During its 11,952-nautical-mile voyage to Venezuela and back, the ship launched a giant kite from its bow, sending it hundreds of feet into the air to capture the stronger and more consistent winds found above. The 1,720-square-foot kite, controlled by onboard electronics, exerted enough pull on the ship to provide about 20 percent of the engine power required for the journey.
"We can once again actually 'sail' with cargo ships, thus opening a new chapter in the history of commercial shipping," said Capt. Lutz Heldt following his return.
Larger, more powerful kites are planned for the future. Savings of 10 to 35 percent will be possible, depending on specific routes and weather conditions, says Stephen Wrage, founder and CEO of SkySails, a company in Hamburg, Germany, that makes the kites. It is planning to equip as many as 35 ships with its kites in 2009 and hopes to increase that to 1,500 ships by 2015.
From kites to new propeller designs to blasting air bubbles along hulls to make them slicker, ways to make ships more energy-efficient have been gaining momentum. The reasons aren't surprising: Fuel costs have ballooned and public pressure to reduce the air pollution and greenhouse gases that ships emit has increased.
A scientific paper published in November showed that ship emissions result in about 60,000 additional deaths per year worldwide from air-pollution-related illnesses.
Cargo shipping is growing briskly, by about 5 percent a year, according to a 2007 study by the International Council on Clean Transportation. Air pollutants from oceangoing vessels include nitrogen oxide (NOx), sulfur oxides (SOx), and particulate matter, all of which have been linked to various health problems.
Ship emissions of carbon dioxide (CO2), a greenhouse gas that contributes to global warming, make up about 4.5 percent of total global CO2 emissions.
That's more than twice as much as those created by the aviation industry, which has come under heavy public criticism for its emissions, says a report sponsored by some member countries of the International Maritime Organization (IMO).
The report estimates that CO2 emission from oceangoing vessels will increase another 30 percent by 2020 if no action is taken.
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