C
6
H
12
O
6
→ 2CH
3
CH
2
OH + 2CO
2
The Promise of Cellulosic Ethanol
The “skeleton” of all plants—generally speaking, the “xylem” — is composed of cellulose, which
cannot be easily decomposed. Most of the solar energy “captured” by plants is stored in the
cellulose. In this process, some special enzymes are used to decompose the cellulose into simple
sugars called saccharides, and then the saccharides can be transformed into energy for human to
use. Cellulose is abundant in nature, the alcohol produced from it is clean, and both the energy
consumed and the greenhouse gas emitted during this producing process are minute. If we can
transform cellulose, which is naturally abundant but not edible, into alcohol, then it would become
feasible to produce a renewable, clean biofuel for industrial and consumer use.
The common raw materials used to produce alcohol from cellulose are stalk, bark, and fibrous
tissues from plants whose cellulose cannot be eaten by humans. The production of ethanol from
food sources such as maize is not an efficient method of ethanol production and could potentially
decrease amount of land available for food production and influence the cost of grain products.
More efficient methods have been developed for ethanol production using plants that can grow in
marginal areas, not only producing greater amounts of ethanol per area of land, but also allowing
C
6
H
12
O
6
→ 2CH
3
CH
2
OH + 2CO
2
The Promise of Cellulosic Ethanol
The “skeleton” of all plants—generally speaking, the “xylem” — is composed of cellulose, which
cannot be easily decomposed. Most of the solar energy “captured” by plants is stored in the
cellulose. In this process, some special enzymes are used to decompose the cellulose into simple
sugars called saccharides, and then the saccharides can be transformed into energy for human to
use. Cellulose is abundant in nature, the alcohol produced from it is clean, and both the energy
consumed and the greenhouse gas emitted during this producing process are minute. If we can
transform cellulose, which is naturally abundant but not edible, into alcohol, then it would become
feasible to produce a renewable, clean biofuel for industrial and consumer use.
The common raw materials used to produce alcohol from cellulose are stalk, bark, and fibrous
tissues from plants whose cellulose cannot be eaten by humans. The production of ethanol from
food sources such as maize is not an efficient method of ethanol production and could potentially
decrease amount of land available for food production and influence the cost of grain products.
More efficient methods have been developed for ethanol production using plants that can grow in
marginal areas, not only producing greater amounts of ethanol per area of land, but also allowing
3
arable land most suited for food crops to be reserved for food production. Most research currently
revolves around the use of grass species such as switch grass, elephant grass, buffalo grass, that
grow very quickly, contain high amounts of cellulose, can be grown in marginal areas that will not
negatively affect food production. As a matter of fact, research indicates that in the fermentation of
switch grass to produce ethanol, the yield of energy in ratio to the amount of energy exhausted to
produce the fuel is as high as 540%, while for corn the same ratio is as low as 24%.
Could ethanol replace batteries in consumer devices?
Demand for storable power is accelerating as more and more features being added to our
portable electronic devices. It is expected that next generation energy storage devices such as
fuel cells could provide longer lasting power than batteries. Fuel cells convert fuel to electricity,
and so far most international research into fuel cells that would use liquid fuels for consumer
electronics has been focused on methanol. Such fuel cells are called Direct Methanol Fuel Cells,
or DMFC. In the last 10 years, DMFCs have received a lot of attention by many companies and
research organizations globally, who are investigating the possibilities of creating a number of
applications with DMFC technology, most of which are as a new power source for consumer
electronics.
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