NPR: Is 'Ghost Gas' Giving Your Wallet a Scare?

Is 'Ghost Gas' Giving Your Wallet a Scare?

One day every week, I put my shoes on around 11 p.m., get in the car and drive to the local gas station, where I fill 'er up (for a better than average price if I'm lucky). Why skulk around in the night for gas? I'm trying to avoid the problem of "ghost gas."

What's ghost gas? Well, when it gets hot during the summer, gas expands. It's a liquid -- remember physics class in high school? The price of gas is calculated on the gas being about 60 degrees Fahrenheit. So when you go to the gas station on a hot day (like today in Washington -- it's about 95 degrees) and put a gallon of gas in your car, you get less actual fuel than you would if you pumped it in cooler temperatures.

The difference can add up to as much as 10 cents a gallon, according to some estimates. And that's put a bee in some lawmakers' bonnets.

Today's Day to Day featured a Marketplace report about how a group of Democratic lawmakers has asked the National Conference on Weights to consider setting new standards for gas.

Here's a shocker: The oil industry wants none of it. Dan Gilligan with the Petroleum Marketers Association of America says retrofitting the pumps with temperature compensation devices would be too costly. Gilligan makes a familiar request in these situations -- let's study it some more. But The Kansas City Star notes that the National Conference on Weights has been debating the issue for three decades.

I first learned about ghost gas -- where else? -- on Car Talk. Tommy and Ray talked about it a couple of years ago while discussing ways to get more value for your buck at the pump.

2:57 PM ET | 07- 9-2007 | permalink

Comments (Send a comment)

This is true, that gas does expand when it is heated. However the gas at fuel stations are stored in underground tanks, where the temp. stays constant. The volume is not going to change at all.

Sent by Rocco S. Rossetti | 3:38 PM ET | 07-09-2007

Gad, ghost gas costing $.10 per gal?? Wrong, other analyses indicate the volumetric expansion of gasoline at high temps is less than 1/2 percent, so no $.10/gal cost. Also, as your gas is in the underground tank before you pump it, the temps down there go thru hardly any diurnal change. If a discernable change occurs, its seasonal at worst. And, your winter gas is more volatile than summer gas, so you probably lose more to the atmosphere then, than during the summer. If you've got a post 1999 vehicle, the gasoline emissions from refueling are captured in a carbon canister onboard your vehicle, and sucking into your engine when it is running. You've got more problems with ethanol in your gas than with phantom gasoline volumetric expansion!

Sent by Neil Moyer | 3:55 PM ET | 07-09-2007

I also have also heard Tom and Ray speak about this topic on Car talk. In the episode I listened to they commented that the amount of money saved by buying gas at a lower temperature (buying gas in the middle of the night) would be minuscule because gas is stored in underground tanks. I believe they also commented that the volume of gasoline does not change much between 50 and 100 degrees Fahrenheit. I'd also like to know where you got the figure of up to 10 cents per gallon. I do not have facts to back up this argument but I would be interested to see the volume difference of gasoline pumped at different times of the day in different places around the country. Another interesting study would be to see how the volume of the underground tanks would differ before and after a station received a shipment of gasoline from a tanker truck which could have spent a day out in the hot sun.

Sent by J. Bengtson | 4:34 PM ET | 07-09-2007

The above statements are true about gasoline in underground tanks not experiencing diurnal temp flucuations. So why do stories like these experience such coverage? It is similar to the great threat posed by the "terrorists" from Trinidad, who wanted to blow-up JFK Int'l by iginiting the jet fuel reserves. It most likely wouldn't have been the monumental (in terms of loss of life) catastrophe invisioned by those who reported on it.

Sent by E.L. Gulbranson | 6:12 PM ET | 07-09-2007

For years I have thought that it was using an airconditioner that made my mileage so awful...now I know...

Sent by helen g. | 8:01 AM ET | 07-10-2007

Yes, underground tanks won't experience much of a temperature swing on a given day. I suspect the difference between winter and summer is greater.

Sent by Keith Tipton | 9:04 AM ET | 07-10-2007

Actually, these are common myths with the issue of hot fuel, see the Myths and Facts page of this site for more:
www.turndownhotfuel.com

Sent by OOIDA | 10:30 AM ET | 07-10-2007

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