17, 2011

The reason for the spherical assumption is that it minimizes the surface area, and, therefore, the blanket's volume. Any other shape would take even more water.

TikiMan | December 17, 2011

Ya know, if you attach this to your home, you could actually maybe get a few re-chargeable miles for your Tesla... http://www.google.com/products/catalog?q=home+windmill+generator&oe=UTF-...

Timo | December 17, 2011

@EdG, that's correct. Sphere is just the smallest possible for protection from all sides. Practical shape is probably something with edges here and there, which would mean even more water.

Brian H | December 17, 2011

Somewhat oval is the actual projection.

ncn | December 18, 2011

Nuclear fusion for power? Great idea -- there's one particular fusion reactor, which is kept safely six light-minutes away and provides for practically all our energy needs.

Building any others is pointless. The energy return is always going to be worse, unless we're merely using it for heat, since we're spending money generating heat and radiation and then trying to catch it and make electricity. Capturing energy efficiently from the massive fusion reactor we already have is going to be better.

Again, the folks I know have got a solar panel design which can be manufactured in existing factories -- cheap, relatively speaking -- with 10 times the energy capture rate of the current best lab designs; it'll take longer to get that built than their battery design, and someone else may perhaps beat them on solar panel design first. Either way, solar is going to take over for electric production, and very quickly.

Thermal applications are another matter, but the economics is starting to point heavily towards use of electricity (heat pumps) rather than fossil fuels for heating, as well, which has surprised me. Passive thermal designs are still better, and solar thermal and geothermal still have an edge.

The fossil fuel age is over, the existing interests just haven't noticed it yet. So is the nuclear-reactors-on-Earth period, and likewise. It'll take a while for people as a whole to notice that we're now in the Solid State Electromagnetic Nanotech age (which has already started). It'll take a while to phase things out, though; the Age of Horses was clearly ending in 1900, but it took until the 1950s for horses to stop being a fixture on city streets.

Timo | December 18, 2011

Nuclear fusion for power? Great idea -- there's one particular fusion reactor, which is kept safely six light-minutes away and provides for practically all our energy needs.

You mean eight minutes? Earth has seasons, bad weather etc. Solar is not solution to everyone, in fact it probably is not solution to majority of people. Sure Sun does radiate to Earth more than we need, but you would need to transport that energy looong distances to cover everybody, and it is vulnerable to just plain bad weather. Think monsoon and winter.

Building any others is pointless. The energy return is always going to be worse, unless we're merely using it for heat, since we're spending money generating heat and radiation and then trying to catch it and make electricity. Capturing energy efficiently from the massive fusion reactor we already have is going to be better.

You are very wrong about that. In every sentence.

Again, the folks I know have got a solar panel design which can be manufactured in existing factories -- cheap, relatively speaking -- with 10 times the energy capture rate of the current best lab designs

How is that possible? What does "10 times the energy capture rate of the current best lab designs" mean when best commercial designs already have over 30% conversion ratio? Are you claiming 300% conversion ratio? Perpetual motion machine? Either your friends are bulls*itting you, or don't know what they are doing, or you didn't understand what they said to you.

Solar radiation is weak. About 1kW/m^2 on clear day near equator at midday. That translates to far less than 10kWh/day/m^2. With current expensive techs that gives 3kWh a day in perfect weather.

Brian H | December 19, 2011

More to the point, the LPP reactor/generator occupies about 200 sq m., and will put out 5MW 24/7/350. Which is 25kwh/sq.m, regardless of weather. At an install cost about 20-50x lower than the best solar.

Solar, wind, and all renewables will be instant economic roadkill the minute feasibility is established. Only really stupid money will stay with them for a while, and then vanish.

Brian H | December 19, 2011

Correction above: 24kW/sq.m', or 600kwh/sq.m/day. Round about 200X better than solar. At under 1/20 the cost.
German example:

2 yrs old, 7+ million Euros. Nominal output about 70% of ONE LPP generator. Care to guess what its actual output is? I wouldn't.

Brian H | December 19, 2011

Sorry 'bout the size. It's smaller on the source page.

VolkerP | December 19, 2011

At least it is a "green" technology :-)

regarding LPP: why does it need shielding when it is aneutronic? Is there some Gamma ray emission?

Brian H | December 19, 2011

Yes, some gamma, some slow neutrons from side reactions. The net result is that after a "cooling off period" of ~9 hrs, the total radiation from the generator and surroundings is "below background". Even while running, it's not all that high.

Timo | December 19, 2011

Problem are those neutrons. They are result of residual fusion/fission of something else than pure boron and hydrogen which is inevitable. That's much less radiation than normal reactor, but it still needs shielding. Gamma-rays are easy to contain, but neutrons pass thru normal matter like if it is not there unless it actually collides with the atoms. That is why shielding needs to be thick.

Liquid or metallic hydrogen would be best stopper for those neutrons, but because that's something that is very very hard to do LPP goes with second best option which happens to be water. Lucky to us that is not scarce.

Brian H | December 20, 2011

Actually, the outer shell of the water shield is to be 1" Boron 10, which is quite happy to accept slow neutrons and become Boron 11.

olanmills | December 20, 2011

LOL why won't this silly thread die? (oops)

Volker.Berlin | December 21, 2011

olanmills, simply because I was careless enough to use the F-word (see my post on page 1, Dec. 16). I take the blame and apologize. Won't happen again.

Timo | December 21, 2011

I don't think you are the culprit for the continuous messages, I think I am. I mentioned "peak oil" which then prompted several messages which included fusion and then it spin out of control.

Leofingal | December 21, 2011

lol