Thermal energy storage system with silica gel/water for trigeneration application onboard large ships

The maritime industry faces increasing pressure to reduce its carbon footprint and adhere to increasingly stringent environmental regulations established in recent years. Specifically, the International Maritime Organization has mandated an urgent need to reduce greenhouse gas emissions from maritime shipping, setting the goal of zero emissions by 2050. Therefore, these concerns are prompting shipbuilders and shipowners to explore innovative technologies aimed at mitigating the environmental impact of ships across all operation conditions. Ships are energy-intensive transportation systems characterized by the availability of waste heat at different temperature levels. This feature arises from several factors, including the mismatch between waste heat generated by engines and the onboard heat demand. During port conditions, when engines are switched off, there is no recoverable waste heat available to meet heat demands. Therefore, to cover heat demand in port, the only solution is switching on oil fuel boilers and releasing greenhouse gasses into the atmosphere, with a notable reduction in overall energy efficiency. Conversely, when engines are running in navigation conditions, recoverable waste heat is often abundant and capable of not only covering heat demand but also being stored. In this paper, a novel thermal energy storage system employing a silica gel/water pair is presented. The thermal energy storage system is modelled in the MatLab environment using a resistive-capacitive thermal network, resulting in the development of a lumped parameter model. To validate the accuracy and reliability of the developed code, it is experimentally validated by comparing simulated results with data obtained from scientific literature. Furthermore, to assess the energy performance and implications of adopting thermal energy storage on ships, the developed code is embedded into a ship energy performance simulation tool. Here all the energy interactions between the thermal energy storage system and the other systems available onboard are taken into account. To show the potential of the considered technology, as well as the developed dynamic simulation tool, a suitable case study referred to a roll-on/roll-off passenger ship is presented. Significant findings reveal potential fuel savings during port operations and throughout operational hours, leading to a consequential reduction in greenhouse gas emissions. Consequently, this technology appears to be a promising strategy for integration into existing onboard technologies aimed at emission reduction. This approach enables shipowners and shipbuilders to progress toward the stringent IMO goal set for 2050.