الفهرس 
chapter 1Only 14 pages are availabe for public view
 |  | from | 137 |  |  |
| | | from | 137 | | |
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.