Environmental

Oil spill in Gulf is much larger, new analyses indicate

Since the Deepwater Horizon leased by BP exploded and sank in the Gulf of Mexico, analysts have been trying to determine how much crude oil has been spewing into the water. The official number for the gushing oil flow, established by the National Oceanic Atmospheric Administration and announced by the U.S. Coast Guard on April 28, is 5,000 barrels (210,000 gallons) per day. However, other scientists and researchers analyzing video footage of the leak say that the actual amount of oil escaping from the broken pipe is likely to be much, much larger.

Two weeks ago, Florida State University oceanographer Ian MacDonald analyzed images of the oil spill provided by the organization SkyTruth and estimated that 26,000 barrels of oil have been erupting from BP’s wellhead. MacDonald also cautioned that his analysis has not been subjected to peer review, as it would be if it were being released through a proper venue such as a scientific journal.

Another independent analysis organized by National Public Radio says the spill could be at least 10 times the official estimates, in which case it would have already far exceeded the Exxon Valdez spill in Alaska, which flooded Prince William Sound with 250,000 barrels of oil.

NPR asked Mechanical Engineering professor Steven Wereley of Purdue University to analyze video footage of the leak on the seabed. Using a proven technique called velocimetry, a computerized tracking method that calculates the speed of particles, Wereley entered a few basic calculations and determined that the well could be releasing 70,000 barrels of oil into the Gulf every day.

The velocimetry method is accurate to a degree of plus or minus 20 percent, which means that the amount of oil gushing from the pipe could fall anywhere between 56,000 barrels to 84,000 barrels per day.

However, oil may not the only substance coming out of the well. Methane gas, brine, and sediment could also be mixed in.

According to NPR, at least two other scientific analyses support Wereley’s conclusion that the NOAA’s estimate is too low.

Timothy Crone, a research scientist at the Lamont-Doherty Earth Observatory, used another accurate fluid flow calculation method and came up with a similar figure.

University of California, Berkeley, astrophysics professor Eugene Chiang used mathematical calculations and found the oil leak falls between 20,000 to 100,000 barrels per day, which would make the median number 60,000 – a number much more in line with Wereley’s figures than NOAA’s 5,000-barrel-per-day guesstimate.

BP spokesman, David Nicholas, said that his company has decided to focus on stopping the leak rather than measuring it.

“I don’t think an estimate of the flow rate would change either the direction or the scale of our response to it,” Nicholas said.

BP’s reluctance to measure the spill could be a very telling gesture. As NPR says, the new, much larger and scientifically valid calculations “suggest that capturing — and cleaning up — this oil may be a much bigger challenge than anyone has let on.”