Next generation cargo ship with 50m high sails uses 30% less fuel
The aim of the Wind Challenger Project is to substantially reduce fuel consumption by large merchant vessels. Under development by a group including members from the University of Tokyo, the idea is to utilize giant retractable sails, 20m wide by 50m high, to make maximal use of wind energy. The group has done simulations for shipping routes such as Yokohama-Seattle. The results indicate that hybrid ships with sails and engines could reduce annual fuel consumption by about 30% on average.
"Using today's technology, it's possible to make big sails, and to control them automatically. Also, navigation technology includes networked maritime information and weather forecasting, so ships like this can travel safely. Using wind energy, as in old-fashioned sailing ships, is actually feasible."
The angle of each sail is controlled individually, to obtain the maximum propulsive force. Also, each telescoping sail consists of five parts, so the sail can be contracted when the ship is at anchor or during rough weather conditions.
"The sails have a curved surface, and they need to be hollow, so they can expand and contract. So they don't use canvas, like conventional sails. Instead, they use aluminum and Fibre-reinforced plastic, which makes them rigid. In other words, with this concept, a ship has wings, like an aircraft."
Computer simulations and wind-tunnel tests using scale models show that this method is especially effective at saving energy if there's a crosswind. In other words, rather than taking the shortest route, this method makes it possible to travel faster and consume less fuel, by choosing an optimal route that takes account of wind strength and direction and the weather.
"These sails cost about US$2.5 million each, but they can reduce fuel consumption by over 25%. In that case, the cost of these sails can be recovered in 5-10 years. We've finished our basic research, so over the next two years, we'd like to build a half-size prototype, to check that this structure is practical. Ultimately, we're aiming for a sea voyage from 2016 onward."
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