GJ is international heat unit. The basic unit is J (joules). There are also extension unit including MJ and GJ.
1GJ=1000MJ, 1MJ=1000J
1 kcal = 1000 cal= 4186.8 J = 4.1868 KJ
1000 kcal = 4.1868 MJ, 10000 kcal = 41.868 MJ
1GJ=1000MJ=238845.9 kcal
1GJ is the equivalent of the calorific value of burning 55.55kg, 4300 kcal coal. (4300 kcal/kg coal also means 18MJ/kg )
The calorific value of several fuels:
Gas: 8600 kcal/m3, the equivalent of 36 MJ/m3
Liquefied petroleum gas: 11000 kcal/kg, the equivalent of 46 MJ/kg
Automotive diesel fuel: 12000 kcal/kg, the equivalent of 50.24 MJ/kg
Motor gasoline: 10800 kcal/kg, the equivalent of 45.22 MJ/kg
Wood pellets: 4300 kcal/kg, the equivalent of 18 MJ/kg
Straw pellets: 3700 kcal/kg, the equivalent of 15.49 MJ/kg
