ALCOHOL- DIESEL BLENDS (DIESOHOL)

3.0 ALCOHOL- DIESEL BLENDS (DIESOHOL)

Apart from ethanol/methanol-gasoline blends, ethanol/methanol-diesel blend is also another alternative option. Ethanol-diesel blend projects are under trial in Brazil and Sweden. Unlike ethanol-gasoline blend, ethanol-diesel blend has some concerns regarding lubricity, reduced flash point and startability problems.

3.1 International Experience:

Several technologies are currently under trials in different parts of the world. An Australian non-profit organization APACE has developed a ethanol-diesel emulsion agent which is under trial in Australia. Thailand, Chile, Malawi, Germany and Sweden. This diesohol technology claims successful blends up to 15% of ethanol in diesel. APACE claims that this emulsion, which allows use of hydrated ethanol with diesel, gives improvements in NOx, PM including PM2.5, hydrocarbons and also increases the thermal efficiency of the engine. Vehicles can use diesohol and diesel fuels interchangeably. The fire point of diesohol is higher than flash point and the magnitude of the difference depends upon the composition of the diesel fuel. Australian Government is currently in the process of developing fuel quality and operability standards for dieshol.

There are still several issues that need to be resolved before diesohol can be introduced commercially, some of the important issues are:

- Vapour lock-use of ethanol changes the vapour lock characteristics of the fuel.
- Material compatibility of pump seals, timing belts and some nitirle rubber seals used in the fuel injection systems of a vehicle is still a concern.
- Toxicity of the emulsifier.
- Dosage quantities of the emulsifier which may vary from base fuel to base fuel.
- Blend stability, especially at low temperature.
- Establishment of diesohol test standards.
- Stability under water addition.

3.2 Indian Initiative on Diesohol:

It is interesting that India was one of the earliest countries to recognize the merits of burning ethanol in diesel engines. The bi-fuel system developed by a German Professor H.A. Havemann & his colleagues at the Indian Institute of Science (IISc), Bangalore, in the early 50's is the earliest original published work in technical literature regarding alcohol diesel.

Government of India has sanctioned Rs. 4 crores for R&D studies on ethanol-diesel blends. MoP&NG is also working on to introduce 5% ethanol-diesel blend. For this purpose Indian Oil Corporation has selected some vehicle models to carry out trial tests on these vehicles. IOC (R&D) has also recommended SIAM members to carry out the tests trials with 5% ethanol-diesel blend, which are to be supplied by IOC. However, as on date BIS specification does not permit blending of ethanol and diesel.

Sufficient field trials in Indian conditions need to be carried out and its benefits on emissions, material compatibility and drivability, etc. may be assessed before trying this fuel in India.

There are some field trials data on methanol-diesel blends. IIP has developed a retrofit kit for dual-fuel operation of diesel vehicles with alcohols. IIP used the fumigation concept for this purpose and successfully demonstrated this system on MSRTC and DTC diesel buses under actual commercial passenger service. The fleet consisted of 25 & 35 buses of Tata and Ashok Leyland respectively with a total cumulative operation of 42,00,000 kms. The methanol fuel consisted of 10% gasoline also; to impart flame luminosity from the safety angle as the methanol flame is almost invisible in sunlight. The findings of the study are tabulated in Table-3.

Table-3: Results of IIP fleet study on Methanol-Diesel Blend

Number of Buses	60 Numbers
Total Operation	42,00,000 kms
Diesel Replacement	15-20%
Fuel Consumption	Comparable
Energy Efficiency	Better
Smoke Reduction	25-40%
Drivability	Good-to-Better
Oil Consumption & Degradation	Comparable
Engine Wear	Lower-to-Comparable
Engine Deposits	Lower-to-Comparable
Sludge Deposits	Marginally Lower
Material Compatibility	Adequate. Rubber components partially hardened

From the above work it was concluded that 15-20% substitution of diesel by alcohols is possible by a simple retrofit fumigation system. Even though more field trials are required on new generation diesel engines to assess the technical feasibility of the fuel.