Waste heat recovery in maritime applications
Waste heat recovery systems (WHRS) have the potential to reduce fuel consumption and emissions by converting waste heat from the ship’s main engines into usable electric power for the ship’s electrical demand, reducing the load on the ship’s generators. There are several technical solutions for the utilisation of waste heat, however in this report we will focus on the organic Rankine cycle (ORC) system.
Organic Rankine Cycle systems
An ORC system operates as a Rankine cycle using an organic compound as the working fluid, making it possible to recover waste heat in the lower temperature ranges, in a sustainable manner. Today, ORC technologies are mainly used for the conversion of thermal power from industrial and geothermal sources. Developing ORC technology, cost-efficient production and the availability of environmentally friendly and effective working fluids makes the use of ORC systems a viable option for the maritime market, at a crucial time for the industry regarding their need to minimize environmental impact and find a carbon neutral way forward. Today, there are limited uses for the low-temperature jacket water heat from the main engine. In some cases, it is discharged into the ocean as waste heat. At the same time, diesel generators are used to provide electricity for the main electrical grid on board the vessel. Instead, an ORC-system can be used to convert the low-temperature heat into electricity to be used on board, as illustrated in below.