Systems Informatics and Analysis - Engineering and Science of Biomass Feedstock Production and Provision - page 208

unit, such as a truck, can be an entity, while operations such as loading, unloading,
and transportation can be various activities performed on those entities.
IBSAL (Integrated Biomass Supply Analysis & Logistics) is a dynamic,
object-oriented modeling framework to simulate the collection, storage, and trans-
port operations for supplying agricultural biomass to a biorefi nery [ 9 ]. It is one of
the fi rst generic models developed to provide a holistic view of the BFPP system.
It uses a DES approach and has been developed using EXTEND, an object-oriented
high-level simulation language. Different modules representing processes/
operations such as swathing, baling, storing, and transportation are developed and
stored in the EXTEND library. Each module is represented using the mass balance
and performance equations and is associated with a list of attributes. To develop a
scenario, the user has to select the relevant boxes and connect them logically using
the EXTEND interface. The discrete events (operations) are represented in the time
domain, and the occurrence of an event adds to the cost and modifi es the unit (bio-
mass) properties. The model inputs comprise the parameters outside the scope of
the supply chain, such as weather conditions, biomass yield and properties, spatial
distribution of the supply locations, and equipment-performance parameters. The
data can be provided through a spreadsheet. The model has been used as the basis
for a number of analyses in the literature [ 9 , 73 , 74 ]. Sokhansanj et al. [ 74 ] have
compared a number of production scenarios for switchgrass and have reported sev-
eral cost and energy consumption values that are very useful.
Ravula et al. [ 75 ] used the DES approach to compare two different strategies to
schedule truck delivery at a biorefi nery of 1,200 Mg d −1 (50 Mg h −1 ) capacity. In
addition, they assumed a supply system consisting of several satellite storage loca-
tions (SSLs) being served by nine loaders for bale loading. The goal was to mini-
mize the total number of trucks required by scheduling the biomass pickup from
different SSLs in the collection region. Two different policies to schedule SSLs
were studied. The total cost was $14.68 and $16.14 dry Mg −1 for different policies,
and the number of trucks varied between 32 and 36 depending on the specifi c sce-
nario. The DES approach was again used by Ravula et al. [ 76 ] to model cotton
module transportation, arguing that several round bales can be put together to create
a transportation module similar to cotton. They developed two management policies
that increased the utilization of the transportation system from 77 to 100 %. They
also developed a knapsack model to obtain a lower bound for the transportation
system. Mukunda et al. [ 77 ] have also used DES to model corn-stover logistics from
on-farm storage to a biorefi nery in Indiana, USA.
The Biochains Economic Evaluation (Bee) model has been developed as part of
the European Union-funded project titled “Bioenergy Chains from Perennial Crops
in South Europe” to perform detailed economic assessment of the complete biofuel
value chain, including biomass conversion to energy. Three different modules,
focused on agricultural production, storage and transportation, and conversion,
are integrated. Multiple feedstocks and multiple energy conversion processes can be
studied. Three different scenarios of agricultural production, ranging from complete
ownership of farms by an investor to ownership by farmers, can be modeled.