If there is one thing we Michiganders are proud of, it's our abundance of water. The quality of that water or what swims in it sometimes, well, sometimes not so much.
The proliferation of non-native species, such as zebra mussels and gobies, has become a hot issue with environmentalists and water enthusiasts alike. But engineers at the University of Michigan think they might have found a way to stem the tide of invasive critters swimming into the Great Lakes basin by creating designs for a ballast-free cargo ship.
"There is no silver bullet. But the ballast-free ship has the potential to be an economic winner while addressing the ballast problem in a serious way," says Michael Parsons, a professor of naval architecture and marine engineering at U-M and a co-leader of the project.
The problem comes from big ocean-going freighters that cruise the Great Lakes (think Edmund Fitzgerald) and use water-filled ballast tanks for stability. The invasive species either cling to the ship's hull or hitch a ride in its ballast tanks, which are sometimes emptied in the Great Lakes giving the little critters a new home.
So far at least 185 non-native aquatic species have been identified in the Great Lakes, and ballast water is fingered as the cause for most of them, including the zebra mussels.
U-M's plans would create a constant flow of local seawater through a network of large pipes that runs along the hull of the ship below the waterline. No more dumping China's water in Lake St. Clair
"In some ways, it's more like a submarine than a surface ship," Parsons said. "We're opening part of the hull to the sea, creating a very slow flow through the trunks from bow to stern."
And vice versa. The concept was born in 2001, patented in 2004 and is getting ready to be built into new vessels. U-M's engineers are testing the new system in a 16-foot-long wooden scale model thanks to funding from the Great Lakes Maritime Research Institute. So far tests have shown the new system will also streamline the ship by helping it save as much as 7 percent of the energy needed to propel it.
That would save $150,000 in fuel for a round trip between Europe and the Great Lakes. That fuel savings would offset the added cost to build the system into a new freighter at an average cost of $70 million. The engineers think the water coming through the new system helps the propeller operate more efficiently.
"We have proven that the technical part is feasible and that it can be applied to new vessel construction," says Miltiadis Kotinis, a SUNY Maritime College engineer, collaborator on the project and a U-M alumnus. "And we have also shown that, regarding the economics, it can reduce the operating cost and reduce or even eliminate the introduction of non-indigenous aquatic species."
Source: University of Michigan
Writer: Jon Zemke
Enjoy this story?
Sign up for free solutions-based reporting in your inbox each week.