This section summarizes the main factors to be used for bioenergy accounting, covering the various types of biofuel and considering the usual information available from primary data sources. It should be observed that the objective here is to obtain the energy worth of a mass or volume flow of some biofuel, so expressions (1) and (2), already presented above, must be used. However, taking into account the substantial variations in heating value and volume with moisture, it is advisable to express the values of biofuels in a dry and without ash basis, especially for accounting in energy balances. Table 7 presents the values for density (necessary when only the biofuel volume is given) and the heating value for typical moisture content.
Table 7: Basic parameters in accounting biofuels
Biofuel |
Primary Data |
Density |
LHV |
Moisture |
(Tons/cum) |
(MJ/kg) |
(%, dry basis) | ||
Direct Woodfuels |
Volume |
0.725 |
13.8 |
30 |
Charcoal |
Mass, volume |
30.8 |
5 | |
Indirect Woodfuels |
Mass, volume |
0.725 |
13.8 |
|
Recovered Woodfuels |
Mass, volume |
0.725 |
||
Wood-derived fuels |
Mass |
- |
||
Black liquor |
Mass |
|||
Methanol |
Mass |
20.9 |
0 | |
Non-forest Biofuels |
Mass |
- |
||
Ethanol |
Mass |
27.6 |
0 | |
Agricultural by-products |
Mass |
(see Table 6) | ||
Animal by-products |
Mass |
- |
13.6 |
|
Agro-industrial by-products |
Mass |
- |
||
Bagasse |
Mass |
- |
8.4 |
40 |
Municipal wastes |
Mass |
- |
19.7 |
- |
* for black liquor accounting as woodfuel, it can be assumed that from one ton of chemical cellulosic pulp production, an amount of liquor equal to 2.27 CUM of woodfuel, in energy terms, results (FAO, 1997).