الفهرس | Only 14 pages are availabe for public view |
Abstract The maritime industry is facing ever increasing pressure to reduce its environmental impact beside the increase in the energy cost so; we will study the conventional propulsion systems and the impact of using electric propulsion. The vast majority of today’s ships are diesel-mechanical; that is, the diesel engine mechanically powers the propellers through reduction gears. Because these propulsion system, and other onboard system, such as cargo-handling, must have their own power sources, most ships have many independent power sources. The disadvantages are evident: noise and environmental pollution, relatively high maintenance cost, high installed power, and inefficient use of space (because generators must be located close to energy system). Instead of several independent power sources, the all electric ship has one integral energy system. The latest developments in power electrics enhance the conversion of power to suit the needs of the various power consumers on board. Electric propulsion systems are also an interesting alternative to conventional configurations for marine vessels. Nowadays much more importance is attached to cost effectiveness than was formerly the case. The same applies to environmental compatibility. The common generation network for propulsion and onboard services with high power ratings permits the integration of high power loads without any problem. Moreover, the flexibility available in the setting up of power generators greatly reduces the hazard length of the units. Mounting of the generating units on anti-vibration foundations reduces noise problems. At present the AES may in some cases, be more expensive than conventional diesel-mechanical vessels. However this price differentiation will soon be eradicated by rapid technical innovations, especially in power electronics, and the continuing optimization of design to harvest potential benefits. In fact, the future development of fuel cells and other emerging technologies will eventually make the AES (much) cheaper than a conventional ship. Electric drive is today an inherent part of ship development and it is one of the cornerstones on the way towards more efficient ship concepts today. Thus ship evolution is really a chance for electric propulsion and the suppliers must consider it as such when developing their own products towards better reliability, simplicity and lower cost. |