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

148 Biomass, Bioengineering of

for these many food and feed uses, as well as available crop various starch fractions in corn or to modify the sugar
and forestry residues. content of sugar cane. Plant breeding has also been used
to alter the composition and amounts of various biomass
fractions for industrial uses, for example, to increase the
C. Biotechnology and Biomass Production resin (rubber) content in the desert shrub called guayule.
1. Modify Biomass Composition Such plant breeding efforts are relatively uncontroversial.
for Easier Processing However, molecular biology/genetic engineering can
also be used to modify the existing genes of plants and to
Plantbreedingand/ormolecularbiologytechniquescanbe transfer entirely new genes into plants. For example, bac-
used to alter the composition of plant matter to make it eas- terial genes for a biodegradable plastic called have been
ier to process. As mentioned previously, given the already successfully expressed in plants, leading to the possibil-
relatively low cost of biomass, it is believed that reducing ity of “chemical plants in green plants.” This is an excit-
the costs of converting biomass to industrial products will ing and technically very promising possibility. It is also a
be the key factor in helping these products compete with
possibility with potentially great environmental benefits.
petroleum-derived products on a much larger scale. For
However, considerably more political and environmen-
example, reducing the lignin content of grasses and trees
tal controversy is likely to surround such efforts. Care-
should make it easier to convert the cellulose and hemi-
ful studies will be needed to demonstrate that expres-
cellulose portions to sugars that might then be fermented
sion of foreign genes in plants destined for industrial uses
or otherwise processed to a wide variety of chemicals and
will not lead to undesired environmental or human health
fuels. Changing the fatty acid composition of a particular
consequences.
plant oil could improve the ability to separate that oil in
a processing facility. The possibilities are quite literally
endless. The ability to modify the raw material composi- III. USES OF BIOMASS
tion and properties has no parallel in petroleum refining
(or hydrocarbon processing generally). This is a major A. Current Uses
potential advantage of biobased industrial products that
should be exploited whenever possible. 1. Food/Feed Consumption and World
Protein/Calorie Demand
Averagehumanrequirementsareapproximately2000kcal
2. Enhance Biomass Yields and Reduce Inputs
of food energy and about 50 g of protein daily, in addi-
As mentioned, both plant breeding and molecular biology tion to smaller amounts of essential oils and vitamins.
can be used to increase the yields of biomass grown for in- Assuming a total world population of 6 billion people,
dustrial uses and to reduce the inputs required to produce then the total human demand for protein is approximately
these industrial crops. High yields are important both to 120 million tons/year and the total calorie requirement is
15
reduce the costs of biobased products and to decrease the about 4.5 million billion kcal/year (4.5 × 10 kcal/year).
total amount of land required to supply these products. Total world grain (corn, wheat, rice, oats, sorghum, bar-
Reductions in crop production inputs such as fertilizers, ley, millet and mixed grains) production in 1998/1999 was
pesticides, herbicides and even water will also tend to approximately 2.1 billion tons.
reduce the costs of biomass production and could have If we assume that grain contains on average 70% car-
very large, positive environmental effects. For example, bohydrate (sugars) and 11% protein, then this grain crop
deep-rooted perennial grass species or trees destined for alone is sufficient to supply all of the calorie needs of
conversion to industrial products might be planted around the world’s people and about 50% more than the protein
fields devoted to row crops such as corn and at the edges needs of all of humankind. If we include the additional
of streams to intercept fertilizers and pesticides in ground- calories and protein available from sugar cane and sugar
water and to reduce soil erosion. Agricultural chemicals in beets, oilseeds and a myriad of other crops such as pota-
runoff are believed to contribute significantly to oxygen- toes and cassava, the total worldwide production of calo-
depleted, and therefore life-depleted, regions in the Gulf ries and proteins is several fold greater than the human
of Mexico and elsewhere. demand.
Obviously, much of the plant matter we grow is used
to feed animals, not people directly. However, if we so
3. New Products
chose, we could easily feed the world’s population with
Breeding has long been used to alter the composition of an adequate, plant-based, diet using a fraction of the land
plant materials, for example to increase the content of now devoted to agriculture and animal husbandry. (There