Load Cycle Assessment for Maritime Batteries

Abstract

Increasing emissions have led to the search for alternate power systems to provide energy for maritime applications. The recent drop in battery prices (over 200 % in the last ten years) has made battery energy storage one of the practical alternatives for fossil fuels to curb emissions and reduce the carbon footprint of the maritime sector. The main criterion for choosing a ship’s battery system is its operational profile. Therefore, this study estimated and studied the operational profiles of three use cases - Superyacht, Bulk Carrier and Ferry. The information about the power requirements for ship activities was obtained from the operational profile. Based on that information, different strategies were presented to implement battery energy storage for each use case. A rule-based controller was developed to simulate the power split between the IC engines and battery packs for hybrid systems. Battery packs were sized according to the batteries’ energy consumption, which was found using the design criteria for each use case. A State of Charge (SOC) estimation model based on Coulomb Counting was developed to study the load cycles of the batteries. The SOC profiles were estimated for the proposed battery-powered systems and then characterised for each use case. Finally, a comparison between the conventional power system and the proposed battery power systems was made based on fuel consumption and greenhouse gas (GHG) emissions.