This page gives technical information about the properties of solid fuels, for more general information and advice, look at the Solid Fuels page.
The composition and calorific values are based on information averaged from official EN Standards, and therefore represents to some extent the 'official' figures, though may not be completely representative of fuels commercially available. Wood Fuel in particular is highly variable.
Typical properties of solid fuels, as supplied
Anthracite
Hard Coke
Soft Coke
Hard Briquettes
Bituminous Coal
Lignite Briquettes
Peat Briquettes
Dry Wood Logs
Wood Pellets
300ºC Charcoal
Dry Baled Wheat Straw
Moisture %
4.5
8.5
8.5
12
7.5
18.5
11.5
18.5
5
2
15
Ash %
8.5
9.5
7
8
5
7.5
5
<1
0.15
3
4
Volatiles %
8.5
1.5
9
11
32.5
56.5
68
84
80
30
72
Hydrogen %
3.5
0.5
2
3
4.5
3.5
5.15
5.5
6
1
5
Carbon %
85
85
80
80
60
52.5
48.5
40
48
67
42
Sulfur %
1
1
1
1
1
2
0.2
0.01
0.01
<0.01
0.2
CO2 MAX
20.1
17
19.1
Siegert number
0.683
0.290
0.290
0.683
0.672
1
0.7
0.650
0.650
...
...
Heat content kJ/kg
31155
27050
28000
29500
26750
19500
18050
18500
18600
26700
16000
* Air required for combustion m³/kg
9.4
8.4
7
7
6.9
5.7
5.7
4.4
4.4
8.4
...
Bulk kg/m³
879
450
410
830
800
720
750
370
650
180
100
Potential Heat kW/kg
8.65
7.51
7.78
8.19
7.43
5.42
5.01
5.14
5.17
7.42
4.44
Bulk Potential kW/m³
7603
3380
3190
6798
5944
3902
3758
1902
3358
1335
444
Auto-ignition temperature ºC
...
400
...
...
300
...
...
270
...
...
...
*Air required for combustion assumes perfect (stoichiometric) mix of fuel and air, in practice this is rare, 2x air is not uncommon. Flue gas emitted (at perfect combustion) is almost exactly the same as the air required for combustion as, although part of the air is absorbed into the ash, this is almost exactly compensated for by the emission of volatiles.
PROPERTIES OF SOME BIOFUELS
After: Smith, K.R.; Kaltschmitt, M.; Thrän, D. 2001