The Oil Drum

55 comments on It's Time for Summer Gasoline

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AlanfromBigEasy on April 16, 2008 - 9:35am

To put a Peak Oil spin on this, NGL (major source of butane) production is increasing and conventional crude oil and condensate (a lesser source of butane) is decreasing.

We can burn more of the increasing stuff in the winter but not in the summer.

In addition, the production mix of oils is shifting towards heavier (lower API) crude oils and I was wondering what this effect had on gasoline yields ?

Also, EU gasoline imports are a growing slice of USA gasoline supply. I think the Euros drive more in the summer as well. Will this also cause another squeeze on summer gasoline supply ?

Thanks,

Alan

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mcgowanmc on April 16, 2008 - 10:40am

I was under the impression that butane, like propane, could only be kept liquid under pressure.

Or why is propane (like butane, 30 years ago for me) always
delivered in pressurized containers?

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Brother Kornhoer on April 16, 2008 - 11:37am

See memmel's explanation downthread. Also, note that no matter what the temperature, all liquids have a vapor pressure of some sort - that's why they evaporate. This vapor pressure increases with increasing temperature. When you get to the boiling point, this vapor pressure equals atmospheric pressure and the liquid vaporizes off at a rate determined by how fast the heat is flowing in to the liquid. When you blend liquids, the individual vapor pressure of each component liquid is protated by that component's mole fraction concentration in the liquid. So, while pure butane's vapor pressure is above atmospheric pressure at room temperature, butane in solution with gasoline has a vapor pressure much lower, so you don't see bubbles of butane boiling out of the gasoline. It does evaporate out though.

FYI, pure butane has a boiling point of approx. 0 C or 32 F, IIRC, so that's why it's not used for heat and cooking like propane is. I think propane boils somewhere near -40 C / -40 F (where the two temperature scales cross).

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biophiliac on April 16, 2008 - 12:35pm

Butane is commonly used for heating and cooking in various parts of the world. See e.g.:
http://es.wikipedia.org/wiki/Butano
It is easily compressed to a liquid for transport in areas outside the natural gas network.

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Jack on April 17, 2008 - 11:35pm

A shift towards heavier crude can be totally compensated for by an increase in the complexity of refineries. This would add a small additional per barrel capital charge, but aside from highr prices shouldn't impact availability of gasoline over the longer term.