How much electricity to produce gasoline?

[Norbert]

Brent, the 10:1 ratio in used to be 100 to 1 was based on data from 2000. (The 100:1 ratio was in 1930). Whereas the 10% figure in http://www.transportation.anl.gov/mo...ries-03-08.pdf is based on data from 2006. Since these ratios are getting worse so quickly (see the graphs in the first link), the two ratios may correspond to each other quite well, even though the 10% from 2006 is for refinery only.

If the efficiency of refinery really declines due to a decreasing quality of crude oil, then the 10% refinery inefficiency number will likely be noticeably larger for 2010.

And, considering the points by dpeilow and BlackbirdHighway, there may be much more to it. None of these numbers are the complete picture.

 

[dpeilow]

I've found it impossible to find a source that says "it takes x amount of hydrogen to make y amount of low sulphur diesel", but there is some info on the issue to be pieced together:

http://www.kfupm.edu.sa/catsymp/Symp13th/13SympPapers/5.pdf

http://www.conocophillipsalaska.com/permits/ULSD/ULSD_PlanOfOperations.PDF

http://www.sulphco.com/pdf/SulphCo_Shareholder_Meeting_Presentation_June_2009.pdf slide 11

http://www.40cetane.com/forums/attachment.php?attachmentid=144&d=1161020189

There is a figure here (with some caveats): ScienceDirect - Catalysis Today : Two stages light gasoil hydrotreating for low sulfur diesel production (I presume Bl is billion litres?)


There a number of contributing factors and variables, it seems. Appendix C here has some useful information on increased CO2 emissions: http://www.theicct.org/documents/Low-Sulfur_ICCT_2003.pdf pp65-66.

 

[Eldictator]

Further to the debate, Oil tankers and shipping which people forget to add in the equation contributes serious amounts of pollution to the process, shipping is one of the least regulated areas and don't forget the oil spillage catstrophes.
Also once they've dropped their cargo they go back empty.Ship pollution - Wikipedia, the free encyclopedia

 

[JRP3]

Let's also add in the electricity used to build an oil tanker :biggrin: And drilling rigs, pipelines, tanker trucks, etc.

 

[johnr]

Let's also add in the electricity used to build an oil tanker :biggrin: And drilling rigs, pipelines, tanker trucks, etc.

My mind hurts just thinking about all that.:tongue:

 

[stopcrazypp]

Ah ha. Robert Llewellyn quotes the figure of 7.5 kWh of energy needed to refine one US gallon. Source?

Seems like Nissan?
http://www.mynissanleaf.com/viewtopic.php?f=13&t=820&sid=0974456652e700408f8a4f76e0651f46

Here's what I found:
85.5% Petroleum Refining Efficiency: 340 ppm S Conventional Gasoline
http://www.transportation.anl.gov/pdfs/TA/166.pdf

83.0% Petroleum refining and distribution efficiency (from 2000).
http://www.epa.gov/EPA-IMPACT/2000/June/Day-12/i14446.htm

Given 33.7kwh/gal as the official EPA conversion factor for gas, 33.7kWh/gal * 100%-83% = 5.729kWh

They may be using crude though (seem to make more sense, since the energy content in gas is AFTER the refining) so 44.5 kWh/gal * 100%-83% = 7.565kWh

Seems like I solved the mystery in the Leaf thread. Anyone with an account there can feel free to post this there.

 

[richkae]

There are many grades of crude oil and many factors in the energy cost of refining and processing it.
The light sweet crude is the "best".
Light crude takes the least energy to pump, and flows more easily out of the ground. Refining can be just separating the oil into the different parts or it can include hydrogen cracking to make more of the lighter components.
More energy can be expended to crack more of the oil into the things we want for gasoline ( with diminishing returns ).
Sweet crude has the least sulfur, the more sulfur it has the more energy you have to spend removing it.
A lot of wells produce oil mixed with water ( especially at the end of their lives and if water injection has been used to force the oil out of the well ) and it takes a bunch of separation effort to remove it - if its salt water you have to remove the dissolved salts too.

Of course since the light sweet crude is the best ( and flows first ) many oilfields deplete the good stuff first and pump the heavier stuff at the end of their lives.
As the quality of the oil goes down the cost of gasoline from a barrel of oil goes up.

I would expect that the petroleum refining efficiency numbers that have been found are for light sweet crude and the numbers are much much worse for heavier oils ( like the ones that come from bitumen ).

 

[TEG]

http://organicconnectmag.com/wp/2010/12/the-electric-cars-revenge/

...“Here’s a fact the oil industry doesn’t want you to know: every gallon of gasoline made from crude oil takes from 4 to 7 kWh of electricity to refine. That’s enough power to drive an electric car at least 16 to 20 miles. And that’s just to refine the oil—not counting the energy to extract it, transport it, or the tailpipe emissions you create when you burn it in your car. For that fact alone, the electric car is far ahead in any environmental debate about how to power our cars."...

 

[TEG]

http://www.ev.com/knowledge-center/the-big-oil-electricity-conspiracy.html

 

[Norbert]

The discussion above (in 2009) contains multiple references to this link:

http://www.transportation.anl.gov/modeling_simulation/GREET/pdfs/energy_eff_petroleum_refineries-03-08.pdf ----- This link is broken now, even the website URL itself has changed.

