March 1, 2010
World's Mightiest Solar Boat Unveiled
The PlanetSolar catamaran will circumnavigate the globe in 120 days running on nothing but the sun's energy
By Christopher Mims
Nearly 500 years after Juan SebastiÃƒÂ¡n Elcano completed the first circumnavigation of the globe using nothing but renewable power, Swiss engineer Raphael Domjan and French sailor Gerard D'Abouville are preparing to repeat Elcano's journey in an all-electric boat powered by the energy gathered by 470 square meters of solar panels.
Unveiled for the first time in a ceremony at a shipyard in Kiel, Germany, last week, their vessel is a catamaran made entirely out of the same kind of carbon-fiber composites that make modern airplane wings strong yet light. On its 40,000-kilometer journey, the 30-meter long and 15.2-meter wide boat, known as PlanetSolar, will have to withstand high winds, stormy seas and days without sunshine. On board, the world's largest lithium-ion battery, a 13-tonne monster capable of storing 1,300 kilowatt-hours of energy when fully charged, will allow the boat to slice through the water at an average speed of 13 kilometers per hour for three days straight in complete darkness before its charge is completely exhausted.
The ship can fully recharge its battery in the span of a little more than two days of full sunshine if it's not drawing power at the same time, such as when it's docked in a marina, according to Domjan, a paramedic turned engineer who is the visionary behind PlanetSolar as well as its co-captain. The ship is designed, however, to operate at sea indefinitely, and under normal conditions its 38,000 solar cells average enough power production to muster the 20 kilowatts of power needed to keep the boat cruising along at its average speed. The maximum electrical output of all the cells together on a sunny day is about 100 kilowatts.
Full article here:http://www.scientificamerican.com/article.cfm?id=worlds-mightiest-solar-boat
Thought this was interesting:
"...PlanetSolar's propeller designÃ¢â‚¬â€both propellers sit at the water line, half in the water and half out. This kind of prop, known as a "surface-piercing" propeller, can be much more efficient than traditional propellers, because it prevents the blades of the propeller from interfering with one another as they push through the water, Morehouse says. The blades of a surface-piercing propeller also experience almost no drag during the time spent out of the water."
also this bit about solar cell efficiency:
"PlanetSolar also uses the highest efficiency mass-produced solar cells. Manufactured by SunPower Corp. for installation on the rooftops of homes and commercial buildings, these cells can convert 22 percent of the sun's energy into electricity, says Joern Juergens, director of components at SunPower. After installation on the ship, however, the cells' efficiency is reduced to 19 percent, because they must be covered in layers of plastic and transparent composites in order to make them immune to the corrosive effects of seawater and variable temperatures."
Planet Solar site here:http://www.planetsolar.org/