With fuel-water emulsion (FWE), the fuel is mixed with water on board the ship. This measure, along with HAM technology, is one of the “wet methods” for reducing nitric oxide levels in exhaust gas. The evaporation of the water in direct proximity to the injected fuel causes local cooling of the combustion in the cylinder. The lower temperatures in turn lead to less NOx build-up.
 
Extensive testing has shown that each percentage of water that is mixed with the fuel reduces NOx emissions by the same percentage. As a result, a reduction rate of up to 30 per cent can be achieved with our engines. Unlike with HAM technology, only fresh water is used with FWE, since the emulsion must be free from salts. The methods developed by our engineers rely on a continuous supply of fuel-water emulsion that is electronically controlled and can be generated while the engine is operating. This method from MAN Diesel & Turbo is already being used successfully on numerous cruise liners and commercial ships.
 
The NOx emissions reduced by FWE can be achieved with relatively manageable investments, and even the on-board footprint is workable. The FWE-Technology is also known as "water in fuel" (WFI) in the two-stroke section.