Here's another alternative energy scheme that would be deployed in the middle of the ocean. While most of us landlubbers think of global warming as a problem caused by coal power plants and automobile exhaust, cargo ships plying the seas spew about 2.7 percent of the world's manmade greenhouse-gas emissions, according to the International Maritime Organization. That works out to about 870 million tons of climate-altering pollution [source: IMO].
Any technology that could help ships to reach their destinations without burning as much fuel would be a big plus. That's why in recent years some visionaries have been trying to revive wind power, a method of ship propulsion that saw its heyday in the mid-1800s, as a way to augment large cargo ships' carbon-burning engines. In the mid-2000s, one company proposed outfitting freighters with gigantic, 13,000-square-foot (1,207-square-meter) kites, which would fly a thousand or so feet (300 meters) above the ship and help pull it along [source: McSweeney]. By one estimate, such a device could reduce a ship's consumption of diesel fuel by as much as 25 percent, which not only would significantly reduce its carbon output into the atmosphere, but possibly save in excess of $1 million in fuel costs for the biggest ships annually [source: McSweeney].
In 2008, 10,000-ton container ship MS Beluga Skysails became the first to use auxiliary kite power, attaching a 160-square-meter (1,722-square-foot) kite 300 meters (984.2 feet) above its bow on a voyage from a German port to Venezuela. The ship managed to cut its diesel fuel expenditures by 10 to 15 percent, and saved between $1,000 and $1,500 per day in the course of the two-week trip. The Beluga Group, the ship's parent company, hopes to eventually use kites to slash its fuel bills by 20 percent [source: Huck].