That's the same number that we use here because it is a basic scientific conversion. Gasoline holds 33.7kWh (115,000 Btu) per gallon and deisel holds 38.2kWh (130,500 Btu) per gallon.
The numbers that the EPA posted about the Leaf also suports another general conversion rule that we use here. Internal Combustion Engines (ICE) operate at about 25-30% thermal efficiency, which means that 25-30% of the energy in the fuel is available as crankshaft power. Electric drives like we use in our conversion operate at around 80-85% thermal efficiency, or about 3 times more efficient than an ICE.
The Versa averages about 33MPG as an ICE and the EPA says that the Leaf averages 99MPG as an electric or about 3 times as efficient.
This means that in general terms, 11kWh of electricity through an electric drive is roughly equivalent to 33kWh (1 gallon) through an ICE.
These are just general estimates, you can drive deeper and find specific conversion values comparing specific systems, but as a general rule of thumb, these conversions hold up across the board. Apparently even in the automotive world. :)
Fair winds,
Eric
Marina del Rey, CA
PS. I was pleased when the EPA published those numbers because they validated the work that has been done by various people on this board.
--- In electricboats@yahoogroups.com, "akenai" <akenai@...> wrote:
>
> EPA calculated the Leaf's fuel economy based on a formula that says 33.7 kilowatts per hour holds the energy equivalent of one gallon of gasoline...
>
> Interesting
> Aaron
>
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