You can think of PlanetSolar as a ship, or a mobile power plant.

The catamaran, scheduled for an around-the-world voyage in 2010, is the latest experiment to demonstrate how the shipping industry can reduce its dependence on diesel. Instead of running on fossil fuels or wind, the ship will collect its power from a large solar array. The power will then be used to charge a large lithium-ion battery pack that will drive the ship's engines.

The group, also called PlanetSolar, hopes to track the equator around the globe in 120 days, moving at an average speed of around ten knots.

Technically speaking, sailboats also run on solar power. (Wind is indirect solar energy.) PlanetSolar, however, will be more like an industrial ship than the sporting craft you see down at the harbor. The completed ship will measure 31 meters long and 15 meters wide and 35 meters wide and 23 meters long with its solar flaps fully unfurled. It will weigh 60 tons and later versions will tip in at 85 tons. The batteries will also mean that it can power ahead in a wider variety of weather conditions.

The 470 square meter array of solar panels on the ship will be the world's largest mobile solar array, according to the group, and the lithium-ion pack will be one of the world's biggest moving lithium packs. The solar modules will be 22 percent efficient. (Hmmm... SunPower maybe?) In all, the ship will hold 200 passengers. PlanetSolar president Raphael Domjan will skipper the boat and he will be taking guests.

Knierim Yachtbau in Kiel, Germany is building the boat. Construction began last December. PlanetSolar will go from digital prototypes to a final product, with no sizeable intermediate physical prototypes in between, said Jeff Wymer, industry solutions manager for Autodesk, which is supplying design software to the organization and sponsoring the effort. For the past few years, software company has tried to highlight the connection between sustainability and product design. In a poll conducted by the company and the American Society of Mechanical Engineers in February, seven out of ten engineers said they were currently working on at least one project to reduce energy consumption.

Despite the presence of the battery pack, Domjan will have to chase the sun the keep the power going as well as avoid rogue waves, hurricanes, storms and other disasters at sea as much as possible.

Shipping remains one of the dirtier industries on the planet. A U.N. study last year estimated that 4.5 percent of greenhouse gases can be attributed to shipping, or over a billion tons of carbon dioxide. That came to more than double aviation.

Chalk it up to a combination of factors: globalization and distributed manufacturing that creates demand for shipping, less-than-stringent regulations, diesel engines not optimized for emissions reductions, and larger ships. The MSC Daniela, a state-of-the-art ship, holds 13,800 containers, twenty times larger than ships in the 1960s.

Various technologies have been studied to reduce fossil fuel consumption.

The easiest solution is biodiesel, which can be consumed by existing ships. Royal Caribbean had at one point agreed to mix biodiesel from Imperium Renewables into its fuel, but Imperium's implosion caused the contract to be terminated.  Some organizations have held scientific challenges to show the feasibility of biodiesel in ships.

Solar Sailor in Australia, meanwhile, has for several years promoted a solar-powered sailboat for local commuter service. The solar panels can be put on the roof of the ship, or on a large sail-like structure. The company has a boat in operation in Australia, but right now there are still more press releases than ships from the company.

Last year, the MV Beluga SkySails, a cargo ship rigged up with a billowing 160-meter sail from SkySails, used approximately 20 percent less fuel than it would have without the sail during a two-month voyage. Put another way, that's 2.5 tons of fuel, or $1,000 a day, in operating costs. Beluga Shipping ultimately hopes to save $2,000 a day with the technology.

More futuristic concepts include the Bubbling Ship devised by Yoshiaki Kodama, director of the Advanced Maritime Transport Technology Department at Japan's National Maritime Research Institute in Tokyo. The ship would blow bubbles from slits near the bow of the ship. The bubbles would travel along the hull, reduce friction, and hence increase gas mileage. It is currently not feasible. 

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