Systems Informatics and Analysis - Engineering and Science of Biomass Feedstock Production and Provision - page 196

Fig. 8.3 Classifi cation of the SIA applications to biomass feedstock production and provision
with important decisions being considered within each class. The spatial scale increases as we
move in the outward direction
achievable yield, optimizing resources such as nutrient and water, and minimizing the
impact of disturbances such as pests and drought. The selection of the right crop and
cultivar for a particular region is also important because the local/regional attributes
such as soil type, rainfall, and temperature impact the achievable yield. Field experi-
ments to study these factors are time consuming, expensive, specifi c, and often non-
repeatable. Therefore, model-based approaches, especially crop growth models that
predict the harvestable yield, have been frequently implemented. These models are
not only important from an agronomy and crop management standpoint, but they also
provide valuable inputs to engineering, economic, and policy research. Consequently,
a substantial amount of effort has been given to developing such models.
Nair et al. [ 25 ] and Miguez et al. [ 26 ] provided an excellent review of the various
bioenergy crop models. Figure 8.4 illustrates various factors, essentially subsystems
as per the previous discussion, impacting growth modeling. While empirical models
have been proposed in the literature [ 27 , 28 ], mechanistic models have been more
popular due to their greater adaptability. Mechanistic models can further be generic,
where model parameters differ for different crop, or can be crop specifi c, where the
model structure itself changes for each crop. Among both classes, some models
simulate the growth of an individual plant, while others simulate crop growth on a
per unit area basis [ 26 ].
All models include three important steps to model biomass production:
• Light interception by crop: Most models use Beer's law or its variation, which
relies on crop-specifi c leaf area index (LAI) and the light extinction coeffi cient
to calculate the intercepted radiation.