Energy and Exergy Analysis of a Cruise Ship

TLDR

The shipping sector faces rising fuel costs and tightening environmental regulations, and passenger cruise ships—though a small but growing share—have complex energy systems where propulsion is no longer the sole major energy consumer. The study analyzes energy and exergy flows of a Baltic Sea cruise ship using operational data and mechanistic system knowledge. The analysis quantified energy use—propulsion 41 %, heat 34 %, electricity 25 %—and exergy destruction, with 88 % of exergy lost in combustion processes and 67 % of total exergy losses in exhaust gases from engines without heat recovery. The results provide guidance for targeting system improvements to reduce energy and exergy losses.

Abstract

The shipping sector is today facing numerous challenges. Fuel prices are expected to increase in the medium - long term , and a sharp turn in environmental regulations will require several companies to switch to more expensive distillate fuels. In this context, passenger ships represent a small but increasing share of the industry. The complexity of the energy system of a s hip where the energy required by propulsion is no longer the trivial main contributor to the whole energy use thus makes this kind of ship of particular interest for the analysis of how energy is converted from its original form to its final use on board. To illustrate this, we perform ed an analysis of the energy and exergy flow rates of a cruise ship sailing in the Baltic Sea based on a combination of available measurements from ship operations and of mechanistic knowledge of the system . The energy analys is allows identifying propulsion as the main energy user (41% of the total) followed by heat (34%) and electric power (25%) generation ; the exergy analysis allow ed instead identifying the main inefficiencies of the system: exergy is primarily destroyed in all processes involving combustion (88% of the exergy destruction is generated in the Diesel engines and in the oil - fired boilers) and in the sea water cooler (5.4%) ; the main exergy losses happen instead in the exhaust gas, mostly from the main engines (6 7% of total losses) and particularly from those not equipped with heat recovery devices . The improved understanding which derives from the results of the energy and exergy analysis can be used as a guidance to identify where improvements of the systems sh ould be directed