The Basics: Oil Spill Dispersants

This week I break down the basics of dispersants used in oil spills.

Of course, a ton of this stuff has been used recently in the attempted clean up of the BP oil spill in the Gulf of Mexico.

Aside from a good ole' fashioned attempt at covering up the leak with a massive dome, these dispersants are one of the primary attempts to contain/clean up the surface spill.

Since such a large volume of these chemicals are being deployed in the Gulf, we thought it best to keep our readers up to speed and just what this stuff is. Nature estimates that at least 325,000 gallons of two types of surface dispersants have been used -- Corexit 9500 and Corexit EC9527A. Sounds lovely.

David Horsup is the division vice-president for research and development at Nalco Energy Services, which manufactures the dispersant products currently in use in the Gulf of Mexico. "One is designed for light, fresh oil or oil which has been released very early on and hasn't been weathered," explains Horsup. "The other is designed for heavier oils and those that have been weathered for a few days." 

So how exactly do these dispersants work?

These dispersants do nothing to remove oil from the water. They instead break down large areas of oil into much smaller pieces which make it easier for all those creatures of the sea to deal with it.

Daniel Cressey of Nature uses a great example:  "They work on the same principle as kitchen washing-up liquids. Both are made up mainly of surfactant molecules, which have heads that are attracted to water and tails that are repelled by water.

The molecules embed themselves at interfaces between oil and water. This lowers surface tension at the interface — that is, the difficulty of disrupting molecules of oil and molecules of water from clinging to their own kind rather than mixing."

The bad news is that dispersants also help to spread the spilled oil more widely into the environment. While many focus on doing everything to prevent the oil from reaching the shore, it's often forgotten that the oil has a large effect on sea floor organisms as well.

"It's a trade-off, and no one will tell you using dispersants won't have an effect. You're trading one species for another," says Carys Mitchelmore, an environmental chemist at the University of Maryland Center for Environmental Science in Solomons.

But it's not just about the surface oil. Dispersants are also being used underwater. Deep underwater. In fact, the use of underwater dispersants has never been used at the depth of the current spill. Bring in the robots.

Robots are now being used underwater to spray dispersant directly onto the oil as it spreads on the ocean floor.  Although controversial, it appears to be somewhat successful.

"Aerial observations indicated that the slick on the surface was significantly reduced once you inject the chemical right at the well head," Horsup says. "You get very rapid dispersion of the oil into the water column."  

Meanwhile, the oil leak continues to spew.  Scientists are relatively unsure about the long-term effects of the chemical dispersants, but you can bet that several studies are underway from the April spill.

Studies that I'll be hoping bring on a new army of oil destroying robots, or at least an appearance from R2-D2 and C-3PO. Does George Lucas read EnergyBoom? Story pending...

Find out everything you want to know about the BP Oil Spill, here.