Work out fuel cost per kwh instantly with clear inputs, formula shown and shareable results.
Each litre of fuel contains its calorific value in megajoules, which divided by 3.6 gives kilowatt-hours of heat, and multiplied by conversion efficiency gives useful electrical kilowatt-hours. Fuel price divided by that figure gives the fuel cost per kilowatt-hour, to which maintenance must be added for a true comparison against grid tariffs.
Cost per kWh
kWh per litre = CV (MJ/L) / 3.6 x efficiency; cost per kWh = fuel price / kWh per litre + maintenance
Because efficiency is around 38% against 45-60% for a modern combined cycle plant, and fuel is bought at retail. Diesel generation typically costs three to five times grid tariff.
For a genuine comparison, yes — add depreciation and financing per kilowatt-hour at the expected annual run hours. For a standby set used rarely, capital dominates the cost per unit generated.