ABSTRACT
The Viswa Group has been providing two important proprietary benchmarks to the marine industry; EFN (Engine Friendliness Number) and TWI (True Worth Index). EFN represents the damage potential of the fuel in terms of erosion and corrosion. The higher the EFN number, the lower the damage potential of that fuel indicating that the fuel is engine-friendly. TWI is the true worth of the fuel which is a ratio of the actual usable power available at the shaft of the
engine to the thermal energy of the fuel when it burns in the engine cylinder. TWI encompasses the end-to-end benefit of the fuel. The Viswa Group has been providing these benchmarks for many years.
With the introduction of the newer fuels, Very Low Sulfur Fuel Oil (VLSFO) since January 2020, the need to revisit the TWI has come up. VLSFOs have wide variability in their characteristics such as the viscosity, which can range between 2.5cst to 700cst; the density, that can range from 830 to 1037 kg/m3, and the MCR that can range from 0.01% to 17%.
The diverse properties of VLSFOs are a result of the fact that VLSFOs are derived from either predominantly paraffinic or aromatic sources. The industry is currently not able to determine what a better fuel is in terms of its contribution to the overall thermal efficiency of the engine. Shipping companies continue to pay for the fuel strictly based on pricing and availability without evaluating the value added by a superior quality of fuel.
The difference in the true worth of the fuel is worth at least thousands of dollars for each voyage and is well worth paying a slightly higher price at the time of purchase. This paper aims to unravel and highlight the true worth of the fuel and how much it matters in terms of dollars saved for fuel users and fuel buyers.