WP6 System Impact when Using Wind, Wave and Solar Energy

In order to reduce fuel consumption and thereby emissions from fuel, attempts have been made in recent years to use wind as a complementary propulsion force. The wind energy can be used either as a direct propulsion force or by generating electricity. The former is probably the most efficient way to use the wind energy on a ship.

At present there are a number of methods using this alternative that are being explored by different companies and organizations:

Kites.

Sky Sails www.skysails.info has been been quite successful in introducing their kite into the market.

This kite is automatically launched and recovered from the forecastle deck of the ship and can reduce the fuel costs significantly.

Flettner rotors.

The Flettner rotor can produce 5-10 times more power than a conventional sail with the same area. The technique is relatively well known and has been tested in different projects since 1930ies. The energy company ENERCON is at present building one ship with Flettner rotors. The Greenwave charity call the Flettner rotor the Green Wind Engine.

Model wind tunnel tests of the Flettner rotor efficiency will be carried out within WP6.

In both cases there will be a significant unloading of the engine and the propeller in favorable wind conditions if the speed of the ship will be kept the same as without wind. If the wind energy is obtained by e.g. wind turbines this problem will not occur, but instead this system will need an electrical machinery or use the electrical energy for other purposes onboard.

In the present project a study will be carried out investigating the possibilities to use wind energy for the proposed ro-ro ship but also for a coastal tanker. In the study a calculation of possible reduction in ships resistance for different conditions will made. Depending on if the ship is equipped with a fixed pitch propeller or a controllable pitch propeller the total efficiency or the total fuel consumption will vary.

Except for mapping the possible fuel reductions by using wind energy, also an economical evaluation of the system will be carried out taken into account the cost for installation and maintenance of the system and possible effects on the ship (more expensive propellers, effect on crew etc.)If using e.g. Flettner rotors the size and numbers of rotors will influence the installation costs significant, but also the possible gain in decreased resistance. Probably there is an optimum level of reduction in resistance taken into account the interaction with propellers and engine. All the time the ship has to be able to reach its design speed, also when there is no wind or in head winds