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RENEE MONTAGNE, Host:
And I'm Renee Montagne, with Lynn Neary.
We'll hear now about a stunning reassessment of the amount of oil spilling into the Gulf of Mexico. According to an exclusive NPR analysis, there's at least 10 times as much oil pouring into the waters as officials estimate.
At NPR's request, experts analyzed video that BP released Wednesday. Their findings suggest that the BP spill is already far larger than the Exxon Valdez spill in Alaska in 1989.
NPR science correspondent Richard Harris has the story.
RICHARD HARRIS: BP has repeatedly said there's no reliable way to measure their oil spill in the Gulf of Mexico by looking at the oil gushing out of the pipe. But scientists say there are actually many proven techniques for doing just that.
We asked professor Steven Wereley at Purdue University to analyze videotape of the sea-floor gusher. He literally co-wrote the book on a technique called PIV.
INSKEEP: PIV is short for particle image velocimetry and conceptually, it's a very simple technique.
HARRIS: A computer program simply tracks particles, and calculates how fast they're moving. Wereley put the BP video of the gusher into his computer. He made a few simple calculations, and came up with an astonishing value for the rate of the oil spill - much higher than the official estimate of 5,000 barrels a day.
INSKEEP: Seventy thousand barrels a day.
HARRIS: Plus or minus how much?
INSKEEP: Oh, about 20 percent.
HARRIS: How confident are you in that?
INSKEEP: Well, I guess I'm quite confident that it's within the bounds that we just discussed.
HARRIS: Given that uncertainty, the amount of material spewing out of the pipe could be anywhere from 56,000 barrels to 84,000 barrels a day. It is important to note that it's not 100 percent oil. The very short video BP released starts out with a shot of methane.
INSKEEP: And at the end, it seems to be mostly oil. And so there's potentially some fluctuation back and forth between methane and oil.
HARRIS: But assuming that the lion's share of the material coming out the pipe is oil, Wereley's calculations show that the official estimates are way low.
INSKEEP: We're talking more than a factor of 10 difference between what I calculate and the number that's being thrown around.
HARRIS: At least two other calculations back him up.
Timothy Crone, from the Lamont-Doherty Earth Observatory, uses another well- accepted method - different from Wereley's - for calculating fluid flows. He says the flow is at least 50,000 barrels a day.
And Eugene Chiang at the University of California, Berkeley, got a similar answer just using pencil and paper.
INSKEEP: I actually teach a class where the whole point of the class is to estimate things based on very limited amounts of information.
HARRIS: Without even having a sense of the scale from the BP video, he correctly deduced that the diameter of the pipe was about 20 inches. And though his calculation is less precise than Wereley's, it is in the same ballpark.
INSKEEP: I would peg it at around 20,000 to 100,000 barrels per day.
HARRIS: So that's five to 20 times larger than the number we've been using.
INSKEEP: Yeah. If you're using numbers like 5,000 barrels per a day, I would say that's almost certainly incorrect.
HARRIS: And given this flow rate, it seems that this is a spill of unprecedented proportions in United States waters.
INSKEEP: It would just take a few days, at most a week, for it to exceed the Exxon Valdez's record.
HARRIS: BP disputes these figures. Bill Salvin is a company spokesman.
MONTAGNE: We've said all along that there's no way to estimate the flow coming out of the pipe accurately.
HARRIS: Instead, BP prefers to rely on measurements of oil on the sea surface made by the Coast Guard and the National Oceanic and Atmospheric Administration. Those are also contentious. Salvin also says these analyses should not assume that the oil is spewing from the 21-inch pipe, called a riser, shown in the video.
MONTAGNE: The drill pipe from which the oil is leaking is actually a nine- inch pipe that rests within the riser.
HARRIS: But professor Wereley says that fact does not skew his calculation. And although scientists hope that BP will eventually release a lot more video and information so they can refine their estimates, what they have now is good enough.
INSKEEP: It's possible to get a pretty decent number by looking at the video.
HARRIS: This new, much larger number suggests that capturing and cleaning up this oil may be a much bigger challenge than anyone has let on.
Richard Harris, NPR News.
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