This is an updated 2010 version of this document:

Updated Estimation of Energy Efficiencies of U.S. Petroleum Refineries
Argonne GREET Publication Details

EDIT:
Following the 2008 version which was originally used in the discussion and Randy Jackson's calculation. It has a few additional tables and explanations. Especially Table 5 is interesting :
Estimation of Energy Efficiencies of U.S. Petroleum Refineries (2008)

It is overall more readable, and shows that the efficiency for gasoline is a bit lower than that for LPG and Diesel (Table 5). Also, the 2010 table showing gasoline refining efficiency includes LPG, which makes the efficiency looks better than it is for gasoline, for no obvious good reason. Otherwise, the values seem to be almost the same. So I'd probably go back to the 2008 doc.

 

[Kevin Sharpe]

some more discussion by Robert Llewellyn;

The LlewBlog - Electric Cars - Dirt anddirtier

 

[dpeilow]

They also talked about this on the My Nissan LEAF forum (apologies if this was already posted as we have members on both).

It's worth reading right through, but the conclusion they came to was that 1) Nissan had nothing to cite directly for the 7.5kWh figure and 2) that it probably derives from the US DoE adding a "refining and distribution factor" of 0.83 for energy losses in gasoline distribution, the energy content of a gallon being 36.6 kWh.

 

[Tdave]

That 83% efficiency is just for the refinery, according to the document Norbert linked. So the 7.5kWh figure is only for refining, and doesn't include exploration, extraction, or any distribution. What do those total?

 

[Norbert]

They also talked about this on the My Nissan LEAF forum (apologies if this was already posted as we have members on both).

It's worth reading right through, but the conclusion they came to was that 1) Nissan had nothing to cite directly for the 7.5kWh figure and 2) that it probably derives from the US DoE adding a "refining and distribution factor" of 0.83 for energy losses in gasoline distribution, the energy content of a gallon being 36.6 kWh.

Looking at how they calculated it, I can now see how it all fits together, and why Randy Jackson's calculation arrived at only 4.1 kWh.

The document for which I just posted the updated link (the 2008 version) has in Table 5 the entry 83.3% in the second column ("less desirable products excluded"). This document describes in detail how they arrived at 83.3% (= 0.83). Randy used the value in the first column (87.7%).

Second difference is that he used the EPA value for the gasoline energy content of 33.7 kWh, instead of 36.6 kWh (I see 36.6 kWh on Wiki and being used elsewhere, but haven't found a more "official" source yet). Yesterday I already started a calculation using the second column (which I do think is the more appropriate column) and the 36.6 KWh value, but didn't yet find the third difference: 36.6 needs to be taken not as 100%, but as 83%. The Argonne document makes this somewhat difficult to see, one is easily led to calculate 36.6 * (100 - 83) instead of (36.6 / 83 * 100) - 36.6.

So, except for not being sure about 36.6 vs 33.7, I'd say the calculation arriving at 7.5 kWh is the "better" one. However, this is an energy-equivalent, not necessarily electricity from a power plant, but likely to produce CO2 in any case.

Randy Jackson may still be correct in that producing the oil (before refining it) requires about "7.9" kWh in addition to that. (After all, he err'ed on the low side for the refining.) If so, then the total is 15.4 kWh (not yet counting transport etc). If this was provided as electricity from a power plant, for an EV, taking off 30% for transmission and battery charging (per dpeilow), leaves about 11 kWh. Which is enough for the Leaf or the Roadster to go more than 40 miles (per EPA rating). Correct me where I'm wrong.

 

[richkae]

The numbers quoted are averages across some set of inputs - everything depends on the quality of the input oil.
Every year we use up more of the light sweet crude and are left with the heavier dirtier stuff, so the numbers will go up every year.

Lighter crude requires less energy to refine.
Sweeter crude requires less energy to remove impurities ( less sulfur )
You can use more energy to get more gasoline and less heavier stuff like diesel ( inject more hydrogen for more cracking )
American refineries typically produce more gasoline and less diesel than european ones because of demand.

 

[richkae]

transportation

Some numbers I cobbled together from googling ( accuracy may be suspect ) - and then some back of the napkin calculations:

Trucks:
a big tanker truck can carry 9000 gallons of gasoline
they get about 6mpg
its 1800 miles from Seattle to the nearest border of Texas/Oklahoma - needing about 300 gallons of diesel to move ( I dont know exactly where Seattle gasoline comes from )
That would be a 3.3% efficiency loss.

Tanker ships ( big VLCCs ):
Carry about 200,000 tons of crude.
Burn between 40 and 90 tons of bunker fuel per day ( bunker fuel is the dirtiest sludge left over from refining that you can still burn in a big diesel )
Go around 16 knots
Would use somewhere between 1500 and 3000 tons of bunker fuel to go 12000 miles.
So thats a loss of 1.5% on the high side.

I read somewhere about proposed legislation to force ships to not burn bunker fuel within 200 miles of the U.S. coast because its so incredibly dirty. The atmosphere's not connected right? Out of sight, out of mind.

 

[richkae]

and then

And then I found this document which states that the gasoline in washington state is all refined locally as of 2004, and it most likely comes in by tanker ship:
http://www.commerce.wa.gov/_CTED/documents/ID_1923_Publications.pdf

So thinking about someone trucking gasoline 1800 miles to washington state is a waste of time.

 

[Norbert]

So thinking about someone trucking gasoline 1800 miles to washington state is a waste of time.

Heh. Probably, but just in case you happen to think about it again, don't forget that the tanker and/or truck has to travel both ways.

 

[Norbert]

Might also be of interest in this context:
Electricity consumption by petroleum refineries by country. Definition, graph and map.

(Note that this only externally purchased electricity, and that refineries have multiple ways of producing electricity/energy internally, most, if not all, of which imply CO2.)

 

[JRP3]

How can you tell it's only externally purchased electricity? I don't see that specified. Are you assuming that on site produced electricity doesn't enter the grid and isn't measured?