5.1. Generating units with auxiliary engines for power generation
Onboard power generating unit (GU) usually consists of a diesel engine and generator or alternator (AC generator). There is the main engine that ensures ship propulsion, and auxiliary engines in combination with generators, that provide power for the power consumers on board. In some installations, the drive for the generator could be the main engine and the rotation is transferred from the main shaft. Such a generator is called a shaft generator.
So, electrical power on board is still based on fossil fuel. Nowadays, dual fuel engines can also be used for this purpose. They are designed to run on two different types of fuel simultaneously, typically a combination of natural gas and diesel, although other fuel combinations are possible as well. Despite this fact, a common marking of GU in the schemes of the Engine Room is DG – diesel generator.
The advantage of using dual fuel comes from the fact that natural gas, when burned, produces fewer emissions (such as nitrogen and particulate matter) than diesel. This results in reduced environmental impact and compliance with stricter emissions regulations. Additionally, the use of natural gas can be cost-effective.
