Fisker Buzz Forums banner

1 - 5 of 5 Posts

·
Premium Member
Joined
·
1,975 Posts
Discussion Starter · #1 ·
This looks pretty cool (conceptually, not aesthetically)... and they have a 1kw system too!

http://gizmodo.com/strap-this-wind-turbine-to-your-electric-car-and-you-ca-1497320336

"When available later this year, they'll come in a simpler 25 watt version, and a more industrial 1,000 watt model which can be used to keep a battery perpetually charging in an electric car. The extra power can also be used to run in-vehicle electronics like a Wi-Fi hotspot or an elaborate entertainment center, and just like their larger counterparts these turbines don't mind a little bad weather."



I think it would be cool for a Tesla or Fisker or BMW to integrate the turbines into the design of the car, maybe an aggressively styled front panel/bumper area.
 

·
Registered
Joined
·
913 Posts
... and a more industrial 1,000 watt model which can be used to keep a battery perpetually charging in an electric car. The extra power can also be used to run in-vehicle electronics like a Wi-Fi hotspot or an elaborate entertainment center.
Yes, it works just as well as lifting yourself off the ground by pulling up on your bootstraps. ;) (And for the same reason, even!)

Seriously, using a wind generator to power electronics in an electric car, where the generator is run by the car's motion, is just a waste of the battery. All the electricity produced by the generator is converted from energy stolen from the car's motion. (OK, that's a plus if you were going to be braking instead—but for that, we have the regenerative braking.)

Many old (1950s and earlier) aerobatics airplanes have no original-equipment electrical system (their engines use magnetos rather than spark plugs, and are hand-crank-started, hence the person at the front of the plane who yanks hard on the propeller to start it). You will sometimes find a small generator mounted to the fuselage to run modern electronics (radio etc) inside the plane. The generator looks like a little propeller attached to a little motor, as if it were some sort of weird auxiliary backup system in case of the main engine failing; it works by the little propellor being spun by the wind produced by the plane's forward motion, just like these wind generators.)

You will also find that there's a device—usually just a stiff wire—that the pilot can jam into the little propeller to stop the generator from generating. You'd think this would reduce the plane's effective MPG ... but in fact, it increases MPG, for the same reason: all the electricity the generator generates comes from stealing some of the flight energy. Block the generator propeller, so that the generator stops generating, and the plane goes further on one tank of avgas. (And with 100 octane avgas prices hovering around $6 in the US, and in some places over $9—see http://www.airnav.com/fuel/report.html for instance—that's a big deal.)

Basically, like solar panels, wind turbines work best with fixed(ish)-location installations. ("Portable" is OK although it comes with size limits, and wind generally improves a lot with altitude so wind generators should usually be mounted up high, on a mast, or on the top or side of a tall building, for instance.)
http://www.symantec.com/connect/blo...-launching-large-scale-ntp-reflection-attacks
 

·
Premium Member
Joined
·
4,659 Posts
The Mythbusters tried a version of this, and shockingly, confirmed that you can move a boat forward to by using a fan on the boat to blow on the sail.


Seriously, this would only be useful if it was meant to generate power when the car was parked in a windy spot. As already explained, in motion, the turbine generates additional drag which slows the car down and you have to expend more energy from the battery to move the car forward at the original speed. You would probably lose less energy if you bolted a small generator to the back wheels. The net result would be the same, but you would not mess up the car's aerodynamic profile.
 

·
Premium Member
Joined
·
1,975 Posts
Discussion Starter · #4 ·
Rather than mounting this on the roof, what if it were mounted behind the front bumper as an air intake. Wouldn't that reduce drag by allowing the air that flows into and around the front of the car to flow instead through the car? In essence you would be turning the frictional force of the air into usable energy via the turbine?
 

·
Registered
Joined
·
913 Posts
Rather than mounting this on the roof, what if it were mounted behind the front bumper as an air intake. Wouldn't that reduce drag by allowing the air that flows into and around the front of the car to flow instead through the car? In essence you would be turning the frictional force of the air into usable energy via the turbine?
That would be an improvement (I think!) but the physics is quite messy. The air coming out of the back of a wind generator is moving more slowly (with respect to the wind turbine) than the air hitting the front of it. In fact, if you attempt to extract too much energy from the wind, the air "piles up" behind the turbine and causes it to lose energy again. This principle (called Betz' Law or the Betz Limit) clearly applies to a vehicle moving through air (as in a wind generator on a car or plane) as well, although this time the analysis gets much messier, as you have a shroud concentrating the mass flow at the front (the air intake) and possible changes in turbulent vs laminar flows of mass at the back (the air being dragged along with the car as a result of its velocity being modified by the turbine, vs the air slipping around the car, some of which is already laminar vs other turbulent).
 
1 - 5 of 5 Posts
Top