User avatar
evnow
Moderator
Posts: 11480
Joined: Thu Apr 22, 2010 11:41 am
Delivery Date: 25 Feb 2011
Leaf Number: 303
Location: Seattle, WA

Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Mon Sep 06, 2010 5:17 pm

indyflick wrote:Interesting report, thanks for the pointer. I have a couple of questions. First, I assume you calculated this from 14% of 36.6 kWh per gallon of gasoline, correct? That would be 5.124 kWh. But how did you derive the 14%? It looks like 8% in the chart, what am I missing?
I used the chart that shows 14% and 16% for petrol & diesel. This is total WTT energy.
Second, I believe MJ/MJ means the megajoules of energy required to produce an energy product which has one megajoules worth of stored energy, correct? The study says (on page 17) that gasoline MJ/MJ is 0.08. I read in this article that's it's more like 0.20 to 0.25 and gasoline from shale is 0.56 to 0.87!
That 0.08 (or 8%) is just refining. They have used marginal energy needed. Shouldn't matter whether the source is really from shale or not. For shale, the production would use up a lot of energy ...

ps : Whenever anyone takes the "worst case" of coal only for EVs, we should compare to shale sourced petroleum. Afterall increasingly that is where our oil in NA comes from.
1st Leaf : 2/28/2011 to 5/6/2013
2nd Leaf : 5/4/2013 to 3/21/2017
Volt : 3/25/2017 to 5/25/2018
Model 3 : 5/10/2018 to ?

indyflick
Posts: 505
Joined: Fri Jul 09, 2010 8:18 am

Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Mon Sep 06, 2010 7:22 pm

evnow wrote:
indyflick wrote:Interesting report, thanks for the pointer. I have a couple of questions. First, I assume you calculated this from 14% of 36.6 kWh per gallon of gasoline, correct? That would be 5.124 kWh. But how did you derive the 14%? It looks like 8% in the chart, what am I missing?
I used the chart that shows 14% and 16% for petrol & diesel. This is total WTT energy.
Second, I believe MJ/MJ means the megajoules of energy required to produce an energy product which has one megajoules worth of stored energy, correct? The study says (on page 17) that gasoline MJ/MJ is 0.08. I read in this article that's it's more like 0.20 to 0.25 and gasoline from shale is 0.56 to 0.87!
That 0.08 (or 8%) is just refining. They have used marginal energy needed. Shouldn't matter whether the source is really from shale or not. For shale, the production would use up a lot of energy ...

ps : Whenever anyone takes the "worst case" of coal only for EVs, we should compare to shale sourced petroleum. Afterall increasingly that is where our oil in NA comes from.
Excellent point. It's self evident oil is getting scarce. They wouldn't be going to deeper and deeper water nor using NG to process oil shale if there were "easy pickin's" available. By the way, do I have the MJ/MJ idea right?

User avatar
evnow
Moderator
Posts: 11480
Joined: Thu Apr 22, 2010 11:41 am
Delivery Date: 25 Feb 2011
Leaf Number: 303
Location: Seattle, WA

Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Mon Sep 06, 2010 8:31 pm

indyflick wrote:By the way, do I have the MJ/MJ idea right?
Yes.
1st Leaf : 2/28/2011 to 5/6/2013
2nd Leaf : 5/4/2013 to 3/21/2017
Volt : 3/25/2017 to 5/25/2018
Model 3 : 5/10/2018 to ?

PaulScott
Posts: 196
Joined: Thu Sep 09, 2010 5:44 pm
Delivery Date: 11 Jan 2012
Location: Santa Monica

Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Thu Sep 09, 2010 6:01 pm

When I saw this number earlier this year, I contacted Tim Gallagher to confirm they had this documented. Turns out they didn't. The best numbers I've seen indicate about .8 - 1.0 kWh of actual electricity is used per gallon, but there is a lot of natural gas used, too. The NG, if used in a combined cycle plant, the number of kWh would probably approach 7.

indyflick
Posts: 505
Joined: Fri Jul 09, 2010 8:18 am

Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Thu Sep 09, 2010 7:49 pm

PaulScott wrote:When I saw this number earlier this year, I contacted Tim Gallagher to confirm they had this documented. Turns out they didn't.
Are you saying he hadn't documented where they located the data point or how they internally derived it?

AndyH
Posts: 6388
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Thu Sep 16, 2010 4:44 am

indyflick wrote:I've read numerous reports where Nissan have stated that "it takes 7.5 kWh of electricity to produce a gallon of gasoline". Of course it's obvious then we could simply skip the gasoline production and instead use the 7.5 kWh of electricity to propel the Leaf 30 miles.

I would like to know if Nissan have a white paper available which shows how they derived the "7.5 kWh of electricity to produce a gallon of gasoline" figure. There are some on the Internet who say it's actually more like 12 to 13 kWh. Other say it's 5 kWh. Still others say its less than 1 kWh.
FWIW: http://gatewayev.org/how-much-electrici ... f-gasoline
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:

Image

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/model ... -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, 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

indyflick
Posts: 505
Joined: Fri Jul 09, 2010 8:18 am

Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Thu Sep 16, 2010 7:45 am

Excellent find Andy! That is really good data. I found a free version of the Hidden Costs of Energy: Unpriced Consequences of Energy Production and Use that you can download.

AndyH
Posts: 6388
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Thu Sep 16, 2010 8:54 am

indyflick wrote:Excellent find Andy! That is really good data. I found a free version of the Hidden Costs of Energy: Unpriced Consequences of Energy Production and Use that you can download.
Excellent - thanks!

The info flowed thru the local EAA chapter yesterday and I thought of this thread. Enjoy!

User avatar
planet4ever
Posts: 4674
Joined: Sat Apr 03, 2010 9:53 pm
Delivery Date: 02 May 2011
Leaf Number: 1537
Location: Morgan Hill, CA, south of San Jose

Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Thu Sep 16, 2010 1:17 pm

Am I not understanding this correctly? It sounds as if they are saying that due to refining inefficiencies the manufacture of gasoline is losing the equivalent of 6kWh of electricity. That is very different from saying that they are actually consuming 6kWh for every gallon produced.

Surely no one is claiming that the generation of electricity is 100% efficient. Why should we fault the oil companies for having some loss in its generation of gasoline?

Note please: I am not an apologist for big oil, and indeed I dream of the day when no oil at all is used for transportation. But I believe we should use fair criticisms of our oil addiction and, so far at least, I am not convinced that the 7.5kWh/gallon accusation is fair.
End of April 2013: Traded my 2011 SL for a 2013 S with charge pkg.

User avatar
evnow
Moderator
Posts: 11480
Joined: Thu Apr 22, 2010 11:41 am
Delivery Date: 25 Feb 2011
Leaf Number: 303
Location: Seattle, WA

Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Thu Sep 16, 2010 2:17 pm

planet4ever wrote:Surely no one is claiming that the generation of electricity is 100% efficient. Why should we fault the oil companies for having some loss in its generation of gasoline?
Nobody is saying this is someone's fault. It is just a fact you need to consider when figuring out the whole carbon footprint or EROI.
1st Leaf : 2/28/2011 to 5/6/2013
2nd Leaf : 5/4/2013 to 3/21/2017
Volt : 3/25/2017 to 5/25/2018
Model 3 : 5/10/2018 to ?

Return to “Environmental Issues”