HEATING VALUE

The 'heating value' or 'calorific value' of a substance, usually a fuel or food, is the amount of heat released during the combustion of a specified amount of it. The calorific value is a characteristic for each substance.
It is measured in units of energy per unit of the substance, usually mass, such as: kcal/kg, kJ/kg, J/mol, Btu/m³. Heating value is commonly determined by use of a bomb calorimeter.
The quantity known as higher heating value (or ''gross calorific value'' or ''gross energy'') is determined by bringing all the products of combustion back to the original pre-combustion temperature, and in particular condensing any vapour produced. The quantity known as lower heating value (or ''net calorific value'') is determined by subtracting the heat of vaporization of the water produced by combustion from the higher heating value.
Most applications which burn fuel produce water vapour which is not used, and thus wasting its heat content. In such applications, the lower heating value is the applicable measure. This is particularly relevant for natural gas, whose high hydrogen content produces much water. The gross calorific value is relevant for gas burnt in condensing boilers which condense the water vapour produced by combustion, recovering heat which would otherwise be wasted.

Contents

Higher heating values of some fuels

Higher heating values of natural gases from various sources

Fuel needed to run a 100W lightbulb for a year (876 kWh)

References

See also

Higher heating values of some fuels

Higher heating value
of some common fuelsNIST Chemistry WebBook

Fuel	MJ/kg	BTU/lb	kJ/mol
Hydrogen	141.8	61,100	286
Methane	55.5	23,900	783
Ethane	51.9	22,400	1570
Propane	50.35	21,700	2220
Butane	49.5	20,900	2875
Gasoline	47.3	20,400
Paraffin	46	19,900	16,300
Diesel	44.8	19,300
Coal	15–27	8000–14,000	200–350
Wood	15	6500	300
Peat	6–15	2500–6500

Higher heating value
of less common fuels

Fuel	MJ/kg	BTU/lb	kJ/mol
Methanol	22.7	9800	726
Ethanol	29.7	12,800	1300
Propanol	33.6	14,500	2020
Acetylene	49.9	21,500	1300
Benzene	41.8	18,000	3270
Ammonia	22.5	9690	382
Hydrazine	19.4	8370	622
Hexamine	30.0	12,900	4200
Carbon	32.8	14,100	393.5

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Higher heating values of natural gases from various sources

These data on higher heating values were obtained from the International Energy Agency: Key World Energy Statistics (2005), page 59

★ Russia: 38,231 kJ/m³

★ United States: 38,416 kJ/m³

★ Canada: 38,200 kJ/m³

★ Netherlands: 33,320 kJ/m³

★ United Kingdom: 39,710 kJ/m³

★ Indonesia: 40,600 kJ/m³

★ Algeria: 42,000 kJ/m³

★ Uzbekistan: 37,889 kJ/m³

★ Saudi Arabia: 38,000 kJ/m³

★ Norway: 39,877 kJ/m³

★ Bangladesh: 36,000 kJ/m³
The lower heating values of the above natural gases are about 90 percent of the higher heating values.

Fuel needed to run a 100W lightbulb for a year (876 kWh)

★ 400 kg (876 lb) of coal

★ 230 kg (508 lb) of oil

★ 170 kg (377 lb), 255 m³, of natural gas

★ .006 kg (.014 lb) of uranium

★ .0000075 kg (.000016 lb) of the Sun

References

See also

★ Heat of combustion

★ Fuel efficiency#Energy content of fuel

★ Energy value of coal

★ Food energy

★ Wobbe index: heat density

★ Energy density

★ Thermal efficiency