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

Mon Jul 26, 2010 10:26 am

evnow wrote: Yes - thats why we should really be talking about energy used rather than electricity used.

Rik, do you know what the kwh equivalent energy that is used for refining ?
Hmmm... we don't normally think if it that way so I'm not sure.

BTW I forgot to mention that natural gas is also used in most oil refineries to make the hydrogen that is consumed in refineries, for the hydrotreating and hydrocracking processes.

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

Mon Jul 26, 2010 10:27 am

Rik wrote:Hmmm... we don't normally think if it that way so I'm not sure.
Would you know how much NG is used on the avg ?
1st Leaf : 2/28/2011 to 5/6/2013
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Rik
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Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Mon Jul 26, 2010 10:38 am

evnow wrote:
Rik wrote:Hmmm... we don't normally think if it that way so I'm not sure.
Would you know how much NG is used on the avg ?
When my work computer comes back from the IT ICU I'll try to estimate that.

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

Mon Jul 26, 2010 11:07 am

Here is a useful document I found.

http://www.cbecal.org/pdf/CBE09Refinery ... ycrude.pdf
Average refinery energy consumed increases by 47%, from approximately 522,000 to 770,000 British thermal units/barrel crude refined, as oil input gravity-plus-sulfur rises from 138 to 143 kg/b.
See appendix table 7 for all fuel inputs.

ps : This 522-770 kbtu is equivalent to 153 to 226 kwh. Divind this by 38 gallons of gasoline equivalent energy you can get out of a barrel of oil (http://evworld.com/article.cfm?storyid=1715), we get between 4 and 6 kwh for a gallon of gas.

That is enough to propel an avg EV 20 miles - the same a gallon of gas propels an avg ICE car.
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Rik
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Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Mon Jul 26, 2010 1:09 pm

evnow wrote:Here is a useful document I found.

http://www.cbecal.org/pdf/CBE09Refinery ... ycrude.pdf
This is a complicated issue to assess. Some of these "fuels consumed" are byproducts from oil refining. It's not clear whether or not they are counting hydrogen twice, both as something that is consumed by refining and also as something produced from natural gas. Also, most hydrogen in oil refineries is used as a reactant in hydroprocessing and not as a "fuel consumed". Residual fuel oil and petroleum coke are produced by oil refineries far in excess of what they consume.

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

Mon Jul 26, 2010 1:43 pm

I don't think most of the kWh consumed by oil refining per gal gasoline numbers being claimed here and on similar forums are even close to being correct. For starters, the claims are a factor of 5 - 15 higher than the oil refinery I support, which because it processes heavy crude, is very complex, runs to high conversions, and produces fuels to California's demanding specifications is probably on the high side of the average in terms of energy consumed.

Oil products have a large EROEI -- a lot more energy is produced when these fuels are burned than goes into making the fuels. This would not be the case if oil products were the large energy consumers that some are claiming.

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

Mon Jul 26, 2010 2:28 pm

Rik wrote:
evnow wrote:Here is a useful document I found.

http://www.cbecal.org/pdf/CBE09Refinery ... ycrude.pdf
This is a complicated issue to assess. Some of these "fuels consumed" are byproducts from oil refining. It's not clear whether or not they are counting hydrogen twice, both as something that is consumed by refining and also as something produced from natural gas. Also, most hydrogen in oil refineries is used as a reactant in hydroprocessing and not as a "fuel consumed". Residual fuel oil and petroleum coke are produced by oil refineries far in excess of what they consume.
It is a complicated issue - but should have been taken care of by this study. I'll try to get in touch with this author - but a basic thing like not double counting etc should be fairly simple to handle. In any energy system, since it is possible to use part of the inputs/outputs to fuel the system itslef, there is nothing novel here.
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johnr
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Re: 7.5 kWh of electricity to produce a gallon of gasoline?

Mon Jul 26, 2010 8:39 pm

... also, we might as well consider the emissions caused by the natural gas that's flared in the oil extraction process ...

Wow, so many steps involved in getting that dino-juice out of the ground and into the gas tank :shock: with energy used every step of the way.

By comparison, getting power into my EV will be way more efficient - the sun shines down on my solar panels, generating an electric current that travels into an inverter and a charger - a 2-step power conditioning process - before being gobbled up by the batteries in my new Leaf :D
My trip to Mineral King and the value of regen

Charging stations, electrical adapters, and portable CHAdeMO quick chargers

2011 upgrade: Fossil < Leaf. 2014 upgrade: Leaf < imiev. 2017 upgrade: imiev < tesla. Done upgrading.

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

Mon Jul 26, 2010 11:03 pm

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?

I'm now of the opinion that, as electric cars come online, petroleum refineries should be restricted from using any grid electricity. That electricity is better used by BEV's

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