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Let's assume the gulf oil disaster has released 100 million gallons of oil. Can you tell us how much land that would cover up to a depth of 1 inch? Also, what is the conversion factor between barrels and gallons?

That much oil, assuming no evaporation or absorption into the ground, would not cover as much ground as you might think.

For math help we turned to Howard Perlman, a hydrologist with the U.S. Geological Survey. He, in turn, pointed us to a nifty calculator

Perlman walked us through it:

"First, make sure the 'Rainfall' box says '1 inch.'

"I can use trial and error until I get to 100 million gallons. I try the square miles box and enter 1. The resulting page tell me 17,378,560 gallons.

"So 100 million divided by the 17.38 million gives us about 5.75. If I enter that into my square miles box it should come up with about 100 million gallons.

"Well, my box will only let me enter a number to the tenths column, so I entered 5.7 into square miles and yes, it says 99,057,792 gallons.

"So I would say that 100 million gallons would cover 5.75 square miles to a depth of 1 inch - of water, that is. And it should not make a difference if it was oil."

Over a grid of St. Petersburg, that square mileage would fill an area approximately from Tampa Bay to 49th St. (about 5 miles) between 22nd Avenue N and Fifth Avenue N (a little over a mile).

There are 42 U.S. gallons in a barrel of oil, according to the Energy Information Administration. Only 19 or 20 gallons are used for gasoline; the rest goes to distillate and residual fuel oils, jet fuel and other products.

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Turning a pesky plant into gas

Has anyone done research into using kudzu for biofuel?

Most efforts today are aimed at trying to kill kudzu, an invasive vinelike weed that has cost billions of dollars in lost crops. However, it has potential as an ingredient for biofuels.

A 2008 study concluded that, under certain conditions, kudzu could produce about 400 liters of ethanol per acre, on par with an acre of corn. The study was conducted by the University of Toronto and the U.S. Agriculture Department's Agriculture Research Service.

The next step is a large-scale project that could prove using kudzu to make ethanol is economically feasible, University of Toronto Professor Rowan Sage said.

That has yet to occur. One reason could be that investment in many areas of alternative energy virtually dried up as the recession took hold and gas prices fell.

Agrogas, which is based in Cleveland, Tenn., is working to raise capital to finance a project to prove the viability of commercial production of ethanol using kudzu. It already has operated test vehicles using limited quantities.