Fuel Water Emulsion technology (FWE)

That adding water to the fuel dramatically sinks both soot emissions and nitrogen oxide emissions from diesel engines has been scientifically proven and recognised for some time. As far as soot reduction is concerned, the best way to add water is to form an emulsion of fuel and water. With our patented Fuel Water Emulsion technology (FWE), we are practically helping diesel engines to stop smoking!

Soot reductions of up to 90%, NOx reductions of up to 45% with simultaneous neutral consumption or even slightly lower consumption are possible. Pollutants that are not produced during combustion do not have to undergo costly elimination in exhaust gas aftertreatment.

The Water Fuel Emulsion is the most efficient technology that enables soot and nitrogen oxide emissions to be reduced at the same time. Another unique selling point is the consumption neutrality: regardless of whether the focus is soot reduction (up to 90%) or nitrogen oxide reduction (up to 45%), fuel consumption is not increased – and can often even be reduced by a few percent (approx. 1% to 5%, significantly more in some operation points).

With FWE, Exomission has a primary technology for the reduction of exhaust gas, which can be implemented and retrofitted on all diesel engines, regardless of whether they are prechamber/swirl chamber engines or unit injector/common rail direct injection engines. The emulsion is produced immediately before the injection pump; no intervention in the engine or the direct injection system is required.


Emulsifiable fuels

Our “on-board emulsion” works for all liquid fuels that are used in combustion engines in accordance with the diesel engine principle, such as

  •      diesel fuel
  •      heating oil
  •      vegetable oil
  •      heavy fuel oil



An emulsion is a finely dispersed mixture of two liquids that cannot normally be mixed without visible separation.

It is also not possible to mix water and diesel, only to emulsify them for a limited time. The “art” here is to create a homogenous emulsion that is as finely dispersed as possible in which every drop of water is completely surrounded by fuel.

In the Exomission emulsification process, water and diesel are fed into a patented emulsion unit almost at the speed of sound. Water and fuel are finely swirled and mixed, creating a homogeneous emulsion. Every drop of fuel now has a core of water. This emulsion is fed into the combustion chamber using the injection system.


Modes of action

Science assumes that the following takes place in the combustion chamber (presented in a simplified manner).

When heat is suddenly added to the combustion chamber, the water core expands as in an explosion. The surrounding diesel drop is torn into countless parts, i.e. even smaller drops, an even finer spray is created in the combustion chamber (the scientific term for this is "microexplosions"). Mixture formation and combustion are more homogeneous, grease and therefore soot formation areas are significantly reduced, the effectiveness of the engine increases slightly, soot emissions sink dramatically.


Reducing peak combustion temperatures

Heat is removed from the combustion chamber in the water evaporation process (evaporation enthalpy). This also results in a sinking of the peak temperatures in the combustion chamber. As the formation of nitrogen oxides increases exponentially with the combustion temperature, NOx formation decreases accordingly at a lower peak combustion temperature.



Water dissociates in the combustion chamber from about 2,000 degrees Kelvin, i.e. the H2O molecule is separated, hydrogen and water are released. Hydrogen takes part in combustion as a combustible gas, the elemental oxygen atom (as what is known as a radical) “tries” to find reaction partners in the combustion chamber. It finds these in the form of non-combusted or partially combusted fuel components, the carbons, i.e. soot particles and hydrocarbons. This again improves the combustion, soot emission is additionally lowered and the scientifically proven reduction of polycyclic aromatic hydrocarbons also takes place accordingly.

The more homogeneous combustion process leads to a noticeable improvement in the smooth operation of the engine.

The patented emulsion procedure distinguishes itself through the following function characteristics:

  •     Highly efficient “on-board” emulsification of water and diesel fuel immediately before the injection pump
  •     Consumption-dependant dosing: the water content in the diesel fuel is varied using an electronic control (0% - 25%) depending on the engine load.
  •     Separate water and diesel fuel circuits, i.e. there is no mixing of the two media in their tanks.
  •     There are no rotating or moving parts involved in producing the emulsion. It is almost free of wear and maintenance.
  •     The technology can be retrofitted for all diesel engines: prechamber and swirl chamber engines, direct injection engines (unit injector, common rail).
  •     No modifications to the engine or the injection system are required.


Areas of application

The possible areas of use of emulsion technology are highly diverse:


  •     inland waterway vessels
  •     combined heat and power units (CHP)
  •     diesel generators
  •     diesel railway vehicles
  •     large land-based mobile machines
  •     seagoing vessels


Thanks to the small space requirement and weight, emulsion technology can also be retrofitted in unfavourable conditions, such as on diesel locomotives whose axle/wheel loads have long been critical. It is also possible in inland waterway vessels, where the installation of exhaust gas aftertreatment systems is often very complex and therefore expensive due to limited space.




Exomission FWE technology is available in two versions:

Cost-efficient static system (CHP engines and diesel generators that are driven at a constant load point)

Dynamic implementation (CHP engines that are driven according to the electrical or heat requirement, boat and railway engines, construction machinery)


FWE technology can be combined with SCR and DFP systems to generate and exploit operating cost benefits. More about the combination options can be found in the individual application areas.


Water treatment

An important prerequisite for the faultless functioning of the emulsion technology is the treatment of the water that is used. The water that is used must be completely desalinated and as free from minerals as possible in order to prevent a negative effect on the injection system.


