Standard Fuel

an arbitrary unit used in calculations of organic fuels to compare efficiencies of different types of fuel and to make general evaluations. One kilogram of fuel with a heat of combustion of 7,000 Calories (kcal) per kg (29.3 megajoules per kg) is the unit of standard fuel used in the USSR. The ratio between the standard fuel and a natural fuel is given by the formula

where B_st is the weight of an equivalent amount of standard fuel (in kg), B_n is the weight of the natural fuel (in kg for liquid and solid fuels or in m³ for gaseous fuels), is the minimum heat of combustion of the given natural fuel (in kcal/kg or kcal/m³), and is the caloric equivalent. The values of E are 1.4 for petroleum, 0.93 for coke, 0.4 for peat, and 1.2 for natural gas.

The concept of a standard fuel is especially convenient for comparing the costs of different thermal power installations. For example, the amount of standard fuel consumed to produce a unit of electric power is often used in calculations in power engineering. This value, g, is expressed in grams of standard fuel required to produce 1 kilowatt-hour of electric energy and is related to the efficiency η of the power installation by the formula g = 860/7η. The concept of a standard fuel is also useful in computing the fuel balance or total energy balance of an industry, a country, or the world.

In some countries, different values for a standard fuel have been adopted. In France, for example, the standard fuel is taken to have either a minimum heat of combustion of 6,500 kcal/kg (27.3 megajoules per kg) or a maximum heat of combustion of 6,750 kcal/kg (28.3 megajoules per kg). In the USA and Great Britain, a unit equal to 10¹⁸ British thermal units (36 billion tons of standard fuel) is taken as the large unit of standard fuel.