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

Posted: Tue Jul 27, 2010 1:21 am
by planet4ever
indyflick wrote:So Rik, if refining gasoline is so efficient, what accounts for the fact that petroleum refineries in the US in 2005 used 48,891,000,000 kWh of electricity?
Well, as I come off the southbound Benicia bridge at night I see what looks like a hundred acre forest all lit up like Christmas trees off to the right. I think that's a Shell refinery. That's got to be a huge amount of electricity spent lighting the sky, and unless they use photons reflected off smoke plumes in the refining process, I don't think it counts as part of the kilowatts per gallon of gas.

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

Posted: Tue Jul 27, 2010 2:09 am
by Rik
indyflick wrote:So Rik, if refining gasoline is so efficient, what accounts for the fact that petroleum refineries in the US in 2005 used 48,891,000,000 kWh of electricity?
indyflick, assuming that number is correct, that's 1.2% of the 4,055,423,000,000 kWh of electricity produced in the US in 2005.

In 2005, US oil refineries produced 17,800,041 B/d of refined products = 6,497,014,965 B/yr = 272,874,628,530 gal/yr.

48,891,000,000 kWh per yr / 272,874,628,530 gal per yr = 0.179 kWh per gallon

It's not even close to 7.5 kWh per gallon.

Source for 2005 US production of refined products and electricity: US Energy Information Administration http://tonto.eia.doe.gov/cfapps/ipdbpro ... Index3.cfm

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

Posted: Tue Jul 27, 2010 8:08 am
by indyflick
Rik wrote:indyflick, assuming that number is correct, that's 1.2% of the 4,055,423,000,000 kWh of electricity produced in the US in 2005.

In 2005, US oil refineries produced 17,800,041 B/d of refined products = 6,497,014,965 B/yr = 272,874,628,530 gal/yr.

48,891,000,000 kWh per yr / 272,874,628,530 gal per yr = 0.179 kWh per gallon

It's not even close to 7.5 kWh per gallon.
Rik, are you messing with us? You have the formula backwards. It would be:
272,874,628,530 gal per yr / 48,891,000,000 kWh per yr = 5.58 kWh per gallon. Of course this is just the refining process consumption of electricity. When the entire supply chain is considered, I suspect it would be well above 7.5 kWh. Some say over 12 kWh. I'm starting to view gasoline as simply a combustible store of consumed electricity.

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

Posted: Tue Jul 27, 2010 8:17 am
by indyflick
UPDATE... I divided incorrectly in the last step. As pointed out by Rik and evnow, this analysis is not correct. This analysis actually indicates 22,587,642,000 kWh / 132,488,160,000 gallons of gasoline = 0.17 kWh per gallon of gasoline in the refining process.

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BTW, the 272,874,628,530 gal per yr is total refined product from the refinery. In my analysis a few pages back, I applied a 46.2 percentage to both the electricity consumed and to account for the percentage of gasoline produced versus all other refined product.

Here's the analysis again:

Electricity consumption by petroleum refineries in the US in 2005 was 48,891,000,000 kWh
http://www.nationmaster.com/graph/ene_e ... ies#source

Gasoline composed 46.2% of all US refined oil products in 2005
http://tonto.eia.doe.gov/dnav/pet/pet_p ... _pct_a.htm

Therefore, we take 46.2% of the total electricity used by the US refineries in 2005 for galoline production. So that would be 22,587,642,000 kWh of electricity. (48,891,000,000 kWh * .462)

In 2005 US refineries produced 132.4 billion gallons of gasoline
http://www.eia.gov/dnav/pet/hist/LeafHa ... frpus2&f=w

Download the spreadsheet and use the 2005 data on gasoline production. The data is the weekly U.S. Refinery and Blender Adjusted Net Production of Finished Motor Gasoline (Thousand Barrels per Day). So you need to add up the weekly totals, multiply by 7 to get the full weeks, multiply by 1000 (data is thousands), and multiply by 42 because there are 42 gallons in a barrel. That gets you to 132,488,160,000 gallons.

