Page 24 - Biomass Gasification, Pyrolysis And Torrefaction Practical Design and Theory

Chapter | 1 Introduction 3

large enough to provide about 26% of the world’s energy consumption,
which is equivalent to 6 billion tons of oil (IFP, 2007).
Biomass covers a wide spectrum: from tiny grass to massive trees, from
small insects to large animal wastes, and the products derived from these.
The principal types of harvested biomass are cellulosic (noncereal), starch,
and sugar (cereal).
All parts of a harvested crop like corn plant are considered biomass, but
its fruit (e.g., corn) is mainly starch while the rest of it is cellulosic.
The cereal (namely corn) can produce ethanol through fermentation, but the
cellulosic part of the corn plant requires a more involved process through
gasification or hydrolysis.
Table 1.1 lists the two types of harvested biomass in food and nonfood
categories, and indicates the potential conversion products from them. The
division is important because the production of transport fuel (ethanol) from
cereal, which is relatively easy and more established, is already being pur-
sued commercially on a large scale. The use of such food stock for energy
production, however, may not be sustainable as it diverts cereal from the tra-
ditional grain market to the energy market, with economic, social, and politi-
cal consequences. Efforts are thus being made to produce more ethanol from
nonfood resources like cellulosic materials so that the world’s food supply is
not strained by our quest for more energy.

1.1.1 Products of Biomass
Three types of primary fuels could be produced from biomass and are as
follows:
1. Liquid fuels (ethanol, biodiesel, methanol, vegetable oil, and pyrolysis
oil).
2. Gaseous fuels (biogas (CH 4 ,CO 2 ), producer gas (CO, H 2 ,CH 4 ,CO 2 ,H 2 ),
syngas (CO, H 2 ), substitute natural gas (CH 4 ).
3. Solid fuels (charcoal, torrefied biomass, biocoke, biochar).

TABLE 1.1 Sources of Biomass
Farm products Corn, sugarcane, sugar beet, wheat, etc. Produces ethanol
Rapeseed, soybean, palm sunflower Produces biodiesel
seed, Jatropha, etc.
Lignocellulosic Straw or cereal plants, husk, wood, Can produce ethanol,
materials scrap, slash, etc. bioliquid, and gas