Quote:
Originally Posted by RobertSmalls
Phil,
There's room for debate on whether equivalent energy is a good basis for judging the merit of using electricity vs. burning gas.
There's less room for debate on what the energy equivalence conversion factor is, when the full life cycle of both energy sources are considered: around 13.4KWh/gal. From a CO2 perspective, it's 15.1 KWh/gal on US grid-average electricity.
According to Wikipedia, "The D.O.E. reports that the lumped average efficiency of electrical production and transmission in the United States, eelectricity, is 0.303 while the efficiency of refining and distributing petroleum, egasoline, is 0.830."
So remember to apply a 17% penalty to gasoline, based on the energy cost of refining and transporting it.
I've done a little math on the merit of grid-charging my 12V and traction batteries. Using US grid average power, electric comes out only slightly ahead, from a resource depletion or CO2 perspective.
But it's a complicated subject, and kilowatt-hours can not be made "equivalent" to a gallon of gas.
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Robert,'complicated' puts it nicely!
Attempting to find a common denominator,moving from EV-speak to Hydrocarbon-speak has me entertaining the notion of a lobotomy.
I like your 13.4 kWh/gallon figure .I came up with 13.376 last night from a 40% maximum efficiency for IC at constant rpm and say 80% load,where the BSFC would be in the 'sweet-spot.'
I recently read William H. Kemp's 'The Zero-Carbon Car',2007.
He took a Miata and converted to BEV with a Fischer Panda marine diesel gen-set of 10 kW in the trunk.
He has 6kW of battery which is good for 12.4 miles of driving at an un-specified velocity,then the generator kicks in.
The original Miata was road-tested by CAR and DRIVER,Sept. 1989 and they recorded a road-load of 12-horsepower at 50-mph.
Kemp's Miata retains the original transmission,driveshaft and differential,and using Ford Motor Co.'s figure of 95% driveline efficiency yields 12.631 Bhp at the 'Motor.'
An 'Excellent' BSFC for a non-turbo diesel is 0.34 pound/horsepower-hour.Using the this would yield 4.2945 pounds diesel.
Dividing by 6.8306 pounds/gallon yields o.6287 gallons/50-miles,or 79.529 mpg.
I'm okay with this figure,as in 1979,Holman & Moody got 84 mpg from a Perkins turbo-diesel powered Ford Capri.
Kemp claims 234-mpg for his Zero-Carbon Car and only 12.4 miles of it's range is on battery power.
The original Miata with gasoline engine gets about 42-mpg at 50 mph according to the late Robert Carrol Parsons who owned one and endeavored to get the highest mpg from it.
I'm simply perplexed with respect to Kemp's claims.
The coup de grace is Kemp's claim that the Zero-Carbon Car was measured at 23 horsepower road load at 50 mph,whereas the original cars had only 12.
He had an overall weight penalty of 480-pounds.
I realize that the EPA has allowed automakers to use a 135-mpg value for hybrids when calculating fleet-averaged CAFE numbers,but that doesn't mean that consumers could ever hope to see numbers like this.