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Encyclopedia of Physical Science and Technology EN002G-61 May 19, 2001 19:33

152 Biomass, Bioengineering of

industry producing over 1.3 billion gallons of fuel ethanol 50–70% of the cost to produce a commodity product from
from corn in highly integrated, efficient plants has arisen petroleum is due to the petroleum cost itself. This is why
in the United States over the past twenty years, based at gasoline prices fluctuate so widely when crude oil prices
least partly on this subsidy. change.
It is not the purpose of this article to argue the pros and However, for the analogous biobased products indus-
consofsubsidizingthecornethanolindustry.However,we tries, the processing costs predominate, rather than raw
note that the existence of the corn ethanol industry pro- material costs. Therefore, a given percentage decrease in
vides a learning opportunity, a production platform and a processing costs has much more impact on the profitabil-
marketing springboard for both a chemicals from biomass ity and economic competitiveness of biobased industrial
industry as well as potentially huge industry based on con- products than does the same percentage decrease in raw
verting lignocellulosic materials to fuel ethanol. Such an materialcosts.Aswehaveseen,thecostpertonofbiomass
industry may eventually arise because lignocellulosic ma- raw materials is generally comparable to (e.g., corn grain)
terials are so inexpensive. or much less (e.g., corn stover) than the cost of petroleum.
While the cost and supply of grain severely limit its Because of this fact, there is real potential for biobased
potential to replace a large percentage of gasoline, the products to be cost competitive with petroleum products
situation for lignocellulose-derived ethanol is very dif- if we can learn how to reduce the costs of processing
ferent. Ample raw material supplies exist for lignocel- biomass to desired products. Before discussing specific
lulosic biomass. Further, because crop residues, grasses, technical areas that seem to offer the best opportunities
hays and wood residues cost much less than grain, fuel to reduce processing costs, a brief discussion of several
ethanol produced from these lignocellulosic materials can lessons from the petroleum and chemical industries will
potentially cost much less than grain ethanol. Assuming be useful.
biomass processing technology at a similar stage of matu-
rity as petroleum processing technology, it has been shown 2. Need for Complete Raw Material Utilization
that the cost of fuel ethanol from lignocellulosics should
be in the $0.50–$0.70 per gallon range, assuming biomass This point is so elementary that it is often overlooked. For
costing about $30.00 per ton delivered. Given low cost processes producing millions of pounds of biobased plas-
corn stover, another estimate projects ethanol costs at less tics or billions of gallons of fuel ethanol per year, essen-
than $0.50 per gallon for large scale plants, assuming best tially all of the raw material must be converted to saleable
laboratory yields. Clearly, there is real potential for low products, or at a minimum, not into wastes requiring ex-
cost fuel ethanol from cellulosic biomass if the process- pensive treatment and disposal. The petroleum refining
ing technology for conversion of biomass can be made industry has over time learned how to convert nearly all
both efficient and inexpensive. Processing technology is of the raw material into products. To compete effectively
the subject of the final section of this article. withthisentrenchedindustry,thebiobasedproductsindus-
try must become similarly efficient. Yield (conversion of
raw material to products) must be increased and improved.
IV. BIOPROCESSING OF BIOMASS A simple calculation will illustrate this point. If a raw
material costing $0.10 per pound is converted into prod-
A. Historical Lessons from the Chemical uct at a yield of 0.9 pounds of product per pound of raw
and Petroleum Processing Industries material, then the raw material cost is about $0.11 per
pound of product. If the same raw material is converted
1. Importance of Raw Material and
to product at a yield of only 0.5 pounds of product per
Processing Costs for Commodities
pound of raw material, the raw material cost is now $0.20
The chemical and petroleum industries grew together over per pound of product, nearly double the previous case.
the past century. These industries add value to raw ma- The petroleum industry is characterized by high yields;
terials by converting them to commodity and speciality the biobased products industry must strive to improve its
products. Processing technologies of various kinds are yields also.
used including chemical, thermal, physical and biologi- While low yields are a definite economic handicap, they
cal methods. By long experience, it has been found that may be an even more severe environmental (and by con-
the cost to produce commodities depends on two major sequence an economic) handicap. Whatever portion of the
factors: (1) the cost of the raw material and (2) the cost of raw material is not converted to saleable products becomes
the conversion process. The industries that produce chem- waste instead. These wastes must be treated before dis-
icals and fuels from petroleum are characterized by high posal, if disposal is possible. Liquid wastes from biobased
raw material costs relative to processing costs. Typically products will likely be characterized by relatively low