Page 80 - Materials Chemistry, Second Edition

66 N. E. Korres

Table 3 Energy balance Energy requirement
based on average values of (MJ ton -1 of processed cane)
sugarcane to ethanol
Feedstock production
Agricultural operations 38
Transportation 43
Fertilizers 66
Lime, herbicides, etc. 19
Seeds 6
Equipment 29
Total for production 201
Process (ethanol production)
Electricity 0
Chemicals and lubricants 6
Building 12
Equipment 31
Total for process 49
Total energy input 250
Energy output
Ethanol 1,921
Bagasse 169
Total energy output 2,090
Net energy balance (out/in) 8.4
Based on Macedo et al. (2003)

collection. For this reason, as Singh et al. (2010) stated, the main goal for LCA of
lignocellulosic ethanol should be to evaluate the environmental impacts of the
system under examination and to quantify the ecological benefits from the
replacement of the conventional or reference system. It may also provide a tool for
policy makers and consumers to determine the optimum eco-friendly fuel. The FU,
depending on the goal of the study, must be expressed in terms of per unit output
(kWh or km) basis. For transport services, the FU ought to be expressed in ‘‘per
km distance travelled’’ and should not be expressed in ‘‘unit energy at fuel tank’’
due to variations of mechanical efficiency between different fuels and type of
engine (Gnansounou et al. 2009; Murphy and Power 2009).

5.2.2 System Boundaries

Inconsistency of system boundaries in LCA analysis of lignocellulosic ethanol
system through omission of the production of various inputs (e.g., thermochemical
or biochemical approach for degradation of cellulosic feedstock, fertilizer, pesti-
cides, and lime) along with bioethamol utilization (Luo et al. 2009; Gnansounou
et al. 2009) could cause a significant variation on the outcome of the analysis.
Table 4 represents clearly the similarities and differences between second (lig-
nocellulosic) bioethanol and bioethanol produced by grain crops.