A Technical Communications Perspective
How about 50,000 Cars on the Pacific Coast Highway?
Or a 747 with 500 on board flying for 57 minutes?
Austin, Texas, May 20, 2010 — What does 5,000 (or 50,000) barrels of oil a day mean to you? We’ve been hearing that number for almost a month now. And there is some debate whether or not those are accurate numbers. But what does it mean other than ‘a whole lotta oil’? This is the question that Global Language Monitor President, Paul JJ Payack examined over the last few days in the following analysis.
Metric Conversion: 1 gallon = 3.79 liters; 1 barrel = 158.98 liters; 1 mile = 1.61 kilometers
Listen or Read: KUHF – Analyst Puts BP Gulf Oil Spill Into Perspectiveto Quantify the Oil Spill at 50,000 Barrels Per Day?
Back when I taught technical and scientific communications at the University of Massachusetts, a key function was to make physical dimensions meaningful to the audience, so we would describe a mainframe computer as the size of a washing machine (used to be an 18 wheeler), a server might be the size of a breadbox (though few have actually seen a breadbox nowadays but we all know it’s about ‘yeah big’). In the same manner Jupiter is about the size of 80,000 Earths, the Moon’s diameter is about equal to the width of the continental US (or the distance from New York to LA), and you could stuff approximately one million Earths into the Sun.
When you describe the volume of a liquid, such as water, you make comparisons like ‘if you emptied Lake Tahoe – which is nearly 1000 feet deep – and spread about 14 inches over the entire state’.
In terms of energy usage, a common description is to equate a megawatt to the number of homes for which it supplies power. So a one megawatt nuclear reactor, or wind farm, can power about a thousand American homes, or 10,000 homes in less-developed parts of the world.
So what does the 5,000 to 50,000 barrels a day mean? First question is ‘what’s a barrel’?’ A barrel is filled with forty-two gallons of oil. So 5,000 to 50,000 barrels equates to some 210,000 to 2.1 million gallons (or 16.8 million half-pints if you’re thinking in terms small milk cartons distributed in schools).
It does not help, of course, when the CEO of BP likens the spill to a drop in the bucket in relation to the capacity of the oceans. This strikes most people as condescending but it is actually NOT true. It is far less than a drop in the bucket when compared to the size of the seas, which contain about 321 million cubic miles of water, so even if the spill is now 1 mile deep by 1 mile wide, by 1 mile in height (USGS numbers) that would be far less than a drop (1 part oil to 321,000,000 parts water). (Though I am definitely not using this explanation to support BP’s argument here.)
Put another way, in light sweet crude you get about 19.5 gallons of gasoline from the 42 gallons of oil. Now if a typical car gets about 20 mpg on the highway, that would be equivalent to about 390 miles per barrel.
This is the distance from Los Angeles to San Francisco (actually 383 miles). So if the spill has been spewing 5,000 to 50,000 barrels per day since April 20; that is enough to power 5,000 to 50,000 cars a day along the Pacific Coast highway (or the I-5) from San Francisco to LA.
One more equivalency. 747 aircraft in flight with about 500 people on board are estimated to use about use about a gallon of kerosene a second. About 4.1 gallons are distilled from each barrel of oil. So 5,000 barrels of crude oil produce 20,500 gallons of kerosene, while 50,000 barrels of oil produce 205,000 gallons of kerosene.
This means 5,000 barrels enables a 747 with 500 passengers to fly 5.7 minutes, while the amount of kerosene from 50,000 barrels of crude oil will allow the same plane to fly almost an hour (56.9 minutes).