ADVERTISEMENT
See Inside June 2006

Carbon Hooch

Heating oil, gasoline, jet fuel, kerosene and plastics. These products and more are derived from crude oil in one big fuming silo, siphoned off and fine-tuned through a bewildering maze of pipes.

Crude oil contains hundreds of different hydrocarbons. Yet U.S. refineries convert half of all crude into gasoline--a blend of fuel stocks, particularly 2,2,4-trimethylpentane (eight carbon atoms chained together) and heptane (seven carbon atoms). The more complex the chain, the more the molecule can be compressed before it ignites spontaneously, allowing an engine to operate at a higher compression ratio--greater power output. The test mixture by which a gasoline's octane rating is judged combines 2,2,4-trimethylpentane and heptane (87 to 13 percent for "87 octane").

Refiners have tried additives over time to boost octane rating. Tetraethyl lead worked in "leaded" gasoline but was phased out because it spoiled catalytic converters. Producers switched to methyl tertiary butyl ether (MTBE), but it has been implicated in contaminating groundwater, and state governments are banning it. An alternative increasingly being used is ethanol, which has an octane rating of 108 or 110; gasoline with 10 percent ethanol is marketed as gas-o-hol.

This is only a preview. Get the rest of this article now!

Select an option below:

Customer Sign In

*You must have purchased this issue or have a qualifying subscription to access this content


It has been identified that the institution you are trying to access this article from has institutional site license access to Scientific American on nature.com.
Click here to access this article in its entirety through site license access.

Rights & Permissions
Share this Article:

Comments

You must sign in or register as a ScientificAmerican.com member to submit a comment.
Scientific American Dinosaurs

Get Total Access to our Digital Anthology

1,200 Articles

Order Now - Just $39! >

X

Email this Article

X