In a significant stride towards sustainable maritime operations, researchers have developed a novel desalination system that harnesses waste heat from ship engines, offering a promising alternative to conventional, energy-intensive methods. The study, led by MD. Shajratul Alam Towhid from the Bangladesh University of Engineering and Technology, Department of Naval Architecture and Marine Engineering, was recently published in the Journal of Eta Maritime Science, which translates to the Journal of Excellent Maritime Science.
Maritime vessels generate a substantial amount of waste heat, with around 51% of fuel energy dissipated during operation. Of this, exhaust heat accounts for the largest portion, approximately 26%. This waste heat, previously overlooked, presents a substantial opportunity to address the critical challenge of freshwater supply onboard ships, particularly for long voyages.
Conventional desalination systems like Reverse Osmosis (RO) and various forms of distillation are notorious for their high energy consumption, large space requirements, and environmental impact due to high brine discharge. The novel system developed by Towhid and his team directly utilizes the exhaust heat from the ship engine, featuring a prototype floating-head shell-and-tube heat exchanger for evaporation and the ship’s natural motion-driven seawater circulation for condensation.
The experimental investigation, conducted using the exhaust of a 1 MW Caterpillar engine, demonstrated impressive results. The system achieved a maximum freshwater production of 1.1815 tons per day, a 97% reduction in brine discharge, and a CO2 emission reduction of approximately 0.0886 tons per year per ship. Additionally, it increased cargo capacity by about 396 tons per year compared to RO-based systems.
Towhid explained, “This study meets the gaps by presenting a simple novel desalination system that directly utilizes the exhaust heat from the ship engine.” He further highlighted that the results indicate a sustainable waste-heat-driven desalination system in maritime applications that economically and environmentally reduces extra fuel and RO replacement costs.
The commercial implications of this research are substantial. Shipping companies could significantly cut operational costs by reducing fuel consumption and increasing cargo capacity. Moreover, the environmental benefits are equally compelling, with reduced CO2 emissions and brine discharge contributing to a lower environmental footprint.
The study also underscores the importance of real-world experiments in understanding the actual desalination feasibility onboard ships. This practical approach ensures that the system is not only theoretically sound but also viable in real-world maritime conditions.
As the maritime industry continues to grapple with the dual challenges of sustainability and efficiency, innovations like this desalination system offer a beacon of hope. By leveraging waste heat, ships can become more environmentally friendly and economically viable, paving the way for a more sustainable future in maritime operations.
Towhid’s research, published in the Journal of Eta Maritime Science, represents a significant step forward in the quest for sustainable maritime technologies. The findings highlight the potential of waste heat recovery in addressing the freshwater needs of ships, offering a practical and environmentally friendly solution to a longstanding challenge.