Sailing toward a solution
Research may make barnacles and other oceanic freeloaders seek alternate transportation
From the ancient Egyptians and Vikings to modern-era nuclear submarine manufacturers, shipbuilders have struggled with a hitchhiker problem of oceanic proportions: what to do with those troublesome little creatures that attach themselves by the collective tons to ship hulls.
Researchers, from left, Carl Lovely, Richard Timmons and John Schetz are developing environmentally friendly ways to control biofouling, which causes a $6 billion-a-year drain on the shipping industry.
It’s called biofouling, where barnacles, mussels or tubeworms set up a watery homestead wherever a current is flowing. It’s a $6 billion-a-year drain on the shipping industry and billions more in power plant cooling converters. Or tidal electric generators. Or offshore wind electric generators. Or canal locks. Or irrigation systems.
Two UT Arlington researchers and one from the University of North Texas Health Science Center in Fort Worth are working to refine the science of biofouling—with a twist. They want to accomplish the task in an environmentally friendly way.
“The issue is a lot bigger than just shipping,” says John Schetz, a pharmacology associate professor at the UNT Health Science Center and an adjunct biology research professor at UT Arlington. Teaming with Dr. Schetz are UT Arlington chemistry professors Carl Lovely and Richard Timmons.
Many freshwater creatures (zebra and quagga mussels) and saltwater dwellers (green-lipped mussels and barnacles) live in currents, filtering and digesting the nutrients that pass by. Often they act as Mother Nature’s little water cleansers.
On the downside, they foul intakes and outtakes at electric plants, water treatment facilities and water locks. The barnacle buildup on ship bottoms increases drag and fuel costs while reducing speed and maneuverability and promoting corrosion.
Early shipbuilders soaked hull boards in arsenic, which had disastrous environmental consequences for shipyard workers and oceanic species. Latter-day solutions involve paints containing heavy metals such as tin, copper or zinc. Some work reasonably well as biofouling preventatives but with a persistent toxic effect.
“We want green solutions that are effective and long lasting and that do no harm to the environment,” Schetz says. “It won’t be dangerous to the biofouling target organisms or non-target organisms. The Office of Naval Research ultimately wants a biofouling solution in which there is no release of chemicals from coatings at all.”
That’s where the current research comes in. A competitive seed grant program between UT Arlington and the UNT Health Science Center is the first such collaboration of its kind for the schools, and the payoff has been impressive: a 16-fold return on the initial investment of grant dollars.
One of the grants is a two-year, $300,000 award from the Office of Naval Research to develop a better way of stopping mussels, barnacles, algae and other marine life from attaching to ship hulls.
“We want green solutions that are effective and long lasting and that do no harm to the environment.”
The grant grew out of a discovery by Schetz and UT Arlington biology Professor Bob McMahon. While working on the zebra mussel problem in fresh water, they discovered that a solution containing chili peppers or other plant extracts prevented the mussels from attaching to submerged surfaces like those found at an electric plant intake.
“The antifouling technology fits into a number of efforts aimed at reducing energy costs and limiting humankind’s environmental footprint,” Schetz says. “It could also be applied toward efforts aimed at preventing the introduction of nuisance species such as green mussels, zebra mussels and quagga mussels.”
But it’s considerably more difficult to provide a chemical barrier for the hull of a giant tanker or aircraft carrier cruising world oceans at 35 knots than to suspend an aqueous solution near an intake grate. The answer must be something that sticks permanently to metallic or coated surfaces while making the harmful hitchhikers look elsewhere for a free ride.
Though the work began with natural products derived from peppers, Schetz says the effect has nothing to do with the plant’s “hotness” molecule. The research has since evolved into distantly similar organic molecules made synthetically.
“Think of them as improvements on nature,” UT Arlington’s Dr. Lovely says.
It’s not clear why creatures like barnacles or zebra mussels won’t attach themselves to some types of coating. It’s those coatings that the researchers seek to refine.
Lovely is working to develop a synthetic molecule that will retain its antifouling qualities and won’t break down and that can bond to a coating that will attach firmly to metal surfaces.
Enter Dr. Timmons, a UT Arlington chemist and international authority on bonding to metallics, with emphasis on a technique called plasma-polymerization. Essentially, his coatings begin as vapors. In this case, one side of the coating attaches itself tenaciously to a metallic surface in a uniform way. The other side can bond with another substance, Timmons says, “like a very large and complex synthetic organic molecule that barnacles or mussels won’t like.”
He can create coatings just a few nanoparticles thick with a reactive side attached—the synthetic organic particles that barnacles avoid, for instance.
“I’m designing the synthetic molecules, Dr. Timmons is making the coating, and Dr. Schetz is testing for effectiveness,” Lovely says. “It’s a true interdisciplinary effort.”
The researchers are entering the second year of the two-year grant, with Schetz set to begin testing with live sea creatures. Along the way, Lovely and Timmons will make adjustments—essentially molecular re-engineering—depending on Schetz’s findings.
“Right now the Office of Naval Research is just interested in proof of concept,” Timmons says. “Once we’ve established that proof, we can start looking at more pragmatic uses.
“It’s possible, for instance, that we may be able to use our findings in something like paint but with an efficiency and environmental safety considerably better than what exists for biofouling solutions right now.”