POWER FROM THE WIND

A power-driven ship generates a lot of breeze as it steams along, even when the air is still and the seas of mirror-like calmness. Common sense tells us that in such conditions of still air, a breeze which is roughly the same velocity as the ship's speed will flow around the vessel. Only when there is a following wind at a speed identical to that of the ship will there be no air movement over and around the ship.
So it is tempting to harness some of this wind with wind turbines and to use it to reduce the electrical power that the ship needs to generate. It would be what might be described as a "win-win" situation, with fuel saved and emissions reduced, were it to be practical. Indeed, a number of Japanese operators have experimented by positioning wind turbines and other devices around the upper decks of car carriers.
But where aboard a ship might it be best to position such devices? Eddies and gusts of wind are often encountered on the upperworks of ships on passage, sometimes blowing in a somewhat inexplicable fashion. Put them in the wrong place and they might be less than effective, or even risk damage, as such devices are not always robust. Lighthouse authorities, which have used such power sources extensively in recent years, have often noted that high winds will have carried away or damaged their turbines. Yachtsmen, who have used them to produce power on passage, have often reported similar damage. So where is the best place to position them?
An interesting research project designed to answer this very question has been completed by a consortium involving Lloyd's Register, Zodiac Marine Agencies and Totempower Energy Systems. Designed to assess the potential for wind-generation aboard commercial ships, the project was centred on the Zodiac bulk carrier Cape Flamingo, aboard which a fully autonomous wind-monitoring system was installed.
Wind sensors were installed around the ship, positioned where it was anticipated the best results would be found, and wind speed, direction and any turbulence were all measured throughout the passage. Optimum locations for situating wind turbines were found and the potential generating capacity for the vessel's trading patterns has also been measured. An unobstructed air flow and a properly designed turbine are the crucial issues.
The project has demonstrated the feasibility of such a means of electricity generation and it has been suggested that such devices, optimally positioned, may be able to contribute to the vessel's power requirements. There is no sense that wind would be able to replace the more conventional equipment entirely, but the project produced a great deal of useful data on the likely economic and environmental benefits.
The project, said the shipping company's environmental superintendent Kalliopi Xypolita, was undertaken over a seven-month period, and the company has a better understanding of the feasibility of using wind turbines and the practical experience of where they may be best sited.
Source: BIMCO