Environmental Engineering Reference
In-Depth Information
If they abandon their corn-based ethanol produc-
tion process at a future date, it would make sense
for Pacific Ethanol to change their cellulosic
ethanol supply chain to use only wheat straw as
a raw material input.
ethanol production this analysis showed forestry
thinnings to be a suitable feedstock. This again
is due to the volume of forestry thinnings avail-
able in the Northwest created by the hundreds of
thousands of acres of forestry lands.
Four basic process approaches were analyzed,
although each basic approach can take somewhat
different forms using specific process steps devel-
oped by different production companies. As shown
in the paper, both the dilute acid and concentrated
acid hydrolysis processes have been around for
many years and have been used for ethanol produc-
tion for several years as well. These production
processes have reached their current limitations
in both production yield and cost. On the opposite
end of the research and development spectrum
is the direct microbial conversion process. This
is the newest process that has yet to uncover its
full production potential as well as the production
cost reductions. Based on the criteria identified
in this paper, the optimal production method is
enzyme hydrolysis. This is due to the current pro-
duction development as well as the simplicity of
the process and the production yield. All of these
factors helped identify this production technique
as the best choice for an Oregon based cellulosic
ethanol company.
After the production of ethanol is completed,
it is critical to the success and profitability of the
company to transport the ethanol to the end cus-
tomers and market through an efficient distribution
mode. As environmental issues become increas-
ingly important, it is also important to choose a
transportation method that has minimal impact
on the environment as well as being low cost per
mile. Based on the analysis and criteria discussed
in this paper, the optimal distribution method is
by barge. This has very limited range, but because
of the minimal environmental impact as well as
low cost per mile, it is the ideal transportation
choice. In order to reach the entire market and
reach all potential customers, this will likely need
to be supplemented with rail transportation. This
CONCLUSION
As we have seen in this paper, there are several
factors influencing the drive towards alternative
fuels, and both biodiesel and ethanol fuels are
beginning to fill this need. Ethanol has many
benefits from reducing the U.S.'s dependency
on foreign oil to reducing greenhouse gases. It
is also a renewable fuel source that can be made
from several sources including corn and cellulosic
biomass. Ethanol is primarily manufactured from
corn in the Midwest due to the simplicity of the
process as well as the volume of corn production.
The sugar molecules are easily extracted from
corn and converted to ethanol.
In the Pacific Northwest, the agricultural di-
versity is significantly different from the Midwest,
and there are several other raw materials that are
suitable for cellulosic ethanol such as agricultural
residues, forestry thinnings, urban greenwastes, or
hybrid poplar. All of these feedstocks are available
as raw material for ethanol production, but through
the analysis in this paper it was determined that
wheat straw is the optimal feedstock. This is due
to the vast quantities of wheat produced in the
Northwest. After the wheat is harvested, the straw
is usually burned or composted. There is currently
no other major use or industry for wheat straw and
therefore it can be collected without competition at
a relatively low cost. The only major consideration
that must be accounted for is the seasonal produc-
tion of wheat. In order to meet the annual demand
of ethanol would require that the wheat straw be
stored for production during the off seasons. This
is an important issue that will have to dealt with in
order to successfully use wheat straw as the main
