Tech Used to Clean Up Oil Spills

By Tracy Staedter

The Deepwater Horizon disaster off the coast of Louisiana is not the first oil spill, but it’s becoming among the worst. As of May 1, 2010, two undersea leaks are gushing crude into the Atlantic Ocean at a rate of 5,000 barrels, or 210,000 gallons, a day.

Oil spill clean up crews are already on the job, doing their best to contain the oil, disperse it, burn it or skim it. Some of the technologies employed for such a task are developed and improved upon at Leonardo, N.J.-based Ohmsett an large-scale oil spill test facility maintained and operated by the Department of the Interior’s Minerals Management Service.

Oil Spill Test Tank

"The heart of Ohmsett is a large outdoor test tank that is 667 feet long, 65 feet wide, 11 feet deep, about the size of two football fields long and contains 2.5 million gallons of water to test all types of oil spill response equipment and train responders," said research oceanographer Joseph Mullin, who has managed the MMS oil spill response research program at the Minerals Management Service for twenty years.

Although the Ohmsett facility is not directly involved with current cleanup efforts in the Gulf of Mexico, many of the people trained here are deployed to oil spill disasters like the Deepwater Horizon, and many of the technologies and techniques developed here are being used in the effort. These are few of those technologies and how responders use them.

Credit: MMS

Remote Sensing

Before an oil spill can be dealt with, first it needs to be found. A timely response requires rapid reconnaissance of the spill site to determine its exact location and the extent of oil contamination -- particularly the thickest portion of the slick. Remote sensing and detection equipment not only helps locate a slick, but also differentiates between a thin sheen and a thick layer. That information is crucial for cleanup.

"You don’t want to be spending your time collecting oil that’s thin; you want to maximize your time by collecting oil that’s very thick,” said Mullin.

A ground-penetrating radar sensor that can be towed along the surface of ice by a vehicle or a helicopter is used in Arctic regions, where oil may be trapped under, or even inside, thick ice. The device shoots sound waves through the ice, where various structures such as water, rock, organic material and potential oil exist. When the sound waves encounter a layer of crude oil, they become distorted and bounce back to the sensor. A computer program analyzes the distorted sound waves and is able to distinguish one material from another, as well as provide an image and map of the environment under the ice.

For oil slicks at sea, a current research project has developed a portable aerial thickness mapping system that uses a multi-spectral camera onboard a plane or helicopter, which is flown over the spill. Instead of sound waves, the camera uses light waves, which reflect off the water and oil to provide an image -- like this one of Angel Island off the coast of California -- that shows the oil’s thickness in millimeter increments and can relay this information to an Internet-accessible database. The aerial thickness sensor has been used to assist in the response to oil spills off the coast of California.

Credit: MMS

Boom and Skimmers

Many images of the oil cleanup off the shores of Louisiana show long orange tubes being pulled by boats. These are booms, inflatable floating barriers that are typically filled with air or Styrofoam and used to contain oil on top of the water.

“You collect oil in the back of the boom to get it thick enough, and then you use the skimmer to remove the oil from the surface,” said Mullin.

Skimmers come in many shapes and sizes, but their job is to scrape, suck or brush oil from the surface without taking up much seawater in the process. In the image above, a small fishing boat contains oil spilled from the Exxon Valdez in 1989 with a boom, while a skimming barge sucks up the mess.

One of the latest skimmers tested at the Ohmsett facility is a drum skimmer that was improved upon by researchers from the University of California-Santa Barbara.

The researchers coated the drum with a material that absorbs oil and also added a grooved pattern to improve the drums pick up efficiency. Coating the drum improved it's efficiency by 20 percent, however adding a grooved pattern improved the efficiency of the skimmer by 200 percent. said Mullin.

Credit: AP Photo/John Gaps III

Chemical Dispersants

As of April 29, British Petroleum said it had deployed 76,104 gallons of dispersant, and had an 89,746 gallons available.

Chemical dispersants are specifically formulated liquid solvent that’s generally sprayed onto ocean slicks from airplanes. The solvents mix with oil and break it down into fine droplets that then disperse with natural water currents.

Dispersants are more effective on fresh oil as opposed to crude oil that has become emulsified with wave action over time. Disperants do not mix well with emulsified crude and run off the oil before they can break it down. That’s why remote sensing technology is so critical, because it can ensure that dispersants are applied to oil slicks where they will be effective and to keep away from areas where it won’t be effective

After the chemicals are dropped over the oil, a crew in a boat visits the patch of oil to test that the dispersants have been effective. They use an instrument called a digital fluorometer, which is lowered underwater where it sends out a specific wavelength of light. The light excites molecules in the oil to make them glow. A similar thing happens when an ultraviolet light, or black light, shines on a white T-shirt in the dark. The white glows brightly.

The emitted light is measured by the detector, and the fluorescence value is displayed on the instrument. The fluorometer measures the concentrations of the oil being dispersed to continue with the response or halt it.

Using the fluorometer, the team can tell how well the oil is breaking down in the water column.

Above, a dispersant plane passes over an oil skimmer as it cleans oil from the Deepwater Horizon oil rig.

Credit: AP Photo/Patrick Semansky

Chemical Herders

Some of the latest chemicals being developed to clean up oil don’t disperse the liquid, but corral it. Called chemical herders, these compounds, which are less toxic than dispersants, can surround a spreading area of thin oil and force it into a smaller, thicker patch. And it doesn’t take much chemical herder to do a big job.

“Eight tiny drops used on oil the size of a kitchen can herd it into the size of a dinner plate,” said Mullin.

That makes it easier to skim, burn or disperse the oil. The chemical herders being developed are in the experimental stage and have not been submitted for testing by the EPA for inclusion on the EPA National Oil and Hazardous Substances Pollution Contingency Plan Product Schedule.

But for now, “easy” is one word no one is applying to the current oil spill disaster in the Gulf of Mexico. And with 210,000 gallons of crude surging into the ocean, it will take more than clean up technologies and techniques to stop this disaster. To date, the well has not been capped and it could take several months to drill another well that would divert the flow of oil into the sea.

Credit: MMS

For more news coverage on the Deep Horizon catastrophe, see Oil Spill in the Gulf of Mexico 2010: Wide Angle.