A secret to improving cargo ship efficiency: Go fly a kite
Designers look to giant kites, bubbles, and new propellers to save on fuel costs and reduce pollution.
from the April 3, 2008 edition
Page 4 of 4
Scientists at the University of Michigan are experimenting with unusual ballast tanks that let seawater flow through them instead of being stored.
Conventional ballast tanks in ships pose environmental problems because the water inside them can carry invasive aquatic species to new regions. The new design would prevent that and provide a potential savings of up to 7.3 percent of the power needed to propel the ship. The researchers calculate that a 650-foot ship hauling 32,000 metric tons of cargo from the Great Lakes to Europe and back could save $150,000 in fuel costs, and emit less CO2 as well.
While some of these technologies are promising, none represents a "silver bullet" in reducing fuel use and emissions, says James Corbett, an associate professor of marine policy at the University of Delaware in Newark, Del., who co-wrote last year's report on ship emissions and health as well as a 2000 IMO study of greenhouse-gas emissions from ships.
"The problem is not simply to choose the best technology or practice, because there isn't a single solution," he says. "Industry and regulators are going to have to look at a variety of solutions and demonstrate the will to take effective action."
While the voyage of the SkySails Beluga has shown kite-power can work, the current design may have only limited usefulness since it appears to operate only at speeds below 17 knots (20 m.p.h.), Dr. Corbett says. "The fastest ships [big container vessels that travel at 20 knots or more] would not yet be able to take advantage of this design."
But even speed can change if the incentive is strong enough. Bunker fuel prices now exceed $450 per ton, and ships already are slowing down to save energy and reduce cost. Just a 10 percent reduction in ship speed saves 25 to 30 percent in fuel burned, Corbett points out.
• Monitor correspondent Tony Azios contributed to this story
Bunker fuel: cheap, but dirty
It can turn as solid as asphalt, but it's considered black gold for oceangoing ships.
Bunkerfuel, also called residual fuel, is what remains after crude oil hasbeen refined into higher grades of fuel, such as diesel.
"Forall intents and purposes, it's a waste product," says T.L. Garrett,vice president of the Pacific Merchant Shipping Association in SanFrancisco.
After decades of engineering improvements, thecolossal marine engines used by cargo ships have learned to love bunkerfuel and burn it efficiently. With a price about half that of marinediesel fuel, bunker fuel has proved to be the perfect choice for movingmassive ships from continent to continent.
Almost.
That'sbecause the tarlike sludge also is rich in contaminants, from toxicheavy metals to sulfur, which are emitted into the atmosphere and arebeing linked to health problems.
Two shipping-industryorganizations – the International Association of Independent TankerOwners and the Pacific Merchant Shipping Association – andenvironmental groups, including Friends of the Earth, have called foran end to the use of bunker fuel in cargo ships.
"Bunkerfuel is the dirtiest fuel on the planet," a Friends of the Earthspokeswoman told the Associated Press last fall. "Ships are being usedas waste incinerators for the oil industry."
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