Gross calorific value (GCV)

Gross calorific value (GCV), or higher heating value, is the total heat released when a fuel is fully burned and the water vapor in the combustion products is condensed back to liquid, recovering its latent heat. For marine residual fuel it runs about 40 to 43 MJ/kg, higher for distillates and far higher for LNG at around 50 to 55 MJ/kg. The net calorific value (NCV, lower heating value) subtracts the latent heat of that water, around 2.0 to 2.5 MJ/kg lower, and is the figure used for engine performance and specific fuel consumption because the exhaust leaves as vapor.