In the 400 years or so leading up to the adoption of steam power in the 19th century, sailing ships ruled the waves. In an effort to cut increasing fuel costs and reduce emissions, sails are set to once again prove their worth. But unlike the sails proposed by B9 Shipping and the Wind Challenger Project, Japan-based Eco Marine Power (EMP) is developing sails with an even more modern twist. Rather than just harnessing the power of the wind, EMP’s EnergySail can be fitted with solar panels to also harness solar power.

The EnergySail is a rigid take on the sail that sits upon a pole and automatically rotates to take full advantage of the wind and help propel the vessel. At the same time, solar panels embedded in the sail harness energy from the sun to provide electrical power to reduce the amount of fuel used by auxiliary generators. In bad weather or when the ship is at anchor, the sails can be lowered and stored.

However, the solar panels can also be used while the ship is in port, with energy stored in battery modules, providing the potential for totally emissions-free operation while not at sea. EMP says a modified version of the EnergySail could also be used to collect solar energy when lowered in the horizontal position. The company claims the rigid sails have been designed to require little maintenance and to withstand the high winds found at sea.

Building on its previous Aquarius Eco Ship concept – a cargo ship design boasting an array of 14 rigid sails – EMP has recently unveiled a modified version of the system aimed at vessels like naval frigates, which would use four sails, and smaller patrol vessels and coast guard ships that might be fitted with just two. Single EnergySails could also be fitted as standalone units on even smaller vessels, such as cable laying vessel or oceanographic ship, while a variation of the EnergySail targeted at even smaller ships, such as ferries or fishing vessels, is also in development.

EMP estimates that, depending on the number, size, shape and configuration of the EnergySails, a fossil fuel-powered ship’s annual fuel consumption could be cut by up to 20 percent, while vessels powered by an electrical propulsion system could cut fuel consumption by around 40 percent. In addition to the fuel consumption and noxious gas emission benefits, EMP says EnergySails could also allow ships to operate more quietly at lower speeds in bays and harbors in comparison to conventional ships.

Currently testing a control system that will automatically raise, lower and position each EnergySail based on the prevailing weather conditions, EMP is hoping to begin sea trials in 2013.

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