Tornado Alley (PROG)

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arizona .. Will the Chevrolet Volt Save You Money?

Friday, April 20, 2012 .. excerpt ..

First we need to calculate the total energy used to move the car over our representative 1389.4 miles. If we assume it's the same for both our Volt and normal car, and that our normal car can average 30 mpg efficiency, then we know the normal car will need 46.313 gallons of gas to go that distance. Since we know how much energy is contained in a gallon of gas now, we can work out that the gas-powered car will use about 1656.16 kW-hrs of energy during the drive. Since the engine is only 20% efficient, only about 331 kW-hrs of that were actually needed to move the car; the rest gets lost as heat, noise, etc.

All of that energy came from burning gasoline for the traditional car, so we can pretty easily calculate the total cost of the drive by using the price of gas and the energy density of gas: about $180.52.

For the Volt, things are slightly more complicated. The electric motor powering the drivetrain is about 80% efficient, so dividing 331 kW-hrs by that gives us 414 kW-hrs, the input energy needed to move the car. Since we know we burned 10.4 gal of gasoline during the trip, we can calculate that about 372 kW-hrs was used by the (20% efficient) gasoline engine. If we assume all of that was used to charge the battery (in reality some would have been used to power the drivetrain, but we'll ignore that for simplicity) that's about 75 kW-hrs of battery charge from burning gasoline. The rest of the battery's charge would have come from the power grid;; we can calculate that by subtracting the gas engine's contribution to charging the battery from the total 414 kW-hr charge. The total energy cost can then be calculated as follows, by adding the battery-charging contributions of the gasoline engine and the power grid:

Cost = (372 kW-hrs)*($0.109/kW-hr) + (414-75 kW-hrs)*($0.115/kW-hr)

The total cost comes out to about $79.50, more than a factor of two less than the conventional car

http://thingsishouldprobablyknow.blogspot.com.au/2012/04/will-chevrolet-volt-save-you-money.html

i can't check it, don't know anything about it all, but sure seems the author has done a decent job
.. if you are happy it's ok i thought, after reading a chat today, you maybe could use it elsewhere ..

LOL .. i didn't 'cus not in the mood .. grin ..