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> And no, electric cars aren’t the answer either; the power to run them has to come from somewhere. The best case is that people will charge them off the grid a

> And no, electric cars aren’t the answer either; the power to run them has to come from somewhere. The best case is that people will charge them off the grid at night. This will require power plants to be burning just as much additional fuel as if the cars themselves were doing it, perhaps more given transmission losses. It has to be said. This guy is simply lazy, and did not do the research necessary to have informed opinions. Here are the facts I gathered in about 5 minutes. (Its pretty sloppy research, but hey-- I'm just posting a comment!) 1) Electric grid transmission efficiency: ~90% http://www.energetics.com/gridworks/grid.html http://www.energetics.com/gridworks/grid.html 2) Internal Combustion Engine Efficiency: ~20% http://en.wikipedia.org/wiki/Internal_combustion_engine#Energy_Efficiency http://en.wikipedia.org/wiki/Internal_combustion_engine#Ener... 3) Power Plant Efficiency: ~33% http://cleantechnica.com/2008/06/26/electricity-generation-efficiency-its-not-about-the-technology/ http://cleantechnica.com/2008/06/26/electricity-generation-e... 4) Battery Efficiency: ~80% http://xtronics.com/reference/batterap.htm http://xtronics.com/reference/batterap.htm 33 * .9 * .8 = 23.76 23.76 > 20

mrtron 18y ago
Also factor in the alternative sources we could use to create electricity that are not practical for having on the car itself. Wind, solar, geothermal, etc. If we could produce endless supplies of cheap renewable energy, it would be a no-brainer to switch to electric cars.
- yters 18y ago
  That's a really good point. It's much more efficient to centralize alternative power production than to decentralize it in a bunch of cars.
  - DaniFong 18y ago
    That's not necessarily true. To decentralize production it merely needs to be the better economic choice. There is no fundamental reason why polluting energy sources should be cheaper: this is only true with most current technologies in most current situations.
DaniFong 18y ago
Also, electric car manufacturers seem to be great at making cars that get more km per kJ. They get 2.18 km/KJ of power, which is more than four times the efficiency of the Prius. http://www.evworld.com/library/Tesla_21centuryEV.pdf http://www.evworld.com/library/Tesla_21centuryEV.pdf
corentin 18y ago
You forgot the efficiency of the electric motor itself and everything between it and the battery pack (converter, etc.)
- lliiffee 18y ago
  That seems like an excellent point. It looks like electric motors are pretty efficient, particularly big, powerful ones. Electric cars, with 100hp or more should achieve about 95% efficiency, according to this: http://www.psnh.com/Business/SmallBusiness/Motor.asp http://www.psnh.com/Business/SmallBusiness/Motor.asp I don't know about converters, or what 'etc' is... (I'd guess you are more qualified than me to factor that in-- any estimate?)
  - corentin 18y ago
    Big electric motors are indeed quite efficient. You don't connect them directly to the battery pack, though. You need "something" in-between (power electronics) to drive the motor. I'd estimate the efficiency of such a controller to be around 80/90%.

mrtron 18y ago

Also factor in the alternative sources we could use to create electricity that are not practical for having on the car itself. Wind, solar, geothermal, etc. If we could produce endless supplies of cheap renewable energy, it would be a no-brainer to switch to electric cars.

yters 18y ago
That's a really good point. It's much more efficient to centralize alternative power production than to decentralize it in a bunch of cars.
- DaniFong 18y ago
  That's not necessarily true. To decentralize production it merely needs to be the better economic choice. There is no fundamental reason why polluting energy sources should be cheaper: this is only true with most current technologies in most current situations.

DaniFong 18y ago

Also, electric car manufacturers seem to be great at making cars that get more km per kJ. They get 2.18 km/KJ of power, which is more than four times the efficiency of the Prius. http://www.evworld.com/library/Tesla_21centuryEV.pdf http://www.evworld.com/library/Tesla_21centuryEV.pdf

corentin 18y ago

You forgot the efficiency of the electric motor itself and everything between it and the battery pack (converter, etc.)

lliiffee 18y ago
That seems like an excellent point. It looks like electric motors are pretty efficient, particularly big, powerful ones. Electric cars, with 100hp or more should achieve about 95% efficiency, according to this: http://www.psnh.com/Business/SmallBusiness/Motor.asp http://www.psnh.com/Business/SmallBusiness/Motor.asp I don't know about converters, or what 'etc' is... (I'd guess you are more qualified than me to factor that in-- any estimate?)
- corentin 18y ago
  Big electric motors are indeed quite efficient. You don't connect them directly to the battery pack, though. You need "something" in-between (power electronics) to drive the motor. I'd estimate the efficiency of such a controller to be around 80/90%.