Page 27 - Biomass Gasification, Pyrolysis And Torrefaction Practical Design and Theory

6 Biomass Gasification, Pyrolysis, and Torrefaction

from vegetable oils such as rapeseed, is used in diesel (compression ignition)
engines.
Pyrolysis, fermentation, and mechanical extraction are three major means
of production of transport fuel from biomass. Of these, the most widely used
commercial method is fermentation, where sugar (sugarcane) or starch (corn)
produces ethanol. The yeast helps ferment sugar or starch into ethanol and
carbon dioxide. The production and refining of market grade ethanol, how-
ever, take a large amount of energy.
The mechanical means of extraction of vegetable oil from seeds like
rapeseed has been practiced for thousands of years. Presently, oils like canola
oil are refined with alcohol (trans-esterification) to produce methyl ester or
biodiesel.
Liquid fuel may also be produced through pyrolysis that involves rapid
heating of biomass in absence of air. The liquid product of pyrolysis is a pre-
cursor of bio-oil, which may be hydro-treated to produce “green diesel” or
“green gasoline.” At this time, ethanol and biodiesel dominate the world’s
biofuel market.
Gasification and anaerobic digestion can produce methane gas from bio-
mass. Methane gas can then be used directly in some spark-ignition engines
for transportation or converted into gasoline through methanol.

1.1.1.4 Environmental Industries
Activated charcoal produced from biomass has major application in the pol-
lution control industries. One of its extensive uses is in water filter.
Activated charcoal impregnated with suitable chemicals like zinc chloride is
very effective in removing mercury from flue gas from coal-fired power

FIGURE 1.2 A modern fluidized-bed boiler firing varieties of biomass plant in Canada.