The lower heating value (also called energy value, or heat of combustion, or calorific value) is the energy (heat) produced by the combustion of the fuel/material without condensation of the flue gas.
|Fuel||Energy value [MJ/kg]||Energy value [kWh/kg]||Density [kg/litre]||Energy value [kWh/litre]|
|Charcoal (from wood)||31,5||8,75||0,4||3,50|
Wood’s energy value varies maximum 15% between different types of wood.
Converting the value to other units
To change the unit of measurement, just multiply the starting value by the unit factor FU = 1, to eliminate the unwanted part of the initial unit of measurement. If necessary, use the inverse (1 / FU), which is still 1.
1 = 1 kWh / 3.6 MJ
1 = 4.186 kJ / 1 kcal
Example 1: We want to convert 10 kWh into Joules
10 kWh * (3.6 MJ / 1 kWh). = 36 MJ.
Note how kWh in the numerator and kWh in the denominator cancel out.
Example 2: we want to convert 1 kWh into kcal
1 kWh * (3.6 MJ / 1 kWh) * (1000 kJ / 1 MJ) * (1 kcal / 4.186 kJ) = 1 * 3.6 * 1000 * 1 / 4.186 = 860 kcal.
Note how the unit factor also works well for changing the unit prefix (from MJ to kJ in this case).
We just found a new unit factor!
1 = 860 kcal / 1 kWh. (or 1 = 1 kWh / 860 kcal)