Technical Meeting Report on: Dr. George Gougoulidis, Lieutenant Commander of the Hellenic Navy and Naval Architect, speech on the subject of: Energy – Savings Basics for the Maritime Industry – Renewable Energy, presented on 19 March, 2015.
By Petros Lalangas
On March 19 the Greek Section held its seventh technical meeting for the 2014-2015 season, during which Dr. George Gougoulidis, Lieutenant Commander of the Hellenic Navy and Naval Architect, presented the above topic in the presence of about 25 members and visitors.
From the five basic forms of renewable energy - wind, solar, water, geothermal, and biomass -, only wind and solar power were presented since they are the more pertinent to marine applications.
The author presented the following main points.
Starting with the wind energy, which is the oldest type of propulsion force, there are four basic ways to exploit this available energy: sails, kites, Flettner rotors and wind turbines. Although the working principles of the sails have not changed since ancient times, the materials used, as well as some new types have made their use an attractive option.
In the traditional flexible type of sails the most modern design is the Dynaring, which is used on the largest sailing vessel, the Maltese Falcon. Although there are a few designs using sails for main or auxiliary propulsion for commercial ships, their use is only limited to sailing yachts. There are also rigid sails, or better called foils, which have a higher lift to drag ratio compared to conventional sails. A series of 17 rigid sail- assisted tankers were built back in the ‘80s.
Towing kites are a newer method, with the most popular system being the Skysails, which has already been applied to five ships. The advantages of the system are the fact that it operates at high altitudes where the wind is stronger, that it does not interfere with cargo handling and that the heeling produced is smaller than that produced by the sails.
Flettner rotors are rotating cylinders generating thrust based on the Magnus effect. The system first appeared in 1926, and was used again on Cousteau’s Alcyone, before its most recent large-scale application on the cargo ship Enercon E-ship 1.
The final option is the use of wind turbines. Their great advantage is that the ship can sail against the wind. However, there are stability, as well as vibration issues, limiting their use only to a few prototypes like the catamaran Revelation II.
The use of solar energy is more straightforward and the basic method for harvesting it, is the use of photovoltaic cells. The principles are exactly the same as in land applications, where there is a lot of experience in their use. In marine applications however, there are limitations related to the energy storage, to space and weight requirements, and to the type of the ship among others. They are more suitable for large ships, where there is enough space for the installation of the panels, and the batteries do not add a significant weight on the vessel. Such an example is the car carrier ships Emerald Ace and Auriga Leader. Current solar cells’ efficiency is around 13%.
All these renewable energy sources, although attractive from an environmental standpoint, they are still at an early stage of development with a limited number of applications. They mostly comprise of bulky and heavy equipment and they have a high initial capital cost. However, the performance of these systems is high and an increasing trend in their use starts to appear.
The meeting was ended by a number of questions & answers and was followed by a reception in an adjacent hall in the hospitable facilities of Maran & Alpha Tankers in Athens.
The whole PP presentation and photos with actual ship applications and other information can be found in the link given below.
From left to right: N. Dionisopoulos & P. Dimitriadis, both subst. EC members; Nikolaos Christou, Member; Agapi Gerogiannaki , Treasurer / Treasurer; Author; P. Lalangas, Membership Chair.
The presentation can be found here: Presentation, Dr. Gougoulidis, 19 Mar. 2015.pdf