## Oil Spill Math

Laura Palombi

By Laura Palombi, Erb MBA/MS student, class of 2011.

The estimates for how much oil is actually leaking into the Gulf of Mexico have been steadily increasing.  Initially, BP claimed that the flow rate was about 1,000 barrels a day but now estimates are up to 35,000-60,000 barrels a day.  While that sounds like an enormous amount, I was left wondering what that number really means in terms of oil consumption in the United States.   Like so many others, I’m appalled by BP’s careless actions and the resulting damage but I don’t think they’re entirely to blame.  They wouldn’t have been there in the first place if we weren’t buying their product.   So I did a few calculations to understand the volume in terms of how much gasoline a typical car uses and to relate the spill to our own consumption.  Here’s how I broke it down.

The U.S. consumes about 20,000,000 barrels of oil a day, about half of which is used to make gasoline.  At a rate of 60,000 barrels a day, the well would have to be left unchecked for almost a year before the volume spilled would add up to just one day’s worth of oil consumed.  Let’s hope it doesn’t take that long.  The rig exploded on April 20th and it doesn’t look like it will be fixed (or at least controlled) until at least mid-July.  If the leak continues for a total of 100 days, the total volume could amount to 3.5-6 million barrels.  The U.S. consumes that much in 4-7 hours.

It takes 1 barrel (42 gallons) of oil to make about 20 gallons of gasoline (the remaining oil is used to make other petroleum products). So the oil spilled over a period of 100 days could have been used to make 70-120 million gallons of gasoline.  Let’s say a typical passenger car fill-up is 20 gallons.  That means that enough oil will be spilled in the gulf to provide 3.5-6 million fill-ups.  In 2007, there were 136 million passenger cars in the U.S.  So, it would only take 2.5-4.4% of all passenger car owners to go to the gas station once for a fill-up to account for half the total volume of oil that will be spilled.

If a passenger car’s fuel efficiency is 30 mpg, that means enough oil will be spilled to fuel about 2.1-3.6 billion miles of driving.  If a vehicle is driven for about 150,000 miles, total, that’s enough to provide all the gasoline that 14,000-24,000 vehicles will use.  That’s less than 0.02% of all the cars in the US.  Last month nearly 600,000 new cars were sold in the US.    All that damage to provide a life-cycle’s worth of fuel for only about 2-4% of the cars sold last month.

It’s quite an image to see even just a tiny fraction of the oil we use on a daily basis concentrated and causing undiluted and undelayed ecological and economic damage to one location.    What I think we all need to keep in mind is that if the spill hadn’t happened, all that oil would end up being used (in a matter of hours!) and all that damage would just be spread through our air, water, and bodies.  The costs of consumption are so diffuse that it is nearly impossible to calculate the damage to our health, environment, and livelihoods in a way that can be measured meaningfully.  To me, this enormous tragedy represents only a tiny portion of the costs associated with continued dependence on fossil fuels that we use every day.