Page 69 - Materials Chemistry, Second Edition

The Application of Life Cycle Assessment on Agricultural 55

Fig. 10 A Generic flow process in agriculture and related energy inputs (based on Matlock et al.
2008)

The types of input energy (IE) analyzed by LCA, according to Eq. (1), include

ð1Þ
IE ¼ E F þ E I þ E IR þ E ED þ E L
-1
E F energy in the fuel consumed by machinery (MJ ha ); E I indirect energy
consumed to produce applied inputs such as seeds, pesticides, fertilizers expressed
-1
in MJ ha ; E IR direct energy used, where necessary, in irrigation expressed in
-1
MJ ha ; E ED indirect embodied energy expended in machinery manufacture or
-1
farm buildings, depreciated over their useful life expressed in MJ ha ; E L indirect
-1
energy consumed in human labor expressed in MJ ha .
In this chapter, only the first three forms of energy will be discussed as the use
of indirect embodied energy and indirect energy consumed by human labor, in
most cases, excluded from the LCI in biofuels (Korres 2013). In several studies,
emissions associated with the production of machines, buildings, and roads are
excluded because the lack of relevant data (Cederberg and Mattsson 2000; Ced-
erberg and Stadig 2003; Casey and Holden 2005).
The energy associated within each task (e.g., seedbed preparation, sowing) can
be either documented from a review of contemporary literature as accurately as
possible to ensure that subsequent decisions based on arguments embodied in the
findings are valid (Sapsford and Jupp 2006; Korres 2013) or calculated. Direct
mechanical energy (i.e., energy from fuel consumption) for each task can be
calculated, for example, by multiplying the estimated fuel requirements (for tractor
or harvester) to complete a task (volume of fuel per unit area of production) by the
energy per unit volume of fuel (i.e., 37.6 MJ L -1 for diesel fuel) (Larson and
Fangmeier 1978; Griffith and Parsons 1983). Alternatively, an algorithm for the
calculation of the direct energy consumed during the field operations as suggested
by Korres et al. (2010) and it is expressed by Eq. (2) can be used.