|Bioconversion of Organic Residues for Rural Communities (UNU, 1979)|
|Analysis of energy cost of integrated systems|
It is assumed that the criteria of social acceptability and pollution levels are analyzed separately. Energy analysis is a tool that offers three types of criteria:
a. A statement about actual energy use, direct and indirect. This is an accounting process. It is not difficult to do, but is often done inaccurately through failure to consider all factors. It can be used to interpret the impact of energy prices on costs.
b. A criterion of economic attractiveness. Here the task is to compare the GER of alternative methods, or to optimize around the least energy-intensive route per unit product, taking into account the GER of all inputs. However, this cannot be considered independent of the production intensity required. Table 3 and Figure 2 show how, even with skilful husbandry, intensification demands an energy requirement.
c. Evaluation of the net energy of biomass systems.
TABLE 3. Output of Selected Natural and Other Systems
|Energy ratio (output/fossil fuel input)||Net energy GJ/ha-yr|
|Kung Bushman, Kalahari Desert||infinite||.003|
|Shifting cuttivators, Congo||infinite||.52|
|Tsenbaga tribe, New Guinea - yams||infinite||.47|
|sweet potatoes infinite||.40|
|Dodo tribes, Uganda||5.0||.64|
|Subsistence agriculture, indict||14.8||9.6|
|Peasant farming, China||41.1||274.|