Exomission usually uses cartridge desalination devices or reverse osmosis systems whose maintenance is matched to suit the required maintenance intervals of the engine and which are characterised by their small space requirement.

In cooperation with a renowned specialist company, Exomission offers solutions that are optimally customised to the technical requirement in question.


Further advantages of FWE            

For vegetable oil CHP, Exomission emulsion technology prevents carbonisation on the injection valves and the piston rings, which would risk the engine’s service life. As a result, the significantly increased fuel incursions in the lubricant oil circuit, which are sometimes the case during operation with vegetable oil, no longer take place, meaning that the oil replacement intervals can be reduced towards the normal amount.

As shown over many years under operating conditions, Fuel Water Emulsion can improve mixture formation, which is usually perceivable in consumption reduction. Another advantage is the improved viscosity of the biofuel as a result of the emulsification process.

The following also applies to CHP operation with diesel or heating oil. Due to the soot particle reduction of up to 90%, the cleaning intervals for the exhaust gas heat exchanger can be extended significantly. Heat yield increases despite the lowering of the exhaust gas temperature, which is associated with lower NOx emissions (Ø 35%) and lengthens the engine service life.

For diesel generators, which are often operated with heavy fuel oil, treated waste oils or a mix of diesel and recycled oils, the soot-reducing effect of emulsion technology is already very visible through the prevention of the black smoke, which is dangerous both to health and the environment. The unpleasant smells, which are extensive in some cases, are also a thing of the past.

Since these systems usually have an electric output of over 1,000 kW (and much higher) and therefore fall under Germany’s TA-Luft, emulsion technology is a highly efficient way of complying with the limit values required here for soot emissions.


Endurance runs/references

Emulsion technology has proven itself over a period of over 10 years, sometimes under very challenging technical conditions:

Endurance runs in various diesel passenger cars (common rail and unit injector), including a BMW 530d that has covered a total of 260,000 km since 1999

CHP endurance run since 2000 with over 75,000 operating hours


Test stand run at an OEM


Prüfstandslauf bei einem OEM

Im Rahmen eines Prüfstandsversuchs bei einem OEM-Partner von Exomission wurden u.a. die E3- und C1-Testzyklen gefahren. Die Ergebnisse bestätigen die hohe Effizienz der Kraftstoff-Wasser-Emulsion, insbesondere bei der Rußreduktion.


Scientific investigations

Quotation from a research paper by Prof. Simon, Trier University of Applied Sciences, 2007:

“To summarise, it can be determined that using a load-dependant controlled diesel/water emulsion not only allows the less problematic pollutant components CO and CH to be reduced significantly, but also that the soot-NOx trade-off, which is highly problematic for diesel engines, can be noticeably weakened. Soot reductions of up to 70% with simultaneous NOx reduction of up to 45% and reduced fuel consumption of approximately 3.5% reveal the diesel/water emulsion to be an exceptionally suitable measure for reducing pollutants in diesel engines."


Quotation from a Trier University of Applied Science research paper, 2008:

“In combination with an exhaust gas aftertreatment system (soot filter, SCR cat.), the use of a diesel/water emulsion would have a positive effect on fuel consumption due to its raw emission reducing effect, which in turn would lead to extended regeneration intervals of the soot filter or to a reduction in the urea required for SCR catalysts, meaning that in this case it would even be possible to speak of a fuel-reducing measure.”



The positive effects of adding water to the combustion process have been known for a long time and can be traced back to the year 1931

(Joseph Vance, “Liquid fuel of hydrocarbon and 40 to 60% water”).

While separate water injection was used in aircraft and Formula 1 to improve performance, water-fuel emulsions are now used to reduce emissions. The focus here was always reducing the NOx for diesel engines, accompanied by a reduction in the combustion temperature.

As current studies prove, emulsion is, however, in a position to lower the production of soot particles significantly while at the same time reducing the nitrogen oxide and often the CO2 emissions and the fuel consumption by optimising the combustion process.

This makes Water Fuel Emulsion the only technology available to-date that reduces two of the main pollutants in diesel engine consumption, PM and NOx, at the same time while being consumption-neutral or even reducing consumption.



The positive effect of adding water to the combustion process in diesel engines has been known for a long time

  •     Emulsion is the most effective technology to simultaneously reduce soot and NOx
  •     Patented Exomission system with many years of experience in the field
  •     University investigations show soot reduction of up to 90% and NOx reductions of up to 45%
  •     Emulsion is neutral as far as CO2 and consumption are concerned, sometimes even reducing these factors – climate protection
  •     Simple system structure, rapid and simple installation
  •     Cost-effective, saves installation space and is virtually maintenance-free
  •     Significant overall cost benefits in combination with DPF and/or SCR
  •     Can be used universally for liquid fuels/sulphur-tolerant (also suitable for heavy fuel oils)
  •     Emulsion dissolves scaling in the combustion chamber/the injection nozzles/valves
  •     Emulsion lowers the peak combustion temperatures and the exhaust gas temperatures


Would you like to find out more about the Exomission FWE technology and the combination options? Read more in the areas of application


  •     Stationary engines
  •     Inland waterway vessels
  •     Seagoing vessels




We look forward to hearing from you.



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