Environmental Engineering Reference
In-Depth Information
Table 2.
Methodology
Component Priority
1. Raw Materials
2. Conversion Process
3. Ethanol Distribution
To select the best components for an Oregon based
cellulosic ethanol supply chain, the following deci-
sion making framework is employed. For simplic-
ity, the three supply chain components are ranked
in order of overall importance. Supply chain
components are evaluated in order of importance,
and with knowledge of previous decisions. This
removes potential complexities in our framework
that might arise due to interdependencies between
supply chain components. Once the priority of
each supply chain component is established, the
individual options for each component are evalu-
ated based on a set of weighted criteria. Specific
criteria are chosen for each component and relative
weighting is achieved by distributing one hundred
points across each of the criteria.
Once the weight for each criterion is estab-
lished, all options are rated for each criterion on a
scale from 1 to 5. This scale is qualitative and each
value is defined for a specific criteria. This pro-
vides a simple formula for component selection.
For example given a supply chain component with
four criteria, the selection formula looks like this.
that it is largely dependent on which feedstock
is used. For this reason the raw materials used is
highest priority. This leads to the following pri-
oritization of supply chain components (Table 2).
Raw Material Selection
Oregon has an abundance of natural resources
and byproducts capable of sustaining an cellulosic
ethanol supply chain. Resources of interest are
principally agricultural residues, forestry thin-
ning, and urban greenwaste. In many cases these
cellulosic feedstocks have little or no commercial
value and may even have costs associated with
their disposal. Conversion of these feedstocks
to cellulosic ethanol creates value and offers
opportunities for economic growth (Graf and
Koehler, 2000).
In addition to these natural resources and
byproducts there is an opportunity to grow en-
ergy crops such as hybrid poplar. Energy crops
are “crops grown specifically for their fuel
value.”(Iowa State University Bioeconomy Insti-
tute, 2008). These crops can be grown to provide a
consistent and managed source of local cellulosic
feedstock for the cellulosic ethanol industry.
S = A×W
1
+ B×W
2
+ C×W
3
+ D×W
4
Where W
n
represents the criteria weight, and
A, B, C, D are the criteria values for a particular
option. The component option with the highest S
value is selected.
Component Priority
Selection Criteria
To prioritize the supply chain components, the
relative priority of each is considered. Ethanol
distribution, while significant, is probably the
least important of the components for Oregon,
because of an abundance of different options that
are available. The conversion process component
is arguably the most important, except for the fact
There are a number of criteria that ought to be
considered for selection of the raw materials
component of a cellulosic ethanol supply chain.
In particular the criteria of yield, availability,
feedrate, collection, and cost are most important.