132,488,160,000 gallons of gasoline / 22,587,642,000 kWh = 5.86 kWh of electricity consumed for every gallon of gasoline produced in the US in 2005.

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

Posted: Tue Jul 27, 2010 8:19 am
by evnow
indyflick wrote:Rik, are you messing with us? You have the formula backwards. It would be:
272,874,628,530 gal per yr / 48,891,000,000 kWh per yr = 5.58 kWh per gallon.
No - Rik is right.

Let us say 10 Gallons of gas requires 100 kwh. So how much does 1 Gallon need ? 100 kwh / 10 Gallons = 10 kwh / 1 gallon. Look at the units to tell you how to calculate.

Since a lot of the refineries even produce their own electricity (apart from using NG etc) - this would be a small amount. Need to look at total energy consumption as I've been saying.

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

Posted: Tue Jul 27, 2010 8:42 am
by Rik
indyflick wrote: 132,488,160,000 gallons of gasoline / 22,587,642,000 kWh = 5.86 kWh of electricity consumed for every gallon of gasoline produced in the US in 2005.
Look at the units you are working with. You calculated gallons per kWh, while it's kWh per gallon we're interested in.

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

Posted: Tue Jul 27, 2010 8:43 am
by indyflick
No - Rik is right.

Let us say 10 Gallons of gas requires 100 kwh. So how much does 1 Gallon need ? 100 kwh / 10 Gallons = 10 kwh / 1 gallon. Look at the units to tell you how to calculate.
Yep, I mangled it. 1000 apologies.

Nissan.... PLEASE tell us how you derived the 7.5 kWh statistic.

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

Posted: Tue Jul 27, 2010 9:44 am
by Rik
evnow wrote: Since a lot of the refineries even produce their own electricity (apart from using NG etc) - this would be a small amount. Need to look at total energy consumption as I've been saying.
I found a document that shows all the refineries in California and their on-site production and usage of electricity. See Table 3-1 here http://www.eia.doe.gov/emeu/steo/pub/sp ... inery.html

For 92% of California's refining capacity (data for the other 8% is not reported)
Total Electricity Consumption: 913 MW
Co-generation Capacity: 1038 MW (= electricity produced by refineries)

Consumption per day: 913 MW * 1000 kW/MW * 24 h/day = 21,912,000 kWh/day

So if in the future all of California's refineries were shut down after a conversion to non-petroleum based fuels, it might not create any additional electricity capacity in the state since the refineries' co-gen units would probably shut down as well. This would free up the natural gas that is used by the co-gen units to make electricity and steam, as well as the natural gas that is burned in refinery heaters and used to manufacture hydrogen.

Total capacity of these California refineries: 1840 mbpsd = 1,840,000 B/day = 77,280,000 gal/day

Electricity used per gallon: 21,912,000 kWh/day / 77,280,000 gal/day = 0.284 kWh / gal

There is also in Table 3-3 a breakdown of electricity usage for each type of unit in a typical 100,000 B/d = 4,200,000 gal/d oil refinery, which adds up to 732,397 kWh/d.

Electricity used per gallon: 732,397 kWh/d / 4,200,000 gal/d = 0.174 kWh / gal

So either way, it's still well under 1 kWh/gal.

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

Posted: Tue Jul 27, 2010 10:20 am
by Rik
indyflick wrote:Nissan.... PLEASE tell us how you derived the 7.5 kWh statistic.
Nissan botched it with this number, but I'll give them a pass since they are a car company and not an oil company. I'm assuming that for the calculations that matter to their core business, Nissan knows what they are doing. Besides, it was probably just the Nissan marketing guys who did this. I don't believe that any Nissan engineer would have made this mistake.

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

Posted: Tue Jul 27, 2010 10:24 am
by evnow
Rik wrote:Nissan botched it with this number....
They probably picked it from some study - but is probably presented wrong. I won't be surprised if the total energy input to get oil (from well to tank) is 7.5 kwh / gallon.