WATER-DIESEL EMULSIFIED FUEL (PURINOX)

12.0 WATER-DIESEL EMULSIFIED FUEL (PURINOX) The benefits of adding water to diesel fuel have been known for some time. Water promotes a finer, cloud-like atomization of the fuel mixture during injection and modifies combustion, resulting in substantial reductions in nitrogen oxides and particulates. However, the challenge has been keeping the fuel/water mixture stable in storage and keeping the water away from engine parts. Several companies are now claiming to have tackled this problem of storage stability by various chemical methods.

Lubrizol Corporation has accomplished this goal by using specialized chemistry to completely surround the water droplets with a chemical shell, which prevents the water from separating out of the fuel, and results in a stable fuel blend. Lubrizol Corporation has patented and termed this as PuriNox. This water-diesel emulsified fuel has shown promising results in reducing emissions of NOx by over 30% and particulates by over 50% when used as an automotive fuel.

TOTALFINAELF, an oil company headquartered in France has also developed one water-diesel emulsification called Aquazole. Aquazole also reduces emissions significantly when used as automotive fuel. Both Purinox and Aquazole have been verified by the CARB for emission performance.

12.1 Production:

Lubrizole's Purinox chemistry allows up to 20% water to be added to diesel fuel to improve combustion and reduce emissions. Lubrizol has developed and patented a blending unit for blending the fuel. This unit has demonstrated its ability to repeatedly produce a stable finished fuel. The blending unit includes safety features such as spill containment and explosion proof controls. Advanced automatic metering technology precisely controls the quality of the fuel.

12.1.1 Emissions:

The California Air Research Board (CARB) has verified both Purinox and Aquazol. In January 2001, the CARB declared the verification of Purinox emulsion by Lubrizol and certified this fuel to provide a NOx reduction of 14% and PM reduction of 62.9%. Soon after, Aquazol of Totalfinaelf was also verified by the CARB and recorded to give 16% and 60% reductions in NOx and PM respectively. This CARB verification confirms the emission reduction ability of the fuels but the verification does not address possible impacts of emulsified fuels on engine durability or performance.

12.2 Advantage of water-diesel emulsion:

Some of the advantages of this emulsified fuel are:

- This is a simple process.
- Very good emission reduction potential, especially NOx and PM.
- Storage (when stable) & distribution is akin to that of conventional fuels.
- The fuel may be used for heavy-duty CI engines also.
- Reduces emissions in old engines also.
- Ample scope of cost reduction in future.

12.3 Disadvantages of water-diesel emulsions:

The following are some of the drawbacks of the fuel:

- Since water carries no energy value, there is a loss of power.
- Long-term storage stability of the fuel is still a concern.
- Engine durability and performance data with the fuel is not adequate.
- Possibility of adulteration cannot be ruled out.

12.4 Operation & Performance:

Currently over 6000 vehicles worldwide run on water-diesel emulsion. Italy has the maximum share of 4000 vehicles. London and Nottingham also has a sizable population of the centralized bus currently running on this fuel. This fuel is found to give reduced power at peak power. More data on engine durability and performance is still required.

12.5 Indian Initiative on water-diesel emulsified fuels:

The issue of water-diesel emulsified fuel was discussed in the Expert Committee of the Auto Oil Policy. Society of Indian Automobile Manufacturers (SIAM) has expressed its reservations on the effect of diesel-water emulsion on the fuel injection pump durability and they also apprehended that the additives used may cause aldehyde emissions.