A brief technical review of emerging waste heat recovery solutions for marine diesel engines

Diesel engines remain the most widely used option to power a wide variety of transport ships. In terms of the maximum installed volume of all shipping vessels, 96% of this energy is generated from diesel engines. Due to the lack of alternative propulsion systems with the same energy density, cost, and fuel efficiency as diesel engines, it is not expected that marine diesel engines will be replaced within an expected 100 years. Modern large diesel engines are about 50% efficient in using the burning thermal energy of the fuel and the rest is lost to the environment as waste heat. The efficient use of waste heat energy can enhance the power system efficiency and reduce emissions, by using a dedicated waste heat recovery system for power generation or heating needs. Technologies that recover waste heat from engines have been around for 30 years, but recovery efficiency, cost of installation, and the ability to take up space in engine room space have caused certain obstacles. This paper conducts a brief review of the techniques and prospects of emerging waste heat recovery technologies from marine diesel engines. The results achieved would be useful suggestions for ship managers and owners in equipping marine fleets with waste heat recovery systems to meet the increasingly stringent IMO requirements for energy efficiency and environmental protection.