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 2 of 4
The politics of marine fuel
The IMO is the United Nations body responsible for reducing the negative impact of ships on the environment. It's meeting this week to consider tightening standards for ship emissions. Commercial ships are not included in the Kyoto Protocol, the international agreement to cut greenhouse-gas emissions signed by most of the world's major emitters.
"There currently is no international agreement on greenhouse-gas emissions from ships," says Lee Adamson, a spokesman for the IMO. The group is studying CO2 emissions and originally had planned to propose regulations by 2010, but that deadline may be moved up, Mr. Adamson says.
The shipping industry continues to point out that moving freight by cargo ship is the most energy-efficient means of transporting cargo, vastly superior to trucking or rail on a ton-per-mile basis.
But the industry also realizes that changes are coming. The International Association of Independent Tanker Owners, which represents about 70 percent of independent tanker owners, and the Pacific Merchant Shipping Association favor ending the use of bunker fuel (see story, left), which emits a high level of toxic contaminants. Ships would switch to marine diesel oil (MDO), a fuel similar to that used by many trucks, buses, and cars. The cost of MDO, however, is currently about twice that of bunker fuel.
"A lot of companies have already embraced this [changeover to MDO]," says T.L. Garrett, vice president of the Pacific Merchant Shipping Association in San Francisco. "It is a public health issue. The industry is sensitive to that."
All that shipowners ask is for one consistent international standard for emissions that would apply worldwide – a "level playing field," Mr. Garrett says. Currently, ports in California, Canada, and Europe have tried to set their own emissions limits, essentially banning bunker fuel, because the IMO has been seen as moving too slowly.
Any increase in the fuel economy of ships would also cut emissions, so companies now have two motivations for trying new techniques.
Innovative propulsion – through bubbles and ballast tanks
Research has been under way for years using air bubbles blown along hulls or air cavities (recesses in the hull that emit air). Since air creates less drag on a hull than water, the design can save energy. Solar power and even wave action are also being looked at as auxiliary power sources.
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
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