Waste heat recovery (WHR)

A waste heat recovery system captures energy from a main engine’s exhaust gas, jacket water, and scavenge air that would otherwise be lost, typically driving a power turbine and an exhaust-gas boiler feeding a steam turbo-generator. On large two-stroke installations it can recover 5 to 10 percent of fuel energy as electrical power, cutting auxiliary fuel and total CO2 and improving the EEDI and CII. Organic Rankine cycle units extend recovery to lower-grade heat. The gain is largest at high, steady engine load, so it suits long deep-sea legs.