Project no. 429
Zero-Emission Power Production for Passenger
Vessels in Harbor
DTU Mechanical Engineering, Technical University of Denmark
High-capacity passenger vessels are characterized by significant electricity demands. When
sailing, electricity can be supplied either by propulsion engines or auxiliary generators using
fossil fuels, or by waste heat recovery (WHR) systems such as organic Rankine cycle
(ORC), using the exhaust gases. During harbor stays, the main engines are shut down and
thus WHR units cannot be operated. Therefore, auxiliary generators commonly produce the
required electricity, which results in additional fuel consumption and emissions of pollutants
in coastal areas. A conventional solution for zero-emission power production in harbor is the
use of batteries, charged by the shaft generators during sailing. However, batteries are
expensive and have a limited lifetime. This master thesis investigates the possibility of
installing a thermal energy storage (TES) on board passenger vessels, to make it possible to
operate the WHR systems also during harbor stays. Figure 1 shows the proposed concept.
During sailing, the exhaust gases supply the ORC, thus producing electricity, and charge the
TES as well. In harbor, the TES releases heat towards the WHR units to produce electricity.
Figure 1: Overview of the system during sailing (left) and harbor stay (right)
The project analyzes a case study on two different ship routes from the company Fjordline,
each requiring 1.0 MW of electrical power, both during sailing and harbor stays.
Based on previous studies, sensible heat storages using thermal oils are the most promising
solution. The hot and cold oil can be stored in either one stratified, or two separate tanks. A
simulation framework developed in Matlab allows comparing the performance and economic
viability of the various options (storage configuration, thermal oil and organic fluid).
The two-tanks option is the most promising configuration, due to its simplicity and reliability.
On the studied routes, the TES-ORC system can supply the required power during the
whole harbor stays with 50 tons of oil (2 tanks of 60 m3). In addition, the ORC allows drastic
reductions of the fossil fuel consumption during sailing. Comparing to the solution using
batteries, such a system is paid back in 5 years of operation, for a ship’s lifetime of 25 years.