Abstract:
At present, the problems on balance of trade caused by the increasing cost of fuel are
influencing to economic situation and state of society. The substitution of diesel oil by CNG
in the concrete mixing vehicle was studied. In Thailand, there are two systems of the fuel
transformation from diesel oil to CNG, they are Diesel Dual Fuel (DDF) and Dedicate. In
the study, the economic sensitivity was tested. The test was performed by increasing and
decreasing of retail price of diesel oil by 5, 10, 15, 20 percents. Moreover, the retail price
of CNG were reduced by 35, 40, 45, 50, 55, 60, 65 percents from the retail price of
diesel oil. The interest rate was considered during 0.5 to 10. Finally, this study was using
the retail price of diesel oil (30.34 baht per liter) and CNG (8.50 baht per kilogram) in
October, 2008. The results of the study indicated that the fuel substitution is not attractive
because the Net Present Value (NPV) is positive when the maximum interest rate is 4%
that lower than Minimum Loan Rate (MLR). The properly retail price of diesel is between
29-351 baht per liter for DDF and between 16-223 baht per liter for Dedicate. When
consider the case based on retail price, the properly distance is between 30-378 km. per
day for DDF and between 21-320 km. per day for Dedicate. The problem on pollution and
financial balance caused by diesel oil may be reduced if CNG is used as a substitute,
because it emits less pollution and has sufficient supplies in Thailand.