Last week someone with EXTENSIVE energy background asked me the following question:
Has anyone compared the amount of CO2 released by making the
electricity to run an electric car to the CO2 released by a
conventional gas engine vehicle? He said: “I bet they
are almost equivalent…”
Well he was really wrong… read on.
My initial reply to him was that our EVs are powered mostly with solar generated electricity, so I knew where my wife and I stood, but I wanted to know more.
Lets not even discuss how much energy might be used to support several wars to protect middle-east supplies.
I should have remembered one of the boards at the Nissan Leaf event at Concord Mills last year:
From the Concord Mills Nissan Leaf Event
So, NOT even considering CO2 released by burning the gasoline, just the energy to make (refine) one gallon of gas can run a Leaf for 30 miles. All this is BACKED UP by the following research, and yes I did check the references…
I look forward to some attempts at rebuttal of the following information.
Here is what I found out for those running a Leaf powered with coal-generated electricity:
First, an email reprinted with permission from the United States Department of Energy:
(note: the following does not count CO2 released by the transportation of gasoline from the refinery to the filling stations… Hence the need to add 1.5 kWh to the 6 calculated below)
Subject: Energy to refine gasoline
Thank you for your 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, http://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, http://cta.ornl.gov/data/
NAS (2009), Hidden Costs of Energy: Unpriced Consequences of Energy Production and Use, The National Academies Press, http://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
Second, Solar Charged Driving ran a really good editorial on this subject as well.
Norby, P. (2011), “Surprise: Gas cars use more electricity than EVs,” Retrieved on 22 January, 2012 from Solar Charged Driving Web site http://www.solarchargeddriving.com/news/scd-editorials/831-surprise-gas-cars-use-more-electricity-than-evs.html
Third, The National Electric Research Laboratory did an extensive report comparing Plugin Hybrid Electric
Vehicles to Gas Powered Vehicles.
Remember that a hybrid still uses gas, but a pure electric vehicle like the Nissan Leaf does not. Results? A Leaf even running from OLD coal emits less than 20 percent of the CO2 released by running a gas powered vehicle, derived by backing CO2 attributed to gasoline from the graph on page 8 (Electric Power Research Institute, 2007)
Electric Power Research Institute (2007), “Environmental Assessment of Plug-in Hybrid Electric Vehicles,” Palo Alto, CA Retrieved 22, January, 2012 from: http://mydocs.epri.com/docs/CorporateDocuments/SectorPages/Portfolio/PDM/PHEV-ExecSum-vol1.pdf
Electric Cars, Nissan Leaf, Renewable Energy | Ken Clifton January 31, 2012 | 
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