With the concept of fuel-water emulsion an add-on system emulsifies and mixes fuel with water, resulting in a homogeneous emulsion. This emulsion consists of oil droplets with a water nucleus, which is injected into the engine. A ‘micro-explosion’ divides each fuel oil droplet in numerous smaller fuel oil droplets, as these smaller fuel oil droplets ignite and burn easier than the bigger droplets. This results in the reduction of potential particle matter and soot creation zones, a cooling down of the combustion chamber temperature and a reduction of fuel consumption.

The share of water in diesel fuel usually ranged from 10% to 20%. The water used for the emulsion can be obtained from the conventional water tank in the vessel, but it is preferable to install equipment to obtain desalinated and demineralised water. The effectiveness of FWE is due to the quality of the emulsion, most efficient is an electronic control determining the required share of water. The fuel injection settings should be adjusted, to avoid a reduced power output. Although FWE has already been used in road vehicles and other mobile machinery, there is currently just one supplier (Exomission) installing this technology on inland vessels and there are only a few inland vessels with this system on board.