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<br />W. Levison/P. Levy 10/26/10 <br /> <br />Relative “Greenness” of Electric Vehicle Technology <br /> <br />A question has arisen as to whether the introduction of electric (battery-powered) vehicles (EV) <br />may be legitimately considered “green” technology compared to an automobile powered by an <br />internal combustion engine (ICE). This simplified analysis considers “greenness” in terms of <br />carbon dioxide emissions. <br /> <br />The analysis proceeds as follows: <br /> <br />1.Compute kWh of battery power to drive a representative EV one mile. <br /> <br />2.Consider charging efficiency to compute kWh from the electric grid to drive 1 mile. <br /> <br />3.Compute the kWh per mile provided by the major CO generating energy sources. <br />2 <br /> <br />4.Compute the pounds/mile of CO generated by the various energy sources to yield the total <br />2 <br />pounds/mile of CO. <br />2 <br /> <br />5.Compute the number of miles/gallon required of a vehicle powered by an ICE to match the <br />EV CO production. <br />2 <br /> <br />Computation of Emissions for Electric Vehicles <br /> <br />The Nissan Leaf is considered here as representative of pure battery-driven electric vehicles, and <br />the Chevrolet Volt as representative of a plug-in hybrid vehicle. <br /> <br />Full battery charge is 24 kWh. <br />http://nissan-leaf.net/2010/05/27/nissan-leaf-battery-specifications/ <br /> <br />Range is stated as 100 miles for city driving based on EPA LA4 test cycle. Can vary from 47 to <br />138 miles depending on conditions. Assume 100 miles for analysis. <br />http://en.wikipedia.org/wiki/Nissan_Leaf <br /> <br />This yields 0.24 kWh/mi from the battery. <br /> <br />Assume 87.5% charging efficiency <br />http://www.dailytech.com/Tesla+CEO+Calls+Nissans+Leaf+Battery+Tech+Primitive+Boasts+ <br />About+Model+S/article19286.htm <br /> <br />This yields 0.24/.875 = 0.274 kWh/mi from the power grid. <br /> 1 <br /> <br />