BP oil spill: By the numbers

How wrong can you be in estimating an oil spill? The first few days after the tragic April 20 blowup of the Deepwater Horizon oil rig off the US Gulf Coast, BP estimated a spill rate of 1,000 barrels per day. This was further revised to 5,000 barrels a day. 

There are 42 gallons in a barrel, so this was about 2.4 gallons per second. Anyone who has seen the video of the spill could have quickly estimated that oil leaked much faster than 2.4 gps. 

The estimate by the governmental Flow Rate Technical Group, before a cap was placed on June 3, was 40,000 barrels a day. In other words, BP’s official estimates were initially off by a factor of 40. So, for the first 44 days, 1.76 million barrels of oil had already spilled. 

After the initial cap, the flow actually increased since a riser pipe was cut, and the estimate grew to 60,000 barrels a day. And oh, the irony — BP reports that the cap collected a rate of 15,000 barrels a day, which happens to be 15 times higher than their initial estimate of the flow. 

Finally, on July 15, pressure tests indicated that a new cap on the well has succeeded — temporarily, at least — in stopping the oil flow. However, the pressure built up on the capped well has caused minor leakage since then. 

In total, as of July 15, the oil well has leaked about 4.28 million barrels of crude oil. Subtracting the amount of oil BP claims to have captured, the total volume of the actual spill is about 3.62 million barrels, or about 152 million gallons.

For historical reference, the disastrous Exxon Valdez spill in 1989 was 10.8 million gallons, so the BP spill is currently the equivalent of about 14 Valdez ships running aground. Another way to look at it is that on average, about 1.77 million gallons spilled every day, the equivalent of an Exxon Valdez disaster every six days. 

Just how much is 152 million gallons of oil? It’s enough to flood about 25 Araneta Coliseums one meter deep. If you filled up 55-gallon steel oil drums, you’d need about 2.76 million drums. If you could stack up these drums, they’d reach about eight million feet into the sky, far enough to reach the International Space Station and back three times. You’d need to stack 274 Mount Everests (29,029 feet each) or 10,226 of the GMA-7 Tower in Tandang Sora, Quezon City (777 feet each) in order to match the stack of barrels. If you laid down the barrels end to end, you could cover the entire length of the Philippines, from the Batanes Islands in the north to the Tawi-Tawi Islands in the south (approximately 1,152 miles, longer than the distance from Aparri to Jolo).

The latest estimate of the oil slick’s cumulative surface area is about 176,119 square km. This is more than enough to cover all of Luzon, or enough to cover 60 percent of the entire Philippines (you can visualize this here — http://www.ifitwasmyhome.com/).

Assuming you get 19.5 gallons of gasoline per barrel of oil, the spilled oil would yield over 70 million gallons of gasoline. This is enough gasoline to drive around the earth 57,000 times (assuming there was a road all the way along the equator) with a car that gets a mere 20 mpg. If you had to replace this gasoline with sugarcane-based ethanol, you would need to plant sugarcane in about 12,000 square km, a land area equal to about 19 Metro Manilas.

If you assume an average formula of C36H74 for the crude oil, disregarding all other gases and released chemicals, the entire oil spill would require 1.7 billion kg of oxygen to fully oxidize the oil, producing about 1.6 billion kg of carbon dioxide. It would take approximately 1.5 million trees their entire lifetimes to absorb all the carbon dioxide produced from the combustion of the spill. 

Hopefully these numbers give you a sense of the magnitude of this oil spill, the greatest environmental disaster in the US. But the most unbelievable numbers are the ones that show the world’s addiction to oil. The entire oil spill, to date, is only enough to supply the oil consumption of the Philippines for 12 days, and is equivalent to the entire world’s oil consumption for a single hour.

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Francis L. de los Reyes III is an associate professor of Environmental Engineering at North Carolina State University. Mia C. de los Reyes just finished sophomore year at W. G. Enloe High School, and is a rising junior at the North Carolina School of Science and Mathematics. E-mail them at [email protected].