by patrick_b » Wed 04 Jul 2007, 17:00:33
$this->bbcode_second_pass_quote('Mesuge', 'T')he efficiency of electric car (incl. energy production/distribution) is roughly 30% as opposed to 14% for various ICEs (bio, CTL, gas, CNG), FC, etc..
Certainly not 88% !
Both numbers are correct !
This is not contradictory...
An electric car has indeed an efficiency of more than 80%.
But if you include the complete cylce from energy input to production and consumption, this goes down a lot. The reason is that converting heat (typically in a coal/gas/oil/wood/nuclear power plant) to mechanical force (to produce electricity) cannot be done without huge losses.. (google for carnot machine)
Typically a nuclear power plant converts only 36% of its input energy to electricity. The rest of the energy is basically heat and is converted to a huge water vapor cloud that comes out of the cooling towers....
If you multiply 88% * 36% you get 31.7%... If you add some other losses like electricity transport, you get about 30%... In our example, there is only about 30% of the heat generated by uranium fission that is actually used to move the car. But at the same time 88% of the electricity consumed moves the car.
The interest of electric cars is also that input energy can be generated in any way.... For example, if someone uses solar panels on his house and backyard to charge his car, it doesn't matter that the solar panels only convert a fraction of the sun's energy because we don't need to pay to receive sunlight. (The problem here is the surface used.) Same with wind turbines: we pay for the turbines, the surface used, but not for wind itself...