The short answer: 6 kilowatt hours.

Long Answer:

Some disinformation in the comments in the Post-Dispatch online forums on a story about stimulus money’s effect on the battery industry reminded me of this question that many people fail to ask when comparing the efficiency of EV’s to internal combustion engine vehicles.  In fact, I had never thought to ask until Jack Rickard discussed it on one of his first episodes of his www.EVTV.me “Friday Shows”.   He had done some research and estimated it was between 4-7.5 Kwh per gallon.  I’ll post my comment:

Your average EV can go 16 miles on 4kwh (20 miles on 7.5kwh)- so that’s on the electricity used to just to refine that gallon of gas, nevermind the energy used to extract and transport the oil, and the tailpipe emission.

Jack inspired me to ask an authoritative source (as if he isn’t?).  The DOE.  So I emailed them, and in less than 5 business days received an answer, which I will post here.

Subject: Energy to refine gasoline

Dear Mr. Armstrong,

Thank you for your December 4, 2009, electronic mail requesting a reputable source to calculate the energy required to refine a gallon of gasoline.  The energy required to refine a gallon of gasoline can be estimated based on the energy content of crude oil and the refinery efficiency of the facility performing the energy conversion; I can provide you a reputable source for both values.

In a 2008 report, Argonne National Lab estimated that the efficiency for producing gasoline of an “average” U.S. petroleum refinery is between 84% and 88% (Wang, 2008), and Oak Ridge National Lab reports that the net energy content of oil is approximately 132,000 Btu per gallon (Davis, 2009).  It is commonly known that a barrel of crude oil generate approximately 45 gallons of refined product (refer to NAS, 2009, Table 3-4 for a publication stating so).  Thus, using an 85% refinery efficiency and the aforementioned conversion factors, it can be estimated that about 21,000 Btu—the equivalent of 6 kWh—of energy are lost per gallon of gasoline refined:

The documents referenced herein are publicly available, as follows:

Wang, M. (2008), “Estimation of Energy Efficiencies of U.S. Petroleum Refineries,” Center for Transportation Research, Argonne National Laboratory, www.transportation.anl.gov/modeling_simulation/GREET/pdfs/energy_eff_petroleum_refineries-03-08.pdf

Davis, S., Susan W. Diegel, and Robert G. Boundy (2009), Transportation Energy Data Book, edition 28, National Transportation Research Center, Oak Ridge National Laboratory, cta.ornl.gov/data/

NAS (2009), Hidden Costs of Energy: Unpriced Consequences of Energy Production and Use, The National Academies Press, www.nap.edu/openbook.php?record_id=12794&page=1

It is worth noting that refining one barrel of oil yields gasoline in addition to other products, so only a portion of the refining energy used to refine a barrel of crude is truly attributable to gasoline.  Even so, in terms of energy equivalencies, the preceding estimation is valid.

If I may be of further assistance, please do not hesitate to contact me.  Your interest in energy efficiency at the Department of Energy is appreciated.

Sincerely,

Jake

Jacob Ward Program Analyst/PMF Vehicle Technologies Program Office of Energy Efficiency and Renewable Energy U.S. Department of Energy

For those who prefer watching TV vs. reading mathematical formulas, starting at 6 minutes in the this 1o minute